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IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 41, NO. 1, JANUARY/FEBRUARY 2005 83

A Hybrid Solution forLoad-Commutated-Inverter-Fed

Induction Motor DrivesSangshin Kwak , Student Member, IEEE, and Hamid A. Toliyat , Senior Member, IEEE

Abstract—A novel, hybrid solution employing a combination of a load-commutated inverter (LCI) and a voltage-source inverter(VSI) is proposed for induction motor drives. By avoiding the useof output capacitors and a forced dc-commutation circuit, this so-lution can eliminate all disadvantages related with these circuits inthe conventional LCI-based induction motor drives. In addition,improved quality of output current waveforms and faster dynamicresponse can be achieved. The proposed hybrid scheme featuresthe following tasks: 1) the safe commutation angle for the LCI,controlled by the VSI in the entire speed region of the induction

motor and 2) a dc-link current control loop to ensure minimumVSI rating. Advantages of the proposed solution over the conven-tional LCI-based induction motor drives include the following: 1)sinusoidal motor phase current and voltage based on the instan-taneous motor speed control; 2) fast dynamic response by the VSIoperation; and3) elimination of motor circuit resonance and motortorque pulsation. The feasibility of the proposed hybrid circuit forthe high-power drive system is verified by computer simulation fora 500-hp induction motor. Experimental results to support the useof theproposed systemare also included for a 1-hp induction motorlaboratory setup.

Index Terms—AC output capacitor, hybrid circuit, inductionmotor, load-commutated inverter (LCI).

I. INTRODUCTION

THE load-commutated-inverter (LCI)-based induc-

tion motor drives have been traditionally used in

very-high-power applications such as pumps, compressors,

and fans drives. The drives are based on economical and reli-

able current-source inverters (CSIs) using thyristors, and rugged

squirrel-cage induction motor. The merits of the LCI-based

system result from the fact that it employs converter-grade

thyristors and utilizes natural commutation of the thyristors.

It provides simplicity, robustness, cost effectiveness, and very

low switching losses [6], [11]. Moreover, because it has the CSI

topology, it has inherent advantages of CSI: 1) short-circuit

protection: the output current is limited by the regulated dc-link

current; 2) high converter reliability, due to the unidirectional

nature of the switches and the inherent short-circuit protection;

and 3) instantaneous and continuous regenerative capabilities

Paper PID-04-28, presentedat the 2003 IndustryApplicationsSociety AnnualMeeting, Salt Lake City, UT, October 12–16, and approved for publication inthe IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Mining IndustryCommittee of the IEEE Industry Applications Society. Manuscript submittedfor review October 15, 2003 and released for publication October 12, 2004.

The authors are with the Department of Electrical Engineering,Texas A&M University, College Station, TX 77843-3128 USA (e-mail:[email protected]; [email protected]).

Digital Object Identifier 10.1109/TIA.2004.841025

[9]. With all these features, the drive is especially beneficial to

milling operations for the mining industry. Research has been

conducted in the last two decades to control the LCI-based in-

duction motor drive and improve its performance for medium-

to high-power applications [2]–[7].

However, the conventional LCI-based induction motor drives

have shown some serious difficulties. Since the system has a

thyristor-based topology, it must guarantee safe commutation

for thyristors, requiring that the LCI be faced with a leadingpower factor in all operating regions. The leading power factor

required for natural commutation is generated by additional

output capacitorsconnected in parallel with the induction motor,

sincetheinductionmotorcannotprovidetheleadingpowerfactor

through excitation control employed for the synchronous motor.

As the power rating of the induction motor is increased, a larger

capacitance is required to create higher leading var requirement

taken by the capacitor, which could become unreasonably

high. Output capacitors also set up resonance phenomena by

the interaction with the motor inductance, seriously restricting

the drive performance and causing inherent instability in the

high-frequency region [4]. Large output capacitors may cause an

undesirable self-excitation under certain conditions, a problemwhich becomes aggravatedat higherspeeds [2]. This approach to

generate the leading power factor through the output capacitor,

although very widely used, has fundamental problems resulted

from the approach itself. In addition, at startup and during

low speed operation, the leading vars generated by the output

capacitor decrease, resulting in the lagging power factor, thus,

load commutation is not possible. Therefore, a complex and

costly forced dc-commutation circuit is required for the LCI

operation at the lower speed region [4]. Moreover, the quasi-

square-wave motor current waveforms in the low-speed region,

rich in low-order harmonics, can produce considerable current

harmonics and resultant losses as well as voltage spikes in thestator leakage inductance of the motor, potentially hazardous

for early machine failure [8], [10].

