IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULY/AUGUST 1986
Microcomputer Control of Switched ReluctanceMotor
BIMAL K. BOSE, SENIOR MEMBER, IEEE, TIMOTHY J. E. MILLER, SENIOR MEMBER, IEEE, PAUL M. SZCZESNY, AND
WILLIAM H. BICKNELL
Abstract-A microcomputer-based four-quadrant control system of aswitched reluctance motor is described. The control was implementedwith a speed feedback loop, a torque feedback loop, and both the torqueand speed feedback loops combined. In addition the controller incorpo-rates a startup operation, sequencing, and synchronized angle steeringcontrol. The angle controller was designed using dedicated digitalhardware, whereas the other functions were implemented using an Intel8751 single-chip microcomputer. The complete control system was testedin the laboratory with a 5-hp drive, and the test results were found to beexcellent.
INTRODUCTION
INTEREST in switched reluctance motor (SRM) drives hasrevived during the last five to ten years. The points in favor
of SRM drives are that the machine is simple in constructionand economical compared to induction and synchronous typesof machines [6]. In addition, the converter which suppliespower to the machine requires fewer power devices and,therefore, is more economical and reliable [7]. The SRMdrives have received wide attention in Europe, and seriousattempts are being made to commercialize them.The literature on SRM drives concentrates mainly on the
analysis of the machine and the configuration of the powerconverters, but very few papers discuss the control a'spects.The control requirements of the SRM drive are so unique thatthe concepts of induction- and synchronous-type machines canhardly be extrapolated to the SRM. The SRM drives discussedin the literature are mainly open-loop control with angle andcurrent amplitude regulation and have usually been designedwith discrete components and dedicated hardware.
This paper describes a microcomputer-based control of theSRM drive system which is capable of operating in all fourquadrants. The microcomputer functions include feedbackspeed and torque controls, computation of the feedback speedand torque, starting, sequencing control, computation of theswitching angles, and a phase-locked loop for the angle
Paper IPCSD 86-1, approved by the Industrial Drives Committee of theIEEE Industry Applications Society for presentation at the 1985 IndustryApplications Society Annual Meeting, Toronto, ON, Canada, October 6-1 1.Manuscript released for publication February 5, 1986.
B. K. Bose is with the General Electric Research and Development Center,Building 37-380, 1 River Road, Schenectady, NY 12345.
T. J. E. Miller and P. M. Szczesny are with the General Electric Company,Corporate Research and Development Center, Building 37-380, P.O. Box 43,Schenectady, NY 12301.W. H. Bicknell is with the General Electric Company, Corporate Research
and Development Center, Building 37-478, P.O. Box 43, Schenectady, NY12301.IEEE Log Number 8608632.
controller. The angle controller, which interfaces to themicrocomputer, has been designed using dedicated hardware.The complete control system has been designed and tested inthe laboratory with a prototype drive system.
POWER CIRCUIT OPERATIONThe control system was developed for a four-phase machine
which has four stator pole pairs and three rotor pole pairs. Thepower converter with a cross section of the machine is shownin Fig. 1. The opposite stator poles are supplied by a converterphase, and the phase current is switched on and off insynchronism with the rotor position. The bifilar winding inseries with the diode returns stored energy to the source whenthe transistor turns off. The transistors conduct in sequence,and the order of conduction depends on the direction of therotation. A dynamic brake exists in the dc link (not shown)which absorbs energy during regeneration.The inductance profile of the stator pole pair with respect to
the rotor angular position is shown in Fig. 2, which alsoindicates typical stator phase current waves. In a forwardmotoring mode, for example, the current pulse is establishedwhere the inductance profile has a positive slope. This isbecause the instantaneous motor torque is given by the relation
ITe(j)= i2M
2 (1)
where i is the instantaneous current and m is the inductanceslope.The current i is switched on at an advance angle 06, and it
rises linearly to the magnitude I at the corner point (00) by therelation
(2)00 =ILmr0
Vd
where Lm is the minimum inductance; wr is the rotor speed,and Vd is the dc link voltage. The current I is maintainedconstant by the chopping control and then turned off at a Opangle so that the current zero angle Oq does not extend muchinto the negative inductance slope region. At high speed themachine counter EMF dominates, and chopping control is lostas indicated by the pulse B, which also indicates the saturationeffect. The current pulse, during forward braking, is nearlyidentical to that of forward motoring at low speed, except thatit is established where the inductance slope m is negative.Since here the Oq angle can freely extend into the minimum
BOSE et al.: MICROCOMPUTER CONTROL OF SWITCHED RELUCTANCE MOTOR
PHASE A9 WIA/!/'G
TRANSISTOR CONVERTER
Fig. 1. Switched reluctance motor with power converter.A4CNIA/16
It8'1 * 24IAIZDUCTAAICEPROFCILE\E
060"
L Ol, - ecy 42" GeROTOR 9NGLE FFORWq kD
I AFORPWARD AM4OTOR ING 8
(FMA) 00
FO JR Wh RDBRA K I AJCG
(FG) 0-
Fig. 2. Typical phase current waves in relation to inductance profile.
