Hybrid Electric Vehicle Training Educator

Hybrid Transaxle Assembly


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The hybrid transaxle assembly manages torque received from the gasoline engine and the electric drive motors and applies it to the front wheels. The hybrid application is different from a conventional transaxle assemble in that it contains two electric motors, working in conjunction with the gasoline engine to propel the vehicle. The motors are named motor generator (MG) 1 and MG2. MG 2 is the main drive motor (traction motor) used to propel the vehicle in electric drive only; it also is used to assist the gasoline engine during normal vehicle operation. MG2 also acts as a generator to charge the high-voltage battery during vehicle braking. The functions of MG 1 are assisting with steady speed changes and serving as the starter motor for the engine.

The hybrid transaxle assembly consists of the power split planetary gear unit, MG1, MG2, and the two-stage motor speed reduction planetary gear unit. The power split planetary gear unit uses a planetary gear to split engine output in accordance with driving requests while the vehicle is driven or the high-voltage battery is charged. MG2 is the main drive or "traction" motor. MG2 also converts the kinetic energy, which would otherwise be wasted in the form of heat during normal braking, into electrical energy. This function is known as regenerative braking and the recovered energy is stored in the high-voltage battery. MG1 generates power, which is used for charging the high-voltage battery or driving MG2. MG1 is used as a starter motor to start the engine.

© 2012 National Alternative Fuels Training Consortium.

Hybrid Transaxle Assembly

Hybrid Transaxle Assembly