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transcript
Sensorless Control of Permanent
Magnet Brushless DC Motors
Satishbabu Bhogineni
DEPARTMENT OF ELECTRICAL ENGINEERINGINDIAN INSTITUTE OF TECHNOLOGY DELHI
OCTOBER 2016
©Indian Institute of Technology Delhi (IITD), New Delhi, 2016
Sensorless Control of Permanent
Magnet Brushless DC Motors
by
Satishbabu Bhogineni
Department of Electrical Engineering
submitted
in fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY
to the
INDIAN INSTITUTE OF TECHNOLOGY DELHI
OCTOBER 2016
CERTIFICATE
This is to certify that the thesis entitled, “Sensorless Control of Permanent
Magnet Brushless DC Motors” being submitted by Mr. SATISHBABU
BHOGINENI for the award of the degree of Doctor of Philosophy is a record
of bonafide research work carried out by him under my guidance and supervision in
the Department of Electrical Engineering of Indian Institute of Technology Delhi.
Mr. Satishbabu Bhogineni has fulfilled the requirements for the submission of
this thesis, which to my knowledge has reached the requisite standard. The results
obtained here in have not been submitted to any other University or Institute for
the award of any degree.
Date:
Place:
Prof. K. R. Rajagopal
Department of Electrical Engineering
Indian Institute of Technology Delhi
Hauz Khas, New Delhi – 110016, India
i
ACKNOWLEDGEMENTS
It is my pleasure to record sincere gratitude to my supervisor, Prof. K. R.
Rajagopal for providing me the opportunity to work under his supervision. I am
heartily thankful to him for his constant encouragement, counsel, direction and
involvement. His valuable suggestions and guidelines kept me focused in my re-
search. His mentorship, co-operation and support have been of utmost importance
for the completion of this dissertation.
I am thankful to IIT Delhi authorities for providing me the necessary facilities for
the completion of my research work.
I am grateful to my SRC committee members, Prof. Balasubramanian, Prof. I. N.
Kar, Dr. A. R. Abhayankar and Prof. Viresh Dutta for their valuable suggestions
and feedback during the course of my research.
I would like to express my gratitude to my teachers Prof. Bhim Singh, Prof. G.
Bhuvaneswari, Prof. M. Veerachary, Prof. S. S. Murthy and Prof. J. K. Chaterjee
for their support during my course work.
I would also like to thank Phaneendra Babu Bobba and Gaurang. I. Vakil for
invaluable support and assistance. I am thankful to my fellow research scholars
and M.Tech students with whom I discussed and shared the lab facilities.
My sincere thanks to the PG Machines Lab staff, Mr. Srichand, Mr. Puran Singh,
and Mr. Jagbeer Singh for providing facilities and equipment required for my work.
I am greatly indebted to Dhirendra Yadav, Surajbhan Sevda and other friends for
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making my stay enjoyable and memorable at Vindyachal house. I am greatly
thankful to my friends Prasad Yanamadala, Raja Shekar, Sudhakar, Sarvesh and
Satish for their support and guidance. This list is still not complete and I apologize
to those not listed by name as you all contributed to my experience.
Most importantly, I would like to express my heart-felt gratitude to my parents,
grand parents, uncles and aunts. None of this would have been possible without
the love and patience of my family. I am also thankful to all who have directly
or indirectly helped me during my Ph.D. Finally, my greatest regards to the Lord
for the love, opportunity and ability face the complexities of life and complete this
dissertation successfully.
Satishbabu Bhogineni
IIT Delhi
ABSTRACT
Permanent magnet brushless DC (BLDC) motor drives are increasingly used
in a variety of applications starting with the most critical ones in aerospace to
high quality toys. As on today, almost all two-wheeler and three-wheeler electric
vehicles are driven by these motors. Apart from its wide acceptance in industry
and also for agricultural pumps, energy efficient domestic appliances such as refrig-
erators, air conditioners, washing machines and ceiling fans are being increasingly
driven by these BLDC motors.
