Fixed-frequency Boundary Control of Buck Converter Based on Discrete Regulator of Hysteresis Band

When the boundary control is adopted for power converters, the switching frequency is dependent on the input voltage, output voltage, and circuit parameters. The converter often operates at a variable switching frequency, which makes the determination of the filter parameters difficult. This paper presents a fixed-frequency boundary control method of Buck converter with high-order switching surface based on varied hysteresis band. Firstly, a discrete dynamic model from switching frequency to hysteresis band is established. Then, a discrete regulator of hysteresis band based on the feedback of switching period error is proposed. The stable region of the feedback gain is given. Simulation results show that the proposed method can rapidly regulate the switching frequency to a reference value under a large disturbance with an excellent steady-state and dynamical performance.