Drive Motor/Generator: Description and Operation

Description

The electric motor is the core technology of a hybrid vehicle. The Hybrid motor system is equipped with two electric motors.These motors are the drive (traction) motor that is used as the primary power source and a HSG, which acts as the starter motor and alternator in a conventional engine. The traction motor operates to move the vehicle and to provide lower Noise, Vibration, Harshness (NVH) during driving and to achieve fuel efficiency.
The electric motor supplements the engine during acceleration to increase power output and to allow the engine to operate in a fuel efficient mode. In addition, the electric motor takes on the role of a generator during deceleration and braking to charge the high voltage battery. The Hybrid Starter Generator (HSG) starts the engine while the vehicle is in motion.






Operation Principle

The drive motor is an IPM(Interior Permanent Magnet) type small-sized/high-efficiency general industrial motor. It is an optimized PMSM (Permanent Magnet Synchronous Motor) for automobile usage that allows high-torque driving and a wide range of speed adjustments.
The PMSM type drive motor is embedded with IPM to provide high-output and high-torque. Its application has rapidly increased in a wide range of hybrid vehicles.




The operating principal of the electric motor is based on the torque generated by the interaction of the electric magnet in the stator and the interior magnet embedded in the rotor.
When the inverter (MCU, Motor Control Unit) 3-phase alternating current flows in the winding coil on the stator coil, a rotating magnetic field is formed. This generates rotating torque through electromagnetic induction from the interaction among the magnets embedded in the rotor. This power rotates the motor.
The speed of the rotating magnetic field applied on the stator and the actual rotator speed are synchronized. Therefore, this motor is also known as the synchronous motor.