These motors are equipped with hall sensors for the rotor position feedback
which is essential in switching currents to the appropriate stator windings in syn-
chronism with the obtained rotor position. Typically, in a three-phase BLDC
motor, apart from the three main power cables, five extra wires are needed for
the rotor position sensors, two for supplying power to these sensor units and the
remaining three for the position signals. These sensor units will occupy some space
anyway and are also sensitive to temperature variations. Use of hall sensors re-
duces the reliability and at the same time increases the cost. Coupled to this with
the problems associated with the assembly and accuracy, it’s always advantageous
to have a position sensor free system for driving this BLDC motor.
The back EMF based sensorless control is widely used in BLDC motors nowa-
days owing to its easy implementation and cost effectiveness. In this method, the
zero crossing point (ZCP) of the back EMF is estimated by detecting the ZCPs of
v
either the phase or the line voltages given to the motor. Among these two voltage
detection based methods, the line voltage ZCP based sensorless control method
uses simple circuits compared to the phase voltage ZCP based method. Moreover,
the line voltage ZCPs can be obtained directly from motor terminals. The investi-
gations carried out in this work on the line voltage ZCP method had brought out
more information on the errors associated with this method and remedial solu-
tions are successfully implemented. The available current in sensorless control can
be advantageously used to improve the line voltage ZCP based sensorless control
method. By using current in addition to terminal voltages, a novel line back EMF
based sensorless control technique is proposed in this work which improved the
performance of the drive. This has been done without using any costly processors
and hence is very economical which is one of the prime concerns addressed in
this work so as to make these sensorless schemes viable for low cost and medium
performance applications like majority of the domestic appliances and automotive
components. Hardware implementation of this proposed scheme is done and the
test results are in agreement with designed and simulated ones. Further studies are
carried out to improve these techniques and some improvements are also suggested
to eliminate the delay caused by the filter used for voltage sensing.
In a three phase BLDC motor, six power devices are usually used in an inverter
configuration. So as to decrease the cost of the drive, reduced parts converters
are being used with induction and permanent magnet synchronous motors. These
are also used in BLDC motors, but with a penalty of having an additional current
sensor. The use of four switches three phase inverter (FSTPI) with BLDC motor
necessitates extra high side current sensing. Addition of extra sensor nullifies
the benefit of having reduced number of switches. In this work, by appropriate
logic, the requirement of this additional current sensor is eliminated thus bringing
back the cost advantage of the reduced number of switches and that too on the
sensorless control mode.
To eliminate high side current sensing, a current reconstruction method is
proposed with a simple low side resistive current sensing which reduces the cost
of the drive. By using the reconstructed current, two direct current control tech-
niques are proposed. The first one is the constant ON/OFF control, where the
current is sensed during lower switch conduction period by fixing the upper switch
conduction time. The second method is the fixed frequency sensing control. Here,
a current sensing state is inserted at fixed intervals in to the operation of motor.
The same logic is extended to PWM control and proposed a modified symmetric
PWM for inserting the sensing states in to the operation. The hardware imple-
mentation of the single resistive current sensing with modified symmetric PWM is
carried out and the test results are again in agreement with the designed and sim-
ulated ones which definitely is a step ahead in having economic sensorless control
of BLDC motors.
