Session 2333
Redefining the Introductory Electrical Energy
Conversion Course
by
L.J. Bohmann, B.A. Mork, and N.N. Schulz
Department of Electrical Engineering
Michigan Technological University
ABSTRACT
An argument is made that the traditional electrical engineering energy conversion course needs to
be redefined. The traditional course is no longer relevant to the majority of electrical engineering
students, and therefore has lost its place as a core course in many curricula. The course needs to
be broadened to include other types of electrical energy conversion such as photovoltaics and
batteries. Modern aspects of electrical machinery, such as power electronics and permanent
magnets, need to be covered. The focus of the course should be the terminal characteristics of the
devices and it should also relate how energy conversion is interconnected to other electrical
engineering disciplines, such as electromagnetics, signal processing, controls, electronics, and
computers. Michigan Tech has started the implementation of this course and some observations
on its success are given.
INTRODUCTION
For many years, the traditional energy conversion course in electrical engineering departments
has been a course covering transformers, dc machines, synchronous machines, and induction
machines. Over the years this has been a good course which introduced students to the principles
of the basic types of electric machines.
This is no longer good enough. Many if not most electrical engineers will not actively deal with
these large machines during their careers. As a result, many universities have dropped this course
from the required curriculum. A course that is more relevant to the majority of electrical
engineers would not only be more interesting to the students but also would be taught as a
required course at more universities.
The question is, "What is a more relevant course?" We propose that the ideal Introduction to
Electrical Energy Conversion course would discuss all forms of energy conversion that involve
electricity and would focus on the type of apparatus that students have a good probability of
encountering during their working careers. The goal would not be to educate students to design
the equipment discussed, but rather to allow them to incorporate the equipment in system-level
design.
BACKGROUND
1
Page 2.342.1
Energy conversion has been part of the curriculum since the inception of electrical engineering as
a separate field of study [1]. The first departments taught courses primarily dealing with
generators and motors, power transmission, and communications.
The first part of this century saw many advances as the field matured. By mid century the
traditional first course in energy conversion had developed. The content of the course included
the study of dc motors and generators, ac motors and generators, and usually transformers. Most
of the advances in this period were in the design or advanced analysis of machines, subjects not
typically taught at this level. Therefore the course content did not change much and the biggest
difference in the texts became the order that the topics were presented. This lead to the perception
among our colleagues that the energy conversion field was fully mature and static.
At the same time there was a rapid expansion of other fields within electrical engineering. The
developments of World War II lead to the emergence of radar, advanced controls, and computers.
Soon there was the development of television and discrete electronics. Each advance brought
new material to be included in the curriculum. As electrical engineering expanded, the need for
all students to study all subjects within electrical engineering was debated. A feeling developed
that a large portion of the students would never need or use some of the more traditional material.
It ceased to be relevant to the students' careers. Pressure was applied to cut some of these more
mature topics. Energy conversion lost out.
Since the late 1970's we have experienced rapid changes within the energy conversion field with
the advent of power electronics and wide spread use of permanent magnets. There has been a
large increase in the use of small motors, not only for mechanical driving but also for control and
other specialty purposes. Energy conversion courses, as measured from available texts, have not
kept up with the rapid changes. The result is a course which has lost its relevance to many
specialty areas of electrical engineering and one that has failed to keep up with the changes in the
way machinery is used in society [2].
MOTIVATION
The consequence has been predictable. The last few decades have seen a continued reduction in
the number of schools requiring an energy conversion course. In the late 70's, energy conversion
was still a required course in a model electrical engineering curriculum [3]. Since then the
number of schools requiring a course in energy conversion has decreased. Even in departments
that report to have an electric power program, the percentage requiring an energy conversion
course has fallen from about 65% to about 47% in the past 15 years. (See Figure 1.) This data
comes from a biannual survey of Power Engineering Programs within Electrical Engineering
Departments [4-13]. These are not scientific surveys since the responses were voluntary and there
were some changes in the survey questions over the years. The response is also skewed toward
universities more likely to require an energy conversion course, since only departments with
strong power programs tended to responded (the typical response rate has been between 70-90 EE
departments out of approximately 230 in the US). It is expected that if the data were available for
all the US EE departments, it would show a smaller percentage and a larger drop. The data does
support the contention that the number of universities that require an energy conversion course
has decreased over the last two decades.
