IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008
3079
A Novel Position Sensorless Control of
a Four-Switch, Brushless DC Motor
Drive Without Phase Shifter
Abolfazl Halvaei Niasar, Member, IEEE, Abolfazl Vahedi, and Hassan Moghbelli, Member, IEEE
Abstract—This paper presents the analysis, design, and implementation of a cost-effective sensorless control technique for a lowcost four-switch, three-phase inverter brushless dc motor drive.
The proposed sensorless technique is based on the detection of zero
crossing points (ZCPs) of three voltage functions that are derived
and
. Six commutation
from the filtered terminal voltages
instants are provided that coincide to ZCPs of voltage functions.
Hence, there is no need for any 30 or 90 phase delay that is
prevalent in conventional sensorless methods. Two low-pass filters
are used for elimination of high-frequency noises and calculation
of average terminal voltages. Also, a direct phase current control
method is used to control the phase currents in the four-switch
inverter. An analytical study on position estimation error is discussed, and a correction method for some typical applications is
suggested. The performance of the developed sensorless technique
is demonstrated by simulation, and then, it is implemented using
TMS320LF2407A DSP. Experimental results are provided to confirm the simulations.
Index Terms—Brushless dc (BLDC) motor drive, four-switch inverter, phase shift, sensorless control.
I. INTRODUCTION
Permanent-magnet brushless dc (BLDC) motor is increasingly being used in automotive, computer, industrial, and
household products because of its high efficiency, high torque,
ease of control, and lower maintenance. A BLDC motor is
designed to utilize the trapezoidal back EMF with square-wave
currents to generate the constant torque [1]. A conventional
BLDC motor drive is generally implemented via a six-switch,
three-phase inverter and three Hall-effect position sensors that
provide six commutation points for each electrical cycle. Cost
minimization is the key factor in an especially fractional horsepower BLDC motor drive for home applications. It is usually
Manuscript received January 27, 2008; revised April 17, 2008. Current
version published December 09, 2008. This paper was presented in part
at the IEEE International Conference on Electrical Machines and Systems
(ICEMS’07), Seoul, Korea, October 8–11, 2007. Recommended for publication
by Associate Editor K.-B. Lee.
A. Halvaei Niasar is with the Iran University of Science and Technology
(IUST), Tehran 16846-13114, Iran and also with the Department of Electrical Engineering, Faculty of Engineering, University of Kashan, Kashan
87317-51167, Iran (e-mail: halvaei@kashanu.ac.ir).
A. Vahedi is with Iran University of Science and Technology, Tehran 1684613114, Iran (e-mail: avahedi@iust.ac.ir).
H. Moghbelli is with Isfahan University of Technology, Isfahan 84154, Iran,
and also with the Department of Science and Mathematics, Texas A&M University at Qatar, Doha 23874, Qatar (e-mail: hassan.moghbelli@qatar.tamu.edu).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TPEL.2008.2002084
achieved by elimination of the drive components such as power
switches and sensors. Therefore, effective algorithms should be
designed for the desired performance. Recently, a four-switch,
three-phase inverter (FSTPI) topology has been developed and
used for a three-phase BLDC motor drive. Reduction in the
number of power switches, dc power supplies, switching driver
circuits, losses and total price are the main features of this
topology. However, in the four-switch topology, conventional
control schemes are not effective for current regulation. Lee et
al. [2] developed a new and effective current control scheme
to obtain 120 rectangular currents based on the independent
control of the phases’ current.
Manufacturing cost of a BLDC motor drive can be reduced
more by elimination of position sensors and by developing
feasible sensorless methods. Furthermore, sensorless control
is the only choice for some applications where these sensors
cannot function reliably because of the harsh environments.
