2.2. Motor Drives (MD)
2.2.1. Introduction
Adjustable-speed motor drives have made tremendous technical strides during the past 30 years,
gaining wide usage and customer acceptance in several key markets including industrial
processes and automation. Motor drives have been readily accepted in many of these
applications because of the impressive system-level energy savings that are available by
introducing adjustable-speed capabilities in place of conventional constant-speed motors.
However, there are other major classes of adjustable-speed drives (ASD) applications such as
heating, ventilation, and air conditioning (HVAC) that offer attractive performance features and
energy savings opportunities but have achieved only limited success in the North American
marketplace. These markets are overwhelmingly driven by the drive purchase cost despite
convincing cases that can be prepared for demonstrating payback periods that are often 18
months or less. Problems with field failures in early generations of adjustable-speed HVAC
drives have contributed to the slow acceptance of ASD technology in these markets. Other costsensitive market applications such as automotive electrical accessories (i.e., pumps, blowers,
power steering) are also at risk of being significantly restricted because of the high cost of
today’s power electronics.
The overall objective of the Motor Drives (MD) subthrust is to explore technical approaches for
applying IPEM technology into future adjustable-speed drives in order to achieve significant
improvements in their cost, reliability, and performance. The Technology Development
subthrusts within CPES offer a rich source of new IPEM technology that can be extended,
adapted, and applied in the MD subthrust to adjustable-speed drives. An important objective of
the MD subthrust is to experimentally demonstrate the value of the IPEM concepts in laboratory
testbed equipment. Such testbed demonstrations provide a powerful vehicle for measuring the
progress of our IPEM developments in cooperation with our CPES industrial testbed partners,
providing a critical link that lies at the heart of the CPES technology transfer process.
Present effort in the MD subthrust is focused on three-phase motor drives in the 1 to 3 kW power
range during the present Generation 2 effort. An important reason for choosing this particular
power range has been to align the resulting IPEM electrical ratings with IPEMs required in the
Distributed Power Systems (DPS) subthrust. Work on smaller fractional-horsepower (hp) and
larger integral-hp drives is being purposely delayed to Generation 3 that is scheduled to begin in
Year 6 of CPES. Nevertheless, much of the technology that is being developed and tested as part
of the Generation 2 effort in the 1 to 3 hp range will be directly applicable later in both larger and
smaller drives.
The present MD subthrust includes four core projects that are directly funded by NSF: Motor
Drive (MD) Technology, Packaged Drive (PD) System Technology, the US-Czech Engineering
research project, and Connectivity Low-Cost Automotive Power Electronics. There are three
additional core projects in the Motor Drive subthrust that were funded by external sources and
are reported in this section under “MD Related Technologies and Applications”. The research in
these core projects can be separated into four major technology areas that each contribute to the
CPES strategic plan. These include:
Elimination of Electrolytic Capacitors – This effort seeks to improve the reliability of future
IPEM-based motor drives by eliminating the need for electrolytic capacitors that are known to be
52
major contributors to drive system failure rates. Three different circuit and control techniques
are being pursued to achieve this objective including a novel type of current-source inverter,
dual-bridge matrix converter topologies with reduced switch counts, and a six-switch bridge
converter designed to deliver smooth power to a dc voltage bus from a single-phase voltage
source.
Active Gate Drives – Future IPEM-based motor drives need new gate drives for MOS-gated
power devices that can provide enhanced performance features at reduced cost and improved
reliability. A wide variety of gate drive circuits are used today that fall short of meeting these
objectives for new IPEMs that are now in development. The purpose of this ongoing project is
to explore technical approaches for developing new active gate drive circuits that have sufficient
features and flexibility to make them useful for the majority of motor drive IPEM applications.
This work includes contributions in the areas of active dv/dt and di/dt control, isolated power
supplies, and improved switch protection that are all compatible with integrated circuit
implementation.
Integrated Motor-Converters – Work is also under way to investigate new approaches for
integrating electric machines and IPEM-based power converters into single combined packages.
This effort includes an initiative to advance the state-of-the-art by constructing the motor drive
using modular phase-drive units that combine the machine electromagnetics and the power
electronics into drive building blocks. The objective of this effort is to apply IPEM concepts to
develop integrated motor-converter packages that can achieve significant improvements in drive
cost, reliability, and performance, consistent with the CPES strategic plan.
Low-Cost Packaged Drives – There has also been core work during this reporting year targeting
low-cost packaged motor drives for Heating, Ventilating, and Air Conditioning (HVAC)
applications. This represents legacy effort from CPES Generation 1 research that seeks to reduce
the cost of low-power single-phase motor drives by reducing the number of required inverter
switches.
In addition to the CPES core effort summarized above, there are a considerable number of
associated research projects in the field of advanced power electronics and motor drives that are
contributing valuable technology in support of the core MD effort. Several of these projects
have been funded by the Wisconsin Electric Machines and Power Electronics Consortium
(WEMPEC) at UW-Madison using membership fees of sponsoring companies that have been
specifically allocated to support CPES research objectives. The remaining associated research
projects have been funded by other external sources.
The associated research projects address a wide variety of motor drive applications ranging from
wind power generators to automotive starter/alternators. Despite such differences, all of these
projects support the objectives of the CPES strategic plan in the areas of improved performance,
lower cost, and increased reliability. More details about each of these associated projects and
their relationships to the CPES strategic plan will be provided in the following subsections.
A. Barriers
Technical progress towards the achievement of CPES objectives for the improvement of future
motor drives is impeded by the following barriers:
53
•
Unacceptably high cost of power electronics, as noted above, represents one of the major
obstacles to the wide application of adjustable-speed motor drives in many promising
applications
•
High failure rates of key power electronics components, particularly under conditions of
frequent thermal cycling and high vibration, make it difficult to win customer acceptance of
motor drives in new potential high-volume applications such as automotive and HVAC
equipment.
•
Thermal limitations imposed by the silicon power semiconductors and key passive
components (e.g., electrolytic capacitors) complicate the plans for combining power
electronics and electric machines into the same physical package.
•
A cost-effective and robust planar interconnect technology for future motor drive IPEMs is
required as a cornerstone in the MD strategic plan.
•
Inexpensive current sensors with good performance capabilities are needed for incorporation
into motor drive IPEMs as key components for achieving the desired machine control
capabilities.
•
Increasing concerns about the utility impact of converter-generated harmonics are producing
growing support for international power quality standards that threaten to add cost to new
adjustable-speed motor drives.
•
Scaling the IPEM technology to higher power levels for larger motor drives presents
technical challenges that must be overcome to realize the MD strategic plan.
B. Strategic Plan
A chart of the strategic decision points for the MD subthrust is provided in Fig. 2.2.1.
GEN II
Year 4
Flexible Active Gate
Drive Development
MD
Double-Sided IPEM
Cooling Development IPEMS
Advanced Current
SensorDevelopment
GEN III
Year 6
Year 5
MD-IPEM
Development
CSI
Gen II Testbed
Design and
Construction
Power Flex Interconnect
Technology Development IP
Yes
Merged IGBT and MPS
APSD
Diode Development
Integrated Motor/Converter
Development
Gen II MD
Testbed
Evaluation
Positive?
No
MD
Proceed
With
Gen III
Adjust Gen III Plans
Bus Capacitor Elimination/
MD
Minimization Technology Development
APSD, CSI, IP
IPEMS
DPS
Provide Technology Input
Receive ApplicationReq’ts
Assist with MD-IPEM Design
Receive ApplicationReq’ts
Share Application Req’ts
And Testbed Data
Fig. 2.2.1. MD Strategic Decision Point Flowchart.
54
2.2.2. Motor Drive Technologies
2.2.2.1.
Motor Drive Technology
A. Project Team
Faculty: Thomas M. Jahns (UW), Thomas A. Lipo (UW)
Graduate Students: Velimir Nedic (UW), Lixiang Wei (UW), Yong-sug Suh (UW), Shi-hong
Park (UW), Rick White (UW)
Undergraduate Student: Nicholas Lemberg
Industry Partners: Ken Phillips (Rockwell), John Hansen (York), Harold Schnetzka (York),
Alberto Guerra (IR), Christian Conrath (Schneider), Jean-Luc Thomas (Alstom)
B. Project Goals
The goal of the Motor Drive Technology project is to develop and apply IPEM technology to
new motor drive systems in order to achieve major improvements in motor drive cost, reliability,
and performance, consistent with the CPES strategic plan. Motor drives in the range of 1 to 3 kW
are the particular focus of this effort during Generation 2. Specific project objectives include:
•
Minimization/elimination of inverter electrolytic capacitors
•
Development of flexible active gate drives for use in future motor drive IPEMs
•
Exploration of new concepts for integrating motors and their power converters into the same
physical structure
C. Support of the Strategic Plan
Activities in this project are aligned very closely with the current CPES strategic plan. For
example, one of the major initiatives appearing in the Generation 2 strategic plan for the MD
subthrust is the elimination of electrolytic capacitors from motor drive power converters.
Surveys of both motor drive manufacturers and users have confirmed that the dc link electrolytic
capacitors are one of the major sources of long-term failures in general-purpose motor drive
products. As a result, the decision to pursue technical approaches that eliminate electrolytic
capacitors from future motor drives has been well received by the CPES industry stakeholders
with interests in the MD subthrust.
Another important initiative in the MD subthrust strategic plan is the development of new gate
drives that can provide enhanced performance features at reduced cost and improved reliability.
Despite the near-universal nature of the key gate drive functions, there has never been much
success in establishing standard gate drive circuits because of the wide variety of gate drive
specifications and circuit topologies defined by motor drive engineers. The purpose of this
ongoing project is to explore technical approaches for developing new active gate drive circuits
that have sufficient features and flexibility to make them useful for the majority of motor drive
IPEM applications.
A third major initiative that appears in the MD subthrust strategic plan is the physical integration
of electric machines and their power converters into single combined packages. Although
motor-controller integration is not a new concept, early product offerings based on this approach
55
have not been widely embraced by the marketplace due to a combination of technical and
customer perception issues. Investigations are focused on the compatibility of IPEM concepts
with integrated motor-converter packages as a means for achieving significant improvements in
drive cost, reliability, and performance.
D. Relevant Work outside CPES
Research in the MD subthrust is being carried out against a backdrop of relevant development
activities that are being carried out in various other locations around the world. A sampling of
these related research projects include the following:
•
Capacitor minimization has previously been studied by Alakula [1] and demonstrates that the
capacitor value can be reduced to roughly 50 mf. This work assumes that the voltages
coming from the utility are perfectly balanced.
•
Prior work at UW-Madison [2] has shown that by proper modification of the PWM
algorithm, a smooth dc link voltage can be achieved in spite of voltage unbalance. However
only quasi-steady state was investigated. Overcoming this problem is a key to successful
reduction of the dc link capacitor.
•
Zmood and Holmes [3] have investigated a variety of PWM algorithms for current-source
converters that are adaptations of modulation schemes originally designed for voltage-source
converters.
•
Blaabjerg et al [4] have reported recent progress in the development of voltage-source matrix
inverters that represent one of the candidate approaches for eliminating electrolytic
capacitors used in conventional motor drive inverters.
