Research On GaN Switches High Frequency Resonant DC-DC Converter

With the development of power electronics technology,it is more and more important to reduce size,weight,cost and improve dynamic performance.Passive components（inductors and capacitors）usually control the size and weight of the power converter.Increasing the switching frequency can reduce the requirement of energy storage and allows the use of smaller passive components.In addition,higher frequencies can significantly improve transient performance and control bandwidth.High enough frequencies allow the use of air cores pave the way for fully integrated power converters.Thus,if the challenges of loss,efficiency and control can be addressed,many benefits can be realized by running power converters at significantly increased switching frequencies.The design of the working frequency of 4-MHz isolation type resonant DC/DC converter,the topological structure of the main power by Class Φ₂ resonant inverter with Class DE resonance rectifier.The working principle of resonant inverter and resonant rectifier is analyzed in detail.The shunt capacitor of the power transistors is charged or discharged and its drain-source voltage will reduce to zero when the driving signal of power switches is applied.The Class DE resonant rectifier designs its resonant parameters by calculating its e quivalent circuit model,and realizes impedance matching between the inverter and the rectifier.PCB plane transformer has the advantages of low height,light weight,fast heat dissipation,small volume,good parameter consistency,etc.PCB plane transformer with magnetic core is selected to realize the electrical isolation of the primary side and the secondary side of the converter.Paper choose a suitable core material,to calculate the parameters of the transformer,and established the PCB transformer in the finite element software HFSS geometric model,get the transformer leakage inductance of the secondary side,and combined with the design target,compromise after considering the geometric parameters of PCB transformer.Hysteresis ON/OFF control is used to achieve closed-loop regulation for output voltage of DC/DC power converter.Low-frequency ON/OFF control signal generated by hysteresis comparator could control the ON or OFF of DC/DC power converter.When converter is in the state of ON,the power converter operates in the optimum state,that is to say,the power semiconductor devices of inverter topology can achieve ZVS turn-on,and the output voltage of DC/DC converter rises.When converter is in the state of OFF,the output voltage decreases accordingly.Output voltage of DC/DC power converter fluctuate between the upper and lower threshold voltage of comparator through this control method,thus the stability of the output voltage can be achieved.Finally,an experimental prototype of 4MHz isolated DC/DC converter was built.The experimental results show that the e Ga N HEMTs can achieve ZVS turnon and effectively controlle the voltage stress at drain-source of e Ga N HEMTs.The output voltage ripple of the converter was 230 m V,which meet the design requirements.