Definition and operation of a switch mode power supply
Switching power supply is a power supply that uses a circuit to control the switching tube to conduct and cut off at high speed. It provides direct current to high-frequency alternating current to a transformer for transformation, thereby generating one or more sets of required voltages.
Switching power supply consists of the following parts:
1, The entire process of the main circuit from AC grid input to DC output, including:
1. Input filter: Its function is to filter out the clutter present in the power grid, while also hindering the feedback of local generated clutter to the public power grid.
2. Rectification and filtering: Directly rectify the AC power supply of the power grid into smoother DC power for down conversion.
3. Inverter: Convert rectified DC power into high-frequency AC power, which is the core part of high-frequency switching power supplies. The higher the frequency, the smaller the ratio of volume, weight, and output power.
4. Output rectification and filtering: Provide stable and reliable DC power supply according to load requirements.
2, On the one hand, the control circuit samples from the output terminal, compares it with the set standard, and then controls the inverter to change its frequency or pulse width to achieve stable output
Three conditions for switching power supply
1. Switch: Power electronic devices operate in a switch state rather than a linear state
2. High frequency: Power electronic devices operate at high frequencies rather than low frequencies close to the power frequency
3. DC: Switching power supplies output DC instead of AC
Working principle of switch mode power supply
Nowadays, most peripherals use switching power supplies for voltage transformation. Although switch mode power supplies have the characteristics of small size, high work efficiency, and good voltage stabilization effect, they are directly connected to the mains power supply, and changes in mains voltage and surges can cause damage to the switch mode power supply. The circuit of a switching power supply is quite complex, and many enthusiasts are helpless when it comes to power supply damage. In fact, as long as we have a certain understanding of it, repairing it is not difficult.
The principle of switch mode power supply is roughly the same. Here, we take the example of the no voltage output of the switch mode power supply that comes with the HP3748 printer to explain the working principle and fault detection methods of the switch mode power supply.