Contents
Certificate i
Acknowledgements iii
Abstract v
Contents ix
List of Figures xv
List of Tables xxi
Abbreviations xxii
Symbols xxv
1 INTRODUCTION 1
1.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 PERMANENT MAGNET BRUSHLESS MOTORS . . . . . . . . . 3
1.2.1 Permanent Magnet Synchronous Motor . . . . . . . . . . . . 6
1.2.2 Brushless DC Motor . . . . . . . . . . . . . . . . . . . . . . 7
1.2.3 Construction and Operation of BLDC Motor . . . . . . . . . 10
1.3 FOUR SWITCH THREE PHASE INVERTER . . . . . . . . . . . 13
1.4 SENSORLESS CONTROL OF BLDC MOTOR . . . . . . . . . . . 14
1.5 MOTIVATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.6 LITERATURE SURVEY . . . . . . . . . . . . . . . . . . . . . . . . 18
1.6.1 BLDC Motor . . . . . . . . . . . . . . . . . . . . . . . . . . 19
1.6.2 Modeling and Control . . . . . . . . . . . . . . . . . . . . . 20
1.6.3 Sensorless Control . . . . . . . . . . . . . . . . . . . . . . . 21
ix
1.6.4 Starting Mechanism . . . . . . . . . . . . . . . . . . . . . . 25
1.6.5 Four Switch Three Phase Inverter . . . . . . . . . . . . . . . 26
1.7 SCOPE OF THE WORK . . . . . . . . . . . . . . . . . . . . . . . 27
1.8 ORGANISATION OF THE THESIS . . . . . . . . . . . . . . . . . 28
2 MODELING AND CONTROL OF BLDC
MOTOR 31
2.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2 MODELING OF BLDC MOTOR . . . . . . . . . . . . . . . . . . . 32
2.2.1 Development of Simulation Model . . . . . . . . . . . . . . . 36
2.2.2 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . 38
2.3 CONTROL OF BLDC MOTOR . . . . . . . . . . . . . . . . . . . . 38
2.3.1 Voltage/Speed control . . . . . . . . . . . . . . . . . . . . . 41
2.3.2 Current/Torque control . . . . . . . . . . . . . . . . . . . . . 41
2.3.3 Pulse Amplitude Modulation Control . . . . . . . . . . . . . 42
2.3.4 Pulse width Modulation Control . . . . . . . . . . . . . . . . 43
2.3.4.1 Bipolar PWM Techniques . . . . . . . . . . . . . . 43
2.3.4.2 Simple Bipolar PWM Technique . . . . . . . . . . 44
2.3.4.3 Complementary PWM Technique . . . . . . . . . . 44
2.3.4.4 Unipolar PWM Technique . . . . . . . . . . . . . . 45
2.3.5 Hysteresis Current Control . . . . . . . . . . . . . . . . . . . 46
2.4 SENSORLESS CONTROL . . . . . . . . . . . . . . . . . . . . . . . 48
2.4.1 Back EMF based Methods . . . . . . . . . . . . . . . . . . . 49
2.4.1.1 Filtered Voltage Methods . . . . . . . . . . . . . . 50
2.4.1.2 Unfiltered Voltage Methods . . . . . . . . . . . . . 52
2.4.2 Machine Equations based Methods . . . . . . . . . . . . . . 54
2.4.3 Model based Methods . . . . . . . . . . . . . . . . . . . . . 55
2.4.4 Inductance based Methods . . . . . . . . . . . . . . . . . . . 56
x
2.5 SENSING CURRENTS AND VOLTAGES . . . . . . . . . . . . . . 57
2.5.1 Current Sensing . . . . . . . . . . . . . . . . . . . . . . . . . 57
2.5.2 Voltage Sensing . . . . . . . . . . . . . . . . . . . . . . . . . 59
2.6 HARDWARE SETUP DESCRIPTION . . . . . . . . . . . . . . . . 59
2.6.1 Experimental Results from DSO . . . . . . . . . . . . . . . . 63
2.6.2 Existing Hall Signals . . . . . . . . . . . . . . . . . . . . . . 63
2.7 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3 LINE VOLTAGE ZCP BASED SENSORLESS CONTROL 69
3.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.2 COMMUTATION INSTANT DETECTION . . . . . . . . . . . . . 72
3.3 VIRTUAL HALL SIGNAL GENERATION CIRCUIT . . . . . . . . 74
3.4 EFFECT OF WINDING RESISTANCE DROP . . . . . . . . . . . 75
3.5 ERRORS IN LV-ZCP BASED SENSORLESS CONTROL . . . . . 78
3.5.1 Error due to Low Pass Filter Used in Voltage Sensing . . . . 79
