What are the application fields of switching power supply?
The high frequency of switching power supply is the direction of its development. The high frequency makes the switching power supply miniaturized, and makes the switching power supply enter a wider range of use, especially in the field of high-tech skills, which promotes the miniaturization and simplification of high-tech commodities. In addition, the development and use of switching power supply has the main meaning in saving energy, saving capital and protecting the environment.
With the rapid development of power electronic skills, power electronic equipment is increasingly closely related to everyone's work and day, and electronic equipment is inseparable from reliable power supply. In the 1980s, the computer power supply has fully completed the switching power supply, first completed the power generation of computers, and in the 1990s, the switching power supply has successively entered the category of various electronic and electrical equipment, program-controlled switches Switching power supply has been widely used in communication, electronic testing equipment power supply and control equipment power supply, which has promoted the rapid development of switching power supply skills. Switching power supply is a power supply that uses modern power electronic skills to control the time ratio of switching transistor registration and off to maintain a stable output voltage. Switching power supply is usually composed of pulse width modulation (PWM) control IC and MOSFET. Compared with linear power supply, the cost of switching power supply and linear power supply increases with the addition of output power, but their increase rates are different. The cost of linear power supply is higher than that of switching power supply at a certain output power point. With the development and innovation of power electronics skills, switching power supply skills are constantly innovating. This cost turning point is increasingly moving to the low output power end, which provides a wide development space for switching power supply.
Classification of switching power supply
The skill category of switching power supply is to develop relevant power electronic equipment while developing switching frequency conversion skills. The two promote each other and promote the development of switching power supply in the direction of light, small, thin, low noise, high reliability and anti disturbance at an increase rate of more than two digits every year. Switching power supply can be divided into AC / DC and DC / DC. DC / DC converter has been modularized, and planning skills and production skills have been sophisticated and standardized at home and abroad, and have been recognized by users. However, due to its own characteristics, AC / DC modularization has encountered more messy skills and skill making questions in the process of modularization. The structure and characteristics of the two types of switching power supplies are described below.
1 DC / DC conversion
DC / DC conversion is to convert a fixed DC voltage into a variable DC voltage, also known as DC chopper. There are two working methods of the chopper: one is the pulse width modulation method, TS unchanged, changing ton (general), and the other is the frequency modulation method, ton unchanged, changing TS (prone to disturbance). The detailed circuit consists of the following categories:
(1) Buck circuit - step-down chopper, whose output uniform voltage uo is less than the input voltage UI, and the polarity is the same.
(2) Boost circuit -- boost chopper, whose output uniform voltage uo is greater than the input voltage UI, with the same polarity.
(3) Buck boost circuit - buck or boost chopper, whose output uniform voltage uo is greater than or less than the input voltage UI, with opposite polarity and inductive transmission.
(4) Cuk circuit - step-down or step-up chopper, whose output uniform voltage uo is greater than or less than the input voltage UI, with opposite polarity and capacitive transmission.
Today's soft switching technology makes a qualitative leap in DC / DC. VICOR plans to produce a variety of ECI soft switching DC / DC converters, with maximum output power of 300W, 600W and 800W, corresponding power density of (6, 2, 10 and 17) w / cm3 and power of (80-90)%. A high-frequency switching power supply module RM series with soft switching skills, which is newly launched by nemic lambda of Japan, has a switching frequency of (200 ~ 300) kHz and a power density of 27
W / cm3, synchronous rectifier (MOS-FET instead of Schottky diode) is selected to improve the power of the whole circuit to 90%.
Development trend of switching power supply skills
The development direction of switching power supply is high frequency, high reliability, low consumption, low noise, anti disturbance and modularization. Because the key skill of switching power supply is