Investigation of PM Demagnetization Characteristics for Axial Split Phase PM Machine With Short-Circuit Fault

Abstract

PM machine suffers high risk of demagnetization in terminal short-circuit (SC) fault and such fault will degrade the torque production capability and raise repair costs. Thus, reducing the risk of PM demagnetization is a key problem in the design of the PM machine used for safety critical applications. An axial split phase PM machine with optimized SC current limitation capability has been proposed. In this paper, the influence of structure parameters on PM demagnetization characteristics is investigated by analytical method and verified by finite element (FE) method. It is proved that the high pole numbers and turn numbers in series per phase of the axial split phase PM machine is benefit in improving PM demagnetization withstand capability. Based on the combination of analytical and FE methods, the axial split phase PM machine is optimally designed, and the risk of PM demagnetization in transient state SC fault is comprehensively assessed by FE method, which further proved that the axial split phase machine has competitive capability of PM demagnetization withstand.