Finite Element Analysis of PMSM Steady State Parameters Considering Cross-saturation Effect

Accurate permanent magnet synchronous motor(PMSM) steady-state parameters such as armature reactance inductance and permanent magnet flux are essentially necessary for many control strategies and performance estimation.The parameters are difficult to be calculated by regular approach because they are seriously affected by the cross saturation effects.To overcome the problem,taking the finite element method(FEA) as a powerful tool,different methods for calculating permanent magnet flux linkage and d-axis,q-axis inductances(Lad,Laq) were analyzed,and the cross-saturation effect which influenced Lad and Laq was also studied.It was shown that cross-saturation would cause mutual inductance between d-axis and q-axis,and permanent magnets arranged at the d-axis would also generate q-axis flux.A freeze element permeability method was proposed to linearization of the nonlinear field problem,and the steady-state parameters varying with d-axis and q-axis current were worked out.By comparing the actual test results and the simulated results using the calculated parameters,they all matched well in no-load and with-load conditions,it was revealed that the frozen permeability method was reliable.