A control system for an electric car driven by an induction motor which is supplied with electric power of a variable frequency and a variable voltage from an inverter comprises means for detecting the car speed, means for setting a slip frequency of the motor, a frequency command generator, control...http://www.google.fr/patents/US4315203?utm_source=gb-gplus-shareBrevet US4315203 - Control system for induction motor-driven car
