Time‐variant PM flux linkages and magnetising inductances of a line‐start PM synchronous motor with composite solid rotor

Abstract

This study conducts a deep research on a line-start permanent-magnet synchronous motor (LSPMSM) with a composite solid rotor through detailed analyses of two sets of intrinsic motor parameters, i.e. (i) the flux linkages stemming from permanent-magnet (PM) poles, or the so-called PM flux linkages, and (ii) the magnetising inductances related to the stator–rotor magnetic couple. The analyses proceed by separating the motor starting process into a series of sub-states with different slips. At each sub-state, the PM flux linkages and magnetising inductances are both susceptible to the varying saturation of motor cores and hence perform as time-dependent quantities alternating exactly in the slip frequency. Accordingly, these parameters are determined as combinations of cosine functions indicating the quantity alternation, by which the rotor resistances and self-inductances are obtained at the same time. Assembly of all the confirmed motor parameters generates an analytical model of the studied LSPMSM. Responses of this model stay totally in good agreement with those from the finite-element method, and the close result correlation offers an effective validation of the analyses presented in this work.