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Drive Motor Generator Power Inverter Module Description and Operation

The power inverter module, often referred to as the drive motor generator power inverter module, converts high voltage direct current (DC) electrical energy to 3 phase alternating current (AC) electrical energy. The power inverter 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 utilises 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.

Direct Current (DC)

The power inverter module assembly is connected to the positive and negative terminals of the high voltage, (DC) drive motor generator battery. Both of the negative and positive high voltage DC battery poles are isolated from the vehicle chassis by a specific amount of resistance. Each high-voltage DC cable is switched ON or OFF by a high- voltage, high-current contactor relay contained within the drive motor generator battery assembly. All high-voltage DC negative and positive DC cables are individually shielded and orange in colour to alert the technician to the potential presence of high voltage. The electric air conditioning compressor high-voltage DC cables are externally connected at the power inverter module assembly.

Three-Phase Alternating Current (AC)

Three individual cables connect each phase of the drive motor to the power inverter module. Each individually shielded cable is orange in colour to alert the technician to the potential presence of high voltage. A single shielded cable connects the auxiliary transmission fluid pump to the power inverter module. This cable contains 3 individual wires that are connected to the 3 phases of the auxiliary transmission fluid pump. The cable is orange in colour to alert the technician to the potential presence of high voltage.

The 14 V power module, also called the accessory DC power control module is the device which converts high-voltage (300 V) DC to low-voltage (12V) DC for accessory electrical operation and to charge the 12 volt accessory battery.

Low-Voltage (12 V) Direct Current

Low-voltage (12 V) cables on the hybrid-electric vehicle do not require unique colouring or servicing procedures.

Overview

The power inverter module contains 3 motor control modules and the hybrid powertrain control module. Two of the motor control modules operate their respective drive motor generators based upon power inverter module commands. The third motor control module controls the auxiliary transmission fluid pump motor. The hybrid powertrain control module and the motor control modules share the power inverter module ignition voltage circuit, battery voltage circuits and chassis earth. All four modules are flash-programmable micro-processors.

Location

The hybrid powertrain control module is a non-serviceable, flash-programmable micro-processor contained within the power inverter module.

Operating Functions

The hybrid powertrain control module is the main controller of powertrain operation. The hybrid powertrain control module determines when to perform normal operating modes such as electric mode, extended range mode and regenerative braking. The hybrid powertrain control module also operates in conjunction with the hybrid powertrain control module 2 to determine when to enable and disable the DC high-voltage circuits. Each motor control module operates the applicable motor based upon hybrid powertrain control module commands.

Communication and Hosted Diagnostics

The hybrid powertrain control module is the host controller for DTC information for the following control modules:

These modules diagnose their own operation and determine when a fault condition is present. The 14 V power module communicates the diagnostic status to the hybrid powertrain control module over serial data.

All 3 motor control modules and the hybrid powertrain control module exchange information and commands on a serial peripheral interface bus internal communication circuit as well as the hi-speed hybrid GMLAN communication circuit.

In the event a hosted module communicates a fault condition, the hybrid powertrain control module will determine if one or more operating modes are affected and notify the vehicle operator by requesting the MIL illuminate and/or by displaying a message in the Driver Information Centre. In addition, the hybrid powertrain control module will store the associated DTC information for retrieval by a scan tool. Some hosted modules may require an ignition cycle to clear certain DTCs from the hybrid powertrain control module.

Circuit Inputs

In addition to data parameters, the hybrid powertrain control module directly monitors the following signal circuits:

Location

Both the electric motor generators and the auxiliary transmission fluid pump motor are located within the transmission. They are each controlled by their own motor control module, each module is a flash-programmable micro-processor. Each motor control module is contained within the drive motor generator power inverter control module assembly. Also contained within the drive motor generator power inverter control module assembly is the hybrid powertrain control module micro-processor.

Operating Functions

The motor control modules operate their respective motors based upon hybrid powertrain control module commands. Each motor control module controls the speed, direction and output torque of its respective traction motor or the auxiliary transmission fluid pump motor through the sequencing actuation of high-current switching transistors called insulated gate bipolar transistors.

Communication and Hosted Diagnostics

In addition to the internal serial peripheral interface bus communication circuit that the hybrid powertrain control module and each motor control module control use to communicate, the motor control module controls also communicate on the Hi-speed and Hybrid serial data circuits. The motor control module control does not store its own diagnostic trouble code (DTC) information. The hybrid powertrain control module will store motor control module control associated DTC information for retrieval by a scan tool. The scan tool can communicate directly with each motor control module control in order to retrieve data parameters only.

Circuit Inputs

In addition to data parameters, each motor control module control monitors its respective motor for voltage, current, speed, direction and temperature. Additionally, the motor control module control monitors the insulated gate bipolar transistor components for temperature and proper operation. Some of the motor control module control operation data is shared with the hybrid powertrain control module.

Circuit Outputs

Each motor control module controls its respective insulated gate bipolar transistor driver board that, in turn, controls each motor. The motors operate using 3-phase alternating current (AC) electricity. Three cables connect each motor generator to the power inverter module. Each individually shielded cable is orange in colour to alert the technician that the potential for high voltage is present. A single shielded cable connects the auxiliary transmission fluid pump to the power inverter module. This cable contains 3 individual wires that are connected to the 3 phases of the auxiliary transmission fluid pump. The cable is orange in colour to alert the technician to the potential presence of high voltage.

Location

The accessory DC power control module, also called the 14 V power module, is located in the rear compartment. Refer to Accessory DC Power Control Module Description and Operation for description and operation information.