In this paper, a novel hybrid solution for the LCI-based in-

duction motor drive using a parallel assembly of an LCI and a

voltage-source inverter (VSI), is proposed. The operation of the

proposed circuit is investigated and described. It is shown that

all problems caused by the output capacitors and the dc-com-

mutation circuit in the conventional LCI-based induction motor

system can be overcome by the proposed solution. This hybrid

solution has the following features and advantages.

1) The leading power factor required for load commutation

of the LCI is fully provided by the VSI in all operating

0093-9994/$20.00 © 2005 IEEE



84 IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 41, NO. 1, JANUARY/FEBRUARY 2005

Fig. 1. Conventional LCI-based induction motor drive.

regions. This safe commutation for the LCI is achieved by

active control of the leading power factor angle through

the VSI.

2) All problems caused by the output capacitor in the

conventional LCI-based induction motor drives, such

as fundamental and harmonic resonance, and inherent

instability in the high frequency region, can be solved

since the VSI emulates the output capacitor.

3) By avoiding the use of complex and costly forced dc-com-mutation circuit, the potential risk of commutation failure

regarding the dc-commutation circuit and the torque pul-

sation of the motor can be eliminated.

4) The motor currents and voltages under all running condi-

tions are nearly pure sinusoidal, containing little harmonic

components.

5) The proposed system shows fast dynamic response by the

VSI operation.

6) Minimum VSI rating and cost are achieved by the pro-

posed strategy.

Simulation and experimental results are shown to demonstrate

the feasibility of the proposed system and control structure.

II. REVIEW OF STANDARD LCI-BASED INDUCTION

MOTOR DRIVE

A typical schematic diagram of an LCI-basedinduction motor

drive is shown in Fig. 1. It consists of a three-phase controlled

rectifier at the input side and a CSI at the output side with a large

dc-link inductor. The amplitude of the currents supplied to the

motor is controlled by the phase-controlled rectifier through

a dc-link inductor. The dc-link inductor reduces the current

harmonics and ensures that the input of the LCI and, hence, to

the motor appears as a current source. The dc current magnitude

as well as the motor current magnitude can be controlled byadjusting the firing angle of the controlled rectifier. The load

inverter can control only the fundamental frequency of motor

currents by selecting the gating instances of thyristors. For

successful commutation of the thyristors in the LCI, the output

current of the LCI, must lead the corresponding motor

phase voltage, . Since motor phase currents in induction

motors always lag the corresponding motor phase voltages by

the induction motor characteristics, a leading power factor is

obtained by the output capacitor. The output ac capacitors are

required to provide a phase shift of the motor phase current,

resulting in a leading power factor. The vector diagram of

Fig. 2 explicitly explains how the output capacitor provides a

phase shift of the current, resulting in a leading power-factorangle . This leading power factor allows thyristors in the LCI

Fig. 2. Vector diagram of the conventional LCI-based induction motor drive.

to commutate at speeds above critical frequency of induction

motors. The output capacitor also smoothes out the output

current waveform coming from the inverter to nearly sinusoidal

in the high-frequency operation by providing a low-impedance

path for current harmonics.

However, at startup and in the low-speed region, these output

capacitors cannot make enough leading angle because the ca-

pacitor currents are too small due to high impedance of the ca-

pacitors. Thus, additional forced dc-commutation circuits are

required to facilitate the commutation from one phase to an-

other phase, by effectively bypassing the flow of dc-link cur-

rent around the load. With the operation of this circuit, the in-

duction motor can start up and bring the operation to above the

critical speed, which will ensure load commutation by output ca-

pacitors. However, this conventional LCI-based induction motor

system with the output capacitor and the dc-commutation circuit

has shown some drawbacks.

1) Since output ac capacitors should fully compensate the

effect of inductance in the induction motor in order to

provide a phase shift, the required capacitor size must beincreased in proportion to the power rating of an induction

motor.

2) Output ac capacitors are not reliable, especially in high-

power applications.

3) Resonance phenomena can be caused by the interaction

between the output capacitor and the inductance of the

motor. These fundamental and harmonic resonance prob-

lems have seriously restricted the system performance.

4) Inherent instability in the high-frequency region can be

caused by the output capacitor.

5) A torque pulsation during low-speed operation can occur

by forced commutation performed in the dc-commutationcircuit.

