Fixed Frequency Pulse-Width Modulation Based Integrated Sliding Mode Controller for Phase-Shifted Full-Bridge Converters

The conventional approach to designing controllers for the phase-shifted full-bridge (PSFB) converter is to design a linear compensator based on the small-signal model, which cannot provide the converter with strong robustness against parametric disturbances and consistent transient responses over a wide range of operating conditions. This paper proposed a fixed frequency pulse-width-modulation (PWM)-based integrated sliding mode (ISM) controller for the PSFB converter. By analyzing the phase-shifted modulation of the full bridge, the dynamic state-space model of the PSFB is established based on the simplified circuit model. On this basis, the sliding motion in state space, the existence condition for steady-state operation, and the indirect PWM control function are discussed. Meanwhile, a switch control is introduced to the control function, and a robustness condition for parametric disturbances is analyzed. The designed PWM ISM controller is applied to a 1-kW PSFB converter prototype. Experimental results verify the effectiveness of the proposed controller by comparison with the hysteresis-modulation-based sliding mode controller and the increment PID controller.