Release Time:2020-11-30 Source:Original Views:3721
The knowledge of switching power supplies requires careful understanding. Only when you are familiar with it can you understand it well. Then you can buy a safe switching power supply that suits you when you buy it. Below we will introduce in detail what is a switching power supply and its working principle.
What is a switching power supply
Switching power supply is a power supply that uses modern power electronic technology to control the switching time ratio to keep the output voltage stable. The switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. At present, switching power supplies are widely used in almost all electronic devices due to their small size, light weight, and high efficiency. It is an indispensable power supply method for the rapid development of the electronic information industry.
With the rapid development of power electronic technology, power electronic equipment is increasingly closely related to people's work and life, and electronic equipment is inseparable from reliable power supply. In the 1980s, computer power supplies fully realized switching power supplies, and were the first to complete the replacement of computer power supplies. Switching power supplies have been widely used in communications, electronic testing equipment power supplies, and control equipment power supplies, and have also promoted the rapid development of switching power supply technology.
Compared with linear power supply, the cost of switching power supply and linear power supply increases with the increase of output power, but the growth rate of the two is different. At a certain output power point, the cost of linear power supplies is higher than that of switching power supplies. With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. This kind of cost reversal point is increasingly shifting to the low output power end, which provides a broad development space for switching power supplies.
High-frequency switching power supply is its development direction. High frequency miniaturizes the switching power supply, and enables the switching power supply to enter a wider range of applications, especially in the high-tech field, which promotes the miniaturization and portability of high-tech products. In addition, the development and application of switching power supplies are of great significance to safety monitoring, energy saving, resource saving and environmental protection.
Working principle of switching power supply:
The working process of switching power supply is easy to understand. In a linear power supply, the power transistor operates in a linear mode. Different from linear power supplies, PWM switching power supplies make power transistors work on and off. In these two states, the VA product added to the power transistor is very small (when turned on, the voltage is low, and the current is high; when the power is turned on, the voltage is low, and the current is large; (when turned off, the voltage is high and the current is small)/power The volt-ampere product on the device is the loss generated on the power semiconductor device.
Compared with the linear power supply, the PWM switching power supply achieves a more effective working process through chopping, that is, the input DC voltage is chopped into a pulse voltage equal to the amplitude of the input voltage. The pulse duty cycle is adjusted by the controller of the switching power supply. After the input voltage is cut into an AC square wave, the amplitude of the square wave can be increased or decreased through the transformer. The output voltage can be increased by increasing the number of secondary windings of the transformer. Finally, by rectifying and filtering these AC waveforms, the DC output voltage is obtained.