Principles and characteristics of switching power supply
working principle
DC switching power supply consists of input part, power conversion part, output part and control part. The power conversion part is the core of the switching power supply. It performs high-frequency chopping of unsteady DC and completes the conversion functions required for output. It is mainly composed of switching transistors and high-frequency transformers. Figure 1 shows the schematic diagram and equivalent principle block diagram of a DC switching power supply. It is composed of a full-wave rectifier, a switching tube V, an excitation signal, a freewheeling diode Vp, an energy storage inductor and a filter capacitor C. In fact, the core part of the DC switching power supply is a DC transformer.
Features
In order to meet the needs of users, major switching power supply manufacturers at home and abroad are committed to the simultaneous development of new highly intelligent components, especially by improving the losses of secondary rectifier devices and improving power ferrite (Mn-Zn) materials. Increase scientific and technological innovation to improve high magnetic performance at high frequency and larger magnetic flux density. At the same time, the application of SMT technology has made great progress in switching power supplies. Components are arranged on both sides of the circuit board to ensure the reliability of switching power supplies. Light, small and thin. Therefore, the development trend of DC switching power supply is high frequency, high reliability, low consumption, low noise, anti-interference and modularization.
The disadvantage of DC switching power supply is that it has serious switching interference and its ability to adapt to harsh environments and sudden failures is weak. Since domestic microelectronics technology, resistive device production technology, and magnetic material technology are still far behind those of some technologically advanced countries, the production of DC switching power supplies is technically difficult, troublesome to maintain, and costly.
