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.