Robot and Servo Drive Lab.
Assessing pulse-width modulation
techniques for brushless dc motor
drives
BY YEN-SHIN LAI & YONG-KAI LIN
IEEE INDUSTRY APPLICATIONS MAGAZINE ∙SEPT j OCT 2008 ∙
WWW. IEEE.ORG/IAS pp34-44.
Student: Tai-Rong Lai
Professor: Ming-Shyan Wang
Department of Electrical Engineering
Southern Taiwan University
2015/4/8
Outline
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Abstract
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PWM techniques for BLDCM Drive
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Driver Circuit
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Reversal dc-Link Current
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Circulating Current of Floating Phase
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Back EMF Detection
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Assessment of PWM Techniques—Theoretical Analysis and Experimental Confirmation

Conclusions

References
2015/4/8
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Robot and Servo Drive Lab.
Abstract

The aim of this article is to assess the PWM techniques for
BLDCM drives.
• Driver circuit
• Reversal dc-link current
• Circulating current of floating phase
• Back-EMF
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PWM techniques for BLDCM Drive
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PWM techniques for BLDCM Drive
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PWM techniques for BLDCM Drive
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Driver Circuit
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Photocoupler driver
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Isolated transformer driver
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Bootstrap driver
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Photocoupler driver
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Isolated transformer driver
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Bootstrap driver
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Driver Circuit
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Reversal dc-Link Current
CH1:chopper
CH2:Vu CH3:Iu CH4:Idc
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Reversal dc-link current, phase U
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Circulating Current of Floating Phase
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Circulating Current of Floating Phase
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Back EMF Detection
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Vp:denotes the terminal voltage for the phase connected to the
positive dc-link rail during PWM control period.
Vn indicates the terminal voltage for the phase connected to
the negative dc-link rail.
Vo is the terminal voltage for the floating phase.
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Back EMF Detection
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Assessment of PWM Techniques—Theoretical
Analysis and Experimental Confirmation
Block diagram of the sensorless experimental system
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Motor specifications
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Number of poles=8
Rated power=70W
V dc= 24 V
Rated speed=2,500 rpm
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CH1: high-side control,
CH2: low-side control,
CH3: terminal voltage
CH4: phase current,
duty = 20%.
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CH1: high-side control,
CH2: low-side control,
CH3: terminal voltage
CH4: phase current,
duty = 80%.
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CH1: high-side control,
CH2: low-side control,
CH3: terminal voltage
CH4: dc-link current,
duty = 20%.
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CH1: high-side control,
CH2: low-side control,
CH3: terminal voltage
CH4: dc-link current,
duty = 80%.
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CH1: terminal voltage
CH2: phase current,
duty = 80%.
No load
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Conclusions

The aim of this article is to assess the special features of five
PWM techniques for BLDCM control. As shown here, the
indexes include reversal dc-link current, circulating current,
driver circuit, and back-EMF detection. Theoretical analysis is
presented and followed by the experimental results. An
inverter-controlled BLDCM drive without using any hall
sensor and current sensor is set up. Experimental results fully
support the analysis. These results provide the whole picture
for applications reference.
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References
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[1] Seiko Epson Corp., ‘‘Brushless dc motor without position sensor and its
controller,’’ E.P. Patent 0 553 354 B1, 1993.
[2] Tokyo Shibaura Electric Co., ‘‘Inverter and air conditioner controlled
by the same,’’ U.S. Patent 5 486 743, 1996.
[3] ST Microelectronics, ‘‘Control of a brushless motor,’’ U.S. Patent 5
859 520, 1999.
[4] J. Shao, D. Nolan, M. Teissier, and D. Swanson, ‘‘A novel
microcontroller-based sensorless brushless dc (BLDC) motor drive for
automotive fuel pumps,’’ IEEE Trans. Ind. Appl., vol. 39, pp. 1734–1740,
Nov./Dec. 2003.
[5] G. J. Su and J. W. McKeever, ‘‘Low-cost sensorless control of
brushless dc motors with improved speed range,’’ IEEE Trans. Ind.
Applicat., vol. 19, pp. 296–303, Mar. 2003.
[6] R. C. Becerra, T. M. Jahns, and M. Ehsani, ‘‘Four-quadrant sensorless
brushless ECM drive,’’ in Proc. 6th Annu. Applied Power Electronics
Conf. Exposition, Mar. 1991, pp. 202–209.
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References
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[7] S. Ogasawara and H. Akagi, ‘‘An approach to position sensorless drive
for brushless dc motors,’’ IEEE Trans. Ind. Applicat., vol. 27, pp. 928–933,
Sept./Oct. 1991.
[8] Y. S. Lai, F. S. Shyu, and Y. H. Chang, ‘‘Novel loss reduction
pulsewidth modulation technique for brushless dc motor drives fed by
MOSFET inverter,’’ IEEE Trans. Power Electron., vol. 19, no. 6, pp.
1646–1656, 2004.
[9] Y. S. Lai, F. S. Shyu, and Y. H. Chang, ‘‘Novel pulse-width modulation
technique with loss reduction for small power brushless dc motor drives,’’
in Conf. Rec. IEEE IAS Annu. Meeting, 2002, pp. 2057–2064.
[10] Tokyo Shibaura Electric Co., ‘‘Drive control apparatus for brushless
dc motor and driving method therefore,’’ U.S. Patent 5 491 393, 1996.
[11] Y. S. Lai, F. S. Shyu, and Y. K. Lin, ‘‘Novel PWM technique without
causing reversal dc-link current for brushless dc motor drives with
bootstrap driver,’’ in Conf. Rec. IEEE IAS Annu. Meeting, 2005, pp.
2182–2188.
[12] Y. S. Lai and Y. K. Lin, ‘‘A unified approach to back-EMF detection
for brushless dc motor drives without current and Hall sensor,’’ in Proc.
IEEE
IECON,
Nov.
2006, pp. 1293–1298.
Department
of Electrical
Engineering
Southern Taiwan University
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References
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[13] L6385: High-Voltage High and Low Side
Driver, ST Microelectronics Datasheet, USA, 1999.
[14] J. T. Strydom, M. A. De Rooij, and J. D. Van
Wyk, ‘‘A comparison of fundamental gate-driver
topologies for high frequency applications,’’ in Proc.
IEEE APEC, 2004, vol. 2. pp. 1045–1052.
[15] S. D. Sudhoff and P. C. Krause, ‘‘Operating
modes of the brushless dc motor with a 120
inverter,’’ IEEE Trans. Energy Conversion, vol. 5,
no. 3, pp. 558–564, 1990.
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Thanks for your listening ！
2015/4/8
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Robot and Servo Drive Lab.