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How Power Supply Works
- Feb 07, 2018 -

The working process of switching power supply is quite easy to understand, in linear power supply, let power transistor work in linear mode, unlike linear power supplies, PWM switching power supplies allow power transistors to work in the conduction and turn-off state, in which the Volt-Ann product added to the power transistor is very small (the voltage is low at the time of conduction, Large current, turn-off, high voltage, small current)/power device on the Volt product is the power semiconductor devices on the loss.

Compared with the linear power supply, the PWM switching power supply is more effective working process through the "Chopper", that is, the input DC voltage into the amplitude equal to the input voltage amplitude of the pulse voltage to achieve. The duty ratio of the pulse is regulated by the Controller of the switching power supply. Once the input voltage is chopped into the AC square wave, the amplitude can be raised or lowered by the transformer. The output voltage value can be increased by increasing the number of two windings of the transformer. Finally, the AC waveforms are rectified and filtered to obtain the DC output voltage.

The main purpose of the controller is to keep the output voltage stable, and its working process is similar to that of the linear controller. In other words, the controller's function block, voltage reference and error amplifier can be designed to be the same as the linear regulator. The difference is that the output of the error amplifier (Error voltage) passes through a voltage/pulse width conversion unit before the power tube is driven. There are two main modes of switching power supply: Forward-excited transform and step-up-transform. Although the layout of their parts is very small, but the work process is very different, in a specific application of the advantages of each.