Fixed Switching Frequency Digital Sliding-Mode-Based Control of a Three-Phase Four-Wire AC–DC Rectifier With Power Factor Correction

This article presents a fixed-frequency digital sliding mode control (SMC) technique to perform power factor correction (PFC) for electric vehicle (EV) charging applications. A three-phase four-wire boost rectifier with split-capacitor topology is selected. Using system model, three decoupled sliding mode controllers are designed to achieve loss-free resistor (LFR) behavior in each phase for PFC. The control law and the dynamic model of the rectifier are obtained by imposing sliding-mode regime in discrete time. To obtain simple expression of the duty cycle for ease of digital implementation in natural frame, the discrete-time model of the system has been used with reasonable approximations. Despite the theoretical stability of the closed-loop system, practical implementation of the control law is limited by digital control delays. To mitigate this problem in practice, a modified control law is proposed to ensure stability by scaling the weighted error in the expression of the control law resulting from the ideal SMC. The combination of the topology and the control method in the natural frame shows improved performance compared to the existing literature. Theoretical predictions are validated by several numerical simulations of the switched model and experimental measurements under different practical scenarios.