A Direct Torque Controlled Interior Permanent Magnet Synchronous Motor Drive without a Speed Sensor

This paper reports results of further investigation of the so-called direct torque control (DTC) technique to an interior permanent magnet (1PM) synchronous motor drive. This torque control technique for IPM motors requires no dq-axes current controllers and coordinate transformnation networks. A completely sensorless 1PM motor drive with DTC, which uses a new speed estimator from the stator flux linkage vector and the torque angle, is presented. It is shown that including the torque angle in the estimation process results in a far more accurate transient speed estimator than what is reported in the existing literature.