Hybrid controller configuration for master–slave paralleling of DC–DC converters with improved sliding manifold

This paper focuses on sliding mode controller (SMC)-based master–slave parallel operation of DC–DC converters using a modified sliding manifold to achieve a fast dynamic response and very low steady-state error. The converter performance is analyzed in a novel way starting from a simple case of paralleling of two converters and then concept is extended for parallel operation of multiple converters. An investigation of the choice of the sliding surface on the performance of parallel converter is carried out in detail, and a mathematical design guideline for sliding coefficients for the proposed manifold for the master converter is derived to achieve stable operation. The proposed manifold ensures an improved dynamic response with an excellent steady-state accuracy in stand-alone mode. However, when it is incorporated with master–slave control for parallel operation with finite tie wire impedance, there is a degradation in the steady-state accuracy. In order to improve the steady-state performance of the sliding mode controller, two new hybrid (SMC + PI) controllers are proposed and implemented for parallel connected DC–DC converters. Finally, the proposed SMC techniques are verified through simulation study and through a scaled down experimental (laboratory) prototype.