Study of a Dual-Loop Digital Control System for High-Power Input-Parallel Output-Series Phase-Shifted Full-Bridge Converters Based on Pole Configuration

Digital control is characterized by mature analysis technology and easy implementation and is widely used in high-power input-parallel-output series (IPOS) phase-shifted full-bridge (PSFB) converters. However, in modern industrial applications, most digital controllers are still designed with traditional technologies, such as PID control. Some characteristics of this control technology, such as control time delay and approximate design process, make the results fail to achieve the expected performance. At the same time, this digital control needs to be tested in the process of use, and the process is cumbersome and difficult to achieve. Based on the existing problems, this paper deduces a discrete state space model from the application of the IPOS-PSFB converter, focusing on the characteristics of control delay. At the same time, this paper puts forward a double-loop control strategy to ensure the accuracy of controller design. Among them, the current and voltage loop designs are independent. The current loop and voltage loop adopts two controllers, namely, the proportional controller and PI plus state feedback controller, and the parameters of the voltage loop controller are accurately calculated according to overshoot and bandwidth index. Finally, the IPOS-PSFB converter is simulated and analyzed by MATLAB/Simulink software, and the controller's steady-state performance and anti-interference are analyzed.