3.5.2 Error due to Winding Impedance . . . . . . . . . . . . . . . 79
3.5.3 Error due to Winding Resistance Drop . . . . . . . . . . . . 80
3.5.4 Error due to Measurement and Signal Processing . . . . . . 80
3.5.4.1 Measurement Errors . . . . . . . . . . . . . . . . . 80
3.5.4.2 Signal Processing Errors . . . . . . . . . . . . . . . 80
3.5.5 Effect of Voltage Spikes due to Residual Current . . . . . . . 81
3.6 SIMULATION RESULTS . . . . . . . . . . . . . . . . . . . . . . . 82
3.7 HARDWARE IMPLEMENTATION . . . . . . . . . . . . . . . . . 88
3.7.1 Hardware Results . . . . . . . . . . . . . . . . . . . . . . . . 89
3.8 EFFECT OF DELAY ON PERFORMANCE . . . . . . . . . . . . 89
3.9 EFFECT OF PARAMETERS ON ERROR . . . . . . . . . . . . . 95
3.9.1 Winding Resistance . . . . . . . . . . . . . . . . . . . . . . . 95
3.9.2 Winding Inductance . . . . . . . . . . . . . . . . . . . . . . 96
xi
3.9.3 Filter Capacitance . . . . . . . . . . . . . . . . . . . . . . . 96
3.9.4 Inertia of System . . . . . . . . . . . . . . . . . . . . . . . . 97
3.10 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4 LV-ZCP BASED SENSORLESS CONTROL WITH UNIPO-
LAR PWM TECHNIQUES 99
4.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
4.2 UNIPOLAR PULSE WIDTH MODULATION TECHNIQUES . . . 99
4.3 ERROR IN COMMUTATION INSTANT DETECTION . . . . . . 103
4.4 SIMULATION RESULTS . . . . . . . . . . . . . . . . . . . . . . . 106
4.5 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5 LINE BACK EMF BASED SENSORLESS CONTROL 111
5.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.2 PROPOSED COMMUTATION INSTANT DETECTION SCHEME 112
5.3 COMMUTATION INSTANT DETECTION . . . . . . . . . . . . . 113
5.4 VIRTUAL HALL SIGNAL GENERATION . . . . . . . . . . . . . 115
5.5 HARDWARE IMPLEMENTATION . . . . . . . . . . . . . . . . . 116
5.5.1 Voltage Drop Estimation Circuit . . . . . . . . . . . . . . . 117
5.5.2 Commutation Signals Generation . . . . . . . . . . . . . . . 118
5.6 SIMULATION RESULTS . . . . . . . . . . . . . . . . . . . . . . . 119
5.7 COMPENSATION FOR FILTER DELAY . . . . . . . . . . . . . . 119
5.8 HARDWARE RESULTS . . . . . . . . . . . . . . . . . . . . . . . . 122
5.9 CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
6 FOUR SWITCH THREE PHASE INVERTER BASED BLDC
MOTOR DRIVE 127
6.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
6.2 FOUR SWITCH THREE PHASE INVERTER . . . . . . . . . . . 129
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6.3 FSTPI BASED BLDC MOTOR CONTROL . . . . . . . . . . . . . 132
6.4 HYSTERESIS CURRENT CONTROL . . . . . . . . . . . . . . . . 137
6.4.1 C–Phase Conduction in Sector II and V . . . . . . . . . . . 139
6.5 VOLTAGE CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . 143
6.5.1 C–Phase Conduction in Sector II and V . . . . . . . . . . . 145
6.6 CURRENT SENSING . . . . . . . . . . . . . . . . . . . . . . . . . 146
6.7 LOW SIDE CURRENT SENSING . . . . . . . . . . . . . . . . . . 147
6.8 HYSTERESIS CURRENT CONTROL USING LOWER SWITCH
CURRENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
6.8.1 Constant ON/OFF Time Control . . . . . . . . . . . . . . . 150
6.8.2 Fixed Time Sensing Control . . . . . . . . . . . . . . . . . . 153
6.9 VOLTAGE CONTROL USING LOWER SWITCH CURRENT . . 155
6.10 PROPOSED CURRENT SENSING IN VOLTAGE CONTROL . . 157
6.10.1 PWM Control Using Lower Switch Currents . . . . . . . . . 158
6.10.2 PWM Control Using Lower Side DC Bus Current . . . . . . 159
6.10.3 Control Strategy . . . . . . . . . . . . . . . . . . . . . . . . 161
