Introduction to the Basic Concepts of Switching Power Supply
With the development of power electronic technology, the relationship between power electronic equipment and people's work and life is increasingly close, and electronic equipment can not be separated from reliable power supply. In the 1980s, computer power supply was fully switched, and it was the first to complete the power replacement of computers. In the 1990s, switching power supply successively entered various fields of electronic and electrical equipment, and switching power supply was widely used in program-controlled switches, communication, electronic detection equipment power supply and control equipment power supply, which further promoted the rapid development of switching power supply technology. Switching power supply is a kind of power supply that uses modern power electronics technology to control the time ratio of switching transistor on and off and maintain stable output voltage. Switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. Compared with linear power supply, the costs of switching power supply and linear power supply both increase with the increase of output power, but their growth rates are different. The cost of linear power supply is higher than that of switching power supply at a certain output power point, which is the cost inversion point. With the development and innovation of power electronics technology, the switching power supply technology is constantly innovating, and this cost reversal point is increasingly moving to the low-output power end, which provides a wide development space for switching power supply. High-frequency switching power supply is its development direction. High-frequency switching power supply makes it smaller, and makes it enter a wider application field, 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 supply is of great significance in saving energy, saving resources and protecting the environment.
Switching power supply is to control the switching tube to turn on and off at high speed through the circuit. It converts direct current into high-frequency alternating current and provides it to the transformer for transformation, thus generating one or more groups of voltages needed! 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 50 Hz, so the switching transformer can be made very small and not very hot when working! The cost is very low. If you don't turn 50 Hz into high frequency, the switching power supply is meaningless! ! Switching transformer is not mysterious. It's just an ordinary transformer! This is the switching power supply. Switching power supply can be roughly divided into two types: isolated and non-isolated. The isolated type must have a switching transformer, but the non-isolated type may not necessarily have it.
At the same power, the higher the switching frequency, the smaller the volume 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 get the required output; Generally, some protection circuits should be added, such as no-load and short circuit protection, otherwise the switching power supply may be burned.
