DC/AC inverter for power supply to an electrical motor for the traction of a vehicle

摘要

Disclosed is a dc/ac inverter for the supply of alternating current to the windings of a synchronous electrical motor, especially for the traction of an electrical vehicle. During each half-wave of the alternating current, the dc/ac inverter with solid-state switches delivers steady levels of constant intensity. During each steady level, the intensity of the current is determined by the cyclical ratio of a chopping signal that controls the conduction of the transistor-based or thyristor-based switches. At zero speed of the rotor, the frequency f of the chopping signal has a value (f', 1 khz) smaller than the chopping frequency (8 kHz) for a speed different from zero. Thus the starting losses or the losses with the rotor off are minimized.