Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 199)

Rockwell Automation Publication 750-RM002B-EN-P - September 2013 199
Motor Control Chapter 4
PWM Control
This type of control to operate the brake IGBT is similar to the way output
voltage to the motor is controlled. As the DC bus voltage increases and hits some
predetermined limit the brake IGBT is turned on/off according to a control
algorithm switched at 1 kHz. This type of control virtually eliminates bus ripple.
The big advantage is when this type of control is in a common bus configuration.
Duty Cycle
t
t
V
dc
V
dc_on+25
V
dc_on+25
–2.5
on
off
Brake IGBT
V
dc_on
100%
90%
750 772.5 775
DC Bus Voltage
Duty Cycle
Linear PWM Hysteretic Full on