6.11 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
7 SENSORLESS CONTROL OF FSTPI BASED BLDC MOTOR 167
7.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
7.2 LINE BACK EMF BASED SENSORLESS CONTROL . . . . . . . 168
7.3 HARDWARE IMPLEMENTATION . . . . . . . . . . . . . . . . . 169
7.3.1 Current Sensing . . . . . . . . . . . . . . . . . . . . . . . . . 169
7.3.2 Voltage Sensing . . . . . . . . . . . . . . . . . . . . . . . . . 171
7.3.3 Control Strategy . . . . . . . . . . . . . . . . . . . . . . . . 172
7.3.4 Hardware Results . . . . . . . . . . . . . . . . . . . . . . . . 173
7.4 STARTING MECHANISM . . . . . . . . . . . . . . . . . . . . . . . 174
7.5 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
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8 MAJOR CONCLUSIONS AND SUGGESTIONS FOR FUTURE
WORK 177
8.1 MAJOR CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . 177
8.2 MAIN CONTRIBUTIONS OF THIS RESEARCH WORK . . . . . 181
8.3 SUGGESTIONS FOR FUTURE WORK . . . . . . . . . . . . . . . 182
REFERENCES 185
Appendix-I 199
Appendix-II 201
Appendix-III 203
Authorbiodata 207
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List of Figures
1.1 Voltage, current waveforms and position information required in
PMSM and BLDC motor . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Different rotor structures used in PMBL motors . . . . . . . . . . . 7
1.3 Vector controlled three phase PMSM motor drive . . . . . . . . . . 8
1.4 Control structure of BLDC motor drive . . . . . . . . . . . . . . . . 10
1.5 BLDC motor construction details . . . . . . . . . . . . . . . . . . . 11
1.6 Phase back EMF, current, hall signal and torque waveforms of
BLDC motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.7 Basic BLDC motor drive structure . . . . . . . . . . . . . . . . . . 12
2.1 Electrical circuit model . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.2 Flux function realisation by IFFT . . . . . . . . . . . . . . . . . . . 37
2.3 Coupled circuit model . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.4 Simulation results using developed model with sinusoidal and trape-
zoidal back EMFs at noload . . . . . . . . . . . . . . . . . . . . . . 39
2.5 Simulation results using developed model with different back EMF
shapes with load . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.6 Different PWM techniques used in BLDC motor control . . . . . . . 47
2.7 Principle of commutation instant detection by phase back EMF zero
crossing point and back EMF integration . . . . . . . . . . . . . . . 50
2.8 Principle of commutation points generation from 3rd harmonic back
EMF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.9 High side and low side current sensing using resistance element . . . 58
2.10 Hardware implementation block diagram . . . . . . . . . . . . . . . 61
2.11 Experimental setup showing all components . . . . . . . . . . . . . 62
xv
2.12 Three phase current waveforms from DSO with normal mode and
precision mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.13 Sensed three phase voltage waveforms from DSO with normal mode
and precision mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
2.14 Measured time periods of existing hall signals . . . . . . . . . . . . 66
2.15 Measured sector widths of existing hall signals . . . . . . . . . . . . 67
3.1 Relation between line back EMF zero crossing point and hall signal 70
3.2 Relation between line voltage zero crossing point and hall signals
when running with sensors . . . . . . . . . . . . . . . . . . . . . . . 74
