Enhanced Adaptive Higher Order Sliding Mode Observer based Sensorless Control.

The traditional higher order sliding mode observer (HSMO) based sensorless control strategy uses a constant gain. However, very large gain value can decrease the output accuracy, while very small gain value will degrade the sliding mode observer’s stability. Therefore, under uncertain disturbances, an adaptive gain should be set for the higher order sliding mode observer. This paper proposes a variable universe fuzzy adaptive high order sliding mode observer based sensorless control (VUF-HSMO) strategy for permanent magnet synchronous machines (PMSMs) to achieve high precision sensorless control. Firstly, fuzzy logic control technique is used to get an adaptive gain in the HSMO. Then, variable universe theory is employed to self-tune the universe of discourse according to the change of inputs, and this results in the improvement in position estimation accuracy. Experiment results under different conditions demonstrate the effectiveness and the superiority of the proposed VUF-HSMO based sensorless control compared with the traditional HSMO and fuzzy logic based HSMO.