Low Speed Performance Improvement of Sensorless Controlled IM Drive Based on Nonlinear Voltage Error Compensated AFO

Nonlinear voltage error (NVE) deteriorates the performance of speed-sensorless controlled induction motor (IM) drive at low speeds, especially for high-power motors. In this article, a compensation algorithm for nonlinear voltage error was derived according to the error vector state equation and the relationship between current error and flux error. The algorithm has established the transfer function from the current error to the current error’s speed error component. According to the transfer function, a compensation coefficient formula is introduced into the speed adaptive law of adaptive full-order observer (AFO). The stability of the strategy and its sensitivity to motor parameters are analyzed. Experimental results verify that the presented algorithm can improve the performance at low speeds under the interference of nonlinear voltage error.