中文版The working process of a switching power supply is quite easy to understand. In a linear power supply, the power transistor operates in linear mode. Unlike a linear power supply, a PWM switching power supply allows the power transistor to operate in both on and off states, The volt ampere product added to the power transistor is very small (during conduction, the voltage is low and the current is high; during shutdown, the voltage is high and the current is low)/The volt ampere product on the power device is the loss generated on the power semiconductor device. Compared with linear power sources, the more effective working process of PWM switching power sources is achieved through "chopping", which chops the input DC voltage into a pulse voltage with an amplitude equal to the input voltage amplitude. The duty cycle of the Bert plot pulse in the switching power supply is adjusted by the controller of the switching power supply. Once the input voltage is chopped into an AC square wave, its amplitude can be increased or decreased through a transformer. By increasing the number of secondary windings in the transformer, the output voltage value can be increased. Finally, these AC waveforms are rectified and filtered to obtain a DC output voltage. The main purpose of the controller is to maintain stable output voltage, and its working process is similar to that of a linear controller. That is to say, the function block, voltage reference and error amplifier of the controller can be designed to be the same as the linear regulator. Their difference lies in that the output of the error amplifier (error voltage) needs to pass through a voltage/pulse width conversion unit before driving the power transistor. There are two main working modes of switching power supply: forward conversion and boost conversion. Although the layout differences between their respective parts are small, the working processes vary greatly and each has its own advantages in specific application scenarios.
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