A novel sliding-mode observer for the sensorless control of permanent-magnet synchronous machines
永磁同步电动机新型滑模观测器无传感器控制

To deal with the chattering in the traditional sliding-mode observer, we propose a novel sensorless control algorithm of the sliding-mode observer for the self-sensing estimation of rotor position. Being different from other observers, the sign function is replaced by a saturation function and the chattering problem is solved by properly choosing the thickness of the boundary layer. To increase the estimation precision of the rotor position at low speed and the stability of the system at high speed, the estimated back electromotive force is fed-back to the current observer. To achieve a better effect in filtration and to simplify the hardware structure, we design a low pass filter with a variable cut-off frequency depending on the rotor speed, which readily compensates the phase-angle delay over the entire speed range. Experimental results show that the proposed scheme is suitable for the sensorless control of a permanent-magnet synchronous machine over a wide speed range, and the novel algorithm is robust to uncertainties in operating conditions and parameters.