INVITED PAPER Hybrid Electric Vehicles: Architecture and ...

INV ITEDP A P E R

Hybrid Electric Vehicles:Architecture and Motor DrivesHeavy hybrid vehicles use their small internal combustion engine in series with

an electric drive; hybrid passenger cars use parallel and series-parallel drives.

By Mehrdad Ehsani, Fellow IEEE, Yimin Gao, and John M. Miller, Fellow IEEE

ABSTRACT | Electric traction is one of the most promising

technologies that can lead to significant improvements in

vehicle performance, energy utilization efficiency, and pollut-

ing emissions. Among several technologies, hybrid electric

vehicle (HEV) traction is the most promising technology that

has the advantages of high performance, high fuel efficiency,

low emissions, and long operating range. Moreover, the

technologies of all the component hardware are technically

and markedly available. At present, almost all the major

automotive manufacturers are developing hybrid electric

vehicles, and some of them have marketed their productions,

such as Toyota and Honda.

This paper reviews the present technologies of HEVs in the

range of drivetrain configuration, electric motor drives, and

energy storages.

KEYWORDS | Drivetrain architecture; energy storage; HEV;

motor drives

I . INTRODUCTION

A hybrid electric vehicle (HEV) uses two power sources to

power the vehicle. At present, one power source is internalcombustion (IC) engine (gasoline or diesel fueled) and the

other is chemical batteries plus an electric motor drive. In

HEVs, high peak power and quick power response of the

electric traction system results in high vehicle perfor-

mance such as quick acceleration. Small IC engine and

optimal operating points and regenerative braking result in

much better fuel economy and lower emissions than IC

engine-alone powered vehicles. High energy density ofpetroleum fuel and convenient fueling systems result in

long operating range and easy refueling. All these

advantages make HEVs the most promising alternatives

for the next generation vehicles.

However, due to the dual power sources, there are

several drivetrain configurations and different control

strategies to control the power sources. These different

configurations and control strategies result in differentvehicle performance and operation characteristics. This

paper mainly reviews the configurations of HEVs and their

operating characteristics, as well as the state of the art of

present components, mostly motor drives and energy

storages.

II . ARCHITECTURE OF HEVDRIVETRAINS

1) Concept of Hybrid Drivetrain: Fig. 1 shows the concept

of a hybrid drivetrain and possible energy flow route.

There are many available patterns of combining the power

flows to meet load requirement as described in thefollowing [1], [22]:

1) powertrain 1 alone delivers power to load;

2) powertrain 2 alone delivers power to the load;

3) both powertrain 1 and 2 deliver power to load at

the same time;

4) powertrain 2 obtains power from load (regener-

ative braking);

5) powertrain 2 obtains power from powertrain 1;6) powertrain 2 obtains power from powertrain 1 and

load at the same time;

7) powertrain 1 delivers power to load and to

powertrain 2 at the same time;

8) powertrain 1 delivers power to powertrain 2, and

powertrain 2 delivers power to load;

9) powertrain 1 delivers power to load, and load

delivers power to powertrain 2.Load power of a vehicle varies randomly in real

operation due to frequently accelerating, decelerating,

and climbing up and down grades, as shown in Fig. 2.

Manuscript received October 16, 2006; revised December 1, 2006.

M. Ehsani and Y. Gao are with the Power Electronics, Motor Drives and Advanced

Vehicle Systems Program, Department of Electrical and Computer Engineering, Texas

A&M University, College Station, TX 77843 USA (e-mail: [email protected]).

J. M. Miller is with Maxwell Technologies, Inc., Advanced Transportation Applications,

San Diego, CA 92123 USA.