•
Alternative active gate drive techniques for controlling the di/dt and dv/dt of IGBTs in hardswitched inverters that lack key features needed for compatibility with future IPEMs have
been reported by authors including Belverde [5] and Igarashi [6].
Additional references are included in Section J of this report.
E. Methodology
Key methodologies being pursued in each of the three major project segments are summarized as
follows:
•
Three potential solutions to the problem of eliminating electrolytic capacitors from motor
drive power converters have been identified. Each of the methods has undergone extensive
analysis and simulation phases. Subsequently, each of the three potential solutions has been
implemented in concept demonstration hardware for laboratory testing that is now under
way.
•
The development of the active gate drive technology began with a review of the technical
literature, including specifications for the latest generation of commercial gate drive
integrated circuits from manufacturers such as International Rectifier (IR). Ongoing
discussions with CPES sponsors including Rockwell Automation and IR are a continual
source of assistance in directing this work. Efforts are also being made to coordinate this
work with technology being developed in the other CPES subthrusts including APSD, IP,
and IPEMS. The development effort consists of a combination of closed-form analysis and
56
simulation using PSPICE. This analytical work has been followed by experimental concept
demonstration using printed-circuit board (PCB) implementations of the new gate drive
circuitry.
•
Initial work on the integrated motor-converter project has consisted of a review of existing
motor drive products that represent the state-of-the-art in integrated drives. For example,
submersible water pumps made by Grundfos in Denmark were investigated in some detail to
understand how the power electronics and machine are integrated into the same cylindrical
steel shell. Experience gained from the CPES Automotive Connectivity project that focused
on development of an electric water pump design is being applied to this project.
Discussions with CPES sponsors such as Rockwell Automation are also proving helpful.
Initial analytical efforts are being focused on developing a 3-D solid-body model of the
proposed new motor drive concept as a prelude to 3-D finite element analysis that will be
used to evaluate the machine performance characteristics.
F. Accomplishments
Major accomplishments of the Motor Drive Technology project during the first three CPES
reporting year included the following key developments:
•
Developed new inverter topologies for single-phase induction motors that reduce the switch
count to as few as two, providing the basis for fractional-horsepower HVAC motor drives
with reduced cost and higher reliability.
•
Designed, built, and tested a first-generation a MD-IPEM that demonstrated state-of-the-art
power components and power module-packaging techniques.
•
Established the basic feasibility of double-sided cooling of future IPEMs using miniature
heat pipes to remove heat from the upper IPEM surface made possible by the use of planar
interconnect techniques.
Significant accomplishments contributed by the research activities in this project during this
reporting year are summarized as follows:
•
A new type of dual-bridge ac/ac converter has been invented that eliminates the dc link
electrolytic capacitor and uses only 9 transistor switches.
•
A new type of current source drive, (dc current link) has been invented that eliminates the
electrolytic capacitor and uses only 3 transistor switches.
•
A new control method for a dc link converter with a reduced dc link capacitor has been
developed which ensures that the dc link voltage can remain smooth despite unbalanced
input voltages or sudden transient changes in these voltages.
•
Experimentally demonstrated new techniques for flexibly controlling the dv/dt and di/dt of
motor drive inverter switches, making it possible to electronically reduce the EMI and
control the switching losses in hard-switched inverters.
•
Invention and experimental demonstration of a new isolated power supply circuit topology
that makes it possible to provide continuous gate drive power to the upper phase-leg inverter
switches at all times without high-frequency magnetics. This type of power supply is a
critical element in the flexible active gate drive that is under development.
57
•
Invention of a new concept for an integrated motor-converter that uses powdered iron to form
individual motor-pole units that are physically integrated with companion inverter phase-leg
units, providing the basis for a truly modular motor/converter drive construction.
G. Deliverables
Project deliverables for this year include:
•
Concept demonstration hardware and test results for the three electrolytic capacitor
elimination approaches that have been investigated as part of this project
•
Concept demonstration hardware and test results for the active gate drive circuitry used to
flexibly control the dv/dt and di/dt of the motor drive inverter switches.
•
Concept demonstration hardware and test results for the new self-boost isolated power supply
circuit developed to provide more robust power to future IPEM gate drives
•
Finite-element analysis results for the new ac machine designed using powdered iron pole
pieces as part of the integrated motor/converter investigation
•
Technical papers summarizing progress to date on each of the MD Technology projects
H. Member Company Benefits
The activities in this project have all been defined to contribute to the objectives of improved
power electronics cost, reliability, and performance as directly as possible. Work accomplished
in this project during the past year has succeeded in demonstrating several promising concepts
that collectively exhibit notable progress towards achieving the ambitious CPES improvement
goals. Efforts are continuing to strengthen our communications with CPES industrial sponsors to
inform them of our technical efforts, to seek their constructive feedback, and to help them
evaluate potential applications of these new concepts in their own products
I. Research Plans
Research efforts in the Motor Drive subthrust during the coming year will continue to focus on
the application of IPEM technology to adjustable-speed motor drives in order to achieve
significant improvements in drive cost, reliability, and performance. Elimination of the
electrolytic capacitors and minimization of energy storage components will be a continuing focus
of the MD research plan, encompassing both voltage-source and current-source converter
topologies. Efforts will focus on determining which of the alternative approaches identified to
date is the best candidate for the 1 to 3 hp HVAC motor drive that is the target for the Generation
2 MD development efforts. This selected configuration will then be constructed in prototype
form for testing on the MD testbed.
Work will also continue on the development of improved techniques for providing active gate
control of future IPEMs intended for motor drive applications. Progress made during this past
year in the areas of dv/dt and di/dt control, isolated power supplies, level shifting, and protection
will be consolidated into a single unified gate drive design that can be implemented as a surfacemount circuit and tested during Year 5. This design work will be coordinated with the MDIPEM development effort that is being carried out under the IPEMS thrust.
The new concept for motor-converter integration using modular pole-drive units that was defined
during this past year will be investigated in more detail during the coming year. Following
58
successful completion of the analysis, this effort will focus on the design, construction, and
testing of the individual motor pole-drive units. Preliminary discussions are already under way
with one of the major manufacturers of powdered iron material to investigate opportunities for
cooperation in the construction of the shaped motor poles. The necessary power electronics will
then be constructed with the appropriate form factor to experimentally verify the key drive
modularity concepts.
J. References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
M. Alakula and J.E. Persson, “Vector controlled AC/AC converters with a minimum of energy storage”,
Fifth International Conference on Power Electronics and Variable-Speed Drives, 1994.
A. Stankovic and T.A. Lipo, “A Generalized Control Method for Input-Output Harmonic Elimination for the
PWM Boost Rectifier Under Simultaneous Unbalanced Input Voltages and Input Impedances”, IEEE Power
Electronics Specialists Conference, Vancouver, June 17-21, 2001.
D. N. Zmood, and D. G. Holmes, “A generalized approach to the modulation of current source inverters”,
IEEE PESC Conference Record, 1998, pp. 739-745.
C. Klumpner, I. Boldea, P. Nielsen, F. Blaabjerg, “New Steps Towards a Low-Cost Power Electronic
Building Block for Matrix Converters”, in Rec. of 2000 IEEE Ind. Appl. Society (IAS) Ann. Mtg., Rome,
Oct. 2000, pp. 1964-1971.
G. Belverde, et al, “Active Voltage Sharing of Series Connected Strings of IGBT Devices in Bridge
Applications,” in Proc. of 1998 IEEE IAS Meeting, pp. 817-824.
S. Igarashi, et al, “An Active Control Gate Drive Circuit for IGBTs to Realize Low-noise and Snubberless
System,” in Proc. of IEEE ISPSD 1997, pp. 69-72.
W. Tang, F. C. Lee, R. B. Ridley and I. Cohen, “Charge Control: Modeling, Analysis and Design”, IEEE
Transactions on Power Electronics, vol. 8, no. 4, pp. 396-403, October 1993.
C. Klumpner, F. Blaabjerg and et al, "A new modulation method for matrix converters", in Proc. of 36th
IEEE Ind. Appl. Society Ann. Mtg. (IAS’2001), vol.3, pp. 2143-2150, Chicago, IL, USA, 2001.
C. Huber, and D. Borojevic, "Space vector modulated three-phase to three-phase matrix converter with input
power factor correction", IEEE Trans. on Ind. Appl., vol. 31, No. 6, 1995, pp. 1234-1246.
Lixiang Wei and T.A. Lipo, "A novel matrix converter with simple commutation", in Proc of IEEE Industry
Applications society conference. (IAS’2001), vol.3, pp. 1749-1754, Chicago, IL, USA, 2001.
Ana V. Stankovic, T. A. Lipo, "A Novel Control Method for Input Output Harmonic Elimination of the
PWM Boost Type Rectifier Under Unbalanced Operating Conditions", in Conf. Rec. APEC 2000, Vol. 1, pp.
413-419.
H-S Song, K. Nam, "Dual Current Control Scheme for PWM Converter Under Unbalanced Input Voltage
Conditions", IEEE Trans. on Industrial Electronics, Vol. 46, No. 5, Oct 1999, pp. 953-959.
P. Rioual, H. Pouliquen, J-P Louis, "Regulation of a PWM Rectifier in the Unbalanced Network State Using
a Generalized Model", IEEE Trans on Power Elec., Vol. 11, No. 3, May 1996, pp. 495-502.
C.B. Jacobina, M.B.R. Correa, T.M. Oliveira, A.M.N. Lima, E.R.C da Silva, "Vector Modeling and Control
of Unbalanced Electrical Systems", in Conf. Rec. IAS Ann. Mtg. 1999, Vol. 2, pp. 1011-1017.
G. F. W. Khoo, D. R. Carter, and R. A. McMahon, “Analysis of a Charge Pump Power Supply with a
Floating Voltage Reference”, IEEE Transactions on Circuits and Systems, vol. 47, no. 10, Oct. 2000.
Ray L. Lin and Fred C. Lee, “Single-Power-Supply-Based Transformerless IGBT/MOSFET Gate Driver
with 100% High-Side Turn-on Duty Cycle Operation Performance Using Auxiliary Bootstrapped Charge
Pumper”, 1997 PESC Conference Record, Vol.: 2, June 1997, pp. 1205-1209.
N. R. Zargari and G. Joos, “A Current-Controlled Current Source Type Unity Power Factor PWM Rectifier”,
in Conference Record IEEE Industry Applications Society Annual Meeting, pp. 793-799, 1993.
H. A. Toliyat, N. Sultana, D. S. Shet and J. C. Moreira, “Brushless Permanent Magnet (BPM) Motor Drive
System Using Load-Commutated Inverter”, IEEE Transactions on Power Electronics, vol. 14, no. 5, pp. 831837, September 1999.
59
[19]
[20]
K. Wang, D. Borojevic, and F. C. Lee, “Charge control of three-phase buck PWM rectifier”, IEEE APEC
Conference Record, 2000, pp. 824-831.
J. C. Bendien and J. Geuenich, “On the Behavior of a Current Fed Synchronous Machine Drive Without DCLink Inductance”, IEEE Transactions on Power Electronics, vol. 5, no. 2, pp. 2465-251, April 1990.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-1]
[MD-2]
[MD-3]
[MD-4]
[MD-5]
2.2.2.2.
