A Single Sided Matrix Converter Drive for a
Brushless DC Motor in AerospaceApplications
Xiaoyan Huang, Member, IEEE, Andrew Goodman, Member,
IEEE, Chris Gerada, Member, IEEE,Youtong Fang, Member,
IEEE, and Qinfen Lu, Member, IEEE
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS,
VOL. 59, NO. 9, SEPTEMBER 2012, Page(s): 3542 ~ 3552
Adviser：Ming-Shyan Wang
Student：Ang-ting Wu
Student ID：MA120112
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Abstract
I. INTRODUCTION
II. SSMC
III. CONTROL STRATEGIES
IV. MULTIPHASE DESIGN
V. PROTOTYPE AND EXPERIMENTAL RIG
VI. EXPERIMENTAL RESULTS
VII. CONCLUSION
REFERENCES
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Abstract
Abstract—This paper describes a brushless dc (BLDC) drive
with a single sided matrix converter (SSMC) for an electrohydrostatic
actuation system in aerospace application. The use of
an SSMC with a BLDC motor is novel and is used to achieve
operation without a microprocessor. A simple hysteresis current
control strategy is implemented to control motor torque. The
multiphase SSMC provides high reliability and fault tolerance
with the penalty of more power devices. A five-phase SSMC
prototype is built. The experiment results are presented to verify
the drive performance.
Index Terms—Brushless dc (BLDC) motor, electrohydrostatic
actuation (EHA) system, hysteresis control, single sided matrix
converter (SSMC).
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I. INTRODUCTION
I. INTRODUCTION
SINCE THE 1970s, the concept of the “all electric aircraft”
and the “more electric aircraft” (MEA) has emerged
promising advantages in terms of reduced weight at system
level, low cost, easier maintenance, increased safety, and enhanced
reliability [1].
The performance of an EHA system is mainly determined by the torque,
speed, and power of its electrical drive.
The BLDC motor has the potential to provide the highest power density
when compared to the aforementioned topologies. The square-wave
current supply effectively utilizes most of the back-electromotive-force
(EMF) harmonics to produce useful power output.
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In this application, a BLDC drive is adopted mainly due to the aforementioned
advantages. The reliability can be further enhanced by adopting a multiphase
design [18]–[20]. In this application, a five-phase BLDC motor driven by a single
sided matrix converter (SSMC) with hysteresis band control has been opted for
due to its high reliability, fault tolerance, and compact structure.
Fig. 1. System block diagram.
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II. SSMC
II. SSMC
In a safety critical aerospace application, all the drive components
need to be individually fault tolerant and have a high
reliability.
For a conventional power electronic converter, the energy
storage device (electrolytic capacitor) can have a significant impact
on the system’s reliability and can be particularly limited
by its operating temperature range of −50 ◦C−80 ◦C.
The SSMC is a type of simplified matrix converter, which keeps the
inherent advantages of a matrix converter but avoids the complex
commutation problems in a conventional matrix converter [23].
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III. CONTROL STRATEGIES
III. CONTROL STRATEGIES
As mentioned previously, one of the main reasons why a
BLDC motor driven by an SSMC has been selected is its simple
control strategy that can be implemented entirely by employing
only a field-programmable gate array (FPGA). Therefore, the
control strategy chosen for the drive system described previously
is based on a hysteresis control technique.
Hysteresis control gives fast response and good accuracy
and focuses on keeping the current within a predefined band.
It has simple control structure, which can be implemented
entirely on an FPGA chip. However, the disadvantage is the
increased unexpected harmonic in the voltage due to the varying
operating frequency.
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A. SB Hysteresis Control
The single-band (SB) control is the simplest type of hysteresis control
which uses the supply phases with the most positive and most negative
voltages to control the current.
Fig. 3. Twelve regions of three-phase voltage supply.
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B. DB Hysteresis Control
Double-band (DB) control is more complicated and intelligent, although it
is based on the same principle as SB control. It uses both inner and outer
hysteresis bands to control the output current.
Fig. 4. DB control.
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IV. MULTIPHASE DESIGN
IV. MULTIPHASE DESIGN
A three-phase drive, the most common topology for industrial drives,
cannot achieve the aerospace requirements in terms of safety and
reliability for this application which instead can be fulfilled by a multiphase
motor-drive design [18]–[20]. There are many possible configurations for
the power converter and the number of motor phases.
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V. PROTOTYPE AND EXPERIMENTAL RIG
V. PROTOTYPE AND EXPERIMENTAL RIG
A. BLDC Motor A 5-phase 4-pole 20-slot 12 000-r/min 12-kW BLDC motor
is designed and manufactured for use with the SSMC, as shown in Fig.
