Optimal Design of High Frequency Transformer for High Power Density Flyback Converter

This brief presents an optimal design of high power frequency transformer for flyback converter based on E-mode GaN device, which could be used in personal portable chargers. The new generation of wide band gap semiconductor GaN switch is used to improve the switching frequency of the circuit. The high-frequency magnetic core and the winding method of magnetic components are optimized. The leakage inductance of the transformer of magnetic components is greatly reduced. Consequently, the overall power density of the circuit is improved. The feasibility of the design scheme is verified by hardware implementation and experimental results. The test results show that compared with the traditional flyback magnetic element design, the volume of magnetic element is reduced by 30%. Meanwhile, the loss is reduced by 30%, and the peak efficiency of the converter can reach 94.2%. The ratio of leakage inductance of magnetic transformer to excitation inductance decreased from 2.2% to 1%. In addition, power density of the converter reached 20.26W/in3, which is much higher than the existing commercial ones.