V. Nedic, N. Lemberg, and T.A. Lipo, “Low-cost Current Source Drive System”, in Proc. 2002 CPES
Seminar, April 2002.
Y-S Suh, P.G. Albano, V. Tijeras, T.A. Lipo, “A Control Method in d-q Synchronous Frame for PWM
Boost Rectifier under Generalized Unbalanced Operating Conditions”, in Proc. 2002 CPES Seminar,
April 2002.
L. Wei, T.A. Lipo, and H. Chan, “Matrix Converter Topologies with Reduced Number of Switches”, in
Proc. 2002 CPES Seminar, April 2002.
S-H Park and T.M. Jahns, “A Self-Boost Charge Pump Topology for Gate Drive High-Side Power
Supplies”, in Proc. 2002 CPES Seminar, April 2002.
S-H Park and T.M. Jahns, “Flexible dv/dt and di/dt Control Method for Insulated Gate Power
Switches”, in Rec. of IEEE Industry Appl. Soc. Annual Meeting, Chicago, Oct. 2001, pp. 1038-45.
US-Czech Eng. Res. on Circuit Design and Control of VSDs
A. Project Team
Faculty: T.A. Lipo, ECE, UW
Visiting Scholar: Miroslav Chomat, Academy of Sciences of the Czech Republic Institute of
Electrical Engineering
B. Project Goals
Develop and implement in hardware a single-phase induction motor drive that uses only two
transistor switches.
C. Support of the Strategic Plan
The integrated power electronics module (IPEM) that is being developed will almost surely
begin its life at low power levels. The single-phase induction motor drive used for furnace fans
is an ideal place to start with applications. We are developing the background technology to
allow rapid deployment in a working power electronic circuit.
D. Relevant Work outside CPES
Various types of inverters for use with single-phase motors have recently been published. The
two-transistor solution that is being developed at WEMPEC uses the fewest number of switches
and is thus potentially the lowest cost solution, an extremely important issue in low power motor
drives.
E. Methodology
Work in the past year has built on previous efforts in which the motor was operated at only two
discrete speeds. The work over this past year has extended the speed range of the system to
operate over a continuous speed from 0.5 to 1 per unit (rated) speed.
60
F. Accomplishments
Major accomplishments of this project include:
•
A working single-phase motor drive has been implemented in hardware and demonstrated.
•
A U.S. Patent has been filed and will be shortly issued.
G. Deliverables
Deliverables of the project are the hardware version of the single-phase motor drive, which was
successfully completed.
H. Member Company (Sponsor) Benefits
Member companies, particularly those in the HVAC industry, have an opportunity for a product
based on this development.
I. Research Plans
Work on this project has been completed, awaiting the development of the first IPEM.
J. References
[1]
[2]
M. Chomat and T.A. Lipo, “Adjustable-Speed Drive with Single-Phase Induction Machine for HVAC
Applications”, IEEE Power Electronics Specialists Conference CD ROM, Vancouver, June 17-21, 2001.
M. Chomat and T.A. Lipo, “Adjustable Speed Single-Phase IM Drive with Reduced Number of Switches”, in
Conf. Rec. IEEE IAS Annual Meeting, Chicago, Oct. 2001, pp. 1800-1806.
2.2.2.3.
Packaged Drive System Technology - Design and Implementation of a
Fuzzy Controller for Thermally Comfortable HVAC Application
A. Project Team
Faculty: A. Homaifar (leader) ECE, NC&AT; F. Fatehi, ECT, NC&AT; H. Singh, ECE,
NC&AT; N. Patel, ECE, NC&AT and T. Lipo, ECE, UW
Graduate Students: I. Baqai, ECE, NC&AT; C. BouSaba, ECE, NC&AT
Industrial Partners: H. Schnetzka, York
B. Project Goals
The main goal of this study was to demonstrate that fuzzy control strategy could reduce energy
consumption for an HVAC Adjustable Speed Drive (ASD) system while maintaining suitable
thermally comfortable conditions. Our simulation proved that using a Variable Air Volume
greatly decreases the amount of energy while taking into consideration the subjectivity of human
sensation. This project also investigated and analyzed the energy savings using an ASD on an
indoor air fan environment. Using the test chamber, we compared constant versus variable speed
operation. A comparison of the energy usage over a given time period, comfort level, humidity
as well as the temperature fluctuations within the space revealed the benefits of a variable speed
system.
61
C. Support of the Strategic Plan
Development of low-cost single-phase technology for fractional HVAC is an opportunity to
deploy the developments from the motor drive IPEM development. We developed expert
systems to increase the intelligence level of IPEM-based drive and improve energy savings in
comfort level applications.
D. Relevant Work outside of CPES
In the US, commercial buildings use approximately one third of total energy consumption [1].
The desire to save energy is rapidly growing due to environmental factors and economical costs
[2]. The shift from Constant Air Volume (CAV) to Variable Air Volume (VAV) in buildings’
Comfort Systems is one way of saving energy while maintaining the same comfort level. In a
Constant Air Volume system, the air is heated or cooled regardless of the actual heating or
cooling loads needed to satisfy the temperature and humidity requirements of the space, and the
energy consumption by the fan system is constant. The inefficiency of CAV systems can be
virtually eliminated by converting the system to deliver only the volume of air needed for
meeting the actual heating or cooling loads. The fan energy consumption significantly decreases
using a VAV system.
E. Methodology
The plan during the third year of this project was to search and develop a “state-of-the-art”
benchmark adjustable-speed drive that represented the best technology available for a selected
application. The HVAC chamber was set up to test Variable and Constant speed operation in the
thermally controlled space. The experiment was done with three different cases (VAV with no
load, CAV with no load, CAV and VAV with external load conditions). The application chosen
is a 0.75 HP fan drive that is used in most of the residential HVAC&R systems. The complete
testbed was created and tested at NCA&T for its performance and efficiency using a fan load.
This formed the basis for comparison of future advanced drive concepts, which will utilize the
IPEM concept.
F. Accomplishments
A complete testbed has been designed, implemented, and used to experimentally compare
variable and constant air volume for HVAC application in a real-word environment. Using a
Variable Air Volume system instead of the Constant Air Volume system saved a considerable
amount of energy while providing better thermally comfortable conditions. A computer
simulation for the months of May, June, July and August (using the ambient temperatures of
Greensboro, NC, as a test case) and a real-world experiment for the month of May in Greensboro
were done with both CCV and VAV systems. A computer simulation showed energy savings of
84.4%, 73.8%, 68.3% and 71.9% for the month of May, June, July and August respectively as
shown in the following figure.
The simulation results were validated through experimental data, by installing the ASD at NC
A&T SU laboratory. A real-world experiment showed energy saving of 84.2% in the month of
May. In addition, saving energy implies better environmental conditions and lower energy cost.
Compressors consume almost ten times the energy consumed by air handling units. If the speed
of the compressors is changed by using an ASD to satisfy the load requirement, it could result in
significant energy savings in an HVAC&R system. It is therefore recommended that this
research be pursued in future.
62
G. Deliverables
Deliverables of the project include the testbed experimental hardware and a technical report
summarizing the results of this work.
H. Member Company (Sponsor) Benefits
Member companies in the HVAC industry can take advantage of this work to demonstrate the
achievable energy savings from using adjustable-speed motor drives in HVAC systems.
I. Research Plans
Work on this project has been completed.
J. References
[1]
[2]
T. E. Mull, HVAC Principles and Applications Manual, 1st ed., McGraw-Hill: New York, 1997.
F. C. McQuiston, J. D. Parker, J. D. Spitler, Heating Ventilation, and Air conditioning Analysis and Design,
5th ed, John Wiley & Sons, Inc: New York, 2000.
2.2.3. Connectivity
2.2.3.1.
Low-Cost Automotive Power Electronics
A. Project Team
Faculty: Thomas M. Jahns (UW), T. Paul Chow (RPI), Ronald J. Gutmann (RPI), Eugene J.
Rymaszewski (RPI), Guo-Quan Lu (VT), T. Keim (MIT), D. Perreault (MIT)
Graduate Students: Nathan Harris (UW), Ying Xiao (RPI), H. N. Shah (RPI), R. Natarajan
(RPI), John Bai (VT), Won-Kyoung Lee (UW)
B. Project Goals
There currently is a major engineering initiative under way in the international automotive
community to electrify many of the existing accessory systems that are presently hydraulic,
pneumatic, or purely mechanical. Technology developed in this project is targeted at the
growing demand for “drive-by-wire” electrical accessory equipment for the full spectrum of
automotive accessory applications including steering, braking, pumps, fans, engine valve control,
and the starter-generator assembly [1].
Success of the drive-by-wire automotive initiative depends critically on the availability of power
electronics that can meet the stringent product requirements. Specifically, these requirements
include: 1) low cost, 2) high reliability, and 3) environmental ruggedness, including the ability
to tolerate high temperatures (e.g., 120 deg.C under-hood ambient conditions). The purpose of
this project has been to pursue significant advances in power electronics technology to
simultaneously accomplish all three of these critical objectives.
The objective of the power electronics packaging effort is to apply well-established flex-circuit
technology to automotive power electronics applications in order to achieve cost savings and
improved robustness compared to conventional wire-bond packages. At the systems packaging
level, the goal is to apply integrated packaging concepts to achieve cost and reliability
63
improvements by combining the power electronics, accessory motor, and load into the same
structure.
This project has been carried out with the active participation of researchers at MIT who are
conducting research in the area of automotive electrical accessory systems with the support of a
50+ member international consortium of major automakers and automotive electrical suppliers.
C. Support of the Strategic Plan
Cost is a major barrier to the growth of "drive-by-wire" technology in future automobiles and
other road vehicles, despite the performance advantages that such advanced accessories have
demonstrated in prototype testing. It is also crucial that these new electrical accessories
demonstrate the necessary long-term reliability for operation in the challenging under-hood
environment. This project is specifically targeted at the development of new power electronics
technology that is capable of meeting these demanding cost and reliability targets. Both of these
objectives directly support the CPES strategic plan.
D. Relevant Work outside CPES
The development of advanced automotive electrical accessories is being actively pursued by
automobile manufacturers and their suppliers around the world. The technical feasibility and
performance advantages of many of these new features including electric power steering, brakeby-wire, electric air-conditioning, and electric suspension have been clearly demonstrated, but
the cost of the power electronics is discouraging their commercial introduction into new vehicles.
Significant effort has been focused on the development of higher-power (>20 kW) power
electronics for electric propulsion drives, but the development of low-cost power electronics for
electrical accessory applications with power requirements of 5 kW or less has not received the
same level of attention or investment. The power levels of IPEM technology now being
developed in CPES are very compatible with these automotive accessory requirements, creating
an exciting opportunity for application of IPEM concepts in the automotive arena.
E. Methodology
This two-year Connectivity project has been split into two major phases. The first of these
phases, Technology Development and Preliminary Design, included tradeoff studies between
alternative power electronics packaging and motor technologies in order to identify the best
candidates to meet the cost and environmental constraints for an electric water pump application.
These tradeoff studies dominated the technical efforts during the first year of the project. The
preferred technologies identified by the tradeoff studies were then applied to develop a
preliminary design of the complete water pump system including the motor, its power converter,
and their integration with the pump into a combined physical package.