3.3 Virtual hall signals generation circuit . . . . . . . . . . . . . . . . . 75
3.4 Error due to winding drop in line voltage zero crossing points . . . 77
3.5 Effect of voltage spikes due to residual current. . . . . . . . . . . . . 81
3.6 Waveforms of BLDC motor running with hall sensors with current
at three different speeds . . . . . . . . . . . . . . . . . . . . . . . . 83
3.7 Waveforms of LV-ZCP based sensorless control at 5000rpm and
2500rpm with hysteresis current control . . . . . . . . . . . . . . . . 84
3.8 Waveforms of LV-ZCP based sensorless control at 1000rpm with
hysteresis current control . . . . . . . . . . . . . . . . . . . . . . . . 85
3.9 Failure mode waveforms at at 1000rpm speed and 1.0A current . . . 85
3.10 Waveforms of LV-ZCP based sensorless control at with PWM con-
trol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.11 Implementation of line voltage ZCP based sensorless control . . . . 88
3.12 Waveforms of with hall sensor with PWM control . . . . . . . . . . 90
3.13 Waveforms of with and LV-ZCP based sensorless control with PWM
control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.14 Waveforms of LV-ZCP based sensorless control with current control 92
3.15 Power developed with delay in commutation . . . . . . . . . . . . . 92
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3.16 Variation power and current with delay angle . . . . . . . . . . . . 93
3.17 Deviation of current in LV-ZCP method form ideal commutation . . 94
4.1 BLDC motor conduction states with unipolar PWM . . . . . . . . . 100
4.2 Floating phase voltages (a) and (b) Upper switch PWM before turn
ON and after turn OFF, (c) and (d) Lower switch PWM before turn
ON and after turn OFF of corresponding phase. . . . . . . . . . . . 101
4.3 Actual average voltage of floating phase. . . . . . . . . . . . . . . . 103
4.4 Average terminal voltage upper switch PWM. . . . . . . . . . . . . 103
4.5 Waveforms of LV-ZCP based sensorless control with H-PWM-L-
PWM technique at 2500rpm . . . . . . . . . . . . . . . . . . . . . . 107
4.6 Waveforms of LV-ZCP based sensorless control with H-PWM-L-ON
and H-ON-L-PWM techniques at 2500rpm . . . . . . . . . . . . . . 108
4.7 Waveforms of LV-ZCP based sensorless control with PWM-ON and
ON-PWM techniques at 2500rpm . . . . . . . . . . . . . . . . . . . 109
5.1 Principle of the commutation instant detection . . . . . . . . . . . . 114
5.2 Comparison virtual hall signals with actual hall signal . . . . . . . . 115
5.3 Generation of switching signals from virtual hall signals . . . . . . . 116
5.4 Schematic diagram of proposed line back EMF based sensorless con-
trol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
5.5 Voltage drop estimation Circuit . . . . . . . . . . . . . . . . . . . . 118
5.6 Commutation Instant Detection Circuit . . . . . . . . . . . . . . . 118
5.7 Waveforms with the proposed line back EMF ZCP method with
different loads and speeds (1) . . . . . . . . . . . . . . . . . . . . . 120
5.8 Waveforms with the proposed line back EMF ZCP method with
different loads and speeds (2) . . . . . . . . . . . . . . . . . . . . . 121
5.9 Compensation circuit for filter delay . . . . . . . . . . . . . . . . . . 121
xvii
5.10 Waveforms with the proposed line back EMF ZCP method and with
improvement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
5.11 Waveforms with the proposed line back EMF ZCP method with
current PI control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
6.1 Four switch three phase inverter based 3- phase motor drive . . . . 129