inductance region, the 0p angle is kept constant at the cornerpoint (360). The advance angle 0 is to be limited because thecurrent in the positive slope region contributes motoringtorque.The current pulse waveshapes in reverse motoring are
identical to those in forward motoring, except these are placedwith respect to slope 2 (see Fig. 2), which appears as a positiveslope in reverse rotation. The cycle periods 0,Y for bothforward and reverse rotations are indicated in the figure.Again, the current pulses in forward and reverse braking areidentical, except the latter is placed on slope 1, which appearsas a negative slope in reverse rotation.A particular phase is fired periodically with a 600 cycle
period and, therefore, for the four-phase machine consecutivephases are fired at a 150 interval. Fig. 3 shows the typicaltorque-speed curve of the SRM in motoring mode, which alsoindicates the current and angle profiles. At speeds typicallybelow a few r/min, defined as the startup mode, full torque isavailable. The chopping mode, which extends up to a basespeed of ob, essentially defines the constant torque regionwhere the current amplitude I is controlled by the chopperoperation. Beyond the chopping mode the curve enters into theconstant power region where the torque is controlled only bythe 0' angle. Then above the critical speed tOri the limiting 0'angle is reached, and the torque falls off with a steeper slope.Note that in the constant power region the chopping mode maybe resumed if the peak current rises above a threshold value.
5TART-UP CHOPP/NG moDEMO0DE\ (CONSTONT 7OR00f)
Fs70iEgw oFig. 3. Torque-speed curve showing modes of operation.
DIGITAL ANGLE CONTROL
The control system incorporates a dedicated hardwaredigital angle controller which receives the angle commandsfrom the feedback loop and translates them into transistorconduction angles which are synchronized to the rotorposition. The basic control parameters of the drive system canbe summarized as follows:
I chopping current level, which is also the peak-limitingcurrent (ip) in the constant power region,
00 transistor turn-on angle, which may be related to theadvance angle 00,
0p transistor turn-off angle.
The machine has a rotor position encoder which consists offour optical sensors and an interrupting type disk with theprofile of the rotor stamping as shown in Fig. 1. The sensorsare mounted at the right edge of each stator pole pair as shownin Fig. 4, which also shows the logic output waveforms fromthe sensors for forward rotation. The signals are also used forthe startup operation discussed later. The signals are mutuallyphase shifted by 150. A monostable captures a 1 -- 0transition, and the outputs are coupled together through an ORgate to generate the 150 pulse train. The pulse train appears inthe sequence 4-3-2-1 and will have the opposite sequence inreverse rotation. The direction of rotation can be detected by
709
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULY/AUGUST 1986
0.
r/ '8-
3o' 60
53
54 _.0 4 3 2
Fig. 4. Sensor waveforms for forward rotation.
875' ILl
>:o(> rCfOCK(PROGRRro,P78LE)
9513
FlPEErDFig. 5. Phase-locked loop generator with programmable clock.