The major sensorless methods published in the literature can
be classified as follows [3], [4]: back EMF sensing techniques,
flux estimation method, stator inductance variations method,
observers, and intelligent control methods. The sensorless
techniques utilizing the back EMF voltage include: 1) terminal
voltage sensing; 2) third-harmonic back EMF voltage sensing;
and 3) freewheeling diode conduction current sensing. Sensorless techniques based on back EMF are the most popular due to
their simplicity, ease of implementation, and lower cost [5]–[7],
which lead to the manufacture of the commercial sensorless ICs
[8]. There are many papers that utilize back EMF voltage and
detection of the zero crossing point (ZCP). A 30 phase delay
between ZCPs and commutation instants is usually carried
out via a speed-dependent phase shifter, a lookup table, or by
using a hardware fixed-phase shifter. It needs more hardware
or complicated software that may lead to computational errors.
Some authors tried to develop a frequency-independent phase
shifter to overcome the mentioned problem [9].
Most of the sensorless methods for a six-switch inverter
BLDC motor drive are not directly applicable to the four-switch
inverter. The main reason is that in the four-switch topology,
some methods detect less than six points, and other commutation instants must be interpolated via software. So far, there are
few researches on sensorless control of a four-switch inverter,
three-phase BLDC motor drive. Lately, Lin et al. [10] proposed
a new sensorless control method for the four-switch topology.
Based on the experimental results, they found that two crossing
points between terminal voltages A and B coincide to two
commutation instants, and other four commutation instants
0885-8993/$25.00 © 2008 IEEE
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
3080
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008
Fig. 1. Four-switch inverter, BLDC motor drive, and equivalent circuit of the
BLDC motor.
Fig. 3. Voltage functions and phase back EMF voltages waveforms in a fourswitch, BLDC motor drive.
TABLE I
COMMUTATION LOGIC WITH RESPECT TO VOLTAGE FUNCTIONS
Fig. 2. Signal waveforms of a BLDC motor.
are attained via interpolation and shift delay software. Halvaei
Niasar et al. [11] introduced three new error functions in the
four-switch inverter topology where their ZCPs are 30 before
the commutation points. Therefore, a 30 shift delay should be
carried out. This paper presents a low-cost sensorless approach
for the four-switch inverter topology, which does not need any
phase shift. The proposed approach uses the ZCPs of three
voltage functions (line-to-line voltages), so that they coincide
to six commutation points. Theoretical analysis, simulations,
and several experiments are conducted to demonstrate the
feasibility of the proposed sensorless method [12].
II. ANALYSIS OF A FSTPI-BLDC MOTOR DRIVE
Fig. 1 shows the configuration of a four-switch inverter including the equivalent circuit of a three-phase BLDC motor. The
typical mathematical model of the BLDC motor is represented
as follows:
(1)
, , , , and
represent the voltage, back EMF,
where
phase current, self-inductance, and mutual inductance of phase
x, respectively (x = a, b, c). Fig. 2 shows phase back-EMF, current waveforms, and Hall-effect sensor signals of a three-phase
Fig. 4. Simulation block diagram of the sensorless-controlled, four-switch
BLDC motor drive.
TABLE II
BLDC MOTOR PARAMETERS
BLDC motor drive in ideal case. During each operation mode,
only two phases are conducting and the third phase is inactive. To drive the motor with maximum and constant torque, the
phase currents should be rectangular. However, in a four-switch
inverter, the generation of 120 conducting current profiles is inherently difficult [2]. Hence, in order to use the four-switch inverter topology for a three-phase BLDC motor, a direct phase
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
HALVAEI NIASAR et al.: NOVEL POSITION SENSORLESS CONTROL OF A FOUR-SWITCH, BRUSHLESS DC MOTOR DRIVE
3081
Fig. 5. Simulation results: terminal voltages, voltage functions, virtual Hall signals, and phase current waveforms of the developed sensorless control method. (a)
At speed of 30 r/min. (b) At speed of 220 r/min.
current (DPC) control approach is used, i.e., the currents of
phases A and B in two modes II and V are controlled via independent current regulators. Therefore, the back EMF voltage
of phase C does not disturb the phase currents. Based on the
independent switching of two phases A and B, current profiles
are similar to the currents of a six-switch inverter BLDC motor
drive.
circuits, zero crossings of VFs are detected, and the virtual Hall
, and
are generated that can be
sensor signals
used for current commutation. Table I summarizes the relation
between virtual Hall sensor signals and the corresponding
operation modes.
