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     Flyback transformer switching power supply means that when the primary coil of the transformer is excited by the DC pulse voltage, the secondary coil of the transformer does not provide power output to the load, but only after the excitation voltage of the primary coil of the transformer is turned off. Provide power output, this kind of transformer switching power supply is called flyback switching power supply.

    The working principle of the flyback power switch: the continuous and discontinuous modes of the flyback power supply refer to the working state of the transformer. In the fully loaded state, the transformer works in a working mode in which energy is completely transferred or incompletely transferred. Generally, the design should be based on the working environment. Conventional flyback power supplies should work in continuous mode, so that the switching tube and circuit losses are relatively small, and the working stress of the input and output capacitors can be reduced, but there are some exceptions. It needs to be pointed out here: due to the characteristics of the flyback power supply, it is also more suitable to be designed as a high-voltage power supply, and the high-voltage power supply transformer generally works in discontinuous mode. I understand that the output of the high-voltage power supply requires the use of high voltage rectifier diodes. Due to the characteristics of the manufacturing process, high reverse voltage diodes have long reverse recovery time and low speed. In the current continuous state, the diode recovers when there is a forward bias. The energy loss during reverse recovery is very large, which is not conducive to the performance of the converter. The improvement of the rectifier tube will reduce the conversion efficiency, severely heat the rectifier tube and even burn the rectifier tube. Since in discontinuous mode, the diode is reverse-biased under zero bias, the loss can be reduced to a relatively low level. Therefore, the high-voltage power supply works in discontinuous mode, and the operating frequency cannot be too high. There is also a type of flyback power supply that works in a critical state. Generally, this type of power supply works in frequency modulation mode or dual frequency and width modulation mode. Some low-cost self-excited power supplies (rcc) often use this form. In order to ensure stable output, transformers The operating frequency changes with the output current or input voltage. The transformer always remains between continuous and intermittent when it is close to full load. This kind of power supply is only suitable for low-power output, otherwise the electromagnetic compatibility characteristics will be very troublesome.