Research And Design Of Flyback Auxiliary Power Supply For Converter

With the continuous improvement of electrification,power electronic equipment has penetrated into all aspects of social production and life,and the stable operation of various power electronic equipment is inseparable from the power supply for its power supply.The continuous development of power electronics technology and control algorithms has promoted the improvement of power supply topology and its control methods.In small and medium power applications,flyback topology DC-DC converters have simple control and high power density compared to linear power supplies.The advantage of stability,in practical applications,the flyback converter basically replaces the linear power supply.Based on the detailed analysis of the commonly used DC-DC topology related theory and working principle,according to the specific requirements of the converter for the auxiliary power supply,choose the isolated single-ended flyback topology suitable for small power,according to the flyback transformation.The closed-loop control principle of the device,taking into account the dynamic response and the linear adjustment rate of the output voltage,determines the double closed-loop control mode of the voltage outer loop and the current inner loop,and completes the flyback in the current interrupt mode in the peak current control mode.Auxiliary power system design,including:high frequency transformer parameter calculation,output rectifier diode and capacitor parameter determination,start circuit,MOSFET start circuit,current sampling and clock circuit,input over voltage circuit,short circuit protection short circuit,RCD clamp absorption circuit The parameter design of the feedback compensation loop based on the K-factor calculation method is verified by simulation.The circuit schematic diagram is designed according to the calculation parameters.The auxiliary power supply is modeled and simulated by Saber.The rationality of the power supply parameters of the design is verified.Finally,the auxiliary power supply schematic diagram and PCB drawing are carried out,and the prototype test is carried out.If the multi-level converter drive requires too much independent DC power supply,there is a problem of poor voltage regulation rate when the same auxiliary power supply has too many output channels.If multiple auxiliary power supplies are used,voltage fluctuation and larger electromagnetic interference may occur.Therefore,the design of multi-level converter auxiliary power supply will be a problem.In this paper,we use the bootstrap principle to creatively design an improved bootstrap multi-level drive scheme with negative voltage,which reduces the number of independent DC power supplies and improves the reliability of the switch during shutdown...