Design Of An Efficient GaN-based Buck Switching Power Supply

Gallium Nitride(GaN)based power devices are expected to be widely used in high-efficiency and high-density converters due to their faster switching speed and lower conduction resistance,compared with the conventional Si devices.Superior switching speed guarantees the low switching loss of GaN device,high switching frequency and small system volume.The low on-state resistance results in the low conduction loss and low system cost benefited from the reduction of chip area.However,to take full advantage of the benefits of GaN power devices,simple acquaintance with device parameters is far from enough.Hence,comparative studies about system analysis and measurement on the Si-based and GaN-based power converters are necessary.In these studies,theoretical analysis of power conversion and numerical simulation are adopted to reveal the characteristics of GaN-based power converter.The main contents of this study are as follows:(1)In order to explore the extent to which existing power conversion systems can be improved by Ga N-based technologies,the basic electrical characteristics of GaN transistors are compared to state-of-the-art silicon power MOSFETs.(2)Circuit simulation and experimental tests are made to reveal the drawbacks in three aspects: the inaccurate analytical switching process model,the dead-time related loss,the sensitivity to parasitic inductance.The proposed methods of dead-time adjustment,reverse parallel schottky diode,loop parasitic inductance optimization are validated with the theoretical analysis and circuit simulation.(3)The agreement between the test data and the design index of the test prototype is testified.Theoretical hypothesis and the simulation results are analyzed with the test results.The solution of the problem is given by the test results,which proves the rationality and effectiveness of the design method.The final experimental results show that the performance of the prototype is in accordance with the expected,and the efficiency improvement means can effectively overcome the shortcomings of the applications with the GaN power devices.