Overview
The drive motor generator power inverter module (PIM) assembly converts high voltage direct current (DC) electrical energy to 3 phase alternating current (AC) electrical energy. The accessory DC power control module (APM) converts high voltage DC electric energy into low voltage (14V) and intermediate voltage (42V) in order to charge the vehicles accessory battery and supply electric energy to the 42V power steering system. The APM and PIM are fastened together and are referred to as the drive motor generator control module assembly. The drive motor generator control module assembly is cooled with pre-mixed Dexcool® circulating through a cooling system that is separate from the engine cooling system. The hybrid cooling system utilizes a heat exchanger at the front of the vehicle and electric pumps to circulate the coolant. The engine control module (ECM) monitors a temperature sensor in the hybrid cooling system and operates the radiator fan and the hybrid coolant pumps in response to system temperature.
Contained within the PIM assembly are the hybrid powertrain control module (HPCM), and two motor control modules (MCM). Each MCM controls its respective motor generator. All three modules are flash-programmable micro-processors.
Vehicles are typically subject to certain legal requirements that limit the amount of electromagnetic interference (EMI) that can be generated by the vehicles electronic devices. Additionally, the electronic devices within the vehicle must be able to withstand a certain amount of EMI without effecting their operation. EMI is generated whenever electrical current flows through a circuit. The amount of EMI generated, or amplitude, is usually dependant upon the amount of current flow, amperage, and the on-off pattern of current flow through the circuit, frequency. The EMI requirements are generally referred to as electromagnetic compatibility (EMC).
There are many ways of ensuring the vehicle meets EMC requirements. These include
- Adding capacitors and resistors to certain electrical circuits
- Regulating the frequency at which a component may operate
- Shielding the wires, cables and components
High Voltage Monitoring Systems Description
The hybrid system monitors several high voltage components for attempted access. Additionally, a minimum amount of isolation resistance is maintained at all times between both negative and positive poles of the hybrid battery and the vehicle chassis. The drive motor generator power inverter module (PIM) microprocessors and the battery energy control module (BECM) monitor the hybrid system for access and loss of isolation detection.
Hybrid Modes of Operation Description
This overview is not a comprehensive list of all aspects of the Two-Mode Hybrid vehicle. Refer to Electronic Component Description for information regarding transmission operation. More detailed and comprehensive information is also available through the dealer training program.
Enhancements to Engine Operation
While not unique to the Two-Mode hybrid vehicle, the following modes of operation benefit from expanded operational ranges. Expanded operational range is possible because the drive motor generators can be utilized to smooth driveline disturbances that would be objectionable without the intervention of the drive motor generator.