Contents
Content
CONTENTS
ABSTRACT
NOMENCLATURE
LIST OF TABLES
LIST OF FIGURES
1 CHAPTER INTRODUCTION
1.1.1 Brush less DC Motor
1.1.2 Advantages of BLDC Motor
1.1.3 BRUSH LESS DC MOTOR DRIVE
1.2 Sepic Converter
1.3 Unipolar Inverter
1.4 PWM Comparator
1.5 Hysteresis band current control PWM
1.6 Control strategies
1.6 Control strategies
1.7 Objective
1.8 Thesis outline
2 CHAPTER UNIPOLAR BLDC MOTOR
2.1 Introduction
2.2 CONSTRUCTION AND OPERATING PRINCIPLE
2.2.1 Stator Operation
2.2.2 Rotor Operation
2.2.2.1 ROTOR MAGNET CROSS SECTIONS
2.3 BLDC MOTOR TRANSVERSE SECTION
2.4 TORQUE/SPEED CHARACTERISTICS
2. 5 COMPARING BLDC MOTORS TO OTHER MOTOR TYPES
2.5.1 COMPARING A BLDC MOTOR TO A BRUSHED DC MOTOR
2.5.2 COMPARING A BLDC MOTOR TO AN INDUCTION MOTOR
2.6 UNIPOLAR Brush less DC Motor
3 CHAPTER PROPOSED TOPOLOGY
3.1 Proposed Topology
4 CHAPTER IMPLEMENTATION PI CONTROLLER TO SEPIC CONVERTER
4. Implementation PI controller to SEPIC Converter:
4.1 PI Controller
4.1.1 Integral and PI Controller Action
4.1.2 Function of the Proportional Term
4.1.3 Function of the Integral Term
4.1.4 Integral Action Eliminates Offset
4.1.5 Challenges of PI Control
4.1.6 Reset Time Versus Reset Rate
4.2 AC SUPPLY OPERATION
4.3 Block Diagram of Controller Ckt
5 CHAPTER RESULTS
5.1 SIMULATION
5.1.1 Comparison Of Input Current Harmonics As A Percentage Of The Fundamental
5.1.2 Comparison Of ThD And power Factor
5.2 Simulation Circuit Diagram
5.3 Simulation Results
CONCLUTIONS
REFERENCES
ABSTRACT
A new converter topology is proposed for driving a permanent magnet brushless dc
(BLDC) motor with unipolar currents. It is based on a front-end single-ended primary inductance
converter (SEPIC) and a switch in series with each phase. All the switches are groundreferenced, which simplifies their gate drives. The available input voltage can be boosted for
better current regulation, which is an advantage for low voltage applications. For operation with
an ac supply, the SEPIC converter is designed to operate in the discontinuous conduction mode.
In this operation mode, it approximates a voltage follower and the line current follows the line
voltage waveform to a certain extent. The reduction in low-order harmonics and improved power
factor is achieved without the use of any voltage or current sensors. The simplicity and reduced
parts count of the proposed topology make it an attractive low-cost choice for many variable
speed drive applications..
NOMENCLATURE
BLDC
Brushless DC motor
PFC
Power Factor Correction
SEPIC
Single Ended Primary Inductance Converter
EMF
Electromotive Force
PI
Proportional Integral
SMC
Sliding Mode Control
Ckt
Circuit
Vref
Sinusoidal reference signal
Ma
Modulation index
RMS
Root Mean Square
DSP
Digital Signal Processor
PWM
Pulse Width Modulation
PS
Periodical Sampling
HB
Hysterisis Band
TC
Triangular Carrier
THD
Total Harmonic Distortion
Nd
Neodymium
Co
Cobalt
Fe
Ferrite
B
Boron
EMI
Electro Magnetic Interference
E
Back emf
Vin
Input voltage
VL1
Voltage across inductor L1
VL2
Voltage across inductor L2
VC1
Voltage across capacitor C1
Wmax
Maximum operating speed
Ke
Phase back emf constant
Rs
Phase resistance
Ls
Phase inductance
I
Phase current
D
Duty cycle
R
load resistance
T
Time period
CCM
Continuous Conduction Mode
CO
Controller output
Cobias
Controller bias or null value
e (t)
Current Controller Error
SP
Set Point
PV
Process Variable
Kc
Controller gain
ADC
Analog to Digital Converter
C1, C2
Capacitors
Da, Db, Dc
Diodes
Sa, Sb
Turn-on and Turn-off switches
LIST OF TABLES
TABLE
TITLE
NO.