Page 2.342.2
2
70
60
50
40
30
20
93-94
91-92
89-90
87-88
85-86
83-84
81-82
79-80
77-78
75-76
73-74
10
0
academic year
Figure 1: Percentage of Universities With a Power Program Requiring a Course in
Energy Conversion [4-13]
The motivation for rethinking the energy conversion course came from planning a new
undergraduate curriculum for the Electrical Engineering Department at Michigan Tech, which we
are presently implementing. In the new curriculum the faculty decided to require two, one-quarter
courses in the electric power area (an increase of one course). One course is in power
transmission and distribution and the other is in electrical energy conversion. The faculty had the
foresight to broaden the material taught in both courses in order to make them useful for all
electrical engineers. We have used this opportunity to redefine the energy conversion course and
refocus it so as to make it relevant to all our students.
GENERAL REQUIREMENTS
Originally most introduction to energy conversion classes provided the foundations for future advanced courses on energy conversions and electric machines. While this continues to be useful
for power engineering students who take those advanced courses, the majority of today's electrical
engineers need an overview of the subject rather than detailed derivations. A required course
should offer all students something of lasting value. One approach is to focus on improving analytic and communication skills [14]. Another is to expand the course from Electro-Mechanical
Energy Conversion to a more general Electrical Energy Conversion. In addition to the traditional
topics this would include other types of electrical energy conversion such as solar-electric and
electro-chemical conversion. The focus on electric machinery would need to change from the
large integral horsepower machines to smaller, special purpose machines, which operate from
variable voltage and frequency supplies.
3
Page 2.342.3
With the increase in the breadth of the course, we will have to limit the depth of coverage of some
topics. For this reason the updated course will focus on the terminal characteristics of the
devices. Our goal is not to educate students to design the equipment we discuss, but rather to
allow them to design with the equipment. The majority of our students will not be power
engineers. They will design, specify, and build a wide range of products and systems. To do so
intelligently they will, on occasion, need to know the characteristics of the energy conversion
equipment that go into or interface to their designs.
The ideal energy conversion class of today should be a "service course" that provides all electrical
engineers with the background to understand important energy conversion topics and
terminology. It should also relate how energy conversion is interconnected to other electrical
engineering disciplines, such as electromagnetics, signal processing, controls, electronics, and
computers, as well as other engineering disciplines such as chemical engineering, mechanical
engineering and materials engineering.
COURSE STRUCTURING SPECIFICS
Our course was thus structured with the goal of expanding the scope to include general electrical
energy conversion topics of interest to all EEs. Three 5-week modules have been defined. These
can be fully covered in a 15-week semester or selectively covered in a 10-week quarter. The
breakdown is:
-
-
-
Static devices (photovoltaic, electrochemical, and electromagnetic).
* Photovoltaic energy conversion
* Solar cells and panels
* Electrochemical energy conversion
* Batteries and fuel cells
* Electromagnetic energy conversion and magnetic circuits.
* Phasor analysis and transformers
Dynamic devices (electromechanical).
* Electromechanical energy conversion
* dc machinery fundamentals
* dc motors and generators, use in control systems
* ac machine fundamentals
* Synchronous machines, single phase and three phase induction motors.
Special purpose devices and system application.
* Introduction to Power Electronics.
* Brushless dc machines, permanent magnet machines, steppers, reluctance machines, etc.
* Other special purpose machines, transducers, etc.
* Control of dc machines using variable voltage sources
* Control of ac machines using variable voltage and frequency sources
* Power Quality, system application considerations, etc.
Each week consists of three hours of lecture and an optional 2-hr lab. When implementing in a
10-week quarter, topics in each module can be culled or emphasized to best match the needs of
that curriculum.
Immediate usefulness of all material to EEs in all specialties should be constantly emphasized.
Regardless of whether a student will specialize in communications, computer engineering,
controls, electromagnetics, electronics, materials, power systems, or signal processing, they
should come away with an appreciation for what they have learned.
