ELECTRICAL
Control Modules
198
M4.3-1055-501
Power Circuit Operation
The traction control module provides signals to the
inputs of the power transistors to switch battery voltage
on and off to provide a pulse width modulated voltage
output and consequently the sinusoidal current wave-
form. The identical inputs occur on the U, V and W
inputs 120 degrees out of sequence for the three phase
output required. The upper bank of transistors pro-
duces the positive pulses and the lower bank of transis-
tors produce the negative pulses.
When the motor is acting as a generator, the diodes in
parallel with the transistors convert the three phase AC
current to DC current that returns energy to the battery.
Figure 14996
ACCESS 3 Traction Control Module
AC Power Base
Phase U
Phase V Phase W
Can Bus
Vector
Generator
and
Current
Regulator
Speed
Regulator
& IO
Module
Crown 2007 PF15712-2
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