Design of a Wide-input Auxiliary Power Supply in the PV Inverter System

According to the requirement of the PV grid-connected inverter system,an auxiliary power supply with an input voltage of 120-850 V is designed.To avoid losing the opening pulse at a high input voltage,a circuit that can change switching frequency based on the input voltage is introduced.The peak current control and DCM work mode is used,and the type-2 compensation circuit in the feedback loop guarantees the rapid adjustment of output voltage and stability of the system.Experimental results show that this auxiliary power supply can adapt to a wide fluctuation of input voltage and provide long-term reliable DC voltage to the PV system.