Comprehensive Investigation of Pulsating Torque Suppressions of Variable Flux Memory Machines During Magnetization State Regulations

Variable flux memory machines (VFMMs) benefit from online re/demagnetizations through <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-</i>axis armature current pulses, while the high current pulses and abrupt magnetization state (MS) variations result in significant pulsating torques. Aiming at the developed segregated dual three-phase (DTP)-VFMMs, the traditional MS manipulation (TM) and step-by-step MS manipulation (SM) methods are comprehensively investigated for pulsating torque suppressions. The negative torques during remagnetizations are theoretically elaborated, and the limitation of the existing methods is identified. Moreover, based on the functional decoupling of the two winding sets and thus the extra control degree of freedom of the idle winding set free from the MS regulations, two novel compensation methods are proposed to further alleviate the pulsating torques during MS regulations. The zero <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis current and the analytically derived compensatory <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis current from torque equations are employed, respectively. The comparison results between the existing and proposed methods validate the effectiveness of the two novel methods. Finally, the proposed strategies are experimentally verified based on a prototype DTP-VFMM.