436 ieee transactions on education, vol. 47, no. 4, november 2004

436 IEEE TRANSACTIONS ON EDUCATION, VOL. 47, NO. 4, NOVEMBER 2004

Versatile Hardware and Software Tools forEducating Students in Power Electronics

Joshua M. Williams, Student Member, IEEE, James L. Cale, Member, IEEE,Nicholas D. Benavides, Student Member, IEEE, Jeff D. Wooldridge, Andreas C. Koenig, Student Member, IEEE,

Jerry L. Tichenor, Member, IEEE, and Steven D. Pekarek, Member, IEEE

Abstract—A new power electronics laboratory has been con-structed at the University of Missouri—Rolla. Key componentsof the laboratory are a set of custom-designed hardware andsoftware tools. The novel hardware tools include five mobile powerelectronics testbeds that each contain the semiconductor devices,gate-drive boards, voltage and current sensors, and computerinterface connections required to study a wide range of circuittopologies and control techniques. Novel software tools include aset of virtual instruments used for control, data capture, and dataanalysis. A description of these tools, along with their use in powerelectronics courses, laboratory exercises, and student researchprojects, is presented.

Index Terms—Digital control, laboratories, motor drives, oper-ational amplifiers, power electronics.

I. INTRODUCTION

POWER electronics systems (PESs) are increasingly beingused in many applications, including vehicular propulsion

and power distribution, home appliances, and manufacturing.Designing these systems requires significant knowledge inmultiple areas of electrical and computer engineering. Theseinclude understanding of electronics, control theory, linear andnonlinear system theory, and electromagnetics. In addition,knowledge of the behavior of electric machinery, modelingtechniques, and microprocessors for control algorithm imple-mentation must be established to create efficient designs.

Recently, a new power electronics and drives laboratory hasbeen constructed at the University of Missouri—Rolla (UM-Rolla). The purpose of the laboratory is twofold. First, it is aresource for undergraduate and graduate students to develop

Manuscript received March 7, 2003; revised September 1, 2003. This workwas supported in part by the National Science Foundation under Grant 995077and by the Ameren Foundation.

J. M. Williams was with the Department of Electrical and Computer Engi-neering, University of Missouri—Rolla, Rolla, MO 65409-0040 USA. He isnow with Caterpillar Electronics, Peoria, IL 61602 USA.

J. L. Cale, A. C. Koenig, and S. D. Pekarek were with the Department of Elec-trical and Computer Engineering, University of Missouri—Rolla, Rolla, MO65409-0040 USA. They are now with Purdue University, West Lafayette, IN47907-2035 USA.

N. D. Benavides was with the Department of Electrical and Computer En-gineering, University of Missouri—Rolla, Rolla, MO 65409-0040 USA. He isnow with the University of Illinois at Urbana-Champaign, Urbana, IL 61801USA.

J. D. Wooldridge was with the Department of Electrical and Computer En-gineering, University of Missouri—Rolla, Rolla, MO 65409-0040 USA. He isnow with Empire District Electric Company, Joplin, MO 64801 USA.

J. L. Tichenor is with the Department of Electrical and Computer Engi-neering, University of Missouri—Rolla, Rolla, MO 65409-0040 USA.

Digital Object Identifier 10.1109/TE.2004.825552

the skills that are required to analyze and design power-elec-tronic-based systems. Second, it is a tool to support research inthe areas of power electronics and electric drives. To facilitateboth objectives, several custom-designed hardware and softwaretools have been developed for the laboratory. The novel hard-ware includes five mobile power electronics testbeds that eachcontain semiconductor devices, gate-drive boards, voltage andcurrent sensors, and computer interface connections. In addi-tion, digital-signal-processing (DSP)-based control boxes havebeen designed to interface directly with one or multiple powerelectronics testbeds. Novel software includes customized vir-tual instruments (VIs) that utilize the commercial package Lab-VIEW [1] for control, data capture, and data analysis. MATLAB[2] is used for time-domain simulations.

