Sliding Mode Control of a Bidirectional Buck/Boost DC-DC Converter with Constant Switching Frequency

In this paper, sliding mode control (SMC) for a bidirectional buck/boost DC-DC converter (BDC) with constant frequency in continuous conduction mode (CCM) is discussed. Since the converter is a high-order converter, the reduced-order sliding manifold is exploited. Because of right-half-plan zero (RHPZ) in the converter’s duty ratio to output voltage transfer function, sliding mode current controller is used. This controller benefits from various advantages such as fast dynamic response, robustness, stable and small variation of the settling time over a wide range of operation conditions. Because the converter operates in both step-down and step-up modes, two sliding manifold is derived for each mode. The existence and stability conditions are analyzed for both SMC in step-down and step-up modes. Finally, Simulation results are also provided to justify the feasibility of the controller using MATLAB/Simulink.