New technology application and development of DC switching power supply
With the rapid development of electronic technology and communication industry, the application of high-frequency switching power supplies is becoming more and more widespread. The continuous increase of switching frequency has further optimized the performance of switching power supplies, with higher integration, lower power consumption and simpler circuits. , the work is more reliable, which is the development direction of switching power supply. At present, high-frequency switching power supplies have been widely used in microwave stations of radio and television in our province. Based on this and combined with actual practice, we will introduce the new technology and advantages of high-frequency switching power supplies by comparing traditional power supplies with modern high-frequency switching power supplies.
Composition principle of high frequency switching power supply
High-frequency switching rectifiers generally first rectify and filter alternating current directly through diodes into direct current, and then convert it into high-frequency alternating current through switching power supply. After transforming and isolating it through a high-frequency transformer, it is output after high-frequency rectification by fast recovery diodes and filtering by inductors and capacitors. ,see picture 1.
The main circuit
The entire process from AC grid input to DC output includes:
(1) Input filter: Its function is to filter the clutter existing in the power grid, and at the same time, it also prevents the clutter generated by the machine from being fed back to the public power grid.
(2) Rectification and filtering: directly rectify the grid AC power into smoother DC power and provide stable DC power to the power factor correction circuit.
(3) Power factor correction: Located between rectifier filtering and inverter, it improves the power factor by eliminating harmonic current pollution caused by the rectifier circuit and reducing reactive power losses.
(4) Inverter: Convert rectified DC power into high-frequency alternating current. This is the core part of high-frequency switching power supply. The higher the frequency, the smaller the ratio of volume, weight and output power.
(5) Output rectification and filtering: Provide stable and reliable DC power supply according to load needs.
Control circuit
On the one hand, samples are taken from the output end and compared with the set standard, and then the inverter is controlled to change its frequency or pulse width to achieve output stability. On the other hand, based on the data provided by the test circuit and identified by the protection circuit, the inverter is provided The control circuit carries out various protection measures for the whole machine.
1.3 Detection circuit
In addition to providing various running parameters in the protection circuit, it also provides various display instrument data for the personnel on duty to observe and record.
1.4 Auxiliary power supply
Provide power supplies with different requirements (voltage power supplies of various levels of AC and DC) required for the operation of all circuits of the switching rectifier itself.
