Fuzzy variable structure control strategy for stable nonlinear dynamic system

This paper presents a fuzzy logic controller (FLC) based on variable structure control (VSC) with sliding mode concept is used to control the speed of switched reluctance motor (SRM) drives. Since, the VSC has several attractive advantages such as high speed response, good transient performance, insensitivity to variation system parameters and external disturbances, simplicity of realization and robustness in nonlinear systems control. A sliding mode controller incorporating fuzzy control helps in achieving reduced chattering, simple rule base, and robustness against load disturbance and nonlinearities. The simulation of nonlinear model SRM using the proposed technique is carried out and the results are compared with those obtained using the conventional PI controller. Also, the experimental setup is verified, which consists of building IGBT inverter H-bridge and associative drive gate with its control circuit and interfacing between control algorithm and experimental hardware. Both simulation and experimental results with the proposed algorithm show that, the system performance is improved significantly in the presence of load disturbance and is insensitive to some parameters variations of the system. Also, the variable structure technique is used to improve the stability requirements of the dynamic system when all the Lyapunov stability condition are realized.