The Design And Research Of Two-switch Quasi Resonant Converter In A Wide Range

In the background of the global energy crisis,Rooftop distributed photovoltaic power generation and large area centralized photovoltaic power generation developed rapidly based on the new policy of "The Belt and Road" in China.In the photovoltaic power generation system,the controller,Miniature relay switch,sampling circuit board,protective circuit board and so on,are all need switching power supply to provide stable and reliable voltage.However,the voltage range of the solar panel is between 300V-1000 V.Therefore,the design of a switching power supply with wide input voltage range and low output voltage has a certain theoretical and practical value.In this paper,a two-switch flyback topology is used to realize the transmission of main power,and the quasi resonant technique is used to control the converter.Compared with the single transistor flyback circuit,the dual tube topology can effectively reduce the voltage stress of the switch tube,and the switch type selection is convenient,and the cost performance ratio is high.The switch with low on resistance can reduce the conduction loss and improve the efficiency of the converter.At the same time,without adding too many additional devices,the leakage inductance energy of the transformer is fed back to the input through the primary clamping diode,and the energy feedback is realized,which greatly improves the efficiency of the whole machine.The quasi resonant technology can realize the function of quasi soft switching circuit,reduce the switching loss of the switch,optimize the dv/dt and di/dt,reduce the temperature rise of the main power device,and improve the efficiency of switching power supply by 5%-10%.The experimental prototype can reach 90% efficiency.This paper focuses on the performance characteristics,working state and implementation process of quasi resonant technology used in double transistor flyback circuit.Two isolated drive circuits are designed to meet the requirements of dual channel topology that requires two completely synchronous isolated drive signals.At the same time,the quasi resonant control chip L6565 D is used to collect the input voltage through the resistance divider to realize the function of self power limiting point and ensure the stable output of the duty cycle of the chip PWM.An experimental prototype of 100 W is designed,and completed the closed-loop control of the circuit,and verified the correctness of the theoretical analysis is.At present,the power supply has been successfully applied to the photovoltaic power station system,and achieved good results.