III. SENSORLESS CONTROL OF AN FSTPI-BLDC MOTOR
DRIVE BASED ON VOLTAGE FUNCTIONS
Fig. 4 shows the overall block diagram of the sensorless-controlled, four-switch inverter BLDC motor drive in Simulink. A
high-torque, low-speed BLDC motor with 16 poles is used for
simulation and its parameters are given in Table II. The speed
control block provides the current reference. In the current control block, the currents of two phases A and B are regulated via
two independent hysteresis controllers with a hysteresis band of
0.05 A. In the power inverter block, proper phase voltages are
generated and applied to the BLDC motor using the developed
duty cycles. The zero crossing detector block detects the ZCPs
of the voltage functions and then develops virtual position Hall
signals for sensorless control. Two second-order Butterworth
low-pass filters with passband frequency of 700 rad/s are used
to eliminate the high-frequency components of PWM voltages.
Fig. 5 shows the estimated operation mode, voltage signals, and
phase currents at speeds of 30 and 220 r/min where the phase
currents are rectangular. The filtered terminal voltages are used
to determine the voltage functions. There are some glitches on
the current due to the position estimation error, which are discussed in the following section.
Terminal voltages of a BLDC motor in the four-switch inverter with respect to the mid-point of the dc bus are as follows:
(2)
Three voltage functions (VFs) are derived from two terminal
and
as
voltages
(3)
Fig. 3 shows the waveforms of voltage functions and phase
back EMF voltages. Neglecting the voltage drop on the stator
impedance, voltage functions lag 30 inherently rather than
phase back EMF voltages, which means that the ZCPs of VFs
coincide to commutation instants. Using simple comparators
IV. SIMULATION RESULTS
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
3082
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008
Fig. 6. Analysis of the estimation error. (a) Voltages signals. (b) Estimation error due to the voltage drop on the stator impedance. (c) Current commutation via
virtual Hall signals. (d) Phase delay of low-pass filters.
V. ANALYSIS OF THE POSITION ESTIMATION ERROR
The position estimation error of the developed sensorless
method is generated by a voltage drop on the stator impedance,
phase delay of the filters, and voltage measurement, which are
explained as follows.
A. Voltage Drop on the Stator Impedance
The developed voltage functions inherently lag 30 from
phase back voltages, as mentioned earlier. It is due to the fact
that the voltage functions contain the line back EMF voltages.
However, the voltage drop on the stator impedance shifts the
ZCPs of the voltage functions from those of the corresponding
line back EMF voltages. The estimation error due to stator
impedance is analyzed for all operation conditions, and analytic
relations are developed as follows. For simplicity, the voltage
) is ignored, which means
drop on the stator inductance (
that the current commutation is considered ideal. It is a true
assumption in most small- to mid-sized BLDC motors because
the resistance voltage drop is usually much larger than the
inductance voltage drop. Fig. 6(a) illustrates a close look at the
is
voltage waveforms of phase A. The zero crossing of
used for current commutation of phase A. There is an inherent
and the line back EMF
delay angle ( ) between the signal
. The voltage function
from (2) and (3) can be
voltage
revised as
In mode I, as shown in Fig. 2, phases B and C are conducting
. Hence, by
the current and then
, the line back EMF voltage
is
neglecting the term
obtained as
(5)
Therefore, at ZCP of
(at = ′), the line back EMF
has the value of RI. The estimation error can be
voltage
obtained easily from the similarity of two triangles OAH and
OA′H′ shown in Fig. 6(a) as follows:
(6)
, and
are the load torque, torque constant,
where
back EMF constant, and the rotor speed, respectively.
