Robust control of parallel DC-DC buck converters by combining integral-variable-structure and multiple-sliding-surface control schemes

We develop a robust controller for parallel DC-DC buck converters by combining the concepts of integral-variable-structure and multiple-sliding-surface control. The advantages of the scheme are its simplicity in design, good dynamic response, robustness, ability to nullify the bus-voltage error and the error between the load currents of the converter modules under steady-state conditions, and ability to reduce the impact of very high-frequency dynamics due to parasitics on the closed-loop system. We describe a method for determining the region of existence and stability of the sliding manifolds for such parallel converters. The results show good steady-state and dynamic responses.