Calculation of inductance of permanent magnet synchronous motor considering permanent magnet flux linkage variation of load conditions

The permanent magnet flux linkage variation of load conditions is not considered in conventional steady-state inductance calculation methodology, which results in the calculation of inductance of load conditions are different from the practical value, and then the accuracy of parameter design of motor characteristic and stability of motor control will be affected. This paper will present an improved steady-state inductance calculation methodology of permanent magnet synchronous motor with high power density used in EV/HEV for dealing with this problem. This methodology calculates the differential of d-axis inductance given by a small incremental current, which eliminates the effect of permanent magnet flux linkage variation. This paper will analyze the influence of saturation and cross-coupling effects to the d-axis & q-axis inductance and permanent magnet flux linkage of interior permanent magnet synchronous motor using FEA software. The experimental result of inductance is in agreement with the calculated result, which verifies the validity of the improved methodology.