Comparative Study of Flux-Weakening Control Methods for PMSM Drive Over Wide Speed Range

Proper flux-weakening (FW) strategy has to be adopted to achieve wide-speed operation of permanent magnet synchronous motor (PMSM). Two flux-weakening methods based on current vector control are investigated in this paper. One is a feedforward method, which is based on the mathematical model of PMSM and requires the motor parameters. The other is a feedback method, which employs a PI compensator to regulate the demagnetizing current reference. To verify and compare the two FW methods, a vector control system for PMSM is developed. The simulation results clarify that both two FW methods extend the constant power region of PMSM effectively, while the feedforward method can generate larger torque in high speed region and provide wider constant power region. Furthermore, comparative investigation of the two FW methods, traditional maximum torque per ampere (MTPA) control and i(d) = 0 control is also carried out.