PXS20RM Datasheet, PDF (669/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

VAL1 ($0100)
VAL3
VAL0 ($0000)
VAL2
INIT ($FF00)
Flexible Motor Control Pulse Width Modulator Module (FlexPWM)
PWMA
no deadtime
PWMB
PWMA
with deadtime
PWMB
DTCNT0
DTCNT1
Figure 25-21. Deadtime Insertion
25.3.3.8.1 Top/Bottom Correction
In complementary mode, either the top or the bottom transistor controls the output voltage. However,
deadtime has to be inserted to avoid overlap of conducting interval between the top and bottom transistor.
Both transistors in complementary mode are off during deadtime, allowing the output voltage to be
determined by the current status of load and introduce distortion in the output voltage. See Figure 25-22.
On AC induction motors running open-loop, the distortion typically manifests itself as poor low-speed
performance, such as torque ripple and rough operation.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
25-23