The advantages offered by these tools are numerous. For one,the power electronics testbeds can be configured using simpleconnections on a faceplate to construct a wide variety of con-verters and inverters. In addition, the testbed can operate froma single-phase (120-V) source, which is useful in a classroomsetting. Op-amps contained in the testbed have been config-ured to act as a four-channel computer-based function gener-ator. This generator is convenient for demonstrations or shortcourses where two- or three-phase power is required but notreadily available. Finally, the devices are rated at voltage andcurrent levels that are consistent with those required in manyindustrial, automotive, and home appliance applications. There-fore, the testbeds are useful as a tool for undergraduate and grad-uate student research.

In this paper, a description of these tools, along withtheir use in power electronics courses, laboratory exer-cises, and student research projects is presented. All soft-ware, circuit schematics, rack layout drawings, and mis-cellaneous technical information are posted on the websitehttp://www.ece.umr.edu/places/Power_Electronics_Lab/. Theultimate goal is to promote adaptation of this testbed at otherinstitutions, to evaluate the testbed’s components, and to de-velop additional tools.

One unique aspect of the laboratory is that undergraduatestudents, under the direction of a graduate student and faculty,designed and constructed a majority of the hardware and soft-ware. This accomplishment has helped to spark student interestin power-related research and has led several students to pursuegraduate schools in this area. An assessment of the laboratory’sinfluence on student interest and achievement is provided inSection VI.

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WILLIAMS et al.: EDUCATING STUDENTS IN POWER ELECTRONICS 437

II. LABORATORY DESIGN CONSIDERATIONS

Over the past decade, several educators have proposed cur-riculum and laboratories to train students in the analysis and de-sign of PESs [3]–[13]. In [6]–[10], the described educational ap-proach supplements course lectures with computer exercises todemonstrate the behavior of power electronic circuits and designcontrol algorithms. Pedagogical approaches emphasizing con-current simulation and hardware are described in [11]–[13]. Inthe courses that utilize hardware-based experiments describedin [11]–[13], students are trained to perform the following:

1) to analyze to establish expected results;2) to simulate to verify the analysis;3) to validate through hardware experiments.

At UM-Rolla, prior to the development of the laboratory, onlya single course on power electronics had been co-listed in theundergraduate/graduate curriculum. In addition, a course hadbeen listed on electric machines/drives. Both have utilized com-puter exercises to supplement course lectures. Although thesecourses were useful in establishing an understanding of the be-havior of the circuits and systems, instructors recognized thatstudents gain a much better understanding of the complexity ofdesigning a physical system if they are exposed to hardware.Specifically, they can observe the effects of parasitics, the phys-ical limitations of devices, and the differences between poorlyand well-designed circuits and software. In addition, they fur-ther develop their skills to obtain meaningful and accurate mea-surements and learn safety measures that are required to workwith power electronics.

Given the motivation to create a curriculum that utilizeshardware-based experiments, a laboratory containing five ofthe power electronics stations shown in Fig. 1 was developed.From the figure, one can see that each station contains a com-puter for control and data capture/analysis, an oscilloscope forobserving/capturing wave forms for analysis with the computer,and an equipment rack containing power electronic devices,sensing equipment, power supplies, and a load box. Also shownis a DSP box that is used for supervisory and switch levelcontrol, as well as data acquisition. Sections III–VI provide adescription of the custom-designed components of the powerelectronic testbed shown in Fig. 1. Included are the equipmentrack, DSP box, and the software used for data capture, analysis,and control.

III. POWER ELECTRONIC TESTBED

The main component in each station is the power electronictestbed shown in Fig. 2. As shown, the testbed consists of mul-tiple racks. The control/sensor rack provides sensors for voltageand current-based control and fault detection, the inverter anddiscrete device racks contain the devices to construct a wide va-riety of circuit topologies, a BUS-level rack provides a meansto make nodal connections, the op-amp rack acts as an arbitrarywave form generator, and the Sorensen DHP series direct cur-rent (dc) supply with 400-V/25-A ratings can be used to providepower for research applications. Overall, the testbed is spaciousand divided into sections; each can be used independently orin conjuction with other testbeds. Removable side panels andpull-out shelves give access to the interior, facilitating design

Fig. 1. Power electronic station.

