Switching power supply is the use of modern power electronic technology, control switch on and off time ratio, maintain a stable output voltage of a power supply, switching power supply is generally by ************** modulation (PWM) control IC and MOSFET. Compared with the linear power supply, the cost of switching power supply increases with the increase of output power, but the growth rate of the two is different. The cost of a linear power supply is higher than that of a switching power supply at a certain output power point, which is called the cost reversal point. With the development and innovation of power electronics technology, the switching power supply technology is constantly innovating, and the cost reversal point is increasingly moving to the low output power end, which provides a broad space for the development of switching power supply.

 

High-frequency switching power supply is the direction of its development, high-frequency switching power supply miniaturization, and the switching power supply into a wider range of applications, especially in the field of high-tech applications, to promote the miniaturization of high-tech products, portable. In addition, the development and application of switching power supply is of great significance in energy conservation, resource conservation and environmental protection. The power electronic devices used in switching power supply are mainly diodes, IGBTs and MOSFETs. SCR in switching power supply input rectifier circuit and soft start circuit has a small number of applications, GTR drive is difficult, low switching frequency, gradually replaced by IGBT and MOSFET.

 

Conditions of switching power supply

 

1. Switching: Power electronic devices work in the switching state instead of the linear state

 

2, high frequency: power electronic devices work at high frequency rather than close to the frequency of the low frequency

 

3. DC: The output of the switching power supply is DC instead of AC