Equation (6) implies that as long as the load torque is increasing, the estimation error also increases, and while the speed
is increasing, the estimation error decreases. Fig. 6(b) shows
variations of the estimation error for different speed and load
conditions. At high speed, the estimation error reduces to 4 .
However, at low speed and under heavy loads, the estimation
error increases, in which the operation of the sensorless algorithm is limited to a certain speed. To obtain this limitation by
using Fig. 6(c), the phase back EMFs and currents in the interval
can be represented as
(4)
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
(7)
HALVAEI NIASAR et al.: NOVEL POSITION SENSORLESS CONTROL OF A FOUR-SWITCH, BRUSHLESS DC MOTOR DRIVE
3083
Fig. 7. Hardware schematic of the sensorless-controlled, four-switch BLDC
motor drive based on TMS320LF2407A DSP.
Hence, the air gap power during interval
is obtained as
(8)
Fig. 8. Main control flowchart of the system software.
To have a reliable sensorless operation at low speeds, a sufficient
condition is that the instant output power of the motor should be
positive (in forward motoring case). Equation (8) shows that the
estimation error must satisfy
. For the BLDC motor
used in this study and by substituting the motor parameters into
(6), the low limit point of the speed is obtained about 40 r/min
in full-load condition. Although this limit point may be a bit
higher due to the voltage drops on power switches, diodes, and
. Therefore, the voltage drop on
also the neglected term
the stator impedance is the main source of the estimation error
at low speed range.
B. Phase Delay of the Low-Pass Filters
Designing the proper filters is important for zero crossing
detection of the voltage functions, because the terminal voltages are PWM signals. In this paper, two second-order Butterworth low-pass filters are designed [13]. To adjust the filters, the
measured PWM voltages have been processed in Matlab, and
the passband frequency of the filters have been set to 100 Hz
(with 0.1 dB attenuation). Fig. 6(d) shows the phase delay
versus frequency for the designed filters. The phase delay at
) and 35 Hz (
two frequencies of 6.5 Hz (
) are 1.5 and 5 , respectively.
C. Measurement Errors
The sensorless algorithm developed in this study is based only
on the filtered terminal voltages
and
. Therefore, the accuracy of the measured voltages directly affects the accuracy
of the position estimation. Using exact components to make
the low-pass filters also reduces the position estimation. Providing the virtual Hall position signals via hardware eliminates
the quantization error due to the analog-to-digital (A/D) conversion.
Fig. 9. Measured back EMF voltages of the employed BLDC motor.
All error sources mentioned in this section cause the estimated commutation instants to lag rather than real commutation instants, and there is no room for compensation. Determination of voltage functions and corresponding virtual Hall signals can be carried out through the software to solve the mentioned problem. Calculated voltage functions are compared with
the proper thresholds. This approach advances the commutation
that can compensate any phase delay. However, it increases the
amount of calculations and leads to more complex algorithms,
which is against the objectives of employing an inexpensive and
simple sensorless control algorithm for a FSTPI-BLDC motor
drive. For some cost-sensitive applications such as fan, blowers,
etc., where the load increases when speed increases, the proposed sensorless algorithm (without error compensation in the
software) is feasible and can be implemented via an inexpensive
microcontroller.
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
3084
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008
Fig. 10. Measured instantaneous and filtered terminal voltages V
(d) 220 r/min.
and V
at (a) 60 r/min and (b) 220 r/min. Voltage functions waveforms at (c) 60 r/min and
VI. DSP IMPLEMENTATION OF THE SENSORLESS TECHNIQUE
Fig. 7 shows the schematic diagram of the hardware
system, where the system is controlled via a DSP controller
TMS320LF2407A [14]. DSP commands are isolated and amplified via HCPL A316J gate drivers and the phase currents
are measured via LA55-P current transducers. The sensorless
technique developed in this study uses the measured terminal
voltages, where the Hall-effect linear transducer LV25-P is
used. Determination of the voltage functions and making the
virtual position signals are carried out via hardware. Therefore,
it is possible to employ the capabilities of the capture unit in
the event manager module of DSP.