Fig. 2. Power electronic testbed.

changes and allowing the laboratory to be modified as technolo-gies change. Safety issues resulting from inadvertent contactwith energized circuits is minimized since all the equipment ismounted inside the enclosure. Details of each rack are describedin Sections III-A–D.

A. Control/Sensor Rack

The control/sensor rack consists of two independent systemsthat provide the following functions through the panel shown inFig. 3(a):

• control power;• manual enable/disable switch for each insulated gate

bipolar transistor (IGBT);• a start/stop for IGBTs;• voltage and current sensor inputs;• digital switching inputs and analog sensor outputs.The switches and digital/analog (D/A) input/output (I/O) con-

nections on the left half of the rack control the devices locatedin the inverter rack, while the switches and D/A I/O connectionson the right half control the devices located in the discrete de-vices rack. The voltage and current sensors shown can be usedwith either rack or an external circuit.


Fig. 3. Control/sensor rack: (a) front panel and (b) interior.

An interior view of the control/sensor rack is shown inFig. 3(b). At the top are four sensor boards, each containingtwo current sensors and one voltage sensor. The measurementrange of the sensors is adjusted by selecting an appropriateoutput scaling resistance. Measurements are accessible througha D-subminiature (D-SUB) connector on the front panel. In themiddle of the rack are the device control boards for the inverterand discrete device racks, left to right, respectively. Eachcontrol board receives transistor–transistor-logic (TTL)-levelswitching signals from the digital input port and provides faultprotection for each of the IGBTs.

B. Inverter Rack

The inverter rack consists of a three-phase full bridge inverterconstructed with discrete 600-V, 30-A IGBTs and 600-V, 50-Aantiparallel diodes. Discrete devices were chosen to minimizecost if an IGBT or diode should fail. The inverter connectionsare made behind the panel shown in Fig. 4(a), thereby mini-mizing the number of front-panel connections. An input filtercapacitor is also included.

The inverter rack connections and gate-drive circuitry areshown in Fig. 4(b). Isolated 20-V gate-drive supplies are shownin the bottom right, and the gate-drive boards are at the topright.

The gate-drive circuits were designed using application notes[14] from the vendor. The gate resistance can be changed sothat the effects of snubber circuits and device rise times can be

Fig. 4. Inverter rack: (a) front panel and (b) interior.

studied by students. The gate-drive boards and snubbers are con-nected to the semiconductor devices using small circuit boardswith terminal blocks and collector, base, emitter (CBE) connec-tors. These boards are placed atop the devices, simplifying thewiring dramatically.

C. Discrete Device Rack

The discrete device rack is similar to the inverter rack. How-ever, the discrete device rack contains fewer semiconductordevices, and each device is connected separately. Each of theIGBTs and diodes are wired directly to the front panel as shownin Fig. 5(a). An interior view is shown in Fig. 5(b). This rack isprimarily used to create dc/dc converters.

D. Op-Amp Rack

The front panel and interior of the op-amp rack is shown inFig. 6. Each amplifier circuit is built using an Apex Microtech-nology [15] PA12A high-power op-amp, setup as a noninvertingamplifier. The devices are rated at 90 V peak to peak, 15 A, andhave a bandwidth of 500 kHz. A current-limiting resistor canbe used to limit output current to safe levels for inexperiencedstudents.

The amplifiers are controlled using the station computerthrough a 25-pin D-SUB connector on the front panel. Thesignal for each op-amp is generated using a custom-designedLabVIEW VI, shown in Fig. 7. Using the VI, students choosethe wave form to generate the peak amplitude, phase shift, dcoffset, and duty cycle. The VI also contains a plot windowthat indicates the wave form being generated for each channel.


Fig. 5. Discrete device rack: (a) front panel and (b) interior.

