This paper presents a new position sensorless control system of a n interior permanent magnet synchronous motor (IPMSM) for electric vehicles. The proposed control system is based on a n injected voltage vector that is synchronized with a PWM carrier of a n inverter. The pole position is estimated from the relation between the injected voltage vector and the saliency of the rotor. The first current difference vector is detected when the injected voltage vector in the estimated pole position direction is added to the motor control voltage vector. Next, the second current difference vector is detected when the injected voltage vector in the opposite direction of the estimated pole position is added to the same motor control voltage vector. Then, the pole position of the rotor with the anti-saliency can be estimated from the first and second current difference vectors. This control needs neither motor parameters nor band pass filters. And the anti-salient pole type IPMSM can be operated over a wide speed range including zero speed, with a quick response. Good driving of electric vehicles is realized using the proposed system.

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A torque controller suitable for electric vehicles is studied. The controller ensures an induction motor generates the motor torque efficiently, stably, and accurately. The torque control system feeds back an assumed motor torque calculated using the secondary magnetic flux and the torque current detected from current sensors of the primary currents. The motor torque is controlled by using the torque current reference determined from the generated secondary magnetic flux and the magnetizing current reference. The magnetizing current reference is determined on the basis of the torque current reference so that the motor torque generation efficiency always becomes the maximum. The magnetizing current regulator is operated according to the magnetizing current reference. This ensures the motor generates the motor torque stably even in transient states. Fundamental performance characteristics, such as response, accuracy, and efficiency of the motor torque are verified by simulation and experiments. The torque controller is judged suitable for the drive system of electric vehicles.

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