Drive Motor with Generator Assemblies

Fig 1: Drive Motor with Generator Assemblies

Courtesy of GENERAL MOTORS COMPANY

Two permanent magnet electric motors mounted inside the transmission enable engine cranking, transmission reverse, and two EV modes of operation. The front, or motor 1 and the rear, or motor 2 each provide 60kW peak power. Both are actively cooled via transmission fluid and are encased in steel housings to facilitate transmission assembly. The front motor is used to start the engine and also react torque from the rear motor. The rear motor propels the vehicle when operating in full-electric mode with the engine off or in reverse. Motor speeds are controlled and monitored by position sensors internal to the motor housings. The drive motor generator position sensor is monitored by the motor control module. The motor control module monitors the angular position, speed and direction of the drive motor generator based upon the signals of the resolver-type position sensor. The position sensor, or resolver, contains a drive coil, two driven coils and an irregular shaped metallic rotor. The metallic rotor is mechanically attached to the shaft of the drive motor generator. At ignition ON, the motor control module outputs a 5 volt ac, 10 kHz excitation signal to the drive coil. The drive coil excitation signal creates a magnetic field surrounding the two driven coils and the irregular shaped rotor. The motor control module then monitors the two driven coil circuits for a return signal. The position of the irregular shaped metallic rotor causes the magnetically-induced return signals of the driven coils to vary in size and shape. A comparison of the two driven coils signals allows the motor control module to determine the exact angle, speed and direction of the drive motor generator. For more information on the drive motor function and system interaction refer to Drive Motor Generator Control Module Description and Operation , and Drive Motor Battery System Description .