Research On 1MHz Self-resonant Reset Forward Converter Based On GaN Transistors

The performance of silicon power devices have come to their theoretical limits. And it is hard to satisfy the requirements of switching power supplies, which feature with high frequency, high efficiency, high power density and high reliability. Enhancement Mode Gallium Nitride FETs(e Ga NFETs) have won wide attention from researchers for the features of high speed, low parasitic parameters and superior electrical performance, which are suitable for high frequency and high reliability applications. It is considered to be a valuable work in this area to do researches on e Ga NFETs.Firstly this paper gives the analysis of different magnetic reset methods for a forward converter, and it is pointed that the self-resonant reset method which fully utilizes the parasitic parameters of components has advantages in high frequency application. Considering the parasitic parameters of the converter in high frequency condition, analysis gives the reference for converter design. Then, traditional and improved driving methods for synchronous rectifiers are introduced and compared. Several high speed drivers have been introduced and the driving method which is suitable for Ga N devices has been chosen. This paper indicates that small parasitic parameters of e Ga NFETs help reduce driving loss and switching loss, which make a higher efficiency of the converter. In addition, an improvement of the oscillation in circuit enhances the reliability of the converter. A 18~36V input, 5V/4A output, 1MHz prototype is fabricated and the experimental results show that e Ga NFET has efficiency advantage and high reliability compared to that of Si MOSFET.