Patent ID: 7841434

Claim:
An electric drive system for a vehicle, comprising: an alternator system driven by power of an engine of said vehicle to generate electric power, said alternator system having at least two stators of a first alternator and a second alternator which are coaxially connected to an output shaft of said engine, wherein said second alternator is controlled to generate a constant voltage independently of an engine rotation speed; a rectifier for rectifying a first electric power output from said first alternator; a first converter for converting an output of said rectifier to an alternating current; a motor driven by an output of said first converter, said motor being rotatable by wheels of said vehicle through a mechanical coupling to generate electric power; a resistor for converting the electric power generated by said motor to thermal energy; a second converter for converting a second electric power output from said second alternator to an alternating current having arbitrary frequency and voltage; and a blower for cooling said resistor, driven by an output from said second converter, wherein said system determines whether or not said vehicle is accelerating, if the vehicle is not accelerating and a vehicle speed is not less than a predetermined value, said resistor is cooled down with the blower, if the vehicle is not accelerating and a vehicle speed is less than a predetermined value, or is in acceleration, the cooling of resistor is stopped after waiting for a predetermined time, a driving of said blower is started from a stopped state of said blower prior to a start of braking operation of the vehicle, and after the braking operation is terminated the driving of said blower is continued in a predetermined time period the driving of said motor is stopped, and after that the driving of said blower is stopped.