Starter/Generator Control Module (SGCM)
The starter generator control module (SGCM) controls the flow of torque/energy into and out of the starter/generator via the 3-phase cables. Overall, the SGCM controls the starter generator engine cranking, torque control, speed control and torque smoothing/active damping functions. The SGCM also controls the 4 types of power:
- Perform bi-directional 42-volt DC to 14-volt DC electrical energy conversion between the 42-volt DC bus and the 14-volt DC bus for system energy management.
- Perform bi-directional DC/AC electrical energy conversion between the 42-volt DC bus and the 3-phase asynchronous machine.
- Provide 120-volt 60Hz AC energy for on and off board electrical equipment.
In the basic, 3-phase inversion/conversion process, 42-volt DC is converted to AC for starting, and, conversely, AC is converted to 42-volt DC for recharging. In addition, 14-volt power is converted to 42-volt for jump-starting, 42-volt power is converted to 14-volt for the battery charging function, and 42-volt power is converted to 120 volts AC for powering the auxiliary power outlets.
The SGCM has 2 discrete crankshaft signal circuits inputs to calculate engine position. One is hard wired and one is a signal on the GMLAN bus. This acts as a back-up system in the event that one signal is interrupted the engine will be able to start and run although a DTC will set.