GaN-Based High Power Density DC/DC Power Supply

The demands for isolated DC-DC converters are growing rapidly in recent years,including but not limited to computers,telecommunication,data centers,battery chargers,industrials,and aerospace applications.The demand for it is also higher and higher.Light,thin,small and low energy consumption have become inevitable trend of development.Switching power supply,as an indispensable part of electronic devices,is constantly improving.More efficient,reliable,low loss,low noise,anti-interference and modularity become the development direction of switching power supply.GaN as the third generation of semiconductor materials,compared with the traditional Si material has a larger band gap,higher breakdown electric field and higher electronic saturation speed,so it has a remarkable application prospect in high temperature,high frequency,high power and so on.Because of its unique material and structure,the switching frequency of GaN E-HEMT can reach more than ten times of Si MOSFET,and its conduction resistance is low,the conduction loss is small,and the switching loss is relatively low because of the opening,closing and breaking speed,so it is suitable for high efficiency applications.And because of its high frequency switch,when the DC/DC converter is applied,the volume of the energy storage element and the magnetic element can be reduced effectively,thus the power density of the converter can be improved.In order to give full play to the performance advantages of GaN E-HEMT,this paper makes a detailed analysis of its unique performance.First,the structure and working principle are analyzed,and then compared with Si MOSFET,the difference between them is pointed out.In order to understand the switching process in detail,the test experiment of double pulse half bridge circuit is carried out,the voltage and current waveform of the transistor is obtained,and the process of its opening and closing is analyzed in detail.In order to use the GaN E-HEMT in practical application,the characteristics of the attention in the application are analyzed and the loss mechanism is analyzed in order to reduce the loss in the application.Based on this,the driving design requirements and layout requirements are put forward,giving full play to the superior characteristics of GaN E-HEMT and reducing the loss.Finally,the DC/DC changer based on LLC resonant circuit is designed.The input voltage 300V-400V DC,the output voltage 12V DC,the switching frequency 470kHz,the half bridge switch tube and the rectifying tube all use GaN E-HEMT,greatly reduce the volume and loss of the converter,basically realize the high power density and high efficiency,and verify the superiority of the GaN E-HEMT performance and the effectiveness of the proposed design method.