A High Torque Estimation Accuracy Direct Torque Control of Permanent Magnet Synchronous Motor Based on a Novel Iron Loss Resistance Observer

Abstract

This paper proposes a direct torque control (DTC) of permanent magnet synchronous motor (PMSM) with high torque estimation accuracy. Based on the PMSM mathematical model considering iron loss resistance, this paper analyzes that when using stator current to estimate torque, the accuracy will be affected by iron loss resistance. Using stator magnetizing current can solve the current deviation caused by iron loss resistance and improve torque estimation accuracy. Since the stator magnetizing current cannot be obtained directly, a novel iron loss resistance observer based on the model reference adaptive system (MRAS) is designed to estimate iron loss resistance and stator magnetizing current simultaneously. Popov’s hyperstability theory guarantees the stability of the designed observer. Finally, a 1kW PMSM experimental platform is constructed to verify the proposed method. Both the simulation and experimental results show that the designed observer is stable, and using stator magnetizing current to estimate torque has better accuracy than stator current.