4
Page 2.342.4
The first module consists of electrochemical and static electromagnetic devices. Photovoltaics
and batteries are key to new advances in electric vehicles and future energy development. They
are also key to communications installations, emergency backup power for computers and
hospitals, and are used extensively in portable consumer electronics. Transformers will include
not only the 50, 60 or 400 Hz power transformers, but also high frequency transformers and
inductors used for electronics.
The second module includes basic rotating machines. The focus is changed however, away from
the large integral horsepower machines and toward smaller fractional horsepower machines. The
focus on small motors recognizes that the majority of motors sold in the United States are
fractional horsepower ac motors [15]. Instead of focusing on internal design, terminal
characteristics are emphasized. The characteristics of the machines must include how they
operate with a variable voltage, and in the case of ac machines, variable frequency supply, since
these are readily available with the use of power electronics [16].
The third module includes specialty motors, variable speed drives, and specialty electromagnetic
transducers. Almost all the motors presently used in automobiles have permanent magnet fields
to cut down on the expense and the reliability problems associated with commutators. Our
electrical engineering students are more likely to need to know something about the permanent
magnet, pancake motor found in a disk drive or a stepper motor on a robotic arm than a threephase induction motor. Basic power electronics is introduced, allowing the discussion of variable
speed ac and dc drives. Applications problems related to variable speed drives are also covered,
including power quality, insulation problems related to IGBT switching devices, etc.
Laboratory Experience
Just as important as the lecture topics are the laboratory exercises used to illustrate them. It is
suggested that 8 labs be offered in a 10-week quarter, or 13 in a 15-week semester. A simple
automotive battery works well to delve into a discussion of new battery types and electric
vehicles. A simple PV cell and an incandescent light can be used to learn about photovoltaic
characteristics. Existing lab equipment can be used to work with transformers, dc machines, and
ac machines. Variable speed drives can be used in conjunction with existing machines. Brushless
dc motors are a good example bridging a switching power supply, dc machines, the use of
permanent magnets, and ac machines.
INITIAL IMPLEMENTATION AND RESULTS TO DATE
The new energy conversion course at Michigan Tech was first taught in the spring of 1996. It is a
10-week course. It represents a rapid transition away from the traditional Electric Machinery
course and toward the course described above. Full implementation of the above course has not
been immediately possible due to:
- Lack of adequate texts covering required material at desired depth.
- Lack of budget to immediately update energy conversion laboratory.
5
Page 2.342.5
All topics in the first two modules are covered in lecture. The traditional treatment of
transformers, dc machines, synchronous machines, and induction machines is being scaled back
to include only terminal characteristics. Meanwhile, coverage of photovoltaics, fuel cells, and
batteries is being increased. Specialty motors and variable speed drives are also covered.
Eight lab exercises have been developed to date, including photovoltaics, battery characteristics,
and six others on transformers, motors, and generators. Labs to be added are: fuel cells, specialty
motors, and variable speed drives.
A certain amount of folklore and misperception towards this course on the part of the students is
gradually being overcome. The traditional electric machines course had in recent years become
known as "the power class," something that "only power types really need to know," a collection
of "old technology," and a class that "we have to take to graduate." With this in mind, it is
imperative to continuously provide practical examples in lecture and interesting up-to-date lab
experiences, to show that the material is applicable to all specialties in EE. Following this tack,
students see the material to be immediately useful and are thus more motivated. Although it may
take some time to reverse the old perceptions of the "power course," students entering this course
seem to have fewer negative preconceptions than in past years.
SUMMARY
The traditional Electrical Engineering Energy Conversion course is broken. We need to fix it by
updating the material, broadening the scope, and shifting the focus. Recent advances in power
electronics and permanent magnets need to be included. Other forms of electrical energy
conversion need to be included. The course should be tailored to students who will use the
technology as opposed to those who will design it. Some of our specific thoughts on how this can
be accomplished have been presented. We will further the development of this course with the
help of a joint National Science Foundation (NSF) and Electric Power Research Institute (EPRI)
initiative, the Innovative Power Engineering Education in a Changing Environment program.
These two agencies are spending over $1.1 million on five, three year projects to revitalize power
engineering education. Since this is a work in progress, we encourage your comments on this
proposal. Please e-mail them to us at 'ljbohman@mtu.edu'.
