Wide-speed-range sensorless control scheme for IPMSMs based on super-twisting observer and HF signal injection

Abstract

In this paper, a novel wide-speed-range sensorless control scheme for interior permanent magnet synchronous machines (IPMSMs) is proposed. At mid-high speed range, the super-twisting observer (STO) is designed to estimate the extended electromotive force (EMF). Adoption of sign function ensures the estimation accuracy without compromising the benefits of the standard sliding mode. The improved observation model combining the super-twisting algorithm (STA) alleviates the chattering problem. A new procedure of obtaining the position estimation error is proposed to eliminate the effects due to the change of the rotation direction. At low speed range, position error is obtained directly by extracting the high frequency current from the sample data. The high frequency signal is further improved by introducing a novel adaptive filter to weaken DC bias component. The transition function provides the position error signal for the speed estimator and ensures a smooth switch between the two methods in the transition zone. The effectiveness of the proposed control scheme has been validated by the experimental results.