Digital Object Identifier: 10.1109/JPROC.2007.892492

Vol. 95, No. 4, April 2007 | Proceedings of the IEEE 7190018-9219/$25.00 �2007 IEEE

Actually, the load power can be decomposed into two

components: one is steady (average) power, which has aconstant value, and other is dynamic power, which has a

zero average. In hybrid vehicle strategy, one powertrain,

which favors steady-state operation, such as an IC engine

fuel cell, can be used to supply the average power. On the

other hand, other powertrains, such as an electric motor,

can be used to supply the dynamic power. The total energy

output from the dynamic powertrain will be zero in a

whole driving cycle. This implies that the energy source ofthe dynamic powertrain does not lose energy capacity at

the end of the driving cycle. It functions only as a power

damper [2].

Generally, the steady-state load power is provided by an

IC engine or fuel cell. Due to the steady-state operating

characteristic, its operating point can be designed and

controlled in the optimal region to obtain highest

operating efficiency. The dynamic load power is provided

by the electric traction system (traction motor andchemical batteries) to meet the peak power demand and

recovering the braking power.

This hybrid drivetrain concept can be implemented by

different architectures (configurations) as follows.

2) Series Hybrid Drivetrain: The series hybrid drivetrain

was developed by adding a small IC engine/generator to

the battery powered pure electric vehicle (EV) in order tomake up the energy shortage of the batteries, as shown in

Fig. 3. The prominent advantages of series hybrid

drivetrains are: 1) mechanical decoupling between the

IC engine and the driven wheels allows the IC engine

operating at its very narrow optimal region as shown in

Fig. 3; 2) single torque source (electric motor) to the

driven wheels simplifies the speed control (similar as

throttle control by accelerator pedal); 3) nearly idealtorque-speed characteristic of electric motor [1], [3]

makes multigear transmission unnecessary; and 4) simple

structure and drivetrain control and easy packaging (the

engine/generator, batteries, and the traction motor are

connected by only electrical cables). However, a series

hybrid drivetrain also bears some disadvantages such as:

1) twice the energy form conversions (mechanical from

engine to electric through generator and then to me-chanical again through traction motor) cause more energy

losses; 2) two electric machines are needed (electric

generator and traction motor); and 3) a big traction

motor since it is the only torque source of the driven

wheels.

Taking advantage of its simple structure, simple

control, and easy packaging, the series hybrid drivetrain

is usually used in heavy vehicles, such as heavy commercialvehicles, military vehicles, buses, and even locomotives.

The major reason is that large vehicles have enough space

for the bulky engine/generator system. The hybrid electric

city buses usually use this configuration, such as manu-

factured by Ebus, Electric Vehicles International, ISE

ResearchVThunder-Volt, etc.

Fig. 1. Conceptual illustration of hybrid drivetrain.

Fig. 2. Load power is decomposed into steady and

dynamic components. Fig. 3. Series hybrid electric drivetrain.

Ehsani et al. : Hybrid Electric Vehicles: Architecture and Motor Drives

720 Proceedings of the IEEE | Vol. 95, No. 4, April 2007

3) Parallel Hybrid Drivetrain: In a parallel hybrid

drivetrain, as shown in Fig. 4, the engine and electric

motor can directly supply their torque to the driven wheels

through a mechanical coupling. This mechanical coupling

may simply be a gearbox, pulley-belt unit or sprocket-chain

unit, even a single axle, as shown in Fig. 5.

The major advantages of the parallel hybrid drivetrainare: 1) both engine and electric motor directly supply

torques to the driven wheels and no energy form con-

version occurs, thus energy loss is less and 2) compactness

due to no need of the generator and smaller traction

motor. One major disadvantage of parallel hybrid drive-

trains are the mechanical coupling between the engine and

the driven wheels, thus the engine operating points cannot

be fixed in a narrow speed region. Another disadvantage isthe complex structure and control.

Due to its compact characteristics, parallel configura-

tion is used by small vehicles. Most passenger cars employ

this configuration, such as the Honda Insight, Honda

Civic, Ford Escape, etc.

4) Series–Parallel Hybrid Drivetrain: Fig. 6 shows a

typical configuration of the series–parallel drivetrain byusing a planetary gear unit to decouple the engine speed

from the wheel speed [1], [20], [21]. The planetary gear

unit and the speed–torque relationship are shown in Fig. 7.