5(a). The power density of the motor was sacrificed for high reliability and
fault tolerance and limited by the SSMC to some degree.
Fig. 5. (a) BLDC motor. (b) Five-phase SSMC.
Fig. 6. Back EMF at 2000 r/min.
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B. SSMC
The SSMC is realized using five power boards, two control boards, one interface
board, one current mirror, and one DSP board. Fig. 5(b) shows the SSMC. The
components in one power board include six switches and isolation and drive
circuits. The control board is based on an Actel FPGA and consists of nine A/D
converter (ADC) channels and two D/A converter channels.
C. Test Rig
The BLDC motor was coupled to a four-quadrant high-speed test rig, as shown
in Fig. 7. The test rig drives or absorbs power from the test BLDC motor using a
40-kW variable-speed ac motor with a maximum speed of 20 000 r/min (loaded
test) or driven by the ac motor (open-circuit test).
Fig. 7. Test rig.
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VI. EXPERIMENTAL RESULTS
VI. EXPERIMENTAL RESULTS
The BLDC motor with SSMC was designed as the pump drive for the EHA
system. The fluid drag loss in the pump at noload condition is approximately
200W. In this case, a minimum torque of 0.96 N · m is required. The first set of
the tests was done at 2000 r/min and 0.96-N · m load using the SB and DB
controllers. The next test was done under an intermediate situation of 6000 r/min.
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A.Test Results at 2000 r/min, Minimum Load Condition Testing of the five-phase
SSMC with SB control was done with a minimum 0.96-N · m load, 115 V, and
400-Hz supply voltage. Output Waveforms Fed to the Motor With SB Control:
The five-phase current waveforms were recorded by the DSP, as shown in Fig.
8. One can see that two phases are conducting at any time to improve the fault
tolerance. The experimental current waveforms conformed to the expected
current switching sequence. A high switch frequency of 10 kHz can be seen in
the current waveforms.
Fig. 8. SB-controlled five-phase output
current waveforms at 2000 r/min.
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B. Test Results at 6000 r/min
An intermediate case of 6000 r/min with a load of 4.8 N · m was investigated. The
five-phase current waveforms are shown in Fig. 16, while the phase-A voltage
and current waveforms are shown in Fig. 17. It should be noted that the
magnitude of the peak back EMF has now increased dramatically, which means
that the voltage available to pull up the current has decreased. Thus, the most
positive or negative voltage can be applied most of the time.
Fig. 17. DB-controlled output phase-A voltage and
current waveforms at 6000 r/min and half load.
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C. Test Results at 12 000 r/min, Full-Load Condition
The peak value of the back EMF at this speed is much greater than that
for low-speed operation. Meanwhile, the conduction period is one-sixth of
that at 2000 r/min. As a result, the current could not reach the target of 40
A within such short period,
Fig. 18. DB-controlled output phase-A voltage and
current waveforms at 12 000 r/min and full load.
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D. Test Results With Field Weakening Control
The torque output can be improved by using phase advance field
weakening control. The output current and voltage waveforms of phase A
at 6000 r/min and half-load condition are shown in Fig. 17. Fig. 19 shows
the output current and voltage waveforms under the same conditions with
phase advance field weakening control. The current was turned in the
negative back- EMF area. Thus, the current rose faster due to a higher
voltage being applied across the inductance to pull up the current.
Fig. 19. DB-controlled output phase-A voltage
and current waveforms at 6000 r/min and half
load with field weakening control.
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E. Test Results at 2000 r/min, 3-N · m Load Under
Single-Phase Open Circuit The single-phase open-circuit test was done in
order to prove the fault-tolerant capability of the drive system. The fivephase current waveforms at 2000 r/min and 3 N · m under normal
conditions with DB control are shown in Fig. 22.
Fig. 22. DB-controlled five-phase current
waveforms at 2000 r/min and 3 N · m under
healthy condition.
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VII. CONCLUSION
VII. CONCLUSION
A fault-tolerant BLDC motor as a pump drive in an EHA system has been designed
and tested. The use of an SSMC with hysteresis current control with a BLDC motor
is novel. It facilitates simple control ensuring small size and weight. The penalty is
complex power electronic switch packaging. There need be little penalty in the size
of the power electronic circuit when all power devices per phase are put into a single
package. This drive has not only the advantages of high efficiency and compact
structure but also the critical advantage in terms of high reliability for aerospace
applications. This is in part due to simplified commutation and in part due to inbuilt
redundancy. The SSMC is shown to be able to drive the BLDC motor with the SB or
DB controller. The test results demonstrate the high reliability potential of the fivephase drive system.
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Thank You For Your Attention!
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