the presence (or absence) of a 0 -- 1 transition of the S2 wave
within pulses 1 and 4 of the pulse train.The 150 pulses are used to generate a pulse train with a
0.250 interval by a digital phase-locked loop method as shownin Fig. 5. This interval constitutes the resolution of the controlangles. A 150 counter accumulates the FOUT clock pulsesduring the 150 interval, and the resulting digital word W, isdivided by 60 to generate the word WPLL for the phase-lockedloop (PLL) counter. The PLL counter is down counted by theFOUT clock. When the counter clears, a pulse is generated atthe output and the counter reloads automatically from its
buffer. A phase-synchronized pulse train at higher frequencyis thus generated by the PLL counter. The speed signal iscalculated from the 15° counter output as shown because it isinversely proportional to the word W,. The FOUT clock is madeprogrammable with speed to maintain a good resolution of the0.250 pulses and to prevent an overflow of the 150 counter atvery low speed. At low speed, FOUT is programmed low, and itincreases in steps as speed increases. Since the same FOUTclock triggers both of the counters, the respective timeintervals remain proportional to their digital words.The angle controller for the drive system consists of four
pairs of programmable down-counters, of which phase A isshown in Fig. 6. Fig. 7 shows the waveforms for the forwardmotoring operation. Each counter operates as a programmableone shot where the digital words Op6,, = 0 + 6p and 00 = 600
9S13 O
PUL5SE WID)7H r TOTRN1s(OAp~- i+ vCOUNTER SGfROr'7 84'G-8G
,J C~URR&AI' CONrAkOLLRFROMf
Mic ROCOflPUTAER(3 335MSAPL,A') 95/3 0.25P ULS/S
eo=°. DEZA Y S X
COUN7eR G 6_0
Fig. 6. Programmable counters for delay pulsewidth generation (shown forphase A only).
- O' are loaded into the buffer of the pulsewidth counter andthe delay counter, respectively. Both the counters are clockedby the 0.250 pulse train. The delay counter is enabled by 600pulses generated by a 1 -+ 0 transition of sensor SI. When thecounter clears at angle 00, it enables the pulsewidth counter,which maintains a logic one at the output during thecountdown period. When the counter clears, it autoreloadsfrom the buffer and locks until enabled again. This output iscoupled with the chopping logic signal from the bang-bangcurrent controller by an AND gate, and the output constitutesthe phase A transistor base drive enable signal. Since thecounters are independent, each can be programmed between
710
BOSE et al.: MICROCOMPUTER CONTROL OF SWITCHED RELUCTANCE MOTOR
60 nPUL 5655
C0UL5E OUTP7ol9Cou#rC aur,
1o~~~~~0
DELAYvCOUA/TZ,e!
PUL SL Al/, 7'COUNNTER
Fig. 7. Counter waves in forward motoring mode.
5 HP S R A &,/8 RroR
`0
k4
Is. 2r 38' 4r 58' S' /,
07T0o P05 /7/M (DLEG)t t
PFtASED P#H*SE PHIASEBa P,5
,9LIGA'ED 4L/6NED d /GNED AL/CAEDFig. 8. Starting torque as function of rotor position.
0-60°, which is essential for four-quadrant operation of thedrive system.
MOTOR STARTING
For a satisfactory starting of the SRM from any arbitraryposition of the rotor, a startup control is essential. For a
forward startup control, the phase current should be estab-lished in the interval between 0-18°. Therefore, the positionsensor signals (see Fig. 4) are sensed and complemented, andthe resulting logic signals are loaded into the transistor basedrivers. For reverse starting the current pulse has to be placedon the negative slope (positive slope for the reverse direction).The logic signals for reverse starting can be generated by ANDcoupling the adjacent sensor signals. This generates 33-60°pulsewidths instead of the desired 42-60° duration. Theexcess 90 causes some additional power dissipation but can beignored, considering the short duration for starting. The start-up algorithm is implemented with the help of the microcompu-ter. Fig. 8 shows the measured starting torque of each phase asa function of the rotor position. The curves deviate from theideal rectangular shape of 180 with a 30 overlapping becauseof the saturation and fringing effects. The resulting torque canbe obtained by summing the components which, obviously,fluctuate with the rotor position. The torque curves remainsymmetrical for both forward and reverse starting. The
magnitude of the starting torque can be controlled byregulating the level of I.
