Research On Solar LED Street Lamp Charging System With Super Capacitor Energy Storage

The energy of solar LED street lamp comes from photovoltaic panels,which does not need to use traditional energy.The solar LED street lamp meets the requirements of energy conservation and environmental protection and has great practical value in remote or insufficient power supply areas.At present,there are some problems in the charging system of solar LED street lamp,such as low charging efficiency,energy storage components can not be effectively charged under weak light conditions,large working current under strong light conditions makes circuit components heating seriously,which affects the charging efficiency of the charging system.To solve these problems,this paper optimizes the charging system from the charging circuit topology and charging control strategy.First of all,the energy type supercapacitor is used as the main energy storage component of the solar LED street lamp charging system.The energy type super capacitor is a new type of green energy storage component,which has the advantages of high power density,moderate energy density,low internal resistance,wide working temperature range,etc.It is suitable for the solar LED street lamp charging system.Secondly,the ZVT-Buck circuit with zero voltage conversion soft switch technology is used as the charging circuit topology to improve the charging efficiency.The operation principle of ZVT-Buck circuit is analyzed and verified by simulation.And then,to solve the problem that the energy storage element of energy storage device can not be effectively charged under the weak light condition,the power type supercapacitor is taken as the secondary energy storage element.A dual mode control strategy is proposed.This control strategy consists of normal light charging mode and weak light charging mode,and can automatically switch the charging mode according to the light condition.Next,a multi-mode charging control strategy is proposed to solve the problem of heating circuit components caused by high current charging under strong light conditions.The control strategy is composed of normal lighting mode,weak lightingmode and limited power mode.According to the current time,the power of photovoltaic panel and the power of energy storage component,the charging mode is reasonably selected to improve the charging efficiency of the circuit and improve the heating condition of the circuit components.Finally,the device parameters in the topology of ZVT-Buck circuit are calculated in detail,so that ZVT-Buck circuit can realize soft switching in the range of 10W~160W input power.According to the calculated devices parameters,the devices are selected,and the charging prototype is designed for experimental verification.The experimental results show that the ZVT-Buck circuit can significantly improve the charging efficiency compared with the basic Buck circuit in the range of 20W~160W input power.The proposed control strategy can automatically switch the charging mode,effectively charge the energy storage elements under the condition of strong light to weak light,and significantly improve the heating condition of power devices in the circuit.