Research On Magnetic Components Of The High-power-density Flyback Converter

Aeronautical Static Inverter(ASI),as an important power supply equipment of the aircraft,has very high requirements on electricity quality,volume,weight and efficiency.As a commonly used two-stage inverter structure,the front-end DC/DC converter should be improvement the power density as much as possible while achieving electrical isolation and high efficiency.In this paper,aimed at improve the DC/DC converter power density,studied the method of improving the power density of the magnetic components in flyback converter.Flyback converter is very simple,less components,with electrical isolation and boost output voltage,has been widely used.In order to improve the output voltage gain of the converter,the paper uses double-voltage rectification on the secondary side of the transformer to achieve high output voltage,turns ratio of transformer reduced by half.This paper,at the beginning of the subject,had been already develope a double-voltaged output flyback converter prototype,and through the loss analysis,volume and weight analysis,get the maximum the limiting factor of improving the converter power density is magnetic components.In order to reduce the number of cores in the converter,the paper first uses the principle of magnetic cancellation cancelde the side legs of the core to achieve the shared core of the two windings.When two windings are interleaving,magnetic cancellation will bring the coupling of the transformer.According to the different position of the air gap,the coupling of the transformer is different.The article analyzes the winding flux and the equivalent magnetic circuit in different modalities,and obtains the coupling situation of the whole transformer.Based on this kind of analysis,double voltage coupled transformer was analysised,and through simulation,the coupling can reduce the transformer core loss.In order to reduce the transformer loss,the article analyzes the loss of the working mechanism of the main parasitic parameters of the transformer,mathematically modeling,compared the accuracy of each parameter model and obtained the best fit equivalent circuit model.Through the loss model,the flyback transformer is optimized,the transformer core,operating frequency and magnetic force structure and winding parameters are selected reasonably,the winding arrangement is optimized based on the maximum magnetic force,and the asymmetrical winding structure is used to obtain the minimum loss and PCB end area.A prototype of 500 W full brick module doubling voltage output flyback converter prototype was developed.Compared the previous prototype,the theoretical analysis and the correctness of the parameter design were verified.