At a given vehicle speed ð!2Þ, the generator/motor speed

ð!1Þ can be adjusted to adjust the engine speed ð!3Þ. Thus

the engine, planetary gear unit, and the generator/motor

constitute the series power flow route. When the

generator/motor speed is negative (opposite directionversus the torque), the generator operates in generating

mode. The engine power is split into two parts; one part is

transferred to the drivetrain and the other to the gener-

ator. When the generator speed is positive, the generator/

motor operates in motoring mode, adding power to the

driven wheels. In these ways, the engine speed can be

adjusted to its optimal region by controlling the generator/

motor speed. The function of the generator/motor can be

Fig. 5. Commonly used mechanical torque coupling devices.

Fig. 4. Parallel hybrid electric drivetrain.

Fig. 6. Series–parallel hybrid drivetrain by using a planetary gear unit.

Ehsani et al.: Hybrid Electric Vehicles: Architecture and Motor Drives

Vol. 95, No. 4, April 2007 | Proceedings of the IEEE 721

removed from the drivetrain by locking the stator and

rotor of the generator/motor together and de-energizing it.

In this way, the planetary gear unit becomes a simple

gearbox with a fixed gear ratio. Another power (torque)source is the traction motor, which directly adds torque to

the drive wheels.

The series–parallel configuration combines the advan-

tages of series and parallel drivetrains. However, it also

needs an additional electric machine and a planetary unit,

which makes the drivetrain somewhat complicated.

Another possible alternative to the planetary gear unit is

a floating-stator electric machine (it is called Transmotor),as shown in Fig. 8. In this configuration, the stator is

connected to the engine and the rotor is connected to the

drivetrain wheel through gears. The motor speed/relative

speed between the stator and rotor can be controlled to

adjust the engine speed at any given vehicle speed. This

drivetrain has similar operating characteristics as those ofthe drivetrain shown in Fig. 6 but is less complex.

The well-known Toyota Prius employed this configu-

ration as shown in Fig. 6.

III . ELECTRIC MOTOR DRIVES

1) Ideal Torque-Speed Profile for Traction: Electric motor

drives play the most important role in HEVs. As mentioned

previously, the electric motor drive is the only torque

source in a series hybrid vehicle. In parallel and series–

parallel hybrid vehicles, the electric motor is the torque

source that provides the peak torque (power) to meet thevehicle performance requirement, such as, acceleration.

Thus, the development of compact, lightweight, high

efficiency, and proper torque-speed profile becomes

crucial.

The ideal torque (power)-speed profile for traction

application is the constant power in all the speed ranges

[4]. The constant power profile can maximize the vehicle

acceleration performance at given power rating orminimize the power rating at given vehicle acceleration

performance [6]. In an engine (gasoline or diesel)-alone

powered vehicle, a multigear transmission is used to

modify the engine torque-speed profile to make the

tractive effort-speed profile on a driven wheel close to

this ideal profile. However, a well-controlled electric

motor drive has the torque-speed profile close to the ideal

one as shown in Fig. 9 [1], [5].The torque-speed profile of a well-controlled electric

motor drive includes two distinguishable segments:

constant torque and constant power. The corner speed is

usually called base speed. At a given power rating and

Fig. 7. Planetary gear unit.

Fig. 8. Series–parallel hybrid drivetrain with transmotor.

Fig. 9. Ideal torque-speed profile required and that a well-controlled

motor can produce.



maximum speed, the lower base speed results in a larger

maximum torque. A term, speed ratio, is defined as theratio of the maximum speed to the base speed.

In vehicle drivetrain design, one of the most important

efforts is to reduce the power rating (volume and weight)

of the drivetrain with a given vehicle performance. Fig. 10

shows the required motor power ratings with different

motor speed ratios, which produce the same vehicle

acceleration performance [5]. It clearly shows that a motor

drive with a long constant power range is preferred.

