A Whole Control Strategy Based on Sliding Mode Variable Structure Control for Cascaded H-bridge Rectifier

The cascaded H-bridge rectifier (CHBR) control consists of two parts, namely whole control and DC voltage balance control. Double closed-loop proportional integral (PI) control strategy with current feedforward decoupling and proportional pulse compensation strategy are typical whole control strategy and voltage balance strategy respectively, which can realize unity-power factor and DC voltage balance with good performance under special working condition. However, when the CHBR system is unstable or disturbed, the conventional double closed-loop PI control would cause some problems such as slow response speed and big overshoot. This paper proposes a sliding mode variable structure control (SMVSC) strategy for whole control through modeling analysis on the CHBR circuit. By choosing the appropriate switching surface to make the system state trajectory set on the sliding mode surface, the proposed SMVSC strategy can improve the response speed of DC voltage and the dynamic performance of the system. Furthermore, modeling analysis for proportional pulse compensation strategy is proposed. Simulation results verify the feasibility and effectiveness of the proposed strategy.