The second module checks the safety of the drive. In the third
module, a startup procedure for the sensorless control is provided. Open-loop starting is a practical control procedure to run
the BLDC motor without position sensors that is accomplished
by providing a rotating stator field with a certain frequency profile [15]. This method should be started from a certain initial
rotor position. However, for a motor with no reluctance variation
around the air gap, determination of the rotor initial position is
impossible, and consequently, the forced alignment of the rotor
must be implemented. In this paper, after energizing two phases
A and B (mode II) for enough time, the next commutation signals advancing the switching pattern by an electrical 60 angle
is given. After that one electrical evolution elapsed, the sensorless closed-loop control is run.
B. Software Organization
C. Experimental Results
The developed software is based on four modules: system
initialization, protection, startup, and run modules, as shown in
Fig. 8. The first step for the development of the software is to
initialize all peripherals on the DSP board, which includes the
initialization of PWM ports, timer interrupt, and A/D converters.
Fig. 9 shows the measured phase back EMF voltages where
the rising edge of position signal
is simultaneous with the
flat part of the back EMF voltage . Fig. 10(a) and (b) shows
the instantaneous and the filtered terminal voltages at two speeds
of 60 r/min (360 electrical r/min) and 220 r/min (1760 electrical
A. System Hardware Structure
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
HALVAEI NIASAR et al.: NOVEL POSITION SENSORLESS CONTROL OF A FOUR-SWITCH, BRUSHLESS DC MOTOR DRIVE
3085
Fig. 11. Developed virtual position signals under different conditions. (a) At 60 r/min and no load. (b) At 60 r/min under 70% full load. (c) At 220 r/min and no
load. (d) At 220 r/min under 70% full load.
r/min). The dc bus voltage is 60 V, whereas the voltage sensors
are set such that the voltage range 35 to 35 V is converted
to 0–3.3 V into DSP. Therefore, the voltage scale in Fig. 10
is 70/3.3 = 21 v/v. Fig. 10(c) and (d) shows the corresponding
voltage functions waveforms at 60 and 220 r/min, respectively,
that have the same amplitude. Fig. 11 shows the estimated position signals at different conditions that indicate that the estimated signals in all conditions are together at 120 . At no-load
condition, the estimation error is 4 and 4.5 at low and high
speeds, respectively. Due to the increase of rotational losses at
high speed for the BLDC motor used, there is actually not a
no-load condition. Therefore, at high speed with no-load condition, there is some estimation error. The estimation error under
70% full-load condition at low and high speeds are 24 and 14 .
The measured estimation errors confirm the simulation and also
the proposed analysis error.
Fig. 12 shows the current waveforms at different conditions
where the current scale is 6 A/V. The motor is started using the
open-loop startup algorithm, as mentioned earlier. Forced alignment takes about 1.2 s, as shown in Fig. 12(a), and the open-loop
control is applied for one electrical cycle. It can be done for less
than one electrical cycle under lower load. Experimental results
show that the developed sensorless algorithm can be applied
at 30 r/min for no-load condition. Fig. 12(b) shows the current
waveforms for no-load condition when the sensorless control is
applied. It indicates that the rotational loss of the BLDC motor
is considerable. Current waveforms under load condition at low
and high speeds are shown in Fig. 12(c) and (d), respectively.
In both cases, the sensorless control of the currents as well as
employing the DPC control method is successful.
VII. CONCLUSION
A low-cost BLDC motor drive is introduced in this study.
Cost saving is achieved by reducing the number of inverter
power switches and also by elimination of the position Hall-effect sensors. For current commutation, virtual Hall signals
are developed by a novel sensorless method using line-to-line
voltages that are calculated from the measured terminal voltages. Simulation and experimental results verify the validity of
the proposed sensorless method. The proposed error analysis
shows that the voltage drop on the stator impedance is the main
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
3086
IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008
Fig. 12. Phase current waveforms using virtual position signals. (a) Motor startup. (b) At 220 r/min and no load. (c) At 60 r/min under 70% full load. (d) At speed
150 r/min under 70% full-load conditions.
error source especially at low speeds. Therefore, the developed
sensorless method is suitable for applications when the load is
increasing as the speed increases. The main advantages of the
proposed method are as follows.
