The Design Of The Quasi Resonant Flyback Switching Power Supply

DC power supply is widely used in People's Daily life.The traditional linear power supply is being replaced by the DC-DC switching power supply because of the loss and efficiency.The present DC-DC switching power supply development and application status is expounded, the key technology to improve the performance of the power supply is studied and analyzed, soft switch technology is used ,a high efficiency and low cost of quasi resonant flyback switch power supply is desinged.The efficient way to increase power density of switch power supply is the high frequency of DC-DC switch, and high frequency must reduce the power pipe switch loss.In recent years, the popularity of soft switch theory has an important effect on reducing power consumption and improving power efficiency. By quasi resonant control method, through testing the master MOSFET drain source voltage, and control the voltage at the bottom opening, greatly reduce the internal loss of the flyback type switch power supply, improve the working efficiency and working frequency of the flyback power supply.The quasi resonant flyback type working mode and working principle is analyzed, the power circuit design based on master control chip NCP1337 is intronduced. According to the design index, the selection of key parts is determined,the master control chip and related peripheral circuit and device parameter calculation is completed.The quasi resonant flyback circuit is constructed and a test prototype is made.By debugging and the experiment test,the feasibility of quasi resonant control bottom opening method is verified the test conclusion of power efficiency reached 90% is obtained.The design of switching power supply with high efficiency, cheap price, small footprint, which can realize multi-channel output characteristics, especially suitable for the power output of 0-150W DC power supply.