6) At startup and during the low-speed region, the

quasi-square-wave motor current waveforms, rich in

low-order harmonics, produce considerable current har-

monics, which can cause losses and heating inside the

machine. Furthermore, they can lead to voltage spikes in

the stator leakage inductance of the motor.

III. PROPOSED HYBRID INVERTER SYSTEM

A. Topology and Properties

A complete power circuit diagram of the proposed system

is illustrated in Fig. 3. It is composed of a three-phase con-trolled rectifier, an LCI followed by a dc-link inductor, and a



KWAK AND TOLIYAT: HYBRID SOLUTION FOR LCI-FED INDUCTION MOTOR DRIVES 85

Fig. 3. Circuit diagram of the proposed system.

three-phase VSI. The VSI is connected with the LCI in parallelthrough a small LC filter. Basically, the proposed system has a

combined inverter topology of an LCI and a VSI. Notice that al-

though this configuration is similar to the topology of an active

power filter or a tandem inverter, its purpose and operation are

quite different from them.

The LCI operates in the quasi-square-wave mode with con-

verter-grade thyristors. Consequently, thyristors in the LCI nat-

urally turn on and off only once per cycle of the output current

and, therefore, their switching loss is negligible.

The main function of the VSI is to apply sinusoidal phase

voltages to the induction motor in order to regulate the motor

speed as well as provide a safe commutation angle for the LCI.The induction motor speed is controlled by transiently adjusting

the output voltage amplitude and frequency of the VSI. In addi-

tion, the phase angle of the output voltage is achieved by shifting

the firing angle of the LCI suitably to obtain a safe load com-

mutation angle. Therefore, the leading power factor for the LCI

operation is entirely obtained by the VSI over the whole speed

range of the induction motor. Based on the leading power factor

for the LCI provided by the VSI, the proposed system can run

an induction motor without the dc-commutation circuit as well

as output ac capacitors of the conventional LCI-based induc-

tion motor drives. As a result, the proposed system can success-

fully solve all problems caused by the output capacitors and

the forced dc-commutation circuit. In addition, the proposed

scheme can generate sinusoidal motor voltages and currents for

all speed regions, leading to a reduction in the low-order har-

monics injected into the motor. This allows elimination of the

torque pulsation and harmonic losses due to motor currents with

quasi-square-wave of the conventional LCI. A small LC filter is

required to smooth out the pulsewidth-modulated voltages gen-

erated by the VSI.

Fig. 4 shows a per-phase equivalent circuit of the proposed

system. The proposed system has a parallel connection of two

inverters, the LCI represented by the current source , and

the VSI represented by the voltage source . The VSI im-

presses a sinusoidal motor phase voltage to the motor. More-over, it controls leading power factor for safe commutation of

Fig. 4. Per-phase equivalent circuit of the proposed system.

Fig. 5. Vector diagram of the proposed system.

the LCI. A motor phase current is determined by the sinu-

soidal motor phase voltage controlled by the VSI. Concur-

rently, the LCI also supplies a current to the motor. There-

fore, the motor phase current is the sum of the LCI output

current and the VSI output current . From the op-

erating point of view, the fast VSI operates as a master inverter

and the slow LCI as a slave. As a result, the proposed system can

show a fast system transient response compared with the con-

ventional LCI-based induction motor drive since the proposedsystem has time response close to the sampling period of the

VSI.

Fig. 5 shows a current vector diagram of the proposed system.

The phase angle represents the leading power-factor angle for

safe commutation of the LCI. This angle is controlled by ad-

justing the phase angle between the motor phase voltage and

the gating instant of the LCI. Therefore, this strategy ensures

safe commutation of the LCI over all operating speeds of the

induction motor. The phase angle denotes the power factor

angle of the induction motor. In terms of power rating sup-

plied to the motor, the LCI supplies the real power to the motor

load, while the VSI provides the real power corresponding tophase shift between the LCI output current and the motor phase

voltage, as well as the reactive and the harmonic power. The

LCI is not comparable to the VSI from the cost point of view.

Therefore, the VSI power rating should be kept to a minimum

to make the proposed system a cost-effective solution. Because

the VSI should supply its output current equal to the difference

between the motor phase current and the LCI output cur-

rent , the VSI output current is proportional to the

phase angle between and , corresponding to .

Thus, the phase angle should be maintained at a minimum

value for small VSI rating. This condition can be obtained by

adjusting the leading angle to the minimum value satisfying

safe commutation, and controlling the induction motor powerfactor. Since a high-power induction motor has better power-




Fig. 6. Overall control scheme of the proposed system.

factor characteristics than a small-rating motor, it is expected

that the power-factor angle is small in high-power motor ap-

plications. It makes the proposed system more competitive and

useful for high-power applications.