The second phase of this project, Concept Demonstration, has consisted of critical experiments
to demonstrate key concepts associated with the system design. In particular, these experiments
have focused on demonstrating the viability of using flex-circuit technology for constructing the
automotive IPEMs [1]-[12]. Although the complete system is not being built as part of this
project, these experiments have been crucial to verifying the technical feasibility of the preferred
technical approach in order to establish credibility for the resulting water pump system design.
64
F. Accomplishments
During the first year of this project, tradeoff studies were conducted to evaluate alternative
power electronics packaging technologies for low-cost automotive applications.
This
investigation led to the choice of the flip-chip-on-flex planar interconnect technology as the most
promising IPEM packaging approach for accomplishing the automotive cost and reliability
objectives. Simultaneously, evaluation of alternative electric machine types for the electric water
pump application led to the selection of the interior permanent magnet (PM) motor as the best
choice for the integrated motor-converter design approach.
Work during the second year of the project has focused on developing a preliminary design of
the electric water pump drive and carrying out critical experiments to test the performance
characteristics of the flip-chip-on-flex packaging technology. The preliminary water pump drive
design that resulted from this effort incorporates an integrated packaging approach by mounting
the machine and the power converter adjacent to each other in the same cylindrical shell (see Fig.
2.2.2). The water pump is mounted at the other end of the motor and pumps the coolant through
an outer water jacket surrounding both the motor and converter for effective cooling before the
coolant is circulated to the rest of the engine.
Pump Outlet
60mm
Module Cooling
Frame - 76mm
Machine Cooling
Frame - 115mm
Pump Inlet
60mm
Filter Cooling
Block
X/Y Caps
Power
Electronics
Module
Electronics
Cooling Block
CM
Inductor
Heat
Sink
IPM Machine
Pump
117mm
Bus
Caps
Fig. 2.2.2. Cross-section of integrated electric water pump design
The IPEM packaging approach was tested by designing and building inverter phase-leg modules
rated at 42 V and 16 A that were based on specifications for the electric water pump application.
IPEM modules were fabricated at both RPI and VT in order to test two alternative approaches for
applying the power-flex technology [6]. Each module consists of two MOSFETs in a totem-pole
configuration along with the necessary gate drive circuitry (Fig. 2.2.3). In addition, printedcircuit-board (PCB) versions of this same phase-leg IPEM were constructed, providing a basis
for performance comparisons with the power-flex units.
Testing of these automotive IPEM modules has been carried out at UW, RPI, and VT using
established double-pulse and continuous duty-cycle switching techniques in order to characterize
the new IPEM modules (see Fig. 2.2.4). This testing has confirmed that the power-flex
packaging approach is capable of providing very desirable IPEM performance characteristics
including low parasitic inductance and low packaging resistance. Separate work on the powerflex technology carried out at VT has also confirmed the promising reliability characteristics
embodied in the power-flex structure using the flexible polyimide substrate to provide thermal
stress relief.
65
(a)
(b)
Fig. 2.2.3. Automotive power-flex IPEMs: a) RPI unit; b) VT unit
18
16
40
14
12
30
10
20
8
10
6
4
0
Load Current (A)
Low Side MOSFET Drain to
Source Voltagre (V)
50
2
-10
0
0
10 20
30 40 50 60 70
Time (us)
80 90
Fig. 2.2.4. Voltage and load current waveforms of a power-flex module during testing at 42V, 15 A.
G. Deliverables
Deliverables include the first year annual report and final report (in preparation) summarizing the
results of this development work, along with technical papers describing key aspects of this
technology development. In addition, the power-flex IPEM modules constructed at VT and RPI
also constitute deliverables of this project.
H. Member Company (Sponsor) Benefits
This work has benefited CPES member companies and other interested companies in the
automotive industry by demonstrating the opportunities provided by the power-flex IPEM
technology for meeting the demanding cost and reliability requirements of the automotive
environment.. In addition, the preliminary design of the electric water pump drive that was
developed has revealed the importance of treating the motor, power converter, and load as one
integrated system in order to achieve the best possible design of future automotive accessory
equipment. A presentation made to the members of the MIT automotive consortium in January
2002 summarizing the key results of this work was well received.
66
I. Research Plans
This research project was formally concluded at the end of 2002, and the final report is being
prepared for submission. Work on the power-flex packaging technology is continuing in the
MD-IPEM core research project that is part of the IPEMS thrust.
J. References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
Ken Gilleo, The Handbook of Flexible Circuits, Van Nostrand Reinhold, New York, 1992.
R. Fisher, R. Fillion, J. Burgess and W. Hennessy, “ High frequency, low cost, power packaging using thin
film overlay technology,” Proc. of the IEEE Applied Power Electronics Conference and Exposition, pp.1217, 1995.
V. Temple, “SPCO’s thinpak package – an ideal building block for power modules and power hybrids,” Int’l
Symposium on Microelectronics, pp. 692 – 696, 1999.
M. Paklastoaul and T. Hauck, “ Flip-chip die attach development for multi-chip mechatronics power
packages,” the IEEE/CPMT Int’l Electronics Manufacturing Technology Symposium, pp. 433-439, 1999
Y. Xiao, R. Natarajan, P. Jain, J. Barrett, E. J. Rymaszewski, R. J. Gutmann, T. P. Chow, “Flip-Chip Flex
Circuit Packaging for Power Electronics”, Proc. of International Symposium on Power Semiconductor
Devices & ICs, Osaka, pp. 55-58, 2001.
Y. Xiao, R. Natarajan, E. J. Rymaszewski, T. P. Chow, R. J. Gutmann, “Flip-chip Flex-Circuit Packaging
Implemented for 42V/16A Integrated Power Electronics Module Applications”, in Proc. of 2002 IEEE
Applied Power Electronics Conferences(APEC), Dallas, March 2002.
Y. Xiao, R. Natarajan, P. Jain, J. Barrett, E. J. Rymaszewski, R. J. Gutmann, T. P. Chow, “Flip-Chip Flex
Circuit Packaging for Power Electronics”, Proc. of Center for Power Electronics Systems (CPES) annual
seminar, pp. 444 448, 2001
Y. Xiao, R. Natarajan, P. Jain, J. Barrett, E. J. Rymaszewski, R. J. Gutmann, T. P. Chow, “Test Vehicle
Design for Flex Packaging”, Proc. of Center for Power Electronics Systems (CPES) annual seminar, pp. 555
- 557, 2000.
R. Natarajan, “Flex-Circuit Packaging for Power Electronics”, Masters Thesis, RPI, Troy, New York, 2001
Xingsheng Liu; Xiukuan Jing; Guo-Quan Lu, “Chip-scale packaging of power devices and its application in
integrated power electronics modules,” IEEE Transactions on Advanced Packaging, vol. 24, no. 2 , May
2001, pp. 206 –215.
Xingsheng Liu; Haque, S.; Guo-Quan Lu, “Three-dimensional flip-chip on flex packaging for power
electronics applications”, IEEE Trans. on Advanced Packaging, vol. 24, no. 1, Feb 2001, pp. 1-9.
Haque, S.; Guo-Quan Lu, “Metallization for direct solder interconnection of power devices”, in Proc. of
2000 Electronic Components & Technology Conference, 2000, pp. 1475–1482.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-6]
Y. Xiao, R. Natarajan, E. J. Rymaszewski, T. P. Chow, R. J. Gutmann, “Flip-chip Flex-Circuit
Packaging Implemented for 42V/16A Integrated Power Electronics Module Applications”, in Proc. of
2002 IEEE Applied Power Electronics Conferences(APEC), Dallas, March 2002.
67
2.2.4. WEMPEC in Support of CPES
2.2.4.1.
Current Shunt Sensors Suitable for IPEM Integration
A. Project Team
Faculty: Robert L. Lorenz (UW)
Graduate Student: Yue Xu (UW)
Sponsor: WEMPEC
B. Project Goals
The IPEM, which is the major deliverable in the project, will incorporate various sensing means,
the major one being current sensing. Current sensors can take on several forms, optical,
magnetic etc. However, the simplest type is a simple shunt. Significant problems remain
concerning temperature drift, frequency dependence, and isolation, which are issues in this
research. The objective of this project is development of current shunts for use in both the
distributed power system and motor drive test bed.
C. Support of the Strategic Plan
Low cost current sensing is a critical issue for both test bed projects. This work concentrates on
methods which are normally categorized as “shunt current” measurements which involve a direct
reading of the voltage drop across a small (parasitic) resistor placed in series with the circuit in
which a current measurement is desired.
D. Relevant Work outside CPES
Current shunts are a well-known current measurement technique and multiple resistor materials
are suitable for IPEM integration. However, they are usually connected in series with the ground
lead to reduce the common mode issues that occur if the signal is not isolated and is floating on
the PWM waveforms. A detailed summary of the effort on isolation in the face of high common
mode voltages is a subject of reprint [1].
E. Methodology
This work has had both analytical and experimental elements. The analytical component has
used simulation tools such as SABER to compute time domain solutions. The experimental
component has used an actual setup measuring the current using different materials.
F. Accomplishments
Work has proceeded on examining different types of materials for use in the current shunt.
Also, substantial work has focused on several isolation techniques which may prove suitable for
IPEM integration..
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing our efforts to
characterize and predict the behavior of various types of current shunt measuring techniques.
The final deliverable will be a comparison of methods, which should propose the most desirable
approach for implementation in the CPES testbeds.
68
H. Member Company (Sponsor) Benefits
Low cost current sensing is also very desirable to member companies. Spin-off that could occur
would have a considerable impact on many member company products.
I. Research Plans
This project is planned to continue over next year and to evolve as facts concerning shunt
material properties, isolation methods, etc. are uncovered.
J. References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
Vishay Intertechnology, “Vishay Thin Film technology overview”, http://www.vishay.com/brands/thin_film
Vishay Intertechnology, “7 Technical Reasons to Specify Bulk Metal Foil Resistors”,
http://www.vishay.com/docs/63000/7reasdis.pdf
IRC Wirewound and Film Technologies Davison, http://www.irctt.com
ISOTEK Corporation: “Advancements in Current-Sensing Resistors Lead to Broader Applications”,
http://www.isotekcorp.com
Paul Pickering, Burr-Brown Corp., “A system Designer’s Guide to Isolation Devices”,
http://www.sensorsmag.com/articles
ISO100 isolation amplifier datasheet, Burr–Brown Corporation
D. Plant (Hewlett-Packard Co.) “Isolation Amplifiers Compete with Hall-Effect Devices as a Current
Feedback Solution”, Power Conversion Intelligent Motion (PCIM), March, 1996.
“Design and application of transformer-coupled hybrid isolation amplifier model 3656,” Burr–Brown
Corporation, Tucson, AZ, Application Bull., 1994.
International Rectifier, “New Monolithic High Voltage Current Sensing IC Simplifies AC Drive Integration”,
http://www.irf.com/product-info/motor/isense.pdf
F. Costa, etc., “The Current Sensors in Power Electronics, a Review”, EPE Journal, Vol. 11, February 2001.
Liang, Y.C.; Samudra, G.S.; Hor, V.S.S., “Design of integrated current sensor for lateral IGBT power
devices”, Electron Devices, IEEE Transactions on, Volume: 45, Issue: 7, July 1998, Page(s): 1614 –1616
Ferreira, J.A.; Cronje, W.A.; Relihan, W.A., “Integration of high frequency current shunts in power
electronic circuits”, Power Electronics, IEEE Transactions on, Volume: 10, Issue: 1, Jan. 1995, pages: 32 -37
Castelli, F., “The flat strap sandwich shunt”, Instrumentation and Measurement, IEEE Transactions on,
Volume: 48, Issue: 5, Oct. 1999, pages: 894 –898
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-7]
2.2.4.2.
