Loss-Minimized-Model-Based Current-Decoupling Control for Interior Permanent Magnet Motor With Hybrid Rotor Poles

The controllable leakage flux permanent magnet (CLF-PM) motor exhibits variable PM flux properties, the q-axis current of which can realize the synchronous control of PM effective flux and output torque by controlling the cross-coupling of the leakage flux with q-axis flux. Thus, different from traditional permanent magnet PM motors, the CLF-PM motor exhibits sophisticated nonlinear parameter characteristics under different operating conditions, which has a significant influence on the optimal current angle control of such motors. In this article, considering the copper loss and core loss, a new mathematical model for CLF-PM motors based on the current decoupling model is proposed to serve as loss minimization control (LMC). On this basis, the variable parameter models of PM flux linkage, inductance, and equivalent core loss resistance are proposed to adapt to the variations of loads. In addition, considering the voltage restraint at high speeds, a flux-weakening (FW) control method combining the feedforward and feedback FW approaches is adopted, where the self-leakage flux and effect of d-axis demagnetization current are both considered. Finally, the proposed method is applied in an interior PM motor with hybrid rotor poles (HRPs) to verify its validity. Experimental results evidence that the proposed method can effectively achieve loss reduction and efficiency improvement.