Introducing a pulse response based rotor position estimator for DTC IPMSM drives

To improve the accuracy of stator flux estimator in Direct Torque Control (DTC) of Interior Permanent-Magnet Synchronous Machine (IPMSM), a pulse response based rotor position estimator is proposed. The current ripples caused by active voltage vectors in DTC are utilized by the rotor position estimator. Then, the estimated rotor position serves as an input for a model-based stator flux estimator in order to steer the switching state generator. The proposed rotor position estimator exhibits a good accuracy without introducing additional test signals. This approach preserves many advantages of DTC in controlling electromagnetic torque and stator flux, such as the absence of a motion state sensor and pulse width modulation strategy. Furthermore, the effect of varying steady-state voltage vector on estimation of rotor position is studied. The rotor position estimation error has positive correlation with the rotational speed when the switching frequency remains constant. Simulation results verify the feasibility and effectiveness of the method in estimating the rotor position and controlling both the electromagnetic torque and the stator flux and the effects of varying steady-state voltage vector on rotor position estimation.