Constant frequency adaptive hysteresis control of grid-connected inverter

This article introduces the basic principles of traditional hysteresis control methods, deduces the relationship between switching frequency and hysteresis loop width, and analyzes and studies the reasons for the unstable switching frequency under hysteresis control, as well as the impact of switching frequency on control accuracy. On this basis, a constant frequency adaptive hysteresis control is proposed. When deriving the formula for calculating the loop width, the reference current slope is taken into consideration, and the relationship between the inductor current on the grid-connected side during the rising and falling phases and the loop width is expressed in sections, thereby achieving real-time regulation of the loop width to ensure constant switching frequency. Finally, simulation results confirm that using this method can achieve a fixed switching frequency in inverter grid connection, and achieve high tracking accuracy under high-frequency switching.