Various DC switching power supply internal component protection circuits
With the development of science and technology, the relationship between power electronic equipment and people's work and life is becoming increasingly close, and electronic equipment cannot do without reliable power sources. Therefore, DC switching power supplies have begun to play an increasingly important role and have entered various fields of electronic and electrical equipment. DC switching power supplies have been widely used in program controlled switches, communication, electronic detection equipment power supplies, control equipment power supplies, etc. At the same time, with the development of many high-tech technologies, including high-frequency switching technology, soft switching technology, power factor correction technology, synchronous rectification technology, intelligent technology, surface installation technology, etc., switching power supply technology is constantly innovating, providing a wide range of development space for DC switching power supply. However, due to the complexity of the control circuit in switching power supplies, transistors and integrated devices have poor resistance to electrical and thermal shocks, which brings great inconvenience to users during use. In order to protect the safety of the switching power supply itself and the load, based on the principles and characteristics of DC switching power supply, overheating protection, overcurrent protection, overvoltage protection, and soft start protection circuits have been designed.
operational principle
The DC switching power supply consists of an input part, a power conversion part, an output part, and a control part. The power conversion part is the core of the switching power supply, which performs high-frequency chopping on unstable DC and completes the conversion function required for output. It mainly consists of a switching transistor and a high-frequency transformer. Figure 1 shows the schematic diagram and equivalent schematic diagram of a DC switching power supply, which is composed of a full wave rectifier, switching transistor V, excitation signal, freewheeling diode Vp, energy storage inductor, and filtering capacitor C. In fact, the core part of a DC switching power supply is a DC transformer.
characteristic
In order to meet the needs of users, major switch power supply manufacturers both domestically and internationally are committed to synchronously developing new types of highly intelligent components, especially by improving the losses of secondary rectification devices and increasing technological innovation in power ferrite (Mn Zn) materials to improve the ability to obtain high magnetic properties at high frequencies and high magnetic flux densities. At the same time, the application of SMT technology has made significant progress in switch power supplies, Arrange components on both sides of the circuit board 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 modularization.
The disadvantage of DC switching power supply is that it has severe switching interference and weak ability to adapt to harsh environments and sudden faults. Due to the gap between domestic microelectronics technology, production technology of resistive and capacitive devices, and magnetic material technology with some technologically advanced countries, the production technology of DC switching power supplies is difficult, maintenance is troublesome, and the cost is high,
Protection of DC switching power supply
Based on the characteristics and actual electrical conditions of DC switching power supplies, in order to ensure safe and reliable operation of DC switching power supplies in harsh environments and sudden faults, this article designs various protection circuits according to different situations.
