Views:101 Author:Site Editor Publish Time: 2019-09-25 Origin:Site
Many electronic products, such as personal computers, are used in our life, but few people know about switching mode power supply, which plays a vital role in our daily use of electronic products. Next, let me introduce some basic knowledge of switching power supply.
Since there is no power frequency transformer, the volume and weight are only 20 ~ 30% of the linear power supply.
The power transistor works in a switching state, so the power consumption on the transistor is small and the conversion efficiency is high, generally 60-70%, while the linear electric power supply is only 30-40%.
Power electronic devices work in a switch state instead of a linear state
Power electronic devices work at high frequency instead of low frequency close to power frequency
Switching power supply outputs DC instead of AC.
High-frequency switching power supply is its development direction. High-frequency miniaturization of switching power supply and its application in a wider range of fields, especially in high-tech fields, have pushed forward the development of switching power supply. It is developing towards light, small, thin, low noise, high reliability and anti-interference at an annual growth rate of more than two digits. Switching power supplies can be divided into two categories: AC/DC and DC/DC. DC/DC converters have been modularized, and the design technology and production process have been mature and standardized at home and abroad, and have been recognized by users. However, the modularization of AC/DC, due to its own characteristics, leads to more complex technical and process manufacturing problems in the process of modularization. In addition, the development and application of switching power supply are of great significance in saving energy, saving resources and protecting the environment.
The power electronic devices used in switching power supply are mainly diodes, IGBT, MOSFET and transformer.
SCR has a small number of applications in switching power supply input rectification circuit and soft start circuit. GTR is difficult to drive and has low switching frequency, which is gradually replaced by IGBT and MOSFET.
The development direction of switching power supply is high frequency, high reliability, low consumption, low noise, anti-interference and modularization. As the key technology of light, small and thin switching power supply is high frequency, foreign major switching power supply manufacturers are committed to synchronously developing new high intelligent components, especially improving the loss of secondary rectifier devices, and increasing scientific and technological innovation in power ferrite materials to improve the high magnetic performance at high frequency and large magnetic flux density (Bs), while the miniaturization of capacitors is also a key technology. The application of SMT technology has made great progress in switching power supply. Components are arranged on both sides of the circuit board to ensure the light, small and thin switching power supply. The high frequency of switching power supply will inevitably innovate the traditional PWM switching technology. The soft switching technology to realize ZVS and ZCS has become the mainstream technology of switching power supply and greatly improves the working efficiency of switching power supply. For high reliability index, American manufacturers of switching power supply reduce the stress of devices by reducing operating current and junction temperature, thus greatly improving the reliability of products.
Modularization is the general trend of the development of switching power supply. Modular power supply can be used to form a distributed power supply system, which can be designed as an N+1 redundant power supply system and realize capacity expansion in parallel. In view of the shortcoming of high operating noise of switching power supply, the noise of switching power supply will increase if it pursues high frequency alone. In theory, partial resonance conversion circuit technology can realize high frequency and reduce noise. However, there are still technical problems in the practical application of partial resonance conversion technology. Therefore, a lot of work needs to be done in this field to make this technology practical.
With the continuous innovation of power electronics technology, the switching power supply industry has a broad development prospect.