Abstract: In order to reach the driving request of electric vehicle(EV), the EV power-driven system is researched, which takes rare-earth permanent magnet machine as key technology. A bran-new automatic control mode of traction motor is researched and applied in the EVs. At the same time a kind of planetary gear transmission case is designed, which has simple structure and excellent characteristics. Otherwise it is controlled by wire. And the influences on EV longitudinal amenity are analyzed, which are from the moment characteristics of the motor driving system. By the strategy of automatic weak- magnetism control, the motor system can fit all the need for driven system of EV. Matching the motor with double shifts, guarantee the drive system work efficiency on a high level when the EV is in the max speed.

Key words: Electric vehicle, Planetary transmission controlled by wire, Rare-earth permanent magnet machine