Research On Active Clamp Bi-directional Flyback Converter Based On Photovoltaic Inverter

Solar energy as a human can be permanently used by clean energy favored by countries,but also an important part of the development of new energy sources.Photovoltaic power generation technology because of the advantages of high utilization of solar energy resources,and has been rapid development.Among them,the independent photovoltaic power generation system in the energy storage link is to ensure stable operation of photovoltaic power generation system,an important prerequisite for improving operational efficiency.Bi-directional DC-DC converter is responsible for the energy transfer between the DC bus and the battery,which is the core component of the independent photovoltaic power generation system.This paper focuses on the bi-directional DC-DC converter used in PV inverters.In this paper,the development of bi-directional DC-DC converter is described,and its research status at home and abroad is reviewed.The main advantage of the active-clamped bidirectional flyback converter is the soft switching technique,which can solve the problems such as high voltage stress,high switching loss,and high switching frequency in the bidirectional flyback converter.It can be seen that the application of active clamp bi-directional flyback converter with soft switch in photovoltaic power generation system is promising.In this paper,we summarize the working principle of the active clamp bi-directional flyback converter,analyze the active time of the active clamp bi-directional flyback converter,deduce the necessary conditions for MOSFET to achieve soft-switching,the main parameters of the active clamp bi-directional flyback converter circuit are designed,and the control circuit and the protection circuit based on STM32 are designed in combination with the practical application requirements of 400 V DC bus and 48 V battery.In addition,the state-space averaging method is used to establish the small-signal model of the active-clamp bidirectional flyback converter.The low-frequency DC component of the circuit is obtained,and the small-signal dynamic analysis is carried out to deduce the duty cycle of the switch to output transfer function.A closed-loop simulation model of the active-clamp bidirectional flyback converter is established by using PSIM simulation software,which proves the feasibility of the topology.Finally,a 1kW active clamp bi-directional flyback converter experimental platform is built,and experimental verification and efficiency analysis are carried out.The results show that the switching device used in the converter is small,and each switching device can realize zero voltage turn-on,energy can flow in both directions.