A constant-frequency parabolic-modulation-based sliding mode controller for buck converters

In this paper, a direct sliding mode (SM) voltage controller based on parabolic modulation is proposed for a buck converter operating in the continuous conduction mode of operation. The objective is to achieve SM control of a switched-mode power converter with a relatively constant switching frequency through a simple control structure. This is achieved by directly modulating the constructed state trajectory through a pair of parabolic carriers. Both the steady-state and the transient performance of the buck converter with the proposed controller are tested. It is shown that the maximum switching frequency deviation throughout the testing condition is merely 3.8%. In addition, the proposed controller achieves good load regulation and dynamic performance.