Principle and characteristics of a switched mode power supply
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, which carries out high-frequency chopping on the unstable DC and completes the conversion function required for the output. It is mainly composed of switching transistors and high-frequency transformers. Figure 1 draws the schematic and equivalent block diagram of the DC switching power supply, which is composed of a full-wave rectifier, a switching tube V, an excitation signal, a current-renewal diode Vp, an energy storage inductor and a filtering capacitor C. In fact, the core part of the DC switching power supply is a DC transformer.
In order to adapt to the user's needs, major switching power supply manufacturers at home and abroad are committed to the simultaneous development of new highly intelligent components, especially by improving the loss of the secondary rectifier device, and increase the science and technology in the power ferrite (Mn-Zn) materials, in order to improve the high frequency and larger flux density to obtain a high level of magnetic performance, while the application of SMT technology has made significant progress in switching power supplies, in the Circuit boards on both sides of the layout of components to ensure that the switching power supply is 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 modularity.
The disadvantage of DC switching power supply is that there is a more serious switching interference, the ability to adapt to harsh environments and sudden failure is weak. Due to the domestic microelectronics technology, capacitive resistance device production technology and magnetic material technology and some technologically advanced countries still have a certain gap, so the production of DC switching power supply technical difficulties, maintenance trouble and high cost.