FEEDBACK SPEED AND TORQUE CONTROL
The drive system was designed with speed feedback control,torque feedback control, and both the torque and speed loopscombined. Fig. 9 shows the block diagram for the speedfeedback control loop. The command speed (w *) is comparedwith the actual speed co, and the error through a proportional-integral (PI) compensator, and an absolute value circuitgenerates the chopping current command I. The advanceangle G is calculated from I* by (1) so that in motoring modesthe current I is built at the beginning of the positive inductanceslope. The angles 00 and Op,, in different modes, can besummarized as follows:
where 0' is the angle between the positive inductance slopepcorner point and the transistor turn-off point. In the FM mode
711
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULY/AUGUST 1986
fORw,D zIReveR,s F'l", FG/ R17, 9G
)YAIvE SENSOR T i A9N2AZ(r COWnPUTAJTON
Fig. 9. Block diagram of speed control system.
the turn-off angle Op = O,, but in the RM mode Op = 420 +
Op. The 6' angle is made programmable with speed as shownto minimize the influence of the braking torque. The maximumvalue of 6' is clamped as shown in Fig. 3 to preventcontribution of the breaking torque by the preceding negativeslope.The feedback speed signal is computed from a position
encoder which has a sampling interval of 150. It seemsobvious that the position encoder cannot be used at low speedwhere the sampling time becomes too large. However, theposition encoder is required for the starting as well as thecontrol of the 00 and Op,, angles. An alternate position encoderwith a large number of pulses per revolution can be used if alow speed range is desired.The system as shown in Fig. 9 will start and run at low
speed with *, 00, and pQ, as control variables. As the speedincreases, the chopping mode will vanish, and the system willenter into the angle control mode. In this condition the peakcurrent ip will remain below the commanded I value.However, if ip tends to exceed I due to transient loading, thechopper will act as a peak-current limiter.A block diagram of the torque control loop is shown in Fig.
10. The consideration of torque control is important in electricvehicle-type applications. In addition, providing a torque loopwithin a speed loop can make the response of the speed loopfaster. The implementation of the torque feedback control inan SRM is difficult because the computation of accuratefeedback torque is not easy. The torque can be computed fromthe dc link power by the following relations:
motoring Te= VdIdl (3)(Ar
regeneration Te- VdId (4)?tar
?orT/GEV
V\J Id
Fig. 10. Block diagram of torque control loop.
where -1 is the efficiency of the converter-machine system.These expressions neglect the delay due to the energy storageeffect in inductances. The efficiency of the particular machinetested was evaluated extensively for different load and speedconditions. The data were available in the form of a lookuptable for the torque computations. The computed torque showsa reasonably good correlation with the measured torque. Thetorque computation, however, remains invalid in the low-speed region because of excessive ripple.As shown in Fig. 10, only the absolute value of the torque is
controlled, and the polarity command actuates the angleswitches as indicated in Fig. 9. The torque loop is active forpositive error only.The torque control loop was implemented within the speed
loop to enhance the system response speed. A high-gain torqueloop linearizes the system, makes the performance insensitiveto parameter variation, and permits the speed loop controllergain to be high within the limit of stability. The overall systemoperates in four quadrants with the absolute value of the torquecontrol in the inner loop.
712
BOSE et al.: MICROCOMPUTER CONTROL OF SWITCHED RELUCTANCE MOTOR
0' t5 30 45* 0)
6FA?Pl/NGDEL ?Y Of 0
,L-
SAFTF.__ _ _ _ /V
or-- t
STA )QT OF AqC71VfTOrIinUo
Fig. I11 Counter waves showing response delay in angle control forward motoring mode.
DYNAMIC MODEL
The dynamic model of the SRM seems to be complexbecause of the nonlinearities and sampling delays, but some
general discussion is appropriate here. At very low speed theangle controller starts with 180 torque-producing pulses(pw,) in motoring, which linearly reduces with speed to 90 at900 r/min. With 180 pulses an overlap of 30 exists for adjacentphases. With 150 pulses this overlap vanishes, and the gap
increases to 60 for a 90 pulse. This corresponds to a
feedforward sampling delay of 1.11 ms at 900 r/min. Thissampling delay can be ignored with the speed control loop ifthe feedback speed is sampled at 15° intervals. In addition tothis sampling delay, the phase coil current has a response
delay which depends on the saturation level.The sampling delay of the SRM is particularly complicated
in the angle control mode. Fig. 11 shows the waveforms forthe worst case in the forward motoring mode. The delay andpulsewidth counters are updated with the sampling time of thefeedback control loop (3.33 ms). Since the delay counters are
enabled at 15° intervals, the worst-case sampling delay at 00 is15° with a step change of AO' as shown. Note that AOpw has tobe appended to the leading edge to establish a steady-statecondition. This requires that the delay counter be cleared witha new 00 value. Otherwise, AGp, will be appended to thetrailing edge, causing a reduction of torque. Therefore, theworst-case sampling delay is 750 as indicated in Fig. 11.
