Synergistic Current Control Strategy for Variable Flux Memory Machines With Reduced Pulsating Torque During Magnetization State Manipulations

This paper proposes a novel synergistic current control strategy to deal with the critical issue of pulsating torque during magnetization state (MS) manipulations for variable flux memory machines (VFMMs). The dual-loop control structure of motor drives is modified by reusing the outer-loop controller as an observer of load torque. On this basis, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis current is synergistically controlled with the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i>-axis current, leading to the neutralization for the increments of permanent magnet (PM) and reluctance torque components during MS manipulations. Regarding the inner loop of current controller, a deadbeat predictive current control (DBPCC) method is designed, which is beneficial in terms of both steady-state performance and dynamic response. Meanwhile, an easy-implemented measuring procedure is designed to obtain the electromagnetic parameters, including PM flux and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i>-axis inductances, which are involved in the proposed strategy and current controller. Finally, the validity of the proposed strategy is verified by experiments. With respect to the normal strategy, the proposed strategy can decrease the pulsating torque and speed fluctuation by about 46.74% and 63.66% for the re-magnetization operation, and by about 55.32% and 63.27% for the de-magnetization operation, respectively.