Yue Xu, R.D. Lorenz, "Design of Integrated Shunt Current Sensors for IPEMS", in Proc. of CPES
Annual Seminar 2002.
On-Line Parameter Estimation
A. Project Team
Faculty: Robert D. Lorenz (UW)
Graduate Student: Hyunbae Kim (UW)
Sponsor: WEMPEC
B. Project Goals
One of the two test beds will deal with AC motor drives. Precise speed and torque control of an
AC motor depends heavily on either expensive feedback sensors or upon accurate knowledge of
the parameters of the motor (resistance, inductance, etc.). Since low cost is imperative, sensing
69
of motor parameters as they change as a result of temperature rise, saturation, etc. becomes a key
concern for good control. The objective of this project is development of means to estimate
parameters of key electrical parameters with an on-line methodology.
C. Support of the Strategic Plan
Robust operation is a critical issue for both test bed projects. Success in this project will
contribute to reducing the cost and improving the reliability of future IPEM-based motor drives.
These objectives directly support the CPES strategic plan.
D. Relevant Work outside CPES
Substantial work has been done on real time, adaptive parameter estimation [1] - [6]. However,
most methods are complex, costly to implement, and lack robustness. No industry-accepted
standardized methods have yet been developed..
E. Methodology
This work has had both analytical and experimental elements. The analytical component has
used simulation tools such as Matlab to compute time domain simulations. The experimental
component has used an actual drive to evaluate performance and robustness.
F. Accomplishments
Excellent success has been achieved, including demonstration of energy efficiency
improvements with simple, on-line, parameter estimation and tuning of the drive.
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing our methods
and the performance improvement which has been demonstrated. The final deliverable will be a
comparison of methods, which should propose the most desirable approach for implementation
in the CPES testbed.
H. Member Company (Sponsor) Benefits
Low cost, robust, parameter estimation is very desirable to member companies. Spin-off that
could occur would have a considerable impact on many member company products and could
result in significant energy savings.
I. Research Plans
This project is planned to continue over next year and to evolve.
J. References
[1]
[2]
[3]
S. Morimoto, T. Ueno, M. Sanada, A. Yamagiwa, “Effects and Compensation of Magnetic Saturation in
Permanent Magnet Synchronous Motor Drives”, Rec. of IEEE Ind. Appl. Society Ann. Conf. pp. 59 –64,
1993.
M. Vélez-Reyes, G.C. Verghese, “Subset Selection in Identification, and Application to Speed and Parameter
Estimation for Induction Machines”, Proc. of the 4th IEEE Conference on Control Applications, Albany
NY, Sep. 28-29, 1995.
H. Kubota, K. Matsuse, T. Nakano, “DSP-based Speed Adaptive Flux Observer of Induction Motor”, IEEE
Trans. on Ind. Appl., Vol. 29, No. 2, pp. 344-348, Mar./Apr. 1993.
70
[4]
[5]
[6]
H. Sugimoto, S. Tamai, “Secondary Resistance Identification of an Induction-Motor Applied Model
Reference Adaptive System and Its Characteristics”, IEEE Trans. on Ind. Appl., Vol. IA-23, No. 2, , pp.
296-303, Mar./Apr. 1987.
R.D. Lorenz, D.B. Lawson, "A Simplified Approach to Continuous On-Line Tuning of Field Oriented
Induction Machine Drives", IEEE Trans. on Ind. Appl., Vol 26, No. 3, pp. 420-425, May/Jun., 1990.
Alonge F., D’lppolito F., Ferranta, G., and Raimondi, F. M., ”Parameter Identification of Induction Motor
Model using Genetic Algorithms”, Proc. of IEEE Control Theory and Applications, vol. 145, pp. 587-593,
Nov., 1998.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-8]
[MD-9]
[MD-10]
2.2.4.3.
Hyunbae Kim, R.D. Lorenz, "Using On-Line Parameter Estimation to Improve Efficiency of IPM
Machine Drives", in Proc. of CPES Annual Seminar, 2002.
P.Y. Chung, M. Dölen, H. Kim, R.D. Lorenz, "A Continuous-Time Observer to Estimate Electrical
Parameters of Induction Machines", in Rec. of IEEE Ind. Appl. Society Ann. Conf, pp. 259-265,
Sep./Oct. 2001.
P.Y. Chung, M. Dölen, H. Kim, R.D. Lorenz, "Parameter Identification for Induction Machine Drives
by Continuous Genetic Algorithms”, Intelligent Engineering System Design through Artif. Neural
Networks, C.H. Dagli et al. (Eds.), vol. 10, pp. 341-346, ASME Press, NY, 2000.
Active Thermal Control of IPEMs
A. Project Team
Faculty: Robert L. Lorenz (UW)
Graduate Student: Dusty Murdock (UW)
Undergraduate Student: Mark Panzer
Sponsor: WEMPEC
B. Project Goals
This research is focused on actively controlling power module temperatures to limit failures
caused by thermal stresses. To control power module device and junction temperature, some
form of temperature sensing is required. This is one focus of the project. To actively control the
power module load cycle temperature a region-based controller is necessary. This is the second
major goal of this work. Since load cycle temperature is known to be a major source of failurecausing stress, the overall goal is to limit such stress and thus substantially reduce failures.
C. Support of the Strategic Plan
Methods to directly improve reliability are critical issues for both test bed projects. This project
concentrates on one such method, active control of the failure-causing stresses. It is expected to
have far reaching in potential impact in meeting the CPES strategic goals.
D. Relevant Work outside CPES
Substantial work on temperature sensing has been done but only very limited work in actual realtime sensing and thermal control of the load cycle temperature has been carried out [1]-[14].
The temperature sensing work has largely been for off-line measurements and has not dealt with
71
the common mode noise problem inherent in device temperature sensing.
methodologies have not yet used region-based control.
The control
E. Methodology
This work has had both analytical and experimental elements. The analytical component has
used simulation tools such as SABER and Matlab to compute time domain solutions. The
experimental component has used an actual setup measuring device temperature and actively
controlling temperature.
F. Accomplishments
The initial sensing and real-time control results have been very promising. The sensing
technologies have been demonstrated to be adequate for current research demonstrations.
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing the key
temperature measurement techniques and the logical structure of the region-based controller.
The final deliverable will be an evaluation of the methods in CPES testbeds.
H. Member Company (Sponsor) Benefits
Robust operation with thermal control is very desirable for member companies. Spin-off that
could occur would have a considerable impact on many member company products.
I. Research Plans
This project is planned to continue over next year and to evolve as facts concerning shunt
material properties, isolation methods, etc. are uncovered.
J. References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
P. Jacob, M. Held, P. Scacco, and W. Wu, “Reliability testing and analysis of IGBT power semiconductor
modules,” IEE Colloquium on IGBT Propulsion Drives, 1995, pp. 4/1-4/5.
E.R. Brown and M.C. Shaw, “Thermomechatronics of power electronic packages,” in Proc. IEEE ITHERM,
Las Vegas, May 2000, pp. 270-278.
D.C. Katsis and J.D. van Wyk, “Void induced thermal impedance in power semiconductor modules: some
transient temperature effects,” in Proc. Center for Power Electronics Systems Power Electronics Seminar,
Blacksburg, VA, April 23-25, 2001.
A. Morozumi, K. Yamada, T. Miyasaka, and Y. Seki, “Reliability of power cycling for IGBT power
semiconductor modules,” in Proc. IEEE IAS, 2001, vol. 3, pp. 1912-1918.
M. Held, P. Jacob, G. Nicoletti, P. Scacco, M.-H. Poech, “Fast power cycling test for IGBT modules in
traction application,” in Proc. IEEE Power Electronics and Drive Systems, 1997, vol. 1, pp. 425-430.
J. Onuki, M. Koizumi, and M. Suwa, “Reliability of thick Al wire bonds in IGBT modules for traction motor
drives,” IEEE Trans. Advanced Packaging, Feb. 2000, vol. 23, issue 1, pp. 108-112.
V.A. Sankaran, C. Chen, C.S. Avant, and X. Xu, “Power cycling reliability of IGBT power modules,” in
Proc. IEEE IAS, 1997, pp. 1222-1227.
Powerex Data Sheet, “General Considerations for IGBT and Intelligent Power Modules” [Online].
Available: www.pwrx.com.
M. Ciappa and W. Fichtner, “Lifetime prediction of IGBT modules for traction applications,” in Proc. of
IEEE International Reliability Physics Symposium, 2000, pp. 210-216.
72
[10]
[11]
[12]
[13]
[14]
T. Kajiwara, A. Yamaguchi, Y. Hoshi, K. Sakurai, J. Gallagher, “New intelligent power multi-chips modules
with junction temperature detecting function,” in Proc. of IEEE IAS, 1998, pp. 1085-1090.
V. Blasko, R. Lukaszewski, and R. Sladky, “On-line thermal model and thermal management strategy of a
three phase voltage source inverter,” in Proc. IEEE IAS, 1999, pp. 1423-1431.
Semikron Data Sheet, “SKiiP Semikron Integrated Intelligent Power,” [Online]. Available:
www.semikron.com/products/skiip.html.
Eupec Data Sheet, “Technical Information – BSM50GP120,” [Online]. Available: www.eupec.com.
Y.S. Kim, S.K. Sul, “On-line estimation of IGBT junction temperature using on-state voltage drop,” in Proc.
of IEEE-IAS, 1998, pp. 853-859.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-11]
2.2.4.4.
D, Murdock, R.D. Lorenz, "Failure Minimizing, Active Control of IPEMs", in Proc. of CPES Annual
Seminar,2002.
Low Cost PWM Inverter
A. Project Team
Faculty: Thomas A. Lipo (UW)
Graduate Students: Brian Welchko (UW), Mauricio Correa (Visiting)
Sponsor: WEMPEC
B. Project Goals
Cost is a major concern in the fabrication of the CPES motor drive test bed. One possible means
to reduce cost is to “piggy-back” our technology onto another which has provided the needed
volume to reduce cost. One such possibility is the automotive industry which uses millions of
MOSFET transistor switches in its products resulting in these devices costing only 30-35 cents.
Unfortunately, the automotive industry requires only 40 V transistors at the present time.
However, this industry is preparing to introduce a 42 V battery standard which would make the
corresponding switch rating rise to about 100 V. This rating is still too small for a conventional
motor drive application running from 115 V AC. However, the so-called “three level” inverter
concept can be applied. This project is intended to demonstrate the feasibility of using
“automotive” type MOSFET devices for the motor drive test bed which would result in a major
cost saving.
C. Support of the Strategic Plan
A low-cost inverter is a critical issue for the motor drive test bed projects and directly supports
the CPES strategic plan in this regard. This feasibility study provides a possible alternative to
other approaches toward the goal of a reliable, low-cost drive solution.