The developed torque of the SRM is related to the activerms phase current by a square law relation. In the choppingmode this current can be assumed as constant, neglecting the,spreading effect. If the angle control effect is ignored inchopping mode, then the torque-current transfer characteristiccan be given by the aforementioned square law relation. In theangle control mode, G' is constant and the rms phase current isregulated by the advance angle G' only. This relation isinfluenced by the machine counter EMF which is, again, a
function of the speed and rms current.
SEQUENCING CONTROL
The drive system has several modes of operation withpermissible transition paths shown by the sequence diagram inFig. 12. The normal running modes (FM, RM, FG, and RG)are grouped into the MOT/GEN mode. For a successful transitionbetween the modes, the conditionals written along the arrowsshould be valid, and then the action routines (indicated bydots) are executed before the transition occurs.The microcomputer initially attains the NEUTRAL mode after
the power is switched on. The system then transitions to theSTART-UP mode if the speed command exceeds a thresholdvalue. Meanwhile, enabling the feedback loop builds up thecurrent command through the PI compensator. The phase-locked loop and speed computation are enabled with a delay of50 ms to ensure a minimum speed so the counters do notoverflow. When the speed exceeds 24 r/min as shown, thesystem transitions to the MOT/GEN mode but returns to theSTART-UP mode if the speed falls below 12 r/min. Thehysteresis band prevents faulty chattering between the modes.The acquisition of a particular running mode depends upon thelogic signals shown in Fig. 9.
MICROCOMPUTER HARDWARE AND SOFTWARE DESIGN
The microcomputer hardware is based on the Intel 8751single-chip microcomputer which is supported by peripheralchips. The peripheral hardware includes AID converters foracquisition of the dc link voltage, current and speed com-mands, a D/A for chopper current command, and two systemtiming controller chips type AM9513 manufactured by Ad-vanced Micro Devices. The AM9513 chip has five softwareconfigurable counter/timers as well as a programmable fre-quency divider. Each of the five counters may be configured inone of 24 possible operating modes.
All of the control and computation functions that are timecritical are implemented in Assembly language, whereas thesequencing function, which is less time critical, is written in
713
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-22, NO. 4, JULY/AUGUST 1986
- ENAaZE PILe ENABLeE (,, COM7PUTATION
*DIS88LE STMR7-UPRoO TIME
* ENRBLE COUNTERS
\ COOU 'TERSaOO / NA
\ . EhA eLE RoT'J 753
STA5R#tT-UP ROUTIDrl#D/RtO* D15 ABLE P-L* ZuIS#f8aLE £,CO/IP?PITATI T* DISABLE PB.CoJrLoJ
Fig. 12. Simplified sequence diagram.
the PL/M language. The program is resident in the 4-kbyteEPROM memory of the microcomputer.The executive software consists of a real-time scheduler
which is responsible for the orderly execution of multiple tasksand their sampling interval generation. The fastest tasks are
the control and computation functions and are executed every3.33 ms. This task also includes a signed 16- 16-bit multiplyand a 32/16-bit divide routine. The sequencing function isexecuted with a sampling interval of 26.67 ms, and high-leveldiagnostics are executed every 213.3 ms. The 8751 chip hastwo external interrupt signals; one is used for the 3.33 ms
clock ticks that activate the real-time scheduler, and the otheris for servicing the 150 interrupt which samples the 150counter and processes data for the phase-locked loop counterand speed computation.
