Accuracy improvement of carrier signal injection sensorless control for IPMSM in consideration of inverter nonlinearity

In this paper, the work has been developed aiming at reduction of inverter non-linear influences on high frequency carrier voltage injection sensorless control algorithm. For this method, inverter non-linear errors introduce distortions of the motor stator voltage that degrade the estimation performance. The main cause is the deviation of the high frequency voltage vector angle used for the demodulation process of extracting the rotor position from negative sequence of high frequency current response. For sensorless applications where the injection frequency becomes comparable to Pulse Width Modulation (PWM) switching frequency, the command voltage compensation method is prone to fail. In this work, the injected high frequency voltage vector angle for current demodulation is calculated with estimated voltage error Look-up-table (LUT), sensorless position estimation accuracy is enhanced compared to feed-forward compensation technique validated by experiment.