D. Relevant Work outside CPES
No work on this concept outside CPES is known. However, the basic three-level inverter
structure that lies at the heart of this configuration has been widely-studied [1] and applied to
high-power applications in order to extend the attainable bus voltage beyond the voltage limits of
individual power switches.
73
E. Methodology
This work has been performed totally experimentally.
F. Accomplishments
The experimental setup has been designed and constructed and is successfully working in our
laboratory [2].
G. Deliverables
Deliverables of the project will be a detailed report summarizing the design of the inverter, its
layout and experimental waveforms.
H. Member Company (Sponsor) Benefits
Low-cost inverter solutions are also very desirable to member companies. Spin-offs that could
occur would have a considerable impact on many member company products.
I. Research Plans
This project is planned to continue over the next year and to emphasize a cost minimized printed
circuit board layout with minimum cost components.
J. References
[1]
[2]
J.S. Lai and F.Z. Peng, “Multilevel Converters - A New Breed of Power Converters,” Proceedings of the
IEEE-IAS’95 Annual Meeting, pp. 2348-2356, 1995.
B.A. Welchko, M.B. Correa, T.A. Lipo, “A Cost Effective Three-Level MOSFET Inverter for Low Power
Drives”, in Proc. of CPES Seminar, April 2002.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-12]
2.2.4.5.
B.A. Welchko, M.B. Correa, T.A. Lipo, “A Cost Effective Three-Level MOSFET Inverter for Low
Power Drives”, in Proc. of CPES Seminar, April 2002.
Soft-Switched Resonant Link Inverter
A. Project Team
Faculty: Prof. T.A. Lipo (UW)
Graduate Student: Jianming Yao (UW)
Sponsor: WEMPEC
B. Project Goals
This project concerns the design and evaluation of a new resonant link inverter concept in which
the solid state devices (transistors) are switched with both zero turn-on losses and turn-off losses.
Zero turn-on losses are achieved by choosing instants only when the voltage across the switched
device is zero while zero turn-off losses are achieved by selecting instants of time only when the
current through the switched device is zero. The objective of this project is to design and
develop a soft-switched inverter/converter solution using this concept for a low-cost ac motor
drive.
74
C. Support of the Strategic Plan
Soft-switched inverters form an important family of dc/ac converters. This family of converters
must be assessed for its feasibility in the ac motor drive testbed. In this feasibility assessment,
cost as well as performance must be addressed.
D. Relevant Work outside CPES
Many soft-switched inverters have been reported over the years, most of these emanating from
CPES researchers. Thus far, no truly zero switching loss circuit has appeared in the literature
either inside or outside of CPES.
E. Methodology
The methodology used to study this problem involves first - analysis, second – simulation and
third – hardware implementation.
F. Accomplishments
The circuit under consideration has been thoroughly analyzed and simulated. The circuit is
presently being implemented in hardware.
G. Deliverables
Deliverables of this project involves primarily the delivery of a working prototype of the
proposed circuit.
H. Member Company (Sponsor) Benefits
Sponsor benefits include exposure to a new inverter circuit solution which could have an impact
on member company products since it offers benefits in terms of reduced losses and better output
waveform.
I. Research Plans
Next year the circuit implementation presently under development will be completed and the
circuit tested to verify simulated prediction of its behavior. A report will be written assessing
cost, performance, etc.
2.2.4.6.
Buck/Boost AC/DC Converter
A. Project Team
Faculty: Prof. T.A. Lipo (UW)
Graduate Student: Jun Kikuchi (UW)
Sponsor: WEMPEC
B. Project Goals
This project concerns the design and evaluation of a novel input-side converter (rectifier) that is
able to buck as well as boost the ac voltage while converting power from ac to dc. This feature
would be beneficial to combat voltage “swells” which frequently appear on the power line in
75
which the voltage briefly increases above rated value. Without a buck capability (as in
conventional PWM rectifiers), this voltage produces a corresponding swell on the dc link,
thereby stressing the electrolytic capacitors leading to a shortened life for these expensive
components. The objective of this project is to design and develop a buck/boost PWM rectifier
for use in the motor drive testbed.
C. Support of the Strategic Plan
Goals of the strategic plan are to develop a motor drive which is not only cost-effective but also
highly reliable. This project addresses the second item: improved reliability but extending the
life of the most expensive component in the power converter: the electrolytic capacitor.
D. Relevant Work outside CPES
To the writer’s knowledge this problem and its solution have not been addressed outside of
CPES.
E. Methodology
The methodology used to study this problem involves first - analysis, second – simulation and
third – hardware implementation.
F. Accomplishments
The circuit under consideration has been thoroughly analyzed and simulated. The circuit
variation has been implemented in hardware. A second circuit variation is under construction.
G. Deliverables
Deliverables of this project involves primarily the delivery of a working prototype of the
proposed circuit.
H. Member Company (Sponsor) Benefits
Sponsor benefits include exposure to a new inverter circuit solution which could have an impact
on member company products since it offers benefits in terms of reduced losses and better output
waveform.
I. Research Plans
Next year the circuit implementation presently under development will be completed and the
circuit tested to verify simulated prediction of its behavior. A report will be written assessing
cost, performance, etc.
2.2.4.7.
Diode Rectifier/Buck Chopper for Low Cost Drive
A. Project Team
Faculty: Prof. T.A. Lipo (UW)
Graduate Student: Jesse Krase (UW)
Sponsor: WEMPEC
76
B. Project Goals
Low-cost drives have many alternatives for their input (rectifier) and output (inverter) stages.
This study is concerned with evaluating the performance of a simple diode rectifier followed by
a buck chopper for voltage control of the dc link. This solution is potentially the simplest
because of the need for only one transistor switch. However, issues such as harmonic currents in
the line, response to rapid motor speed commands, regeneration, etc. need to be addressed. The
goals of this project are to develop a working prototype of the diode rectifier/buck chopper input
converter in order to assess 1) cost tradeoffs, 2) steady-state performance (harmonics, EMI, etc.)
and 3) transient performance (rapid increases or decreases in ac motor speed command,
regeneration and braking, etc.)
C. Support of the Strategic Plan
This project is one of a number of efforts devoted to exploring options for implementing the
input-side converter for an ac drive testbed.
D. Relevant Work outside CPES
The writer is not aware of similar work which is being conducted outside of CPES.
E. Methodology
The work involves the design and construction of a working prototype.
F. Accomplishments
The circuit under study has been thoroughly simulated and analyzed. The circuit is presently
under construction
G. Deliverables
The deliverable of this project is a working prototype of the proposed circuit and a report
summarizing cost and performance details.
H. Member Company (Sponsor) Benefits
Member companies will benefit from data obtained from this work which will allow them to
make a decision on the utility of the concept for their products.
I. Research Plans
Next year this circuit will be completely assembled and tested and a final report will be written.
77
2.2.5. MD Related Technologies and Applications
2.2.5.1.
Automotive Starter/Alternator Control System
A. Project Team
Faculty: Thomas M. Jahns (UW)
Graduate Student: Jackson Wai (UW)
Sponsor: MIT
B. Project Goals
The objective of this project has been to develop a high-performance vector control algorithm for
an interior permanent magnet (PM) synchronous machine for use in a direct-drive automotive
starter/alternator application. In addition to providing the required starter torque at low speeds, a
major challenge in this project has been to design the control algorithm to yield constant power
alternator operation over a wide speed range extending from 600 rpm idle speed up to 6000 rpm
maximum engine speed conditions.
C. Support of the Strategic Plan
Automotive electric accessories represent a major market opportunity for future power electronic
systems provided that new equipment can provide high performance at very low cost. The
starter/alternator represents one of the highest cost subsystems in the electrical systems
architectures that are being proposed for future automobiles. This control system supports the
CPES strategic plan objectives of high performance and low cost by extracting the maximum
possible power from the new interior PM starter/alternator drive system.
D. Relevant Work outside CPES
Significant work is being pursued by automakers and their major electrical equipment suppliers
to develop new starter/alternator equipment. However, the majority of this work has focused on
the use of induction and surface PM machines for this application, leading to problems in
achieving wide constant-power alternator operation.
E. Methodology
This work has been carried out using a combination of analysis and experimental verification.
The analysis has been conducted by means of closed-form control analysis and Matlab/Simulink
simulations. Subsequently, this new control algorithm has been implemented in a high-speed
DSP and tested on a prototype interior PM starter/alternator machine mounted on a
dynamometer.
F. Accomplishments
The simulation and laboratory testing have demonstrated that the new vector control algorithm
performs as desired in achieving high-torque starting as well as wide ranges of constant-power
operation with an interior PM starter/alternator machine [1].
78
G. Deliverables
Deliverables include technical reports summarizing the results of this work, as well as the DSPbased control hardware and software that were used to verify the new control algorithm.
H. Member Company (Sponsor) Benefits
This work is benefiting sponsors by demonstrating that the interior PM machine can be
controlled very well to deliver its maximum available performance as an automotive
starter/alternator.
I. Research Plans
This research project is now in the process of being concluded in 2002.
J. References
[1]
J. Wai and T.M. Jahns, “A New Control Technique for Achieving Wide Constant Power Speed Operation
with an Interior PM Alternator Machine, in Conf. Rec. IEEE IAS Annual Meeting, Chicago, Oct. 2001, pp.
807-814.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-13]
2.2.5.2.
J. Wai and T.M. Jahns, “A New Control Technique for Achieving Wide Constant Power Speed
Operation with an Interior PM Alternator Machine, in Conf. Rec. IEEE IAS Annual Meeting, Chicago,
Oct. 2001, pp. 807-814.
Design of a PM Motor for a Hybrid Vehicle
A. Project Team
Faculty: Thomas A. Lipo (UW)
Graduate Student: Metin Aydin (UW)
Sponsor: ENOVA
B. Project Goals
One leading candidate for the motor component of the ac drive to be used in the CPES test bed is
a permanent magnet machine. This type of machine has major advantages including smaller size
and better efficiency than other options. However, this type of machine has a major
disadvantage, the tendency to have poor efficiency at high speed (field weakening). The
objective of this project is to develop a new permanent magnet motor design that provides good
efficiency both at low speed and at high speed during field weakening.
C. Support of the Strategic Plan
The strategic plan specifically includes four generations of motor drive test beds. On leading
candidate for the motor of these drives is the permanent magnet motor. Successful application of
this machine depends on the ability to weaken the air gap field in a non-lossy manner. This
project contributes to the CPES strategic plan in support of the objectives of increased
performance and reduced cost in future automotive traction drives.
79
D. Relevant Work outside CPES
Very little work on this problem has been done outside of WEMPEC. The standard solution to
the problem which can be considered as the state of the art is to control the stator current in such
a manner so as to produce a current component (d-axis current) which is oppositely directed
(opposes) the permanent magnet flux. This approach is very lossy since the ampere-turns
required to oppose the magnet field is very large due to the large effective airgap caused by the
permanent magnet.
E. Methodology
The work has been carried out using the finite element (FEM) code of Ansoft. A three
dimensional solution has been obtained. The finite element work has been backed up with
analytical work to help predict the general machine size and shape.
F. Accomplishments
The motor design has been completed and all dimensions needed to undertake a fabrication of
the motor has been done.