ACKNOWLEDGMENT
The authors would like to thank the National Science Foundation and the Electric Power Research
Institute whose support (grant no. ECS-9619320) helped us develop our ideas.
Page 2.342.6
6
REFERENCES
[1] L.P. Grayson; The Making of an Engineer: An Illustrated History of Engineering Education in the US and
Canada; Chapter 2; John Wiley and Sons, Inc.; 1993.
[2] W.R. Conrad; "Future Direction of Electrical Machinery"; 1995 ASEE Annual Conference Proceedings, pp.
1408-1412.
[3] C.J. Baldwin, C.R. Cahn, J.W. Forman, H. Lehmann, and C.R. Wischmeyer; "A Model Undergraduate Electrical
Engineering Curriculum"; IEEE Transactions on Education, Vol. E-22, No. 2, May, 1979; pp. 63-68.
[4] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1973-1974"; IEEE
Transactions on Power Apparatus and Systems, Vol. PAS-95, No. 4, pp. 1194-1201; July-August, 1976.
[5] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1975-1976"; IEEE
Transactions on Power Apparatus and Systems, Vol. PAS-97, No. 3, pp. 802-809; May-June, 1978.
[6] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1977-1978"; IEEE
Transactions on Power Apparatus and Systems, Vol. PAS-100, No. 2, pp. 721-728; February, 1981.
[7] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1979-1980"; IEEE
Transactions on Power Apparatus and Systems, Vol. PAS-100, No. 11, pp. 4456-4463; November, 1981.
[8] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1981-1982"; IEEE
Transactions on Power Apparatus and Systems, Vol. PAS-103, No. 5, pp. 921-932; May, 1984.
[9] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1985-1986"; IEEE
Transactions on Power Systems, Vol. PWS-3, No. 3, pp. 1340-1353; August, 1988.
[10] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1987-1988";
IEEE Transactions on Power Systems, Vol. 6, No. 2, pp. 379-392; February, 1991.
[11] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1989-1990";
IEEE Transactions on Power Systems, Vol. 7, No. 4, pp. 1611-1622; November, 1992.
[12] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1991-1992";
IEEE Transactions on Power Systems, Vol. 9, No. 3, pp. 1182-1193; August, 1994.
[13] "IEEE Power Engineering Society Committee Report, Electric Power Engineering Resources, 1993-1994";
IEEE Transactions on Power Systems, Vol. 11, No. 3, pp. 1146-1158; August, 1996.
[14] H.L. Hess; "Successful Teaching Methods for the Mandatory Junior-Level Electric Machines Course"; 1995
ASEE Annual Conference Proceedings, pp. 1413-1417.
[15] J. Douglas; "Advanced Motors Promise Top Performance"; IEEE Power Engineering Review, Nov. 1992.
[16] H.L Hess; "Incorporating Electronic Motor Drives into Existing Undergraduate Electric Energy Conversion
Curriculum"; 1996 ASEE Annual Conference Proceedings; Session 2333, paper 1.
BIOGRAPHICAL INFORMATION
Leonard J. Bohmann is an Associate Professor of Electrical Engineering at Michigan Tech. He earned his MSEE
and PhD from the University of Wisconsin-Madison in 1985 and 1989 and a BEE from the University of Dayton in
1983. He is a member of the Energy Conversion and Conservation, Educational Research and Methods, and Electrical Engineering Divisions of ASEE, an active member of IEEE, and a Licensed Professional Engineer in Michigan.
Bruce A. Mork joined the EE faculty at Michigan Technological University after receiving his PhD from North
Dakota State University in 1992. He also has the BSME and MSEE degrees. He worked several years as a design
engineer for Burns & McDonnell in Kansas City, Missouri, and two years as a researcher in Norway. He is a
member of ASEE, IEEE, and NSPE, and is a Licensed Professional Engineer in Missouri and North Dakota.
Noel N. Schulz received her BSEE and MSEE degrees from Virginia Tech in 1988 and 1990, respectively. She
received her PhD in Electrical Engineering from the University of Minnesota in 1995. She is an Assistant Professor
of Electrical Engineering at Michigan Technological University. She has been active in the New Engineering
Educators Division of ASEE and IEEE Power Engineering Society.
Page 2.342.7
7