Circuit Design Of Active Clamp Forward DC-DC Converter In Electric Vehicles

At present,switching power supplies are developing in the direction of high frequency,high power density and high efficiency.The traditional forward converter circuit has the advantages of simple structure,small number of components,and small output ripple.The disadvantage is that the working mode of the power tube is hard switching,which makes it difficult to increase the switching frequency of the converter;High-frequency transformers require magnetic reset.The energy consumed by the reset cannot be reused,which increases the transformer's losses;and the transformer core can only work in the first quadrant.Obviously,the traditional single-ended forward converter is difficult to adapt to the development trend of switching power supplies.Active clamp forward converter is a new type of topology structure,which has soft switching and automatic core reset function,which can adapt to the development trend of switching power supplies.In this paper,the working principle of the buck converter is fully analyzed,which mainly explains the impact of the clamping voltage and the drive signal delay on the soft switching conditions.The advantages of active clamp forward converter are summarized through comparison.Through research on key technologies,including soft switching,synchronous rectification,and high-frequency transformers,effective choices have been made for circuit parameters such as clamping capacitors,transformers,power switches,synchronous rectifiers,and output filters.The main circuit,control circuit and optocoupler feedback circuit of the module power supply are designed around the control chip LM5025 A.Protection circuits such as output anti-reverse connection,input current limit and input over and under voltage are also designed,and the design of the active clamp forward converter is completed.The design parameters of the active clamp forward converter were simulated with Saber software,and the correctness of the converter design was verified.By optimizing the experimental results,the performance of the active clamp forward converter can be effectively improved,which can meet the performance requirements of switching power supplies.