Application Of Low Voltage Gallium Nitride In High Frequency Power Converter

With the progress of power electronics technology,the development direction of low power switching power supply tends to be high frequency and miniaturization,and the demand for high efficiency and high power density is increasingly strong.Following silicon and gallium arsenide,the third generation of wide band gap semiconductor materials,represented by gallium nitride,appeared in semiconductor materials.Its characteristics include high critical breakdown electric field,high saturated electron velocity,high electron density,high electron mobility and high thermal conductivity.It is a kind of semiconductor material suitable for high frequency,high voltage,high temperature and high power with high anti-blitz level.As a new generation of semiconductor devices,GaN devices have the tendency to replace silicon power semiconductor devices which gradually reach the theoretical limit.Si MOSFET is increasingly difficult to meet the requirements of future power conversion devices,so GaN power transistors emerge as the times require.In this paper,EPC's low-voltage GaN device is taken as the research object.Firstly,the research background and significance,the development history and current situation of GaN are introduced.GaN materials,devices,silicon materials and devices are compared and analyzed.The differences and advantages of GaN in parasitic parameters,switching frequency,packaging,power density and efficiency improvement are explained.Then the influence of parasitic parameters such as high frequency loop inductance and common source inductance on the switching characteristics of devices and the reliability of driving circuits is discussed.The reverse conduction characteristics of GaN devices are emphatically studied.Two sets of experiments are carried out with synchronous buck as the research scheme.The switching frequency is 1MHz.One group adopts traditional driving mode and the other uses resonant driving mode.Each group adds a bias voltage to the gate of synchronous continuum tube to observe whether the reverse voltage drop decreases or not.The efficiency under different bias voltage is compared and verified by experiments.Before threshold voltage,with the increase of bias voltage,the efficiency of reverse voltage drop decreases obviously,and the resonant driving circuit has higher driving reliability.This paper introduces the development of modular power supply,and applies low-voltage GaN device to quarter-brick modular power supply.The main circuit topology is full-bridge hard switch,and synchronous rectification technology is used to complete the selection of main circuit parameters calculation device.The TM5036 of TI is used as analog control chip to complete the calculation of compensation parameters,peripheral circuit parameters of controller,switching frequency 300 kHz,input.Voltage range 36-72 V,output 12 V,rated power 300 W.Efficiency under different input voltage is compared.Load switching,output ripple and other related experimental tests are completed.Voltage adjustment rate and load adjustment rate of the module power supply are calculated.It shows that the module power supply has good voltage stabilization accuracy.