Switching power supply is a kind of power supply that uses modern power electronic technology, uses power semiconductor devices as switches, and adjusts the output voltage by controlling the time ratio (duty cycle) of switching transistors on and off to maintain stable output. As early as the 1980s, computer power supplies were fully realized as switching power supplies, and the first to complete the replacement of computer power supplies. In the 1990s, switching power supplies have been widely used in various electronic and electrical equipment, program-controlled switches, communications, power testing equipment power supplies and control equipment power supplies. Among. The switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. Compared with the linear power supply, the cost of the switching power supply increases with the increase of the output power, but the growth rate of the two is different. The cost of the linear power supply is higher than the switching power supply at a certain output power point, which is called the cost reversal point. With the development and innovation of power electronics technology, the switching power supply technology has also been continuously innovated. This cost reversal point is increasingly moving to the low output power end, thus providing a broad development space for switching power supplies.
The high frequency of the switching power supply makes it the development direction, and the high frequency makes the switching power supply smaller, and makes the switching power supply enter a wider range of applications, especially the application in the high-tech field, which promotes the miniaturization of high-tech products. Lightweight. In addition, the development and application of switching power supplies are of great significance in saving energy, saving resources and protecting the environment.
The development direction of switching power supply is high frequency, high reliability, low consumption, low noise, anti-interference and modularization. Since the key technology of light, small and thin switching power supply is high frequency, foreign switching power supply manufacturers are committed to the simultaneous development of new and highly intelligent components, especially to improve the loss of secondary rectifier devices, and to improve the power of ferrite Increased technological innovation on bulk (Mn-Zn) materials to improve high magnetic performance at high frequencies and large magnetic flux density (Bs), and miniaturization of capacitors is also a key technology. 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 that the switching power supply is light, small and thin. The high frequency of the switching power supply will inevitably innovate the traditional PWM switching technology. The soft switching technology of ZVS and ZCS has become the mainstream technology of the switching power supply, and the working efficiency of the switching power supply has been greatly improved. For Lianhe's high reliability index, American switching power supply manufacturers reduce the stress of the device by reducing the operating current and lowering the junction temperature, which greatly improves the reliability of the product.
Modularity is the general trend of the development of switching power supplies. Modular power supplies can be used to form a distributed power supply system, and can be designed as an N+1 redundant power supply system, and realize capacity expansion in parallel mode. In view of the shortcoming of high operating noise of switching power supply, if you pursue high frequency alone, its noise will also increase. With partial resonant conversion circuit technology, theoretically high frequency can be achieved and noise can be reduced. Part of the practical application of resonant conversion technology still has technical problems, so a lot of work in this field is still needed to make many technologies practical. With the continuous innovation of power electronics technology, the switching power supply industry has broad development prospects. To speed up the development of my country's switching power supply industry, it is necessary to take the road of technological innovation, walk out the road of joint development of industry, university and research with Chinese characteristics, and make contributions to the rapid development of my country's national economy.
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