6.2 Switching states of four switch three phase inverter . . . . . . . . . 130
6.3 State voltages of four switch three phase inverter . . . . . . . . . . 132
6.4 Four switch three phase inverter based BLDC motor drive . . . . . 133
6.5 FSTPI BLDC states . . . . . . . . . . . . . . . . . . . . . . . . . . 134
6.6 FSTPI BLDC Three Phase Conduction . . . . . . . . . . . . . . . . 135
6.7 SSTPI based BLDC Hysteresis Control . . . . . . . . . . . . . . . . 136
6.8 FSTPI based BLDC Hysteresis Control . . . . . . . . . . . . . . . . 136
6.9 FSTPI based BLDC motor hysteresis current control using (a) four
states and (b) eight states . . . . . . . . . . . . . . . . . . . . . . . 137
6.10 Hysteresis Control using Eight States . . . . . . . . . . . . . . . . . 138
6.11 Experimental results (a) Independent control of two phase currents
and (b) maximum DC current is controlled by hysteresis control . . 139
6.12 C-phase conduction (a) Average model and (b) Equivalent circuit . 142
6.13 Experimental waveforms for voltage controlled PWM (a) without
C phase current control and (b) with C phase current control . . . . 146
6.14 current sensor positions in FSTPI-BLDCM . . . . . . . . . . . . . . 147
6.15 Resistive Current sensing positions . . . . . . . . . . . . . . . . . . 147
6.16 Constant ON time control . . . . . . . . . . . . . . . . . . . . . . . 151
6.17 Constant OFF time control . . . . . . . . . . . . . . . . . . . . . . 151
6.18 Phase A current waveform with constant ON/OFF control . . . . . 152
6.19 Waveforms with constant ON/OFF control (a) Three phase currents
and switching signals and (b) Magnified phase currents . . . . . . . 153
xviii
6.20 Principle of current sensing in constant frequency sampling control . 155
6.21 Waveforms with constant frequency sampling control at 2000rpm
(a) 0.3A (b) 0.5A loads . . . . . . . . . . . . . . . . . . . . . . . . . 156
6.22 Waveforms with constant frequency sampling control at 1900rpm
(a) 0.3A (b) 0.5A loads . . . . . . . . . . . . . . . . . . . . . . . . . 156
6.23 Different PWM techniques used in sector II and V . . . . . . . . . . 159
6.24 Simulation results with PWM control . . . . . . . . . . . . . . . . . 161
6.25 Hardware results with PWM control at 1900rpm (a) Uncontrolled
C phase current at no load, (b) Controlled C phase current at no
load, (c) Uncontrolled C phase current with load and (d) Controlled
C phase current with load . . . . . . . . . . . . . . . . . . . . . . . 162
6.26 Hardware results with PWM control (a) Lower side switch cur-
rents sensing at 1250rpm, (b) Lower side DC bus current sensing at
1250rpm and (d) Lower side DC bus current sensing at 1900rpm . . 163
6.27 PWM control logic . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
7.1 Block diagram of FSTPI based sensorless control . . . . . . . . . . 169
7.2 Current sensing with single low side current sense resistor . . . . . . 170
7.3 Simulation results explaining principle of current sensing with single
low side current sense resistor . . . . . . . . . . . . . . . . . . . . . 171
7.4 Commutation instant detection logic . . . . . . . . . . . . . . . . . 173
7.5 Experimental waveforms of FSTPI based sensorless control with
single resistive current sensing (a) With IR drop compensation (b)
With complete compensation . . . . . . . . . . . . . . . . . . . . . 174
7.6 Experimental waveforms of FSTPI based sensorless control with
single resistive current sensing with phase advancing . . . . . . . . . 174
7.7 Starting mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
xix
List of Tables