Presently, this module can generate sinusoidal, square, trian-gular, and sawtooth wave forms. The speed of the computer(1 GHz) and data acquisition card limit the fundamental fre-quency of the wave forms to 10 kHz.

The flexibility provided by the op-amp rack is significant.First, it provides a means to generate two- and three-phase sig-nals with arbitrary harmonic content. This capability is usefulfor classroom demonstrations where multiphase power is typ-ically not available. It is also useful for short courses that areoften held in hotels or conference centers without multiphasepower. Further, since the wave forms generated can have arbi-trary harmonic content, the racks can be used to study the ef-fects of voltage harmonics on the behavior of a system (powerquality).

IV. DATA ACQUISITION, ANALYSIS, AND

SWITCH-LEVEL CONTROL

Along with the power electronic testbed, each laboratory sta-tion is equipped with a digital oscilloscope, a computer withdata acquisition cards, and a DSP box. This equipment is de-signed to provide relatively fast data collection, support anal-ysis, and changes in switch level and supervisory control. Cus-tomized tools are highlighted in Section IV-A and B.

A. Instrumentation and Analysis Software

Efficient data collection is important. It helps maintain stu-dent interest, and for research projects where multiple studiesand vast data storage are sometimes required, it reduces the time

Fig. 6. Op-amp rack: (a) front panel and (b) interior.

required to perform experiments. Each station in the power elec-tronics laboratory contains the instrumentation/computer com-bination listed in Table I. The VIs used in the power electronicslaboratory are listed in Table II.

Data collection and analysis is performed using VIs coupledwith the general-purpose interface bus (GPIB) computer cards.Once a wave form is captured on the oscilloscope and the probescales are set in the GetScope VI, the data is downloaded intoan ASCII file. This downloading allows the data to be read intoMATLAB or another VI for analysis.

Fig. 8 shows two profiles obtained from the data analysisVI. The top VI displays the time-domain data for each channel.The same VI is then used to display frequency-domain data, asshown in Fig. 8(b). All of the VIs were written by UM-Rollaundergraduate students as part of their senior design projects.

B. Computer and DSP Control

The computer and data acquisition card at each station can beprogrammed to implement open-loop, switch-level control. Thisprocedure is useful for illustrating basic concepts, such as 180conduction and sine-triangle pulsewidth modulation. LabVIEWVIs have been written for this purpose and are listed in Table III.Although many aspects of power electronics can be learnedusing open-loop control of circuits and systems, students ob-tain a sense of accomplishment and a better understanding ofcontrol theory by designing and programming closed-loop con-trols and implementing them in hardware. To obtain experiencewith closed-loop control design, a DSP is incorporated into thelaboratory. Since the objective of the laboratory is not to learn


Fig. 7. Function generator virtual instrument FunGen VI.

TABLE IINSTRUMENTATION AND COMPUTER SPECIFICATIONS

the intricacies of DSP programming, the DSPs are set up so thatthe students only need to determine and code the control lawusing C. The code necessary to access data ports, handle inter-rupts, etc., are provided to students, minimizing the program’scomplexity.

TABLE IILABVIEW VIs FOR POWER ELECTRONICS LABORATORY

The DSP board used is manufactured by Technosoft and uti-lizes a Texas Instrument (TI) TMSA320LF2407 DSP chip. It isa 30-MHz fixed-point DSP with 3.3-V I/O levels. Since it is afixed-point DSP, students are required to use integer values andadjust measured values for scales and dc offsets.

As shown in Fig. 9, each board is contained in its ownhousing, along with a power supply and interface board. Com-munication with the PC occurs through a nine-pin D-SUBconnector on the front panel, and the two 25-pin D-SUB con-nectors carry the digital outputs and analog I/O signals. Theexternal interface board, which was designed and built by anundergraduate student, provides buffering and signal condi-tioning for the DSP I/O. Each digital output is buffered with aunity gain op-amp to prevent a short circuit or low impedance.


Fig. 8. Data analysis VI: (a) time display and (b) fast Fourier transform (FFT).