2.1
2.2
5.1
Comparing a BLDC motor to a brushed dc motor
Comparing a BLDC motor to an induction motor
Comparison of Input Current Harmonics as a Percentage of the
5.2
Fundamental
Comparison of THD and Power Factor
PAGE NO.
LIST OF FIGURES
FIGUR TITLE
E NO.
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.1
2.2
2.3
2.4
3.1
4.1
4.2
4.3
4.4
4.5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
Conventional six-switch inverter used for BLDC motor drive
Simple unipolar converter for three-phase BLDC motor
AC motor drive with active power factor correction stage
AC motor drive with integrated PFC stage and inverter
Brushless DC motor drive waveforms
Unipolar switching circuit
Voltage source converter topology
PWM carrier Technique
Current waveforms
Circular core with different magnets
BLDC motor transverse section
Torque /speed characteristics
Back-emf,phase current and output torque waveforms with
(a) bipolar excitation and
(b) unipolar excitation
Schematic of SEPIC converter based BLDC motor drive
Function of the Proportional Term
Function of the Proportional Term & controller error
Function of the Integral Term
Schematic of the proposed converter operating from an ac supply
Block diagram of the drive system
Simulation Circuit Diagram SEPIC Converter Topology
Power Factor Correction With SEPIC Converter
Source voltage and dc output voltage at diode rectifier
speed curve of induction motor drive
dc output voltage at diode rectifier
stator current of induction motor drive at load side
Torque curve of induction motor drive
PAGE
NO.
ABSTRACT
NOMENCLATURE
LIST OF TABLES
LIST OF FIGURES
1 CHAPTER INTRODUCTION
1.1.1 Brush less DC Motor
1.1.2 Advantages of BLDC Motor
1.1.3 BRUSH LESS DC MOTOR DRIVE
1.2 Sepic Converter
1.3 Unipolar Inverter
1.4 PWM Comparator
1.5 Hysteresis band current control PWM
1.6 Control strategies
1.6 Control strategies
1.7 Objective
1.8 Thesis outline
2 CHAPTER UNIPOLAR BLDC MOTOR
2.1 Introduction
2.2 CONSTRUCTION AND OPERATING PRINCIPLE
2.2.1 Stator Operation
2.2.2 Rotor Operation
2.2.2.1 ROTOR MAGNET CROSS SECTIONS
2.3 BLDC MOTOR TRANSVERSE SECTION
2.4 TORQUE/SPEED CHARACTERISTICS
2. 5 COMPARING BLDC MOTORS TO OTHER MOTOR TYPES
2.5.1 COMPARING A BLDC MOTOR TO A BRUSHED DC MOTOR
2.5.2 COMPARING A BLDC MOTOR TO AN INDUCTION MOTOR
2.6 UNIPOLAR Brush less DC Motor
3 CHAPTER PROPOSED TOPOLOGY
3.1 Proposed Topology
4 CHAPTER IMPLEMENTATION PI CONTROLLER TO SEPIC CONVERTER
4. Implementation PI controller to SEPIC Converter:
4.1 PI Controller
4.1.1 Integral and PI Controller Action
4.1.2 Function of the Proportional Term
4.1.3 Function of the Integral Term
4.1.4 Integral Action Eliminates Offset
4.1.5 Challenges of PI Control
4.1.6 Reset Time Versus Reset Rate
4.2 AC SUPPLY OPERATION
4.3 Block Diagram of Controller Ckt
5 CHAPTER RESULTS
5.1 SIMULATION
5.1.1 Comparison Of Input Current Harmonics As A Percentage Of The Fundamental
5.1.2 Comparison Of ThD And power Factor
5.2 Simulation Circuit Diagram
5.3 Simulation Results
CONCLUTIONS
REFERENCES
ABSTRACT
A new converter topology is proposed for driving a permanent magnet brushless dc
(BLDC) motor with unipolar currents. It is based on a front-end single-ended primary inductance
converter (SEPIC) and a switch in series with each phase. All the switches are groundreferenced, which simplifies their gate drives. The available input voltage can be boosted for
better current regulation, which is an advantage for low voltage applications. For operation with
an ac supply, the SEPIC converter is designed to operate in the discontinuous conduction mode.
