Fault-Tolerant Control of IPMSMs Based on an Modified Sliding Mode Observer

This paper proposes a fault-tolerant control system for interior permanent magnet synchronous motor (IPMSM) drives operating in the middle and high speed regions. The proposed control system is capable of dealing with encoder's failures, hence increase the reliability and performance of PMSM. Sensor's setup of the control system consists of an actual sensor (encoder's model) and the virtual sensor (Sliding Mode Observer, SMO). The work focuses on performance of SMO when the encoder fails in low speed operation. In normal operation, position and speed signals from the encoder will be sent to the controller. When the encoder's failures are detected, the estimated values from the SMO are used. Presence of the noise in SMO observer operation affects dramatically to the stability of the control system. To reduce the noise low pass filters are added to the observer design. Finally, phase-locked loop (PLL) technique has been used to estimate of rotor's position and velocity. The feasibility of the proposed controller is confirmed via simulations of IPMSM drive model in MATLAB/Simulink software.