A New Sensorless Drive Control System for Transmissionless EVs Using a Permanent-Magnet Synchronous Motor

One of the most important technologies for electric vehicles (EVs) will be drive control technology for main traction motors. It is desired for the drive control system to have the following characteristics: 1) it is based on vector control methods that allow quick, efficient and/or precise torque production; 2) it can produce 150-250% rated torque at standstill and can have wide driving-range, consequently can allow development of EVs with no variable-transmission; 3) it does not require a position/speed sensor for controlling motor drive, which has been mounted on a rotor shaft. This paper proposes a new sensorless drive control system for such EVs using a permanent-magnet synchronous motor as a main traction motor. Potential usefulness of the proposed drive control system is examined through the development of a prototype EV capable of driving on public road.