B. Control System Structure

The general control block diagram of the proposed hybrid in-

verter based drive is shown in Fig. 6. The overall control strategyis composed of two main control loops.

The first control loop is the motor speed control based on

operation of the VSI. The motor speed can be regulated using

a closed-loop speed controller using the slip-speed regulator,

which determines the slip-speed reference. The synchronous

speed, obtained by adding the actual speed and the slip speed,

sets the inverter operating frequency. The voltage amplitude

command then is set from the inverter frequency using a func-

tion generator, which ensures a nearly constant flux operation.

Finally, the phase angle of the motor voltage is decided in order

to provide a leading power factor ( ) for the safe commutation

of the LCI. The space-vector modulator produces the switchingpattern based on the amplitude, frequency, and phase command

signal for the sinusoidal output voltage of the VSI. This speed

loop control implemented by the VSI ensures a fast dynamic re-

sponse with much faster sampling period than the conventional

LCI.

The second control loop is for the dc-link current control

using the controlled rectifier. This scheme varies the dc-link cur-

rent in order to keep the VSI rating minimized at steady state.

The main function of this loop is to set the dc-link current ref-

erence in such a way that the VSI rating is minimized, based

on the motor current amplitude and the phase angle . The

next section demonstrates theoretically that the converter rating

of the VSI can be effectively minimized by properly adjustingthe dc-link current.

Fig. 7. LCI current, motor phase voltage, motor phase current, and VSIcurrent.

C. Converter Size Consideration and VSI Rating Minimization

Strategy

Since the proposed hybrid circuit consists of two inverters, the

output power distribution between them, given a certain motor

power requirement, is important. A rating factor is defined as

the ratio of the LCI rating and the VSI rating. Note that two

inverters are connected with the same motor phase voltage in

their output terminals by assuming that voltage drop due to the

output LC filter for the VSI is negligible. Therefore, the rating

factor is directly proportional to the ratio of rms values of the

VSI output current and the LCI output current

(1)

The large-power VSI required for the drive results in a very

high system cost, which will limit the proposed system. From

the cost point of view, the LCI is not comparable to the VSI.

As a result, it is desirable to minimize the rating factor under

an operating power required for the induction motor. In order

to derive the dc-link current control to minimize the VSI rating,

the dc-link stage of the LCI is modeled by a pure current source.

Fig. 7 illustrates the plots of output currents of the two inverters,

the motor phase voltage, and the current. Since the motor cur-

rents are sinusoidal quantities and the LCI currents have no

ripple components in the dc link, the LCI output current and

the motor output current are expressed by

(2)

where is the amplitude of the sinusoidal motor phase cur-

rent.

The rating factor can be derived, using (1) and (2), by

(3)

In (3), it should be noticed that motor phase current amplitude

depends on the motor shaft speed and leading power-factorangle is a control factor for the safe commutation of the LCI.




Fig. 8. Ratio of the dc-link current and motor phase current amplitude as afunction of phase angle.

In addition, is the lagging power-factor angle of the induc-

tion motor, which is detectable. Then, the dc-link current value

which minimizes the VSI rating can be obtained by setting the

derivative of with respect to the dc-link current to zero

(4)

This yields a dc-link current command given by

(5)

Equation (5) allows the dc-link current control to achieve

the minimum VSI rating requirement based on the motor cur-

rent and phase shift between the motor current and the LCI

output current. This dc-link current control algorithm is imple-mented by the controlled rectifier. It is worth noting that from

(5), with increased power-factor angles , the dc-link cur-

rent value to minimize the rating factor also increases. Fig. 8

illustrates the plot of the dc-link current command as a function

of motor phase current amplitude versus phase angle.The mini-

mized rating factor is

(6)

It is important to note that the dc-link current value and the cor-

responding minimized rating factor are unique at every oper-

ating point of the induction motor and a given leading powerfactor angle . Fig. 9 shows a minimized rating factor with the

dc-link current value of (5) as a function of phase angle.

IV. SIMULATION RESULTS

In order to investigate the performance of the proposed hybrid

system, a detailed computer simulation was performed using

a 500–hp induction motor whose parameters are given in the

Appendix .

Fig. 10 depicts the motor shaft speed under full load. Motor

shaft speed was set to 900 r/min, resulting in the frequency of the

inverter being 30 Hz. Fig. 11 shows the three-phase motor phase

currents and the LCI output currents at steady state. The motorphase current has a phase delay with respect to the LCI output

Fig. 9. Minimized rating factor versus phase angle.

