APPARATUS AND METHOD FOR CONTROLLING ELECTRIC CAR

摘要

A PWM (pulse width modulation) inverter generating an a.c. output having a variable voltage and a variable frequency supplies a.c. power to a linear induction motor. An electric car supported by wheels is driven by a driving torque produced by the linear induction motor. While the electric car is running, the motor torque varies due to various factors among which a variation of the air gap length is representative. The power factor cos .PHI. of the PWM inverter is detected to calculate the motor torque, and the output voltage of the PWM inverter is regulated or mechanical brakes are controlled so as to compensate the torque variation. Thus, the variation of the air gap length, which is representative of the factors giving rise to torque variations and which has been difficult to be detected, can be reliably detected to permit torque control according to the torque variation of the linear induction motor.