2) Candidates of Electric Motor Drives for Traction: An

electric propulsion system consists of three main parts: an

electric motor, a power electronics converter, and its

controller. Traditionally, dc motor drives have the proper

characteristics for traction application and were popularly

used a couple decodes ago. However, dc motor drives have

bulky construction, low efficiency, the need of mainte-nance, and low reliability, mainly due to the presence of

the mechanical commutator (brush). With the coming era

of power electronics and digital microprocessor control

technology, other advanced motor drives are mature to

replace the dc motor drive in traction applications. At

present, permanent magnet brushless dc (BLDC) motors,

induction motors (IM), and switched reluctance motors

(SRM) are considered to be the most likely candidates forthe vehicle propulsion application.

For traction application, the torque density is the most

important criterion of the electric motors, which reflects

the volume and weight of machines at given torque

demand. Table 1 lists the typical torque density values for

different motor types [6].

Table 1 shows that the PM machines enjoy the highest

torque density and therefore will potentially have thelowest weight for given torque and power ratings.

However, the fixed flux magnets limit its extended speed

range. The induction machine and switched reluctancemachine have similar torque density. More details of the

operation characteristics of these three machines are

described as follows.

A. Permanent Magnet (PM) Motor DrivesAs mentioned above, since the magnetic field is excited

by high-energy PMs, the overall weight and volume can be

significantly reduced for given output torque, resulting inhigher torque density. Because of the absence of rotor

winding and rotor copper losses, their efficiency is

inherently higher than that of induction motors. The

brushless dc motor and interior permanent magnet motor

are two typical motor drives for HEV applications.

However, PM motors inherently have short constant

power range due to its rather limited field weakening

capability, resulting from the presence of the PM field,which can only be weakened through production of a

stator field component, which opposes the rotor magnetic

field. Typical characteristics of the BLDC motor are

shown in Fig. 11. The speed ratio x is usually less than

two [7].

Table 1 Typical Torque Density Values for Different Motor Types

Fig. 10. Tractive effort and power versus vehicle speed with

different speed ratio x.

Fig. 11. Typical characteristics of PM BLDC motor.



Recently, the use of additional field windings to extendthe speed range of PM brushless dc motors has been

developed [8]. The key is to control the field current in

such a way that the air-gap field provided by PMs can be

weakened during high-speed constant-power operation.

Due to the presence of both PMs and the field windings,

these motors are so-called PM hybrid motors. The PM

hybrid motor can achieve a speed ratio of around four [8],

[9]. However, the PM hybrid motors have the drawback ofa relatively complex structure. The speed ratio is still not

enough to meet the vehicle performance requirement,

especially for off-road vehicles. Thus, a multigear trans-

mission is required.

A new concept of field reconstruction technology has

been developed recently at Texas A&M University. This

technology can effectively enhance the torque capacity,

reduce the torque ripple, and obtain long constant powerrange for PM brushless dc motor and interior PM motor

drives.

B. Induction Motor (IM) DriveField orientation control (FOC) of an induction motor

can decouple its torque control from field control. This

allows the motor to behave in the same manner as a

separately excited dc motor. Extended speed rangeoperation with constant power beyond base speed is

accomplished by flux weakening. However, the presence

of breakdown torque limits its extended constant power

operation as shown in Fig. 12. At the critical speed !mc,

the breakdown torque is reached. Any attempt to operate

the machine at the maximum current beyond this speed

will stall the machine. Generally, for a conventional

induction motor, !mc is around two times the synchronousspeed !ms.

Nevertheless, a properly designed induction motor,e.g., spindle motor, with FOC can achieve a field

weakened range of about three to five times its base speed

[10]. This approach, however, results in an increased

breakdown torque, thereby resulting in oversizing of the

motor. A special winding changeover technique of a field

orientation controlled induction motor is also reported

which demonstrates long field weakening operation [11].

