Sliding Mode Observer Enhanced for Sensorless Permanent Magnet Synchronous Motor Control

A second order sliding-mode observer enhanced similar in structure and computational cost to a classical proportional-integral controller is proposed. This observer eliminates efficiently the chattering problem and preserves the robust properties of sliding mode. Owing to its advantages, the proposed observer is used for reconstructing the back electromotive force of a permanent magnet synchronous machine, it estimates the motor speed and position. These estimations are feedbacked in a vector control scheme, where the need for the mechanical position/speed sensor is eliminated. MATLAB™ simulations of the proposed observer demonstrate the accurate reconstruction and zero phase delay estimation of the back electromotive force. Experimental results of a sensorless speed control for a 7.46 kW permanent magnet synchronous motor validate the proposed observer. The advantages of the proposed observer are better compared to the sensorless control strategies LO and Q-SMO.