Switching power supply basic analysis

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Summary:

Switching power supply is a widely used power supply, widely used in high-power electronic and electrical equipment such as color TVs, computers and copiers. Compared with the series-type regulated power supply, the switching power supply has the following features:

1 high efficiency and low power consumption. The efficiency of the switching power supply is generally above 80%, and the efficiency of the series-regulated power supply is only about 50%.

2 wide voltage range. The switching power supply has a voltage regulation range of 130~260V, and the excellent switching power supply can reach 90~280V, while the series-regulated power supply has a voltage regulation range of 190~240V.

3 light weight and small size. Switching power supplies generally use small-sized switching transformers. They do not need bulky and bulky power transformers, and because of high efficiency and low loss, switching power supplies do not need to be equipped with large heat sinks. Although the switching power supply has many advantages, the circuit is complicated, the maintenance is difficult, and the interference is strong.

Three basic types of switching power supplies

There are many types of switching power supplies, but they can usually be divided into three basic types: series switching power supplies, parallel switching power supplies, and transformer-coupled switching power supplies.

Series switching power supply

Parallel switching power supply

Transformer coupled switching power supply

Self-excited switching power supply circuit

When the switching power supply is working, a circuit is needed to provide a control pulse signal for the base of the switching tube. The actual switching power supply itself should have such a circuit. Some switching power supply switching tubes and other components constitute an oscillating circuit to generate a control pulse, which is provided to the switching tube. The switching pulse supplied to the switching tube by the switching tube is called a self-excited switching power supply. .

The actual switching power supply circuit is generally composed of a rectifying and filtering circuit, an oscillating circuit, a voltage stabilizing circuit and a protection circuit.

The basic knowledge of switching power supply can be found in the PDF document.