Drive system for electric vehicle

摘要

A drive system for an electric vehicle has a synchronous motor (16), an inverter (14) to power it from the battery (10), a smoothing capacitor (18) and a PWM control unit (20) for the inverter switches using the setpoint torque and motor current as switching parameters. A peak value of the induced emf in the motor at a maximum speed is adjusted to be a value that corresponds to the permitted capacitor voltage or is much less than this, as well as being equal to, or much less than, the maximum permitted voltage for the inverter switches. The current through the inverter switches is adjusted to be equal to, or greater than, the maximum three-phase short circuit current of the motor.