Switching power supply is to control the high-speed switching of switching tube through circuit. It converts direct current into high-frequency alternating current and provides it to the transformer for transformation, thus generating one or more required voltages! The reason for switching to Huawei's high-frequency alternating current is that the efficiency of high-frequency alternating current in transformer transformation circuit is much higher than 50Hz, so the switching transformer can be made very small and will not be very hot when working! The cost is low

The working principle of switching power supply is:

1. AC power input enters DC after rectification and filtering;

2. The switch tube is controlled by high frequency PWM (pulse width modulation) signal, and the DC is added to the primary of the switching transformer;

3. The secondary of the switching transformer induces high-frequency voltage, which is provided to the load through rectification and filtering;

4. The output part is fed back to the control circuit through a certain circuit to control the PWM duty ratio and achieve the purpose of stable output.

When AC power is input, it usually passes through something similar to a current loop to filter out the interference on the power outage network, and at the same time, it also filters out the interference from the power supply to the power grid;

Under the same power, the higher the switching frequency, the smaller the size of the switching transformer, but the higher the requirements for the switching tube;

The secondary of the switching transformer can have multiple windings, or one winding has multiple taps to obtain the required output;

Generally, it is necessary to add some protection circuits, such as no-load and short-circuit protection, otherwise it may burn out the switching power supply.