LABORATORY TESTS
The SRM used in testing has a nominal rating of 5 hp with a
peak current of 60 A and is supplied from a regulated voltagesource of 100 V. A dc load machine is coupled to the shaft toapply a variable load torque. The SRM was first tested open
loop with the newly developed angle controller. Then feed-back control was added for the speed loop, the torque loop,and the speed loop with the inner torque loop. The drivesystem was tested extensively in all four quadrants under bothsteady-state and transient conditions.The speed signal, computed from the 150 pulse position
encoder, was found to have some jitter due to blade tolerance.Since this is unacceptable at high speed because of low digitalcounts, the signal was averaged over four consecutive inter-vals above 800 r/min. Again the sampling time interval,corresponding to 150, was too large at low speeds and,therefore, was restricted to 50 r/min. A Teledyne sensor,
having 2400 pulses/revolution was used with a pulse integra-
Fig. 13. Phase current waves in chopping mode at 550 r/min (t = 1.50,0,W = 140). Top to bottom: i_, ibb i,id (10 A/div, 5 ms/div).
66( -,#)/d
°)r
0
66i6h7m/d
ko)0
to ,,eIb/d
to In Ib/d0
i re/
24dI
0
iO ;n AD/d'i
TIME 1.05 r-
Fig. 14. Transient performance of speed control system with inner torqueloop.
tion method over a sampling interval of 3.33 ms, enabling thelowest speed of 12 r/min.
Fig. 13 shows the typical steady-state phase current waves
in chopping mode, indicating the well-balanced operation ofthe machine. The chopping frequency is higher initially, butreduces gradually because of the increasing inductances. Theovershoot of the sensor current, due to large di/dt at a higherfrequency, causes tapering of the chopping current profile.Fig. 14 shows the typical transient response of the speedcontrol system with the inner torque loop closed. The
j-OJIM R - UPIAI} TifAL ZATION
i'M __AAfl
714
BOSE et al.: MICROCOMPUTER CONTROL OF SWITCHED RELUCTANCE MOTOR
computed torque Tel and the measured torque from aHimmelstein torque meter are shown in the figure forcomparison. The latter incorporates a low-pass filter toattenuate the ripple. The longer duration of braking isevidently due to the lower clamping of braking torque.
CONCLUSION
The paper describes the development, design, and labora-tory test of an Intel 8751 microcomputer-based control of a 5-hp SRM drive system. The control functions include feedbackcontrol with speed loop, torque loop, sequencing control,starting, and position synchronized angle control. Because ofthe critical timing requirement, the angle control was imple-mented with dedicated digital hardware. The feedback speedsignal was synthesized from the 15° pulse position encoder inthe higher speed range, whereas in the lower speed range aTeledyne type sensor was used. The feedback torque wascomputed from electrical signals and was valid except at verylow speeds due to excessive ripple. The complete drive systemwas tested thoroughly in all the four quadrants under bothsteady-state and transient conditions, and performances werefound to be excellent.
REFERENCES[1] P. J. Lawrenson et al., "Variable-speed switched reluctance motors,"
Proc. Inst. Elec. Eng., vol. 127, pp. 253-265, July 1980.[2] W. F. Ray and R. M. Davis, "Inverter drive for doubly salient
reluctance motor: Its fundamental behavior, linear analysis and costimplications," Electric Power Appl., vol. 2, pp. 185-193, Dec. 1979.
[3] R. M. Davis, W. F. Ray, and R. J. Blake, "Inverter drive for switchedreluctance motor: Circuits and component ratings," Proc. Inst. Elec.Eng., vol. 128, pt. B, pp. 126-136, Mar. 1981.
[4] T. J. E. Miller, "Converter volt-ampere requirements of the switchedreluctance motor drive," in Proc. IEEE Ind. Appl. Soc. Annu.Meeting, 1984, pp. 813-819.
[5] P. H. Chapple, W. F. Ray, and R. J. Blake, "Microprocessor controlof a variable reluctance motor," Proc. Inst. Elec. Eng. vol. 131, pt.B, pp. 51-60, Mar. 1984.
[6] M. R. Harris, T. J. E. Miller, and J. Finch, "A review of the switchedreluctance drive," presented at the IEEE Ind. App!. Soc. Annu.Meeting, Toronto, ON, Oct. 1985.
[7] J. T. Bass, M. Ehsani, T. J. E. Miller, and R. L. Steigerwald,"Development of a unipolar converter for variable reluctance motordrives," in Proc. IEEE Ind. Appl. Soc. Annu. Meeting, 1985, pp.1062-1068.