In this operation mode, it approximates a voltage follower and the line current follows the line
voltage waveform to a certain extent. The reduction in low-order harmonics and improved power
factor is achieved without the use of any voltage or current sensors. The simplicity and reduced
parts count of the proposed topology make it an attractive low-cost choice for many variable
speed drive applications..
NOMENCLATURE
BLDC
Brushless DC motor
PFC
Power Factor Correction
SEPIC
Single Ended Primary Inductance Converter
EMF
Electromotive Force
PI
Proportional Integral
SMC
Sliding Mode Control
Ckt
Circuit
Vref
Sinusoidal reference signal
Ma
Modulation index
RMS
Root Mean Square
DSP
Digital Signal Processor
PWM
Pulse Width Modulation
PS
Periodical Sampling
HB
Hysterisis Band
TC
Triangular Carrier
THD
Total Harmonic Distortion
Nd
Neodymium
Co
Cobalt
Fe
Ferrite
B
Boron
EMI
Electro Magnetic Interference
E
Back emf
Vin
Input voltage
VL1
Voltage across inductor L1
VL2
Voltage across inductor L2
VC1
Voltage across capacitor C1
Wmax
Maximum operating speed
Ke
Phase back emf constant
Rs
Phase resistance
Ls
Phase inductance
I
Phase current
D
Duty cycle
R
load resistance
T
Time period
CCM
Continuous Conduction Mode
CO
Controller output
Cobias
Controller bias or null value
e (t)
Current Controller Error
SP
Set Point
PV
Process Variable
Kc
Controller gain
ADC
Analog to Digital Converter
C1, C2
Capacitors
Da, Db, Dc
Diodes
Sa, Sb
Turn-on and Turn-off switches
LIST OF TABLES
TABLE
TITLE
NO.
2.1
2.2
5.1
Comparing a BLDC motor to a brushed dc motor
Comparing a BLDC motor to an induction motor
Comparison of Input Current Harmonics as a Percentage of the
5.2
Fundamental
Comparison of THD and Power Factor
PAGE NO.
LIST OF FIGURES
FIGUR TITLE
E NO.
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.1
2.2
2.3
2.4
3.1
4.1
4.2
4.3
4.4
4.5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
Conventional six-switch inverter used for BLDC motor drive
Simple unipolar converter for three-phase BLDC motor
AC motor drive with active power factor correction stage
AC motor drive with integrated PFC stage and inverter
Brushless DC motor drive waveforms
Unipolar switching circuit
Voltage source converter topology
PWM carrier Technique
Current waveforms
Circular core with different magnets
BLDC motor transverse section
Torque /speed characteristics
Back-emf,phase current and output torque waveforms with
(a) bipolar excitation and
(b) unipolar excitation
Schematic of SEPIC converter based BLDC motor drive
Function of the Proportional Term
Function of the Proportional Term & controller error
Function of the Integral Term
Schematic of the proposed converter operating from an ac supply
Block diagram of the drive system
Simulation Circuit Diagram SEPIC Converter Topology
Power Factor Correction With SEPIC Converter
Source voltage and dc output voltage at diode rectifier
speed curve of induction motor drive
dc output voltage at diode rectifier
stator current of induction motor drive at load side
Torque curve of induction motor drive
PAGE
NO.
