Research Of Multi-output Drive Power Supply With High Isolation And Low Coupling Capacitor

The switch made of the third generation wide band gap semiconductor material,such as SiC and GaN,is more and more widely used in the case of high voltage and high frequency(HV-HF)because of its excellent performance such as high withstand voltage,high switching frequency and low loss.High-power power electronic equipment usually has multiple SiC and GaN switching devices.In HV-HF applications,the switching devices withstand a large dV/dt.The isolation voltage of the ordinary isolated driving power supply is not enough,and it is not suitable to achieve multi-channel output,and there is a large coupling capacitor Cio between the input and the output.In the case of large dV/dt,the driving power of the large coupling capacitor will generate a large common-mode current,which will cause a large interference to the normal operation of power electronic equipment.Studying the power supply for SiC and GaN switching devices under HV-HF conditions is beneficial to the application of SiC and GaN switching devices with excellent performance,especially in the case of HV-HF.Based on the analysis of the problems of conventional isolated driving power supply,this paper studies and designs a multi-output high isolation,low coupling capacitance driving power supply.According to the optimized design of the structure of the high-frequency transformer,a transformer structure based on current transformer was selected.The transformer of this structure can reduce the number of windings and winding turns,thereby reducing the coupling capacitance.At the same time,this form of isolation is easy to achieve multiple output and high isolation voltage of the driving power supply.By comparing and analyzing the input source of the transformer,it is concluded that the current source performs better.Modeling and analyzing the value of transformer structure and coupling capacitance,the design method of current transformer type small coupling capacitor transformer is given.Aiming at the problem of the primary side circuit design in the isolated power supply of the transformer,the primary side circuit of the LCL-T resonant network is proposed to use,and the working process and constant current characteristics of the inverter circuit and the LCL-T resonant network are analyzed.The characteristics of the primary circuit parameters are shown.The LCL-T circuit structure realizes the conversion function from the voltage source of the circuit input to the high-frequency current source of the transformer input,and the current source has low harmonics and good constant current performance.The output terminal of the transformer is connected to the secondary-side rectifier bridge.Because the secondary-side circuit needs to achieve a constant voltage output,this paper proposes a current-type Boost switch circuit to achieve a regulated output.The circuit structure is analyzed and modeled,the compensation network is designed,the appropriate DC-DC integrated control chip is selected,the corresponding protection and peripheral circuits are designed,and finally the regulated output is realized.The simulation verifies the structure of adopting the inverter circuit and LCL-T resonant network on the primary side of the power supply and the current-type Boost circuit on the secondary side,which can achieve the design purpose.Finally,by designing a power supply prototype with 24 V input and three output 24 V / 6W,the correctness of the related design in this paper is verified.