Novel Integral Sliding Mode Control Applied to High-Power DC Power Supplies

In this article, a novel integral sliding mode controller is proposed to ensure the output accuracy of the high-power dc power supply with variable output voltages and unknown loads, and the proposed controller is applied to a 3.2-kW high-power dc power supply. Conventional sliding mode control (SMC) is robust to matched disturbances, while it is sensitive to switching frequency and mismatched disturbances. In the proposed controller, the switching function is scaled and added to the control law, so that the integral term can act directly on the control law and help eliminate the influence of the switching frequency and the output error. The recommended values of the designed parameters are given to simplify the computation and improve the robustness. Moreover, the relationship between the output error and convergence time is analyzed. The simulation and experiment results show that compared with conventional integral SMC, the proposed method alleviates the influence of the low switching frequency and improves the output accuracy and output ripples; compared with PI control, the proposed method shows better dynamic characteristics.