Chattering reduction applied in PMSM sensorless control using Second Order Sliding Mode observer

The paper proposes a new method of chattering reduction based on Second Order Sliding Mode (SOSM), which is applied in sensorless control of Permanent Magnet Synchronous Machine (PMSM). In this implementation the PMSM model and proposed SOSM observer are both expressed in the γδ estimated reference frame. An augmented state observer uses the provided equivalent control input to bypass the high frequency component for optimum estimation of modified back EMF and disturbance rejection. Minimization of oscillation frequency is demonstrated by means of simulation results in sensorless speed control of PMSM considering uncertainty conditions.