Applications and characteristics of switching power supplies
Switching power supply has the following main features:
1. Small size, light weight: because there is no industrial frequency transformer, so the volume and weight of only 20 to 30% of the linear power supply.
2. Small power consumption, high efficiency: power transistors work in the switching state, so the power consumption on the transistor is small, the conversion efficiency is high, generally 60 to 70%, while the linear power supply is only 30 to 40%.
The working principle of switching power supply is.
1. AC power input is rectified and filtered into DC; 2.
2. Through the high-frequency PWM (Pulse Width Modulation) signal control switching tube, the DC added to the primary switching transformer.
3. Switching transformer secondary induction of high-frequency voltage, rectified and filtered to supply the load.
4. The output part is fed back to the control circuit through a certain circuit to control the PWM duty cycle to achieve the purpose of stable output.
AC power input is generally to go through a current loop things, filter out the grid interference, but also filter out the power supply on the grid interference; in the same power, the higher the switching frequency, switching transformer size is smaller, but the higher the requirements of the switching tube; switching transformer can have more than one secondary winding or a winding with a number of taps, in order to get the desired output; generally should also add some protection circuit, such as no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, no-load, and so on. Generally, some protection circuits should be added, such as no-load, short-circuit protection, otherwise the switching power supply may be burned.
