Flux weakening method for sensorless PMSM control using torque decoupling technique

The present paper describes a new flux-weakening (FW) algorithm for speed control of permanent magnet synchronous machine (PMSM) using a sliding mode observer (SMO) for rotor speed and position estimation. In flux weakening techniques needed to applications requiring constant torque and power operation, the produced torque is depended on the negative d-axis stator current applied to waken the magnetic flux of the permanent magnets. The proposed method uses a simple torque decoupling technique to regulate the q-axis reference current embedded into the speed controller. A flux weakening controller (FWC) is used to adjust the d-axis stator current based on the q-axis reference voltage. The performance of the overall control system is examined using Matlab/Simulink facility. Simulation results demonstrate the effectiveness of the proposed flux weakening control method.