Automeasurement of the Inverter Output Voltage Delay Curve to Compensate for Inverter Nonlinearity in Sensorless Motor Drives

In order to improve the performance of sensorless field-oriented controlled motor drives at low speed, the inverter nonlinearity should be compensated for by an accurate voltage error-model. This paper proposes a novel method to automatically obtain the total output voltage delay curve, which is a significant part of the inverter voltage error model. Unlike manual measurements of the output delays in earlier literature works, the proposed automatic measurement method achieves low cost in time and labor. Meanwhile, the compensation accuracy based on the automeasured output voltage delay curve is approaching to the performance of compensation by the manual measurement method, far better than the accuracy of compensation by the standard square-wave model at low speed. Moreover, in contrast to other inverter nonlinearity automeasurement methods, the measured results of the proposed method can be applied to compensate for inverter nonlinearities at different switching frequencies. The effectiveness of this method is validated in a voltage source inverter fed induction motor drive system experimentally.