This approach, however, requires winding tap changingand contactors. A contactless control scheme for extending

the speed range of a four-pole induction motor was

presented in [12]. This scheme uses two inverters, each of

half the rated power rating, that, in theory, can extend the

constant power operating range to four times the base

speed, for a motor, that would otherwise be limited to two

times the base speed. It may be mentioned here that the

torque control in induction motor is achieved throughPWM control of the current. In order to retain the current

control capability in the extended speed constant power

range, the motor is required to enter the field weakening

range before reaching the base speed, so that it has

adequate voltage margin to control the current [13]. This

would, however, oversize the motor slightly. Current

regulation with a synchronous current regulator [14] may

be the preferred choice. It can regulate current with alower voltage margin. The availability of a long field

weakened range, obviously, makes the induction very

suitable for vehicle application.

C. Switched Reluctance Motor (SRM) DriveSwitched reluctance motor (SRM) is gaining interest as

a candidate of electric propulsion for electric vehicles and

HEVs because of its simple and rugged construction,simple control, ability of extremely high speed operation,

and hazard-free operation. These prominent advantages

are more attractive for traction application than other

kinds of machines.

SRM can inherently operate with extremely long

constant power range. The serial design and simulation

results, performed in the SRM research group at Texas

A&M University, show that the speed ratio of both 6-4 and8-6 SRMs can reach 6-8 as shown in Fig. 13 [15]. This long

constant power range makes the SRM highly favorable for

vehicle traction application.

The major disadvantage of SRM drive is the high torque

ripple and acoustic noise. However, through employing

advanced control and field reconstruction technology de-

veloped at Texas A&M University, the torque ripple and

acoustic noise can be effectively reduced to the acceptabledegree for vehicle application.

To reduce the motor size and weight for a given power

rating, high-speed operation is expected to reduce the

torque rating and, thus, the current rating. However, high-

speed operation may cause high mechanical losses due to

aerodynamics drag and viscosity losses. To reduce the me-

chanical losses, the shape of the rotor should be optimallyFig. 12. Speed-torque curve for variable frequency control of

induction motor.



designed especially for SRM drive, where the rotor isshaped like a gear, which causes high aerodynamic drag at

high speed.

IV. ENERGY STORAGE

1) Chemical Batteries and Ultracapacitors: Energy storage

is another important component in a hybrid electricdrivetrain. It is required to have sufficient peak power and

energy capacity to support the operation of the vehicle. At

present, almost all the vehicles use chemical batteries as

their energy storage. Table 2 shows the status of battery

systems potentially available for EVs and HEVs [16].

It can be seen that although specific energies are high

in advanced batteries, the specific power does not have

any significant improvement. About 300 W/kg might bethe optimistic estimate. Recently, SAFT has reported their

Li-ion high-power and high-energy batteries with about

4000 and 600 W/kg, respectively. However, their prac-

ticality and cost reduction in the future need to be further

proven.

Ultracapacitor is another candidate as potential energy

storage for hybrid vehicles. The ultracapacitor is charac-

terized by high specific power, high efficiency, excellenttemperature adaptability, and long service life. However, it

has suffered from very limited specific energy. The

characteristics of a 42-V ultracapacitor pack specifically

designed for HEV and produced by Montena Company are

listed in Table 3 [18]. Maxwell Technologies [19] havereportedly developed 2700-F ultracapacitors with 2.5-V

cell voltage, 2.55-kW/kg specific power, and 3.23-Wh/kg

specific energy, respectively. It is believed that the unit

power cost of the ultracapacitor is lower than that of

batteries. However, due to its low specific energy and

dependence of voltage on the state-of-charge, it is difficult

to use ultracapacitors alone as the energy storage on hybrid

vehicles. The most promising approach is to hybridize theultracapacitors with other energy storages, such as

batteries and flywheel, which will be discussed in the

following sections.

