An Improved High-Order Sliding Mode Observer for IPMSM Sensorless Drive

Aiming at the problems of chattering and poor observation accuracy of traditional high order sliding mode observer (THSMO), a sensorless control scheme of interior permanent magnet synchronous motor (IPMSM) based improved high order sliding mode observer (IHSMO) is proposed. By contrast with the THSMO, the hyperbolic function is employed instead of nonlinear sign function as the switching function in IHSMO, and the stability is analyzed by using the idea of equivalent control and Lyapunov function. On this basis, to avoid the influence of rotational velocity change on position estimation accuracy, a self-adjusting observer gain is designed with the velocity. Finally, the proposed IHSMO scheme is verified and contrasted with traditional method by an IPMSM experimental platform.