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ELG4139 ELG4139 Julio Pimentel Kylowave Inc.
ELG4139ELG4139
Julio Pimentel
Kylowave Inc.
Class 1
What you will learn� Introduction on PWM modulators
� Introduction on three-phase inverters
� Fundamentals of Brushless DC motors
Operation of BLDC motors using six-steps control � Operation of BLDC motors using six-steps control algorithm
� Speed and torque control of BLDC motors
A BLDCM Control System
Note: drawing from Microchip AN885
Some general classes of power
electronics circuits� Families of solid state power converters categorized
according to their conversion function
AC
Vac1 f1
ACRVac1, f1
AC
Vac2, f2
DC
Vdc1
DC
Vdc2
DC-DC
Converters
AC-DC
Rectifiers
DC-AC
Inverte
rs
DC
Link
AC-AC Converters
Cicloconverters
One of our subjects for today’s class
PWM – Pulse Width Modulation� The idea is to modulate the width of a stream of pulses, keeping the
carrier frequency constant, such that the low pass frequency spectrum produces the required waveform
LP Filtered signal
HF Stream of
Pulses
PWM in Wikipedia
Introduction to 3-phase inverters� 6 Transistors Power Converter
Note: drawing from Freescale AN1916
Half Bridge section
Fundamentals of Brushless DC
motors� BLDC Motor Cross Section
Note: drawing from Freescale AN1916
Fundamentals of Brushless DC
motors� Types of Back Electro Magnetic Force (BEMF)
� Depends on BLDCM physical construction
Trapezoidal
Sinusoidal
Note: drawing from Microchip AN885
Trapezoidal
Fundamentals of Brushless DC
motors� Internal View of the Stator and Rotor of a BLDC Motor
StatorRotor
Note: drawing from Microchip AN885
Fundamentals of Brushless DC
motors� Three-Phase Hall Sensors
120 degrees
Note: drawing from Microchip AN885
Fundamentals of Brushless DC
motors� Winding Energizing Sequence
� Dependent on hall sensor encoding
6 possible vectors for the 60 degree
sectors
vectors for the magnetic field
Note that all ZEROS is open circuit and all ONES is short circuit. Why?
BLDCM Theory of Operation� six-steps control algorithm
� Control logic is not complicate to implement
� Capable of very high speed operationoperation
� Relatively high torque ripple compared to other methods (Sinusoidal BEMF, Sinusoidal PWM, FOC, SVM, etc.)
� High current ripple implies high harmonic content and higher operating temperature (for the same operating conditions)
Note: drawing from Microchip AN885
Speed control of BLDC motors
PI or PID PI or PID Filter
SpeedEstimator
Note: drawing from Freescale AN1916
Torque control of BLDC motors
PI or PID PI or PID
Note: drawing from Freescale AN1916
PI or PID Filter
PI or PID Filter
SpeedEstimator
Putting it all together� Control Block Diagram
Note: drawing from Microchip AN885
Putting it all together
For further study� Two others interesting examples on power electronics
Example #2
Spontaneous switching - RectifiersSingle phase Three phaseD1
D1N4002
V2
FREQ = 60
VAMPL = 10
VOFF = 0 R1
1K
L1
10uH
C1
5u
V VI
D1
D1N4002
R1
1K
V2
FREQ = 60
VAMPL = 10
VOFF = 0
PHASE = 120
D2
D1N4002
L1
10uH
C1
5u
D3
D1N4002
D4
D1N4002
D5
D1N4002
D6
D1N4002
V3
FREQ = 60
VAMPL = 10
VOFF = 0
PHASE = 240
V1
FREQ = 60
VAMPL = 10
VOFF = 0
PHASE = 0
I V
V
Smoothinginductance
V2 1K PHASE = 120 PHASE = 240PHASE = 0
Example #3
Forced switching� phase controlled rectifier DC-DC Converter
R3
20
V1 = 0V2 = 2
L1
5mh
V3
D1
D1N4002
C1
10n
Q1Q2N2222
R4
10
I
VV1
FREQ = 60
VAMPL = 50
VOFF = 0
PHASE = 0
R3
100
X1
2N1595
PER = 16.6667ms
V1 = 0V2 = 5
L1
5mh
R4
1k
V
V
V2
TD = 0
TF = 10ns
PW = 30u
PER = 100u
TR = 10ns
V2 = 2
20V
V2
TD = 3ms
TF = 10ns
PW = 0.2ms
TR = 10ns
V2 = 5V
Conclusion
Resources available� Orcad version 16.3 Student Edition – Free
� http://www.cadence.com/products/orcad/pages/downloads.aspx
� NOTE: The student edition has limitations in terms of # � NOTE: The student edition has limitations in terms of # of components, # of pins, etc.
� We will publish a copy of the example circuits
� The internet has many useful links� Search for “ pspice and power and electronics”
References on Power Electronics� This is one of the best references
� Erickson, R. W. & Maksimovic, D., “Fundamentals of Power Electronics,” 2nd Edition, University of Colorado, Boulder, http://ecee.colorado.edu/copec/book/slides/slidedir.html
� These are good references as well� These are good references as well� Ramshaw, E. & Shuumman, D. C., “PSpice Simulation of
Power Electronics Circuits: An Introductory Guide,” Springer Verlag, 1996
� Ferrieux, J. P. & Forest, F., “Alimentation à découpage -Convertisseurs à résonance: principes, modélisation, composants,” Collection technologies, Masson, Paris, 1987, ISBN 2-225-81205-5
� Tolyat, H. A. & Campbell, S., “DSP-Based Electromechanical Motion Control,”CRC Press, 2003
References on Control of BLDCM� 1) Leonard N. Elevich, “3-Phase BLDC Motor Control
with Hall Sensors Using 56800/E Digital Signal Controllers,” Freescale Semiconductor, AN1916, Rev. 2.0, 11/200511/2005
� 2) Padmaraja Yedamale, “Brushless DC (BLDC) Motor Fundamentals,” Microchip Technology Inc., AN885, 2003