Fig. 10. Induction motor shaft speed under full load.

Fig. 11. Motor phase currents and output currents of the LCI at steady state.

current, corresponding to the sum of leading power-factor angle

( ) and the load power-factor angle ( ). The leading power-

factor angle ( ) is controlled for the safe commutation of thyris-

tors using the VSI. A 10 leading angle ( ) between the motor

phase voltages and the gating instants of the LCI was used to

ensure safe commutation for corresponding thyristor switches.

On the other hand, the load power-factor angle ( ) between themotor phase voltage and the motor phase current is determined




Fig. 12. LCI output current, motor phase current, output current of the VSI,and dc-link inductor current.

by the motor characteristics, which was about 30 in this simu-

lation. The dc-link current command was set by (5) in order

to minimize the VSI rating. It is noticed that the dc-link current

is regulated to about a 18% higher value than the motor cur-

rent amplitude with 40 phase-shift angle between the LCI

and the motor currents.

Fig. 12 shows the LCI output current, the motor phase cur-

rent, the VSI output current, and the dc-link inductor current

at steady state, respectively. It can be noted that the VSI output

current provides the difference between the motor phase currentand the LCI output current in order to supply the active power

for the phase shift as well as the reactive power to the motor.

The dc-link inductor current shows some harmonic ripple com-

ponents because of the finite dc-link inductor, which appear in

the LCI output current.

V. EXPERIMENTAL RESULTS

To validate the proposed topology and control algo-

rithm, the prototype hybrid system was developed using

an LCI, a phase-controlled rectifier, and a VSI. An insu-

lated-gate-bipolar-transistor (IGBT)-based commercial inverter(SEMIKRON) was used as a VSI. In addition, a prototype of a

phase-controlled rectifier and an LCI was fabricated in the lab-

oratory. A 120-mH dc-link inductor was used for the LCI. The

proposed control structure was implemented with a fixed-point

digital signal processor (DSP) board (TMS320LF2407). The

VSI control signals were provided through the PWM ports

of the DSP board. On the other hand, the gating pulse com-

mands of the controlled rectifier and the LCI were generated

with digital I/O port signals of the DSP board and 20-kHz

external oscillator signal due to limited PWM ports of the

DSP board. The pulse trains through pulse transformer boards

(FCOAUX60) were used to turn on the thyristors of the con-

trolled rectifier and the LCI. In the experiment, a 230-V 60-Hz1-hp general-purpose induction motor was employed as the

Fig. 13. Output current waveforms of the proposed system at steady state at(a) 20 Hz, (b) 40 Hz, and (c) 60 Hz (upper trace: LCI output current [1 A/div);middletrace: VSIoutputcurrent (1 A/div); lower trace:motor current (1 A/div)].

load. A three-phase output filter was implemented using a

0.5-mH inductor and a 50- F capacitor.

Steady-state operation of the proposed system with differentoutput frequency (20, 40, and 60 Hz) is illustrated in Fig. 13.

The current waveforms show that the motor currents are si-

nusoidal with little harmonics and the VSI injects output cur-

rents corresponding to the difference between the LCI and the

motor current. Fig. 14 illustrates the LCI output current and

the motor phase voltage. A leading power-factor angle ( ) be-

tween the LCI output current and the motor phase voltage was

set to 5 to ensure safe load commutation. Based on this angle,

the LCI can operate successfully without any commutation fail-

ures over all speed ranges. Fig. 15 shows the LCI output cur-

rent and the motor current at steady state. Since the 40 phase

angle ( ) between the LCI and the motor current was de-

tected, the dc-link current was regulated to about 18% highervalue than the motor current amplitude by the proposed control




Fig. 14. LCI output current and output phase voltage (1 A/div, outputfrequency of 60 Hz).

Fig. 15. LCI output current and output current (1 A/div, output frequency of 60 Hz).

Fig. 16. (a) Supply line voltage and input current of the controlled rectifier (1A/div) and (b) dc-link current at steady state (1 A/div).

strategy to minimize the VSI power rating. Fig. 16 shows thesupply line voltage, the input current of the controlled rectifier,

Fig. 17. Output current waveforms with a rapid amplitude change at 60-Hzoutput frequency [upper trace: LCI output current (1 A/div); middle trace: VSIoutput current (1 A/div); lower trace: motor current (1 A/div)].

