Improvement of Inductance Measurement of IPMSM

The standstill flux-linkage based inductance measurement method applies square wave d-q voltage to the motor winding from an inverter with current control. Usually, in this method, only the stator current is measured, and the reference voltage is assumed as the actual voltage to calculate the flux-linkage. However, the deadtime, dc bus resistance and switch on-resistance cause a difference between the actual and reference voltages. Hence, the calculated inductance by this method can be inaccurate, especially for Permanent Magnet Synchronous Motors (PMSMs) with small inductance and resistance. This paper proposes a voltage compensation method to improve the accuracy of the measured inductance. Both simulation and experimental results verify the effectiveness of the proposed compensation method.