Main components of switching power supply
1. Input grid filter: eliminates interference from the grid, such as motor start-up, electrical switches, lightning strikes, etc., while also preventing high-frequency noise generated by switching power supplies from spreading to the grid.
2. Input rectifier filter: Rectify and filter the input voltage of the power grid to provide DC voltage for the converter.
3. Inverter: It is a crucial component of a switching power supply. It converts DC voltage into high-frequency AC voltage and serves to isolate the output part from the input power grid.
4. Output rectifier filter: Rectify and filter the high-frequency AC voltage output by the converter to obtain the required DC voltage, while also preventing high-frequency noise from interfering with the load.
5. Control circuit: detects the output DC voltage, compares it with the reference voltage, and amplifies it. Modulate the pulse width of the oscillator to control the converter and maintain stable output voltage.
6. Protection circuit: When the switching power supply experiences overvoltage or overcurrent short circuit, the protection circuit stops the switching power supply from working to protect the load and the power supply itself.
Switching power supply rectifies alternating current into direct current, then inverts the direct current into alternating current, and finally rectifies and outputs the required direct current voltage. This way, the switching power supply eliminates the transformer and voltage feedback circuit in the linear power supply. The inverter circuit in the switching power supply is completely digitally adjusted, which can also achieve very high adjustment accuracy.
The main working principle of a switching power supply is that the Mos tubes on the upper and lower bridges alternate conduction. First, current flows in through the Mos tubes on the upper bridge, and the coil's storage function is used to gather electrical energy in the coil. Finally, the Mos tubes on the upper bridge are turned off and the Mos tubes on the lower bridge are turned on, and the coil and capacitor continue to supply power to the outside. Then close the lower bridge Mos tube and open the upper bridge to allow current to enter, and repeat this process. Because the Mos tube needs to be switched on and off alternately, it is called a switching power supply.