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing our efforts to
design the motor. Also to be delivered is a finalized prototype to be fabricated external to
WEMPEC but tested in our laboratory.
H. Member Company (Sponsor) Benefits
This work was carried out solely with support from Enova, Los Angeles CA. Member company
benefits are essentially spin-offs which include generation of technical papers outgrowing from
this work.
I. Research Plans
The planned work, over the next year will concentrate on the testing of the prototype machine.
J. References
[1]
J.A. Tapia, F. Leonardi and T.A. Lipo, “CPPM: A Synchronous Permanent Magnet Machine with Field
Weakening”, in Proc. of International Aegean Conf. On Electrical Machines and Power Electronics,
Kusadasi Turkey, June 2001.
2.2.5.3.
Design and Test of a Resonant DC Link Converter for Wind Turbine
Applications
A. Project Team
Faculty: Thomas A. Lipo (UW)
Graduate Students: Eric Benedict (UW); Damir Zarko (UW)
Post-Doc: Debiprasad Panda, India Institute of Science
Sponsor: National Renewable Energy Labs
80
B. Project Goals
The objective of this project is to develop a 50 kW variable speed generating system for
powering a wind turbine using a doubly-fed induction. The design uses novel concepts for
dealing with the power which must be fed to the rotor to obtain variable speed operation. In
addition, the inverter uses a new concept to ensure balanced currents at the input to the converter
feeding the rotor.
C. Support of the Strategic Plan
The strategic plan specifically includes four generations of motor drive test beds. The doublyfed type arrangement, studied in this project, is a possible type of motor that could be used in the
CPES project should the speed range requirements be narrow. This project supports of the CPES
strategic plans in the areas of reduced cost and higher reliability in future machine drives
intended for distributed power generation systems.
D. Relevant Work outside CPES
Work outside of CPES has concentrated exclusively on feeding power to the rotor using slip
rings. This is a costly and unreliable method which we are eliminating by the use of a rotating
transformer.
E. Methodology
The work has been carried out using the finite element (FEM) code of Ansoft. A three
dimensional solution has been obtained. The finite element work has been backed up with
analytical work to help predict the general machine size and shape. The power electronic portion
is presently under construction.
F. Accomplishments
The motor design has been completed and all dimensions needed to undertake a fabrication of
the motor has been done. The actual fabrication will be undertaken by WEG, a company located
in Brazil.
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing our efforts to
design the motor. Also to be delivered is a finalized prototype to be tested in our laboratory.
H. Member Company (Sponsor) Benefits
This work was carried out solely with support from the National Renewable Energy Labs.
Member company benefits are essentially spin-offs which include generation of technical papers
outgrowing from this work.
I. Research Plans
The planned work, over the next year will concentrate on the testing of the prototype machine.
81
2.2.5.4.
Advanced High Power Conversion Systems for EMALS/EARS Phase IState of the Art, Development and Baseline Metrics
A. Project Team
Faculty: T. A. Lipo, ECE, UW and G. Venkataramanan, ECE, UW
Associated Investigators: Dr. A. Tuckey (visiting); Dr. G. Stumberger, (visiting) and Dr. M.
Aydemir (visiting)
Graduate Student: A. Bendre, ECE, UW
Sponsor: Virginia Tech/ONR
B. Project Goals
The goal of this project is to conduct a state of the art study for high power conversion systems
(200 MW range) suitable for electromagnetic aircraft launch systems. Project activities focus on
linear electromagnetic conversion machines and multilevel converter topologies.
C. Support of the Strategic Plan
Propulsion and actuation systems for marine applications represent an important application area
in the field of power electronics at high power multimegawatt applications. This project aims at
techniques of using Plug-and-play strategies to be used in a modular fashion to realize high
power converters that can be used for traction, propulsion and utility applications.
D. Relevant Work outside CPES
Multiple teams around the nation are developing EMALS systems using current generation of
power electronic devices and components. The major focus of the current research is to
synthesize approaches for the future to develop architectures that would improve the
performance levels further.
E. Methodology
After a careful review of literature, a test circuit that consist of two inverters with dsp control
system with current and voltage controllers for the LC filters have been developed. The test
circuit can be used to evaluate various control algorithms presented by various researchers, as
well as develop new control algorithms to be developed under the current project.
F. Accomplishments
Several hardware topologies suitable for high power conversion in the 200 MW power levels
have been investigated. Bottlenecks from the point of view of realizing high power density using
multilevel converters have been identified to be the dc link capacitors. Modulation strategies that
minimize the size of the dc link capacitors are being developed. Advanced motor topologies that
employ superconducting systems have been proposed.
G. Deliverables
Publications documenting the results from the project are being prepared and presented at
international conferences. A final report summarizing the activities, findings and implications of
the project will be issued at the completion of project.
82
H. Member Company (Sponsor) Benefits
Publications are being prepared under the project will be made available to member companies
as they become available.
I. Research Plans
Using the experimental benchmarking system and the computer simulation models, control and
topological architectures for high power converters will be studied further.
J. References
[1]
[2]
R. Limpaecher, "Novel Converters for Ship Propulsion System and Shipboard Power Conversion", Science
Applications International Corportation.
G. Ries, H.W. Neumueller, "Comparison of Energy Storage in Flywheels and SMES", Physica C 357360(2001) 1306-1310, Elselvier Publications.
K. Reprints of Selected Publications
Publications under this project are under preparation. No preprints are available at present.
2.2.5.5.
Topological Synthesis of Multilevel Inverters
A. Project Team
Faculty: Giri Venkataramanan (UW), Thomas A. Lipo (UW)
Graduate Student: Yusuke Fukuta (UW), Poh Chiang Loh (Monash University, Australia)
Sponsor: DOD Navy
B. Project Goals
The goals of this project are: (a) To develop a synthesis procedure to derive hybrid converters
from the various topological families of multilevel converters; (b) To conduct a critical
evaluation of members of various topological families of multilevel converters and their hybrids;
(c) To develop and map an association matrix between various topologies of multilevel
converters and different application arenas.
C. Support of the Strategic Plan
Multilevel converters represent an important application area in the field of power electronics at
high power multimegawatt applications. This project aims at developing techniques for applying
IPEM-based technology in a modular fashion to realize high power converters for traction,
propulsion and utility applications. As a result, this work supports the CPES strategic plan in the
areas of reduced cost and increased reliability for high-power power electronics applications.
D. Relevant Work outside CPES
Several researchers have been working on presenting multilevel converter applications,
modulation strategies and topologies [1]-[6]. This new work is particularly focused on
systematically unifying the various approaches in developing hybrid topologies for realizing
higher performance levels than possible otherwise.
83
E. Methodology
The project activities begin by conducting a detailed taxonomy of the multilevel converter
families and the relationship among them. Following the taxonomical classification, a synthesis
method is developed to derive hybrid converters by combining topologies from members of
multiple families. Particular attention is paid to the emergence of synergism in the combination.
A critical evaluation of the converter topologies is made to characterize their potential for
performance in real-world application, constrained by the properties of power semiconductors,
capacitors, inductors and transformers. A mapping of association matrix between different
topologies and application arenas is developed. The matrix may be used to identify the most
suitable multilevel converter for a given application. In order to develop the association matrix,
criteria such as use of isolated dc buses, power flow requirements (e-g. reactive compensation,
harmonic compensation, regeneration) and multiple winding transformer arrangements.
Application areas considered include: medium voltage drives, static var compensation,
photovoltaic power system interface, fuel cell power system interface and distributed microturbine generation.
Computer simulation of various multilevel converter topologies is used as the primary tool to
study the developments made during the project. Selected hardware investigations are also
conducted, in order to verify key concepts.
F. Accomplishments
A detailed classification of multilevel converter topologies and their applications matrix has been
completed. Modulation techniques the specifically reduce the current ripple requirements of dc
bus capacitors have been developed.
G. Deliverables
Publications documenting the results from the project are being prepared and presented at
international conferences. A final report summarizing the activities, findings and implications of
the project will be issued at the completion of project. In addition, specific software tools
developed during the project will be made available for use for the technical community.
H. Member Company (Sponsor) Benefits
Publications being prepared under the project will be made available to the project sponsors as
they become available.
I. Research Plans
A bank of nine bidirectional isolated dual H-bridge converter modules is under construction and
this project. They may be used to verify control and modulation techniques for various
applications in a flexible fashion. This will be completed by Summer 2002. A five-level three
phase bidirectional converter module is also being planned under the project. This will be
complete by Winter 2003.
J. References
[1]
Schibli, N.P.; Tung Nguyen; Rufer, A.C., “A three-phase multilevel converter for high-power induction
motors”, IEEE Transactions on Power Electronics, vol. 13, no. 5 , Sept. 1998, pp. 978 –986.
84
[2]
[3]
[4]
[5]
[6]
J.S. Lai and F.Z. Peng, “Multilevel Converters - A New Breed of Power Converters,” Proceedings of the
IEEE-IAS’95 Annual Meeting, pp. 2348-2356, 1995.
M. Marchesoni, M. Mazzucchelli and S. Tenconi, “A Non-conventional Power Converter for Plasma
Stabilization,” IEEE-PESC’88 Conference Record, pp. 122-129, 1988.
R.H. Osman, “A Novel Medium Voltage Drive Topology with Superior Input and Output Power Quality,”
Report prepared by Robicon division of High Voltage Engineering.
W. A. Hill and C. D. Harbourt, “Performance of Medium Voltage Multilevel Inverters,” Proceedings of the
IEEE-IAS’99 Annual Meeting, pp. 1186-1192, 1999.
Madhav D. Manjrekar, "Topologies, Analysis, Controls and Generalization in H-Bridge Multilevel Power
Conversion", Ph.D. Thesis, University of Wisconsin-Madison, 1999.
2.2.5.6.
Investigation of a High Switching Speed Hard Switching Voltage Source
Inverter
A. Project Team
Faculty: Thomas A. Lipo (UW)
Graduate Student: Alessandro Moreira (UW)
Sponsor: ABB
B. Project Goals
One significant problem which must be addressed during the implementation of the Intelligent
Power Electronics Module (IPEM) is the issue of EMI. This project addresses passive filtering
means for reducing damaging ground mode currents that flow to ground in a motor drive. The
work also concentrates on development of suitable analytical models to predict the differentialand common-mode currents that flow when a motor is powered by a pulse-width-modulated
(PWM) inverter. Specific objectives include:
•
Development of line (cable) models to predict overvoltages across the motor windings and
across the inverter terminals due to reflections caused by switching of the pulse width
modulated inverter. The models to be developed must predict both differential and common
modes effect.
•
Development of motor models to help predict these same overvoltages.
•
Development of line filters to suppresses overvoltages caused by long feeder lines between
the inverter and the motor
C. Support of the Strategic Plan
The CPES strategic plan specifically includes four generations of motor drive test beds. The fast
switching of the inverter caused by newer IGBT and MOSFET devices will aggravate the
common mode problem which results in premature failure of the motor insulation and/or motor
bearings. This problem must be solved to satisfy the reliability requirements of the drive. This
project is an approach to the solution of this problem focusing on inserting passive filters in the
lines of the inverter output feeding the motor.