1) Full (six) commutation points are detected in the fourswitch inverter drive. Therefore, extra phase-shifting circuits or interpolation in the software for prediction of other
commutation points are not required.
2) Commutation points immediately follow the developed
virtual Hall sensors. Therefore, 30 phase shifting as used
in the methods based on back EMF voltage is not required.
3) Voltage functions are determined directly from the terminal
voltages A and B without making the motor neutral point.
4) The proposed sensorless technique is independent of the
back EMF waveform that can be applied to permanentmagnet synchronous [brushless ac (BLAC)] motors.
For low-cost applications, the implementation of the proposed method is easier and less expensive than that of other
methods even with the sensorless methods based on back EMF
voltage. Therefore, it is more attractive and cost-effective, and
it can be implemented as integrated circuits (ICs).
REFERENCES
[1] P. Pillay and R. Krishnan, “Modeling, simulation, and analysis of permanent-magnet motor drives. II. The brushless DC motor drive,” IEEE
Trans. Ind. Appl., vol. 25, no. 2, pp. 274–279, Mar./Apr. 1989.
[2] B. K. Lee, T. H. Kim, and M. Ehsani, “On the feasibility of four-switch
three-phase BLDC motor drives for low cost commercial applications:
Topology and control,” IEEE Trans. Power Electron., vol. 18, no. 1, pp.
164–172, Jan. 2003.
[3] J. P. Jahnson, M. Ehsani, and Y. Guzelaunler, “Review of sensorless
methods for brushless DC,” in Proc. IEEE IAS Annu. Meeting Conf.,
1999, pp. 143–150.
[4] P. P. Acarnley and J. F. Watson, “Review of position-sensorless operation of brushless permanent-magnet machines,” IEEE Trans. Ind.
Electron., vol. 53, no. 2, pp. 352–362, Apr. 2006.
[5] J. Shao, D. Nolan, and T. Hopkins, “A novel direct back EMF detection
for sensorless brushless DC (BLDC) motor drives,” in Proc. IEEE Appl.
Power Electron. Conf. Expo., 2002, vol. 1, pp. 33–37.
[6] G. J. Su and W. McKeever, “Low-cost sensorless control of brushless
DC motors with improved speed range,” IEEE Trans. Power Electron.,
vol. 19, no. 2, pp. 296–302, Mar. 2004.
[7] G. Zhou, Z. Wu, and J. Ying, “Improved sensorless brushless DC motor
drive,” in Proc. IEEE Power Electron. Spec. Conf. (PESC 2005), pp.
1353–1357.
[8] C. Wang, G. Sung, K. Fang, and Sh. Tseng, “A low-power sensorless
inverter controller of brushless DC motors,” in Proc. IEEE Int. Symp.
Circuits Syst. (ISCAS 2007), pp. 2435–2438.
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.
HALVAEI NIASAR et al.: NOVEL POSITION SENSORLESS CONTROL OF A FOUR-SWITCH, BRUSHLESS DC MOTOR DRIVE
[9] Q. Jiang, C. Bi, and R. Huang, “A new phase-delay-free method to
detect back EMF zero-crossing points for sensorless control of spindle
motors,” IEEE Trans. Magn., vol. 41, no. 7, pp. 2287–2294, Jul. 2005.
[10] C. T. Lin, C. W. Hung, and C. W. Liu, “Sensorless control for fourswitch three-phase brushless DC motor drives,” IEEE Trans. Power
Electron., vol. 23, no. 1, pp. 438–444, Jan. 2008.
