Application Research On High Frequency PFC Power Converter With GaN HEMT Device

PFC converter is the front stage of power system.By increasing the power density of PFC converter,the power density of the whole power system can be improved effectively.Compared with the silicon material which has approached its theoretical limit,wide bandgap semiconductor gallium nitride(GaN)has lots of advantages,such as small junction capacitance,fast switching speed and low on-state resistance,which makes the GaN high electron mobility transistor(HEMT)becomes the main power semiconductor device in high frequency field.However,because of the narrow driving voltage of GaN HEMT,the design of driving circuit is relatively difficult.For GaN HEMT devices driven by a conventional voltage source,when the switching frequency reaches 1MHz,the parasitic inductance in the driving circuit will cause the gate-source voltage to oscillate.Then the gate-source voltage of the GaN HEMT device will exceed its gate-source withstand voltage and damage the device.The resonant gate drive(RGD)circuit is one of the effective ways to solve the problem of driven by conventional voltage source.By using the LC resonance,a low impedance path clamp is provided when the GaN HEMT device is turned on and off,and then the gate-source voltage can remain stable.Meanwhile,The principle analysis and parameter design were carried out,and the design of RGD drive circuit was completed by DSP28035 and CPLD.The resonant gate drive circuit is applied to CCM mode Boost PFC converter based on GaN HEMT device,and the switching frequency is 1MHz.A 300 W Boost PFC experimental prototype was built,and Si-MOSFET was used as a comparative experiment to obtain the relevant experimental waveforms and data.It is verified that the resonant driving circuit can reliably drive GaN HEMT devices.By comparing the efficiency of 1MHz single-phase Boost PFC converter based on GaN HEMT device under different driving voltage.It is verified that the efficiency can be improved by choosing the appropriate driving voltage on the premise of guaranteeing the reliable driving of GaN HEMT devices.By comparing the efficiency of Si-MOSFET and GaN HEMT device prototype,the high efficiency of GaN HEMT device in high frequency PFC powerconverter is verified.Because the traditional Boost PFC converter operates with many semiconductor devices,the conduction loss is large.GaN HEMT device does not have reverse recovery.In order to further improve efficiency,GaN HEMT device is applied to totem pole bridge-less PFC converter,which works in CCM mode with a switching frequency of 500 kHz.The experimental prototype was built and the relevant experimental waveforms and data were obtained.The experimental results show that the totem pole bridge-less PFC converter based on GaN HEMT device can operate stably in CCM mode.