85
D. Relevant Work outside CPES
Ground mode effects has been recognized as a major problem in AC drives, particularly for
smaller AC drives where the ground wall and turn-to-turn insulation is marginal and where the
switches turn-on and turn-off very rapidly (less than 100 nanoseconds). While many papers have
appeared concerning this problem, they are generally focused on higher power inverters. In the
motor drive test bed, we intend to utilize roughly a five horsepower motor which will have
severe ground mode issues. Papers can be segregated into two categories: 1) papers which
manipulate the PWM switching algorithm to reduce dv/dt effects, and 2) papers which explore
various filtering techniques to reduce the ground (common mode) current. These papers have
concentrated on relatively costly solutions which are generally inappropriate for a 5 HP motor
drive.
E. Methodology
This work has had both analytical and experimental elements. The analytical component has
used simulation tools such as SABER to compute time domain solutions. The experimental
component has used an actual inverter set-up using switches in which the turn-off and turn-on
characteristics can be adjusted.
F. Accomplishments
Previous years has concentrated on development of analytical models. The work in the current
year has taken up the experimental phase which includes careful measurement of overvoltage
transients with and without various types of passive filters.
G. Deliverables
Deliverables of the project are primarily a series of detailed reports, summarizing our efforts to
characterize and predict the behavior of various types of filters.
H. Member Company (Sponsor) Benefits
This work was carried out solely with support from ABB, Mannheim Germany. Member
company benefits are essentially spin-offs which include generation of technical papers
outgrowing from this work.
I. Research Plans
This work, which began three years ago, will be concluded in June 2002.
J. References
[1]
A.F. Moreira, T.A. Lipo, G. Venkataramanan and S. Bernet, “High Frequency Modeling for Cable and
Induction Motor Over-Voltage Studies in Long Cable Drives”, in Conf. Rec. IEEE IAS Annual Meeting,
Chicago, Oct. 2001, pp. 1787-1794.
86
2.2.5.7.
Integration of High-Speed AC Induction Motor/Inverter System for FuelCell Powered Electric Vehicle Auxiliary Motor Drives & An Integrated
Motor-Drive Module for DOE Carat Program (Sponsored by VPT, Inc)
A. Project Team
Faculty: J.S. Lai (leader), ECE, VT and D. Nelson, ME, VT
Graduate Students: C. Liu, ECE, VT; H. Yu, ECE, VT; H. Kouns, ECE, VT; X. Wang, ECE,
VT
Undergraduate Students: J. Reichl, ECE, VT; M. Gilliom, ECE, VT; C. Smith, ECE, VT; D.
Miller, ECE, VT
Industrial Participant: Bud Konrad (VPT, Inc)
B. Project Goals
This project is aimed for automotive high-speed auxiliary drive requirements in the 3 to 5 kW
range. These applications include the compressor motor for fuel cells, active suspension, heatventilation and air conditioning system, and power steering.
C. Support of the Strategic Plan
Thermal management improvement by soldering power modules directly onto the heat sink, as
well as integration of motor/inverter into one package are closely related to the Center’s goals to
developing integrated power systems with improved performance, cost and reliability.
D. Relevant Work outside CPES
The power modules that are popularly used in today’s power devices such as power diodes and
Insulated Gate Bipolar Transistor (IGBT) are becoming the industry standard for high-power
electronics applications because of its ease of mounting and integration. To mount power
modules onto heat sinks, solder or thermally conductive epoxy can be used to eliminate the air
gaps from the thermal interface between the module and the heat spreader by conforming to
surface irregularities. Recently, the direct-soldered technique was introduced to the integrated
inverter-motor propulsion drives for hybrid electric vehicle applications [1].
E. Methodology
• Integrated high-speed motor/inverter in one housing with reduced interconnects and
improved reliability
•
Significantly improved thermal interface by soldering the IGBT modules directly onto the
heat sink
•
Advanced digital signal processor based sensorless control of the motor
F. Accomplishments
The major accomplishments are the inverter design and packaging for 10 kW and 75 kW
induction motors. A DSP controller is being laid out. The sensorless control algorithm has been
simulated.
87
G. Deliverables
Deliverables are inverter prototype and design report.
H. Member Company (Sponsor) Benefits
The major benefits for the sponsor are gaining experiences on
•
High power IGBT module direct mounting
•
High power inverter design with integration to the induction motor
•
Speed sensorless controller development to reduce the cost and to improve the reliability
I. Research Plans
The plans for next year are to test the motor and inverter assembly and to implement sensorless
control algorithm with DSP controller.
J. References
[1]
Toyota Technical Review, Vol. 48, No. 2, Mar. 1999, pp.29-30.
K. Reprints of Selected Publications (see Volume II, Part 2)
[MD-14]
J. S. Lai, J. Kim, and C. E. Konrad, “Direct-Soldered Mounting Inverter Modules for Traction Motor
Drives,” to be published in SAE Congress, June 2002.
2.2.5.8.
A High-Frequency Switching Inverter for Motor Drive and Power Device
Characterization
A. Project Team
Faculty: J.S. Lai, ECE, VT
Graduate Students: H. Yu, ECE, VT
Industrial Participant (Rutgers University): Dr. J. Zhao and Dr. B. Wright
B. Project Goals
• To design a DSP-based high-frequency switching three-phase 5-kW inverter for motor drive
applications
•
To design an inverter power stage that allows devices voltage and current to be viewable
•
To design an inverter power stage that allows devices to be replaceable with minimum effort
C. Support of the Strategic Plan
Characterization of power devices for motor drives power electronics circuits supports improved
efficiency and reduced EMI, which directly reflects in enhanced reliability because the voltage
and current stresses are reduced with improved devices and circuits.
D. Relevant Work outside CPES
The silicon carbide (SiC) Junction Barrier Schottky (JBS) diode has been reported as a near ideal
diode for power supply and motor drive applications [1] [2]. Because the SiC JBS diode has
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nearly zero reverse recovery time, it is well suited for high-frequency power-switching
applications, both hard and soft-switching circuits. In hard-switching circuits, the reductions are
mainly in device turn-on loss and associated electromagnetic interference (EMI) [1]. In softswitching circuits, the main diode can be of a slow-recovery type, but the auxiliary diode used in
the resonant circuit for soft switching should be extremely fast. Currently available high-voltage
Si diodes are too slow to prevent over-voltage ringing during the auxiliary diode turn-off [3].
E. Methodology
The work started with circuit design and layout for high frequency inverter operation. The power
circuit includes current sensors for IGBT and diode current measurement. All the diodes are
discrete so that they can be replaced with SiC diodes for efficiency comparison.
F. Accomplishments
The major accomplishment was an inverter prototype that operates at high frequency for SiC
diode testing.
G. Deliverables
Deliverables are a report for circuit design, a prototype inverter that can fit Si and SiC diodes
along with IGBT devices for 5-kW induction motor drive.
H. Member Company (Sponsor) Benefits
The major benefits for the sponsor are
•
High-frequency inverter that allows fast SiC diode to operate without nuisance tripping
•
Efficiency evaluation and comparison using Si and SiC diodes in inverter motor drives.
I. Research Plans
The plan for next year is to incorporate SiC transistors in inverter design and testing.
J. References
[1]
[2]
[3]
A. R. Hefner, Jr., D. W. Berning, J.-S. Lai, C. Liu, and R. Singh, “Silicon Carbide Merged PiN Schottky
Diode Switching Characteristics and Evaluation for Power Supply Applications,” in Conf. Rec. of IEEE IAS
Annual Meeting, Roma, 2000, pp. 2948 – 2954.
C. Winterhalter, H.-R. Chang, and R. N. Gupta, “Optimized 1200V Silicon Trench IGBTs with Silicon
Carbide Schottky Diodes,” in Conf. Rec. of IEEE IAS Annual Meeting, Roma, 2000, pp. 2928 – 2933.
W. McMurray, "Resonant snubbers with auxiliary switches," IEEE Trans. on Ind. Appl., Vol. 29, No. 2,
Mar./Apr. 1993, pp. 355 - 362.
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2.2.5.9.
WEMPEC Research Report
A. Project Team
Faculty: Thomas A. Lipo (UW), Thomas M. Jahns (UW), Robert D. Lorenz (UW), Giri
Venkataramanan (UW), Robert H. Lasseter (UW)
Graduate Students: Metin Aydin (UW), A. Bendre (UW), Ian Brown (UW), Gary
Buckingham (UW), Sibaprasad Chakrabarti (UW), Ho Chan (UW), Chirdpong Deelertpaiboon
(UW), Christoph Giebeler (UW),, Jason Hartwig (UW) , E. Kayickci (UW), Jun Kikuchi (UW),
Hyunbae Kim (UW), Rick Kieferndorf (UW), Ned Lebens (UW), Michael Leetmaa (UW),
Dustin Murdock (UW), Jonathan Nord (UW), Dejan Raca (UW), Ben Razidlo (UW), Ronghai
Qu (UW), Vijay Srinivasan (UW), Juan Tapia (UW), Jackson Wai (UW).
Sponsor: WEMPEC
B. Project Goals
WEMPEC research is being conducted in the broad area of power electronics and AC motor
drives. Research performed at UW-Madison using WEMPEC financial support that is not part
of the “WEMPEC in Support of CPES” project effort described in the preceding subsections is
summarized here. These projects include:
1. Development of inverter with an optimized dc link voltage
2. Development of buck-boost converter
3. Development of an inverter with resonant commutation
4. Development of a thyristor bridge with active commutation
5. Development of a radial flux PM motor with field weakening
6. Development of a double air gap PM motor
7. Development of a levitated vehicle using permanent magnets
8. Sensorless Controls for AC induction and permanent magnet machines
9. AC motor control utilizing low-cost sensors
C. Support of the Strategic Plan
The CPES technology roadmap specifically includes four generations of motor drive test beds.
These projects address advanced concepts for achieving combinations of performance, cost, and
reliability improvements in inverters, motors, and their controllers. These objectives are
supportive of the CPES strategic plan.
D. Relevant Work outside CPES
Research work that is relevant to these projects is under way at a variety of academic and
corporate research institutions around the world. Unfortunately, the list of project activities
being summarized here is too broad to provide a thorough review of the relevant outside work in
this condensed reporting format. A survey of the Proceedings of the most recent IEEE Industry
Applications Society Annual Meeting (2001) would identify several paper topics that are related
directly or indirectly to the projects described here. However, each of these WEMPEC projects
has been defined to extend the state-of-the-art in some distinct dimension.
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E. Methodology
This work has both analytical and experimental stages. The analytical project effort uses
simulation tools such as SABER and Simulink to compute time domain solutions. Finite element
programs are also extensively used in the machine analysis. The experimental project effort uses
prototype motors, inverters, and controllers in order to verify the concepts.
F. Accomplishments
Projects 1 and 2 listed above under the “Project Goals” heading have been successfully
completed, projects 3 and 4 have completed their analytical phases and construction is being
planned. Projects 5 and 6 have been successfully completed; projects 7 and 8 are in their
analytical stages, and project 9 is in the midst of hardware development.
G. Deliverables
Deliverables of the project are primarily a series of published papers, summarizing research
activities in this area.
H. Member Company (Sponsor) Benefits
This work will benefit WEMPEC member sponsors since they specifically address issues of
interest to them.
I. Research Plans
This work is part of ongoing research within WEMPEC, and projects are beginning and ending
as funds and students become available.
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