TABLE IIILABVIEW SWITCH-LEVEL CONTROL VIs

Fig. 9. DSP & Interface board: (a) front and (b) inside.

from damaging the DSP. Similarly, the eight 10-b analog in-puts are isolated through an Analog Devices AD215 amplifierand provide a differential voltage measurement. The two 12-banalog outputs are buffered through unity gain op-amp circuits.Since the TI DSP chip does not have D/A converters built in,D/A I/Os were created by using the Technosoft board’s D/Aconverters, These are accessed through a serial digital outputfrom the TI DSP.

V. SAMPLE EXPERIMENTS

In the new power electronics course, experiments are used tovalidate analysis and design controls for converters, inverters,and rectifiers. In addition, experiments are performed to demon-strate the influence of parasitics on system performance (elec-tromagnetic interference, power quality, acoustic noise, etc.). Inthe machines/drives course, experiments are being designed to

Fig. 10. Single-phase half-wave rectifier.

Fig. 11. Rectifier circuit with sinusoidal input.

implement the control of brushless dc machines, stepper motors,and volts/Hertz control of induction machines. To demonstratethe utilization of the testbed in representative applications, twoexamples are provided.

A. Single-Phase Half-Wave Controlled Rectifier

Although quite simple, a single-phase half-wave controlledrectifier circuit demonstrates many of the testbed’s features, themost important of which is the op-amp rack. Other tools uti-lized include the LabVIEW modules FunGen, GetScope, andData_Analysis, the op-amp rack, and the discrete device rack.

Fig. 10 shows the schematic of the circuit. The source voltageis produced by using the op-amp rack to amplify the waveformproduced by the “FunGen” output.

Since the original wave form is produced by FunGen, thetiming information is known, and it can be synchronized withthe second channel in FunGen that is used for controlling theswitch. This procedure allows for phase control to be imple-mented easily.

To illustrate the flexibility of the FunGen module and op-amprack, two different wave forms were input to the rectifier cir-cuit. The results for a sinusoidal input are shown in Fig. 11. Theoutput voltage for firing angles of 0 and 30 are shown belowthe input voltage.

The results for a square-wave input, with the same firing an-gles, are shown in Fig. 12. In the figure, the upper trace is onecycle of input voltage, the middle trace is the 0 phase-delayhalf-wave rectified output voltage, and the bottom trace is the30 phase-delay rectified output voltage, respectively.

In the 30 firing angle studies, the output voltage is appliedto the load for a shorter duration of time; therefore, the averageoutput voltage over a cycle is less. This finding is supportedby the harmonic calculation shown in Fig. 13. As can be seen,


Fig. 12. Rectifier circuit with square-wave input.

Fig. 13. Rectifier output harmonics.

Fig. 14. dc/dc converter.

in both the sinusoidal and square-wave input, the 30 phase-delayed case has a reduced dc component. Also of note, andshown in Fig. 12, the phase delay introduces significant evenharmonics in the output voltage with a square-wave input. Thespectral components are obtained using the spectrum analysistool within the Data_Analysis VI.

B. dc/dc Converter

Another experiment that demonstrates the capabilities of thetestbed is a dc/dc converter, shown in Fig. 14. The input is adc voltage provided by the Sorenson power supply. Open-loopcontrol is achieved by controlling the switch with a square wavecreated in FunGen.

Closed-loop control of the switch is accomplished usingthe DSP. Specifically, the sensors on the control rack are set

Fig. 15. Step change voltage.

Fig. 16. Step change inductor current.

to match the analog inputs of the DSP. A template programhas been set up that provides the students with access to alldigital and analog I/O. Students are then required to createcode implementing a proportional-integral control. Controllerparameters are selected using Nyquist-based techniques basedupon a linearized average-value model of a buck converter(assuming continuous conduction). The parameter selection istested in simulation before running the system in hardware.The students create simulations in MATLAB and compare pre-dicted responses with measured data. A typical wave form thatis established in the laboratory is shown in Fig. 15. Depictedis the output voltage response when the load undergoes a stepchange from 150–100 . The corresponding inductor currentresponse is shown in Fig. 16. Both the simulation and measureddata are plotted. The responses compare favorably, which helpto ensure confidence in the students that the analysis performedis valid.


