Electromagnetic devices and circuits

Applications of power electronics in motor drives are becoming increasingly frequent and the six papers presented in the Wednesday afternoon parallel session appear to emphasize this fact. The first paper by Katta of the Teito Rapid Transit Authority and eight colleagues from Hitachi present the details of a control strategy for a 1,500 V, 1,000 KVA PWM inverter drive for a transit car. At low speeds the torque is adjusted by increasing the inverter current amplitude and frequency proportional to a torque demand. Upon reaching a predetermined inverter output voltage at high speed a control automatically switches over to a voltage regulated system. The system is operational on a standard TRTA transit car and measured results of various tests are given in the paper.