3.1 Delay variation with speed and load . . . . . . . . . . . . . . . . . . 86
4.1 Unipolar PWM commutation instants . . . . . . . . . . . . . . . . . 106
5.1 The Commutation Instant Detection Logic . . . . . . . . . . . . . . 114
5.2 Decoding of Switching Signals . . . . . . . . . . . . . . . . . . . . . 115
5.3 Virtual Hall Signal Generation . . . . . . . . . . . . . . . . . . . . . 116
6.1 Switching states and corresponding voltages of FSTPI . . . . . . . . 131
6.2 States used and corresponding voltage . . . . . . . . . . . . . . . . 148
6.3 Currents sensed in different sectors of operation . . . . . . . . . . . 149
6.4 Current sensing in constant ON/OFF time control . . . . . . . . . . 153
6.5 Current sensing in constant frequency sampling control . . . . . . . 156
6.6 Current sensing in PWM control . . . . . . . . . . . . . . . . . . . 159
6.7 Current sensing in DC bus in different sectors of operation . . . . . 160
xxi
Abbreviations
AC Alternating Current
ACP Actual Commutation Point
ADC Analog to Digital Converter
ALV Average Line Voltage
AlNiCo Alluminium Niclel Cobalt
ANN Artificial Neural Networks
ASIC Application Specific Integrated Circuit
BLDC BrushLess DC
BLDCM BrushLess DC Motor
DC Direct Current
DSP Digital Signal Processor
EMF Electro Motive Force
EMI Electro Magnetic Interference
EV Electrc Vehicle
FSTPI Four Switch Three Phase Inverter
H Hall Signal
IC Integrated Circuit
ICP Ideal Commutation Point
IGBT Insulated Gate Bipolar Transistor
IM Induction Motor
IPM Intellignet Power Module
LPF Low Pass Filter
MMF Magneto Motive Force
MOSFET Metal Oxide Semiconductor Feild Effect Transistor
NdFeB Neodymium Ferrous Boran
PAM Pulse Amplitude Modulation
PCB Printed Circuit Board
PI Proportional Integral
PID Proportional Integral Derivative
PM Permanent Magnetxxiii
PM BLDC Permanent Magnet BrushLess DC
PMDC Permanent Magnet DC
PMSM Permanent Magnet Synchronous Motor
PMBL Permanent Magnet BrushLess
PSO Particle Swam Optimisation
PWM Pulse Width Modulation
RMS Root Mean Square
RTOS Real Time Operating System
RTW Real Time Workshop
SmCo Samarium Cobalt
SPM Smart Power Module
SSTPI Six Switch Three Phase Inverter
SVM Space Vector Modulation
TI Texas Instruments
VH Virtual Hall Signal
VLSI Very Large Scale Integration
VSI Voltage Source Inverter
ZCP Zero Crossing Point
xxiv
Symbols
D Duty ratio
KE EMF constant
KT Torque constant
Kp Proportional gain
Ki Integral gain
p Time derivative operator
Te Electromagnetic torque developed
TL Applied load torque
X Any switch state
Z High impedance state/ leg both switches are off
ω Angular rotor speed
ωe Electrical rotor speed
ωr Rotor speed
ωm mechnical rotor speed
N Rotor speed in rpm
Ts Sampling time
F Frequency
t Time
Fs Switching frequency
d− axis Direct axis
q − axis Quadrature axis
Vd d− axis voltage
Vd q− axis voltage
Id d− axis current
Iq q− axis current
τx Time constant
Pag Air gap power
Pave Average power
Pcap Power capability
xxv
Ploss Power loss
Idc DC-link current
Sx Switch x
emax Phase back EMF maximum value
Sx − Sy Switch x to y in numerical order
yx∗ Reference value of that variable yx
Idm Maximum DC-link current
Vdc DC-link voltage
Ra, Rb, Rc Phase resistances
La, Lb, Lc Phase inductances
ea, eb, ec Phase back-EMFs
eab, ebc, eca Line back-EMFs
ia, ib, ic Phase currents
va, vb, vc Terminal voltages of the
A, B and C phases respectively
van, vbn, vcn Terminal voltages of the
A, B and C with respect to neutral
Ha, Hb, Hc Hall signals
corresponding to A, B, C phases
θ Angular position
φ Difference angle
J Rotor inertia
B Friction factor
xxvi