VI. STUDENT ASSESSMENT OF LABORATORY COURSE

Initially, this laboratory course has produced a favorableresponse from students. The course has had full enrollment thetwo semesters it has been offered and has received a 3.6/4.0rating for its educational value from student evaluations. Thisrating compares with an average rating of 2.9/4.0 for electricaland computer engineering courses at UM-Rolla. One of thecourse’s stated goals is to help students develop the skills nec-essary to design and analyze power-electronic-based systems.Written comments on the evaluations indicate that the course ismeeting this goal. Students have found that the course providessignificant practical experience and effectively integrates themany topics associated with power electronic systems. In par-ticular, students have commented that the closed-loop controldesign experiments are particularly beneficial. Although stu-dents have had classes in linear systems and control theory, veryfew have practical experience applying this knowledge to thecomplete design of a system. In terms of student achievement,all of the students involved in the laboratory’s developmenthave chosen to pursue graduate school or a career in power-re-lated fields.

VII. SUMMARY

In this paper, key components of a new power electronics lab-oratory at UM-Rolla are described. The novel hardware toolsinclude five mobile power electronics testbeds that each con-tain the semiconductor devices, gate-drive boards, voltage andcurrent sensors, and computer interface connections required tostudy a wide range of circuit topologies and control techniques.Novel software tools include a set of virtual instruments (VIs)used for control, data capture, and data analysis. The results ofexperiments are used to explain their use in a power electronicslaboratory.

REFERENCES

[1] LabVIEW User Manual, National Instruments, Austin, TX, 1998.[2] MATLAB: The Language of Technical Computing. Natick, MA: The

MathWorks, Inc., 1996.[3] N. Mohan, W. P. Robbins, P. Imbertson, T. M. Undeland, R. C.

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[4] P. T. Krein and P. W. Sauer, “An integrated laboratory for electric ma-chines, power systems, and power electronics,” IEEE Trans. Power Syst.,vol. 7, pp. 1060–1067, Aug. 1992.

[5] P. T. Krein, Elements of Power Electronics. New York: Oxford Univ.Press, 1998, pp. XIV–XV.

[6] R. W. Erickson and D. Maksimovic, Fundamentals of Power Elec-tronics. Norwell, MA: Kluwer, 2001, pp. 813–841.

[7] N. Mohan, T. M. Undeland, and W. P. Robbins, Power Electronics: Con-verters, Applications, and Design. New York: Wiley, 1995, pp. 61–75.

[8] L. Goel, T. T. Lie, A. I. Maswood, and G. B. Shrestha, “Enhancing powerengineering education through the use of design modules,” IEEE Trans.Power Syst., vol. 11, pp. 1131–1138, Aug. 1996.

[9] R. M. Bass and M. M. Begovic, “A senior design course bridging powersystems and power electronics: Power quality impacts of electric vehiclecharging,” IEEE Trans. Power Syst., vol. 12, pp. 1040–1045, Aug. 1997.

[10] D. W. Hart, “Circuit simulation as an aid in teaching the principles ofpower electronics,” IEEE Trans. Educ., vol. 36, pp. 10–16, Feb. 1993.

[11] H. Widlok, “The applications of concurrent simulation in the power elec-tronics laboratory,” in Proc. IEEE Int. Symp. Industrial Electronics, vol.2, June 1996, pp. 573–577.

[12] S. S. Ang, “A practice-oriented course in switching converters,” IEEETrans. Educ., vol. 39, pp. 14–18, Feb. 1996.

[13] D. A. Torrey, “A project-oriented power electronics laboratory,” IEEETrans. Power Electron., vol. 9, pp. 250–255, May 1994.

