A Novel Current Control Strategy for Magnetization State Manipulation of Variable Flux Memory Machine Based on Linear Active Disturbance Rejection

In this article, a novel current control strategy is proposed to manipulate the magnetization state of the variable flux memory machine (VFMM) through a newly developed linear active-disturbance-rejection-based feedforward current controller. A linear extended state observer is designed to estimate the sum of the permanent magnet (PM) induced voltage and the disturbance voltage caused by the susceptible machine parameters to compensate for the linear state error feedback output. The voltage across the winding resistance and the cross-coupling voltage are calculated by the voltage equations and fed forward to the output of the current controller. Meanwhile, the magnetizing current pulse amplitude can be determined by the target PM flux linkage obtained by looking up the table according to the mechanical speed. Since the
q
-axis disturbance voltage can commonly be ignored during the steady operation, the
q
-axis observed voltage after low-pass filtering can be directly utilized to estimate the PM flux linkage, which is compared with the target PM flux linkage to determine whether the current manipulation is needed to achieve online remagnetization or demagnetization. Experimental measurements on a hybrid-magnetic-circuit VFMM verify the effectiveness and superiorities of the proposed current control strategy.