Distortion Voltage Compensation in Field-Weakening Region of IPMSM

An optimal field weakening (FW) control for interior permanent magnet synchronous motor (IPMSM) considering the nonlinearities of IPMSM and inverter is presented in this paper. Nonlinearities of inverter cause distortion voltage (DV) which considerably affects the efficiency of IPMSM in FW region. In FW operation, the efficient utilization of available voltage is extremely important. Typically, in conventional FW control the ideal reference voltage is used as a feedback voltage. However, due to DV the actual voltage is not same as reference voltage. In addition, in high speed, the nonlinear characteristics of IPMSM, due to saturation and cross magnetization degrade the motor performance. Thus, under such circumstances tracking the optimal FW operating point became challenging. This paper proposes a hybrid FW control method to compensate the dead time effect and inverter voltage drop considering the nonlinear parameter of IPMSM. The compensated input phase voltage allow us to track the optimal operating point for IPMSM and enable us to achieve an accurate and optimal field weakening operation, which improves torque and speed capability in the flux-weakening region. The significance of the proposed method is verified by simulation and experiment.