User Manual

3-PHASE BLDC MO
T
PWM3
S
BT
PWM4
S
BT
PWM5
S
CT
PWM6
S
CT
PWM1
S
AT
PWM2
S
AB
POWER
SOURCE
DC VOLTAGE
PWM1 PWM2 PWM3 PWM4 PWM5 PWM6
DSP56F80X
3-PHASE POWER STAGE
A
B
C
PULSE WIDTH MODULATOR
(PWM) MODULE
MOSFET/IGBT DRIVERS
Control Technique
3-Phase BLDC Motor Control with Sensorless Back-EMF, ADC, Zero Crossing, Rev. 3
16 Freescale Semiconductor
Preliminary
Figure 5-1. PWM with BLDC Power Stage
PWM1 S
At
PWM2 S
Ab
PWM3 S
Bt
PWM4 S
Bb
PWM5 S
Ct
PWM6 S
Cb
electrical angle
0 60 120 180 240 300 360
I
A
I
B
I
C
commutation
commutation
commutation
commutation
commutation
commutation
commutation
A-off
A-off
B-off
A-off
A-off
B-off
B-off
B-off
C-off C-off
C-offC-off
C-off
A-off
A-off
B-off
C-off
B-off
A-off
A-off
C-off
C-off
C-off
A-off
Figure 5-2. 3-phase BLDC Motor Commutation PWM Signal