[14] (2003) IGBT-Driving Hybrid IC’s (EXB8…-Series) Application Manual.Fuji Semiconductor. [Online]. Available: http://www.fujisemiconductor.com/pdf/app_notes/reh982.pdf

[15] (2003) Power Integrated Circuit Data Book. Apex Microtechnology.[Online]. Available: http://www.apexmicrotech.com

Joshua M. Williams (S’96) was born in Peoria, IL, on September 1, 1977. Hereceived the B.S., M.S., and Ph.D. degrees in electrical engineering from theUniversity of Missouri–Rolla, in 1999, 2001, and 2004, respectively.

He was a National Science Foundation Integrative Graduate Educationand Research Traineeship (IGERT) Program Fellow at the University ofMissouri-Rolla. His interests include finite-element and magnetic-equivalentcircuit modeling techniques, machine design and optimization, and hybridelectric vehicle propulsion systems. He is currently with Caterpillar Electronics,CGT-Advanced Engineering Division.

Dr. Williams is a Member of Eta Kappa Nu, Phi Kappa Phi, and Tau Beta Pi.He received the Grainger Award for Outstanding Power Engineering Student in2001.

James L. Cale (M’03) received the B.S. (highest distinction) degree in electricalengineering from the University of Missouri—Rolla in 2001 and the M.S. degreein electrical engineering from Purdue University, West Lafayette, IN, in 2003.He is currently working toward the Ph.D. degree in electrical engineering atPurdue University under a National Science Foundation Integrative GraduateEducation and Research Traineeship (IGERT) fellowship.

He served in the United States Army Reserves from 1994 to 2003 and internedat the Cooper Nuclear Reactor, Brownville, NE, in 2000. His interests includeelectric machinery and drives, power electronics, electromagnetics, and geneticalgorithms.

Nicholas D. Benavides (S’00) was born in St. Louis, MO, on August 17, 1981.He received the B.S. degree in electrical engineering from the University ofMissouri—Rolla, in 2003. He is currently working toward the M.S. degree inelectrical engineering from the University of Illinois at Urbana-Champaign.

He worked as a Research Assistant under Dr. S. Pekarek while at the Uni-versity of Missouri—Rolla from 2001 to 2003. He is currently working as aResearch Assistant under Dr. P. Chapman at the University of Illinois at Ur-bana-Champaign.

Mr. Benavides received the Grainger Award for Outstanding Power Engi-neering Students in 2003.

Jeff D. Wooldridge was born in Springfield, MO. He received the B.S. degreein electrical engineering from the University of Missouri—Rolla in 2001.

He was a co-op student with City Utilities of Springfield, MO, from 1999to the end of 2000 and was a Research Assistant while an undergraduate. Heis currently a System Protection and Planning Engineer at the Empire DistrictElectric Company, Joplin, MO.

Mr. Wooldridge is an active Member of the Joplin Chapter of the MissouriSociety of Professional Engineers as an engineer-in-training. He received theGrainger Outstanding Power Student Award in 2001.

Andreas C. Koenig (S’99) was born in New Orleans, LA, on August 15, 1979.He received the B.S. and M.S. degrees in electrical engineering from the Uni-versity of Missouri—Rolla in 2001 and 2003, respectively.

He is currently a National Science Foundation Graduate Research Fellow atPurdue University, West Lafayette, IN. His interests include hardware design,numerical analysis, and automated control of power electronic systems and elec-tric machinery.


Jerry L. Tichenor (S’94–M’96) was born in Springfield, MO, on August 26,1971. He received the B.S. and M.S. degrees in electrical engineering from theUniversity of Missouri—Rolla in 1994 and 1996, respectively.

He is currently an Associate Research Engineer at the University of Mis-souri—Rolla. His research interests include power electronics and electric drivesystems.

Steven D. Pekarek (M’92) was born in Oak Park, IL, on December 22, 1968.He received the B.S.E.E., M.S.E.E., and Ph.D. degrees from Purdue University,West Lafayette, IN, in 1991, 1993, and 1996, respectively.

He is currently an Associate Professor of Electrical Engineering at PurdueUniversity. His interests include power electronics, electric machines, numericalanalysis, and automated control.

436 ieee transactions on education, vol. 47, no. 4, november 2004

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