[11] A. Halvaei Niasar, H. Moghbelli, and A. Vahedi, “Sensorless control of
a four-switch, three-phase brushless DC motor drive,” presented at the
Iranian Conf. Electr. Eng. (ICEE 2007), May, Iran Telecommun. Res.
Center (ITRC), Tehran, Iran.
[12] A. Halvaei Niasar, “Sensorless control of four-switch, three-phase
brushless DC motor drives for low-cost applications,” Ph.D. dissertation, Dept. Electr. Eng., Iran Univ. Sci. Technol., Tehran, Iran, Dec.
2007.
[13] L. Qiang, L. Mingyao, H. Minqiang, and G. Weigang, “Research
on filters for back EMF zero-crossing detecting in sensorless BLDC
motor drives,” in Proc. IEEE Int. Conf. Ind. Technol., Dec. 2006, pp.
1899–1905.
[14] TMS320LFLC240xA DSP Controllers Reference Guide–System
and Peripherals (in Texas Instruments Incorporated) , Literature no.
SPRU357B. Dallas, TX, Dec. 2001.
[15] R. Krishnan and R. Ghosh, “Starting algorithm and performance of a
PM DC brushless motor drive system with no position sensor,” in Proc.
IEEE Power Electron. Spec. Conf. (PESC 1989), pp. 815–821.
Abolfazl Halvaei Niasar (S’04–M’09) was born in
Kashan, Iran, in 1974. He received the B.S. degree
from Isfahan University of Technology (IUT),
Isfahan, Iran, in 1998, the M.S. degree from the
University of Tehran (UT), Tehran, Iran, in 2000, and
the Ph.D. degree from Iran University of Science and
Technology (IUST), Tehran, Iran, all in electrical
engineering
He is currently an Assistant Professor at the
Department of Engineering, Faculty of Engineering,
University of Kashan, Kashan, Iran. His current
research interests include DSP-based control systems, electric drives, permanent-magnet brushless dc motor drives, sensorless drives, and design of high
speed motors.
Dr. Halvaei Niasar is a Member of the IEEE Power Electronics Society
(PELS) and the IEEE Industry Applications Society (IAS).
3087
Abolfazl Vahedi was born in Tehran, Iran, in 1966.
He received the B.S. degree from Ferdowsi Mashhad
University, Mashhad, Iran, in 1989, and the M.S. and
Ph.D. degrees from the Institut Nationale Polytechnique de Lorraine (INPL), Nancy, France, in 1992
and 1996, respectively, all in electrical engineering.
He is currently an Associate Professor and a
member of the Center of Excellence for Power
System Automation and Operation, Iran University
of Science and Technology (IUST), Tehran. He has
directed several projects in the area of conventional
and special electric machines and drives. His current research interests include
design, implementation, and optimization of electric machines including
traction motors and drives.
Dr. Vahedi is a member of the Institution of Electrical Engineers (IEE) and
the Society for Electrical Engineering (SEE).
Hassan Moghbelli (M’90) was born in Isfahan, Iran,
in 1950. He received the B.S. degree from Iran University of Science and Technology (IUST), Tehran,
Iran, in 1973, the M.S. degree from Oklahoma State
University, Stillwater, in 1978, and the Ph.D. degree
1989 from the University of Missouri-Columbia
(UMC), Columbia, in 1989, all in electrical engineering.
He is currently an Assistant Professor at Isfahan
University of Technology, Isfahan. He is also a Visiting Assistant Professor in the Department of Science and Mathematics, Texas A&M University at Qatar, Doha, Qatar. He has
directed several projects in the area of electric drives, power systems, electric
vehicles, hybrid electric and fuel cell vehicles, and railway electrification. His
current research interests include electric drives, power electronics, and design
of electric and hybrid electric vehicle.
Dr. Moghbelli is a member of the American Society of Mechanical Engineers
(ASME) and the Society of Automotive Engineers (SAE).
Authorized licensed use limited to: IEEE Xplore. Downloaded on December 28, 2008 at 07:37 from IEEE Xplore. Restrictions apply.