Fig. 18. Output current waveforms with a frequency change from 30 to 60 Hz[upper trace: LCI output current (1 A/div); middle trace: VSI output current (1

A/div); lower trace: motor current (1 A/div)].

and the dc-link current. The dc-link current is regulated by the

phase shift information between the LCI output current and the

motor current. Figs. 17 and 18 depict the output current wave-

forms under a rapid amplitude change and a rapid frequency

change, respectively.

VI. CONCLUSION

In this paper, a new hybrid solution for the LCI-based induc-

tion motor drive has been proposed based on the parallel as-

sembly of the LCI and the VSI. The proposed strategy allowsthe operation of the LCI with a safe commutation angle provided

by the VSI, regardless of the load speed and torque. By elimi-

nating the requirement of the output capacitors and the forced

dc-commutation circuit for the conventional LCI-based induc-

tion motor drive, this solution is quite free from all problems,

such as resonance, inherent instability, and torque pulsation,

caused by the conventional LCI drives. In addition, sinusoidal

motor phase currents and faster response are obtained with the

proposed system. The dc-link current control strategy has been

derived and implemented to achieve minimim VSI power rating,

according to the phase angle between the motor current and the

LCI output current. This paper includes the simulation and ex-

perimental results that validate the feasibility of the proposedtopology and control algorithm.




APPENDIX

INDUCTION MOTOR PARAMETERS

Induction motor parameters are as follows:

rated power 500 hp;

inertia (J) 11.06 kg m ;

number of poles 4;

0.262 ;0.187 ;

54.02 ;

1.206 ;

1.206 .

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Sangshin Kwak (S’02) received the B.S. and M.S.degrees in electronics engineering from Kyungpook National University, Taegu, Korea, in 1997 and1999, respectively. He is currently working towardthe Ph.D. degree in electrical engineering at TexasA&M University, College Station.

During the summer of 2004, he was with theWhirlpool R&D Center, Benton Harbor, MI.

His main research interests are ac/dc, dc/ac, andac/ac power converters topologies and controls,adjustable-speed drives, and DSP-based power

electronics control.

Hamid A. Toliyat (S’87–M’91–SM’96) received theB.S. degree from Sharif University of Technology,Tehran, Iran, in 1982, the M.S. degree from West Vir-ginia University, Morgantown, in 1986, and thePh.D.degreethe from University of Wisconsin, Madison, in

1991, all in electrical engineering.Following receipt of the Ph.D. degree, he joined

the faculty of Ferdowsi University of Mashhad,Mashhad, Iran, as an Assistant Professor of Elec-trical Engineering. In March 1994, he joined the

Department of Electrical Engineering, Texas A&MUniversity, College Station, where he is currently the E. D. Brockett Professorof Electrical Engineering. His main research interests and experience includeanalysis and design of electrical machines, variable-speed drives for tractionand propulsion applications, fault diagnosis of electric machinery, and sen-sorless variable-speed drives. He has authored over 230 published technical

papers in these fields and has ten issued or pending U.S. patents. He is activelyinvolved in presenting short courses and consulting in his area of expertise to

various industries. He is the author of DSP-Based Electromechanical Motion

Control (Boca Raton, FL:CRC Press,2003) and the Co-Editor of the Handbook

of Electric Motors (New York: Marcel Dekker, 2004, 2nd. ed.).Dr. Toliyat received the prestigious Cyrill Veinott Award in Electromechan-

ical Energy Conversion from the IEEE Power Engineering Society in 2004,TEES Fellow Award in 2004, Distinguished Teaching Award in 2003, E. D.Brockett Professorship Award in 2002, Eugene Webb Faculty Fellow Award in2000, and Texas A&M Select Young Investigator Award in 1999 from TexasA&M University. He also received the Space Act Award from NASA in 1999,

and Schlumberger Foundation Technical Awards in 2000 and 2001. He is anEditor of the IEEE TRANSACTIONS ON ENERGY CONVERSION and was an As-sociate Editor of the IEEE TRANSACTIONS ON POWER ELECTRONICS. He is also

Chairman of the Electric Machines Committee of the IEEE Industry Applica-tions Society and a Member of Sigma Xi. He is a Senior Member of the IEEE

Power Engineering, IEEE Industry Applications, IEEE Industrial Electronics,andIEEE Power Electronics Societies, andthe recipientof the1996 IEEE PowerEngineering Society Prize Paper Award for hispaper, “Analysis of ConcentratedWinding Induction Machines for Adjustable Speed Drive Applications—Exper-imental Results.”.

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