2) Hybrid Energy Storage: Compared to ultracapacitors,

the chemical has a much higher specific energy but much

less specific power. When chemical batteries or an

ultracapacitor alone are taken as the energy storage, heavyweight will be unavoidable, because the former needs

large weight to meet the power requirement and the latter

needs weight to meet the energy requirement. However,

when both of them are properly combined, an energy

storage with high power and high energy can be obtained.

This energy storage is called hybrid energy storage, in

which the batteries supply the energy demand and the

ultracapacitors supply the power demand.The most straightforward approach is to directly

connect ultracapacitors to batteries as shown in Fig. 14.

This configuration has the simplest structure and no

control unit is needed. The behavior of the ultracapacitors

Table 2 Status of Chemical Battery Systems for EV



is more like a current filter, so that high battery peak

current is leveled, as shown in Fig. 15.

The leveled battery current by the presence of

ultracapacitors can result in many benefits to the batteries,

such as small battery pack, high operating efficiency, easy

thermal management, and longer battery life. The lesser

variation of terminal voltage can also release the burden of

the following power converter. With proper design of allthe components, this simply structured energy storage may

result in a high power, high energy, and high efficiency

energy storage system.

Clearly, in the passively connected battery/ultracapa-

citor system, the power flows between the battery pack and

ultracapacitor pack, and when the load cannot be

managed, consequently, the high-power characteristic of

the ultracapacitors can be fully used. Fig. 16 shows the

concept of an actively controlled battery/ultracapacitor

system. In this system, a power electronics based power

regulator is used to manage the power flow between the

battery back, ultracapacitor pack, and the load.

Basically, the power conditioning operation can bedivided into three different modes [23]: 1) ultracapacitor

peaking operation for high power demand (positive and

negative); 2) ultracapacitor charging from batteries; and

3) batteries-alone operation. These operation modes are

implemented by a central control unit. The central control

unit commands the power electronics, according to the

control strategy (control logic), and receives signals

through current and voltages sensors, as shown in

Fig. 13. Speed-torque characteristic of SRM with four different

designs. Fig. 14. Passively connected batteries/ultracapacitors system.

Table 3 Characteristic Data of a 42 V Ultracapacitor [18]



Fig. 11. The control objectives are: 1) to meet the power

requirement; 2) to keep the battery current in a preset

region; and 3) to keep the battery SOC in its middle region

(0.4 to 0.6 for example), in which the battery efficiencies

are usually optimized.

This system can potentially fully use the high power

property of the ultracapacitors, therefore resulting in asmall battery pack. The actively controlled battery current

can potentially lead to more efficient battery operation and

easier thermal management.

V. CONCLUSION

This paper systematically reviews the state of the art of

modern hybrid vehicle technologies, including architec-tures, electric motor drives, and energy storage. For the

architectures, series, parallel, and series–parallel are the

most commonly used architectures. For the advantages

and disadvantages, series hybrid configuration is mostly

used in heavy vehicles, military vehicles, and buses. On the

other hand, parallel and series–parallel are mostly used in

small automobiles, such as passenger cars. Regarding to

the electric motor drives, a long constant power region cansignificantly reduce the power rating of the electric system

and therefore reduce the total weight of the system. A

hybrid energy storage combining chemical batteries and

ultracapacitors will certainly be the most promising way to

meet the energy and power demands with a compact and

lightweight structure. h

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ABOUT THE AUT HORS

Mehrdad Ehsani (Fellow, IEEE) has been at Texas

A&M University, College Station, Texas since 1981,

where he has been the Robert M. Kennedy Pro-

fessor of electrical engineering and Director of

Advanced Vehicle Systems Research Program since

2004. He is the author of over 300 publications in

specialty power systems, pulsed-power supplies,

high-voltage engineering, power electronics and

motor drives, and automotive power and pro-

pulsion systems. He is the Coauthor of several

books on power electronics, motor drives, vehicle power and propulsion

systems, and a contributor to an IEEE Guide for Self-Commutated

Converters and many monographs. He is the author of over 20 U.S. and

EC patents. His current research work is in power electronics, motor

drives, hybrid electric vehicles, and vehicle power systems.

