Direct Torque Control of Permanent Magnet Motors Using a Single Current Sensor

This paper describes a Speed Sensorless Permanent Magnet Synchronous Motor (PMSM) Direct Torque Control (DTC) using single dc-link voltage and current sensors. The phase currents are estimated in a two-stage process: prediction and adjustment. Prediction is based on the dynamic motor model, whereas adjustment relies on the inverter switches states and the measured dc-link current. This system is then incorporated into a speed sensorless DTC scheme. The rotor speed is estimated from the instantaneous stator flux linkage position and load angle value.