Fuzzy Sliding Mode Control of DC-DC Boost Converter with Right-Half Plane Zero

DC-DC converters, classified as nonlinear systems are needed to be averaged and linearized to obtain a linear time-invariant model and the design of high-performance control for them is a challenging issue. In general, a good control for dc-dc converters should ensure stability at all operating conditions. Moreover, a good response in terms of rejection of load variations, input voltage changes and parameter uncertainties are also required for a typical control scheme. A major problem arises in the controller design when the transfer function of control-to-output voltage has right-half plane (RHP) zero. The effect of RHP zero predominates in the transfer functions of boost and buck-boost converters leading to a tedious controller design. Hence in this work, the design of linear and nonlinear controllers for a dc-dc boost converter is discussed. To achieve large signal stability, robustness, good dynamic response and simple implementation, an additional inner loop employing sliding mode control (SMC) with boundary layer is proposed in the current mode control (CMC) scheme is employed in this work. The conventional PI controller is then designed for the outer loop. To reduce chattering and to improve transient response, a fuzzy sliding mode control (FSMC) is proposed in the inner loop of CMC. Extensive simulation studies are carried out for dc-dc boost converter with RHP zero to verify the merits of FSMC over SMC using Matlab/Simulink software.