Dr. Ehsani has been a member of IEEE Power Electronics Society

AdCom, past Chairman of PELS Educational Affairs Committee, past

Chairman of IEEE-IAS Industrial Power Converter Committee and

Founding Chairman of the IEEE Myron Zucker Student-Faculty Grant

program. He was the General Chair of IEEE Power Electronics Specialist

Conference for 1990. He is an IEEE Industrial Electronics Society and

Vehicular Technology Society Distinguished Speaker and IEEE Industry

Applications Society past Distinguished Lecturer. He has been the

Associate Editor of IEEE Transactions of IES and IEEE VEHICLE TECHNOLOGY

SYSTEMS. He is the founder of IEEE Power and Propulsion Conference of

Vehicular Technology and Power Electronics Societies and the Chairman

of its Steering Committee. He was elected to the Board of Governors of

IEEE-VTS in 2003. He also serves on the IEEE Power Electronics Society

Administrative Committee. In 2005, he was elected Fellow of the Society

of Automotive Engineers (SAE). He is also a registered professional

engineer in the State of Texas. He has been the recipient of the Prize

Paper Awards in Static Power Converters and motor drives at the IEEE-

Industry Applications Society 1985, 1987, and 1992 Annual Meetings. In

1992, he was named the Halliburton Professor in the College of

Engineering at Texas A&M. In 1994, he was also named the Dresser

Industries Professor at the same college. In 2001, he was named the Dow

Chemical Faculty Fellow of the College of Engineering at Texas A&M

University. In 2001, he also received the James R. Evans Avant Garde

Award from IEEE Vehicular Technology Society. He is the recipient of

IEEE Field Award in Undergraduate Teaching in 2003.

Yimin Gao received the B.S., M.S., and Ph.D.

degrees in automotive engineering in 1982, 1986,

and 1991 respectively, all from Jilin University of

Technology, China. He specialized in the develop-

ment, design and manufacturing of automobiles.

From 1991 to 1995, he was an Associate

Professor and Automotive Design Engineer in the

Automotive Engineering College, Jilin University

of Technology. He joined the Advanced Vehicle

Systems Research Program at Texas A&M Univer-

sity, College Station, in 1995. Since then, he has been working in this

program as a Research Associate on the research and development of

electric and hybrid electric vehicles. His research interests include the

fundamentals, architecture, control, modeling, and systematic design of

electric and hybrid electric vehicles.

John M. Miller (Fellow, IEEE) received the BSEE

degree from the University of Arkansas, Fayette-

ville, in 1976, the MSEE degree from Southern

Methodist University, Dallas, TX, in 1979, and the

Ph.D. degree from Michigan State University, East

Lansing, in 1983, all in electrical engineering.

In 2006, he joined Maxwell Technologies as

Vice President of advanced transportation appli-

cations. In this capacity, he supports strategic

marketing and product applications through sys-

tems level analysis, modeling, simulation, and customer collaboration in

emerging technical areas. He brings Maxwell Technologies a systems

perspective and works closely with the engineering and business sides of

the company. He has authored over 120 publications on automotive

electrical and electronic systems, utility power systems and transporta-

tion systems and holds 51 U.S. patents. He is author of the book

Propulsion Systems for Hybrid Vehicles (IEE Press Power & Energy Series

PO045, London, U.K., 2003) and Coauthor of two additional books:

Handbook of Automotive Power Electronics and Motor Drives, (Marcel

Dekker, 2004) and Vehicular Electric Power Systems: Land, Sea, Air, and

Space Vehicles, (Marcel Dekker, December 2003). He also developed the

IEEE Expert Now Interactive Course: Exploring the Electronic Continu-

ously Variable Transmission.

Dr. Miller is a registered and practicing Professional Engineer in

Michigan since 1980 and an IEEE Power Electronics Society Distinguished

Lecturer and Editor-in-Chief of the Power Electronics Society newsletter.



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