Bimal K. Bose (S'59-M'60-SM'78) received theB.E. degree from Calcutta University, Calcutta,India, in 1956, and the M.S. degree from theUniversity of Wisconsin, Madison, in 1960, and the
* | Ph.D. degree from Calcutta University in 1966.He was a Member of the Faculty at Calcutta
University where he was awarded the PremchandRoychand Scholarship and the Mouat gold medalfor research contributions. In 1971 he joined Rens-selaer Polytechnic Institute, Troy, NY, as a memberof faculty in the Electrical Engineering Department
where he was responsible for organizing the undergraduate and graduatepower electronics programs for five years. He was a consultant for severalindustries, including the General Electric R & D Center, Bendix Corporation,Lutron Electronics, and PCI Ozone Corporation. Since 1976 he has been withGeneral Electric Corporate Research and Development, Schenectady, NY.His research interests are power conversion systems and microcomputer-based performance optimization of power electronic systems. He holds 15U.S. patents. He edited the IEEE Press book Adjustable Speed AC DriveSystems (translated into Chinese) and contributed the article on ac drives inthe International Encyclopedia on Control and Systems'published by
Pergmon Press. He has written a book Power Electronics and AC Driveswhich has been published by Prentice-Hall, Inc. Another IEEE Press bookMicrocomputer Control ofPower Electronics and Drives sponsored by theIndustry Applications Society is in progress. He is currently an AdjunctFaculty Member in the Rensselaer Polytechnic Institute.
Dr. Bose was Chairman of the IEEE TRANSACTIONS Review of StaticPower Converter Committee for eight years (1976-1983). He is a member ofthe Power Electronics Committee and Microcomputer Control Committee ofthe IEEE Industrial Electronics Society, a member ofthe Scientific Committeeof the International Conference on Digital Control of Electrical Machines, theProgram Committee of the International Static Power Converter Conference,the Committee on Automotive Applications of Microprocessors, the FellowNominating Committee for the Static Power Converter Committee, and theProgram Committee of the Tokyo International Power Electronics Confer-ence. His biography has been published in Who's Who in Engineering, UK,Who's Who in Technology, USA, and Directory of World Researchers inJapan. The Institute of Electronics and Telecommunication Engineers, India,has established the Bimal Bose Award in Power Electronics which is awardedannually to an Indian engineer for an outstanding contribution in powerelectronics.
Timothy J. E. Miller (M'74-SM'82) received theB.Sc. degree from the University of Glasgow andthe Ph.D. degree from the University of Leeds in1970 and 1977, respectively, both in electricalengineering.He joined the research staff of the General
Electric Company, Corporate Research and Devel-opment, in 1979. He has worked on the design ofpermanent-magnet ac motors and generators, on the
_ l_ control system for thyristor-switched capacitors forpower system compensation, and on the develop-
ment of power electronic converters and control systems for switchedreluctance motor drives. His technical work includes the analysis of thedynamic performance of permanent-magnet ac motors during starting andwhen operating from solid-state power supplies. He has designed the world'slargest permanent-magnet generator for industrial applications. His work onswitched reluctance systems includes the development of novel types of powerelectronic converters with associated analysis. He is presently Manager of thePower Electronics Control Program, Power Electronics Laboratory. He isalso an instructor in the Reactive Power Control course which he helped toestablish at the University of Wisconsin. He is the author of a textbook onreactive compensation for electric power systems, which is the only textdealing with modern power electronic techniques. He is also an AdjunctAssociate Professor at Union College in Schenectady, NY, where he teachescourses in electrical energy conversion and electronic control of motor drives.lIe holds eight patents and has authored 28 technical papers in addition to histextbook.
Dr. Miller is a Chartered Engineer in the United Kingdom and an AssociateFellow of the Institute of Mathematics and its Applications.
Paul M. Szczesny, for a photograph and biography please see page 1191 ofthe September/October 1985 issue of this TRANSACTIONS.
William H. Bicknell received the associates degreein applied science from Hudson Valley CommunityCollege, Troy, NY, and the B.S. degree in electri-cal engineering from Union College, Schenectady,NY, in 1976 and 1983, respectively.
Since 1983, he has worked as a Research Special-ist for General Electric Corporate Research andDevelopment in Schenectady, NY. He has beenengaged in developing microprocessor-based con-trol systems for power electronic circuits. Hiscurrent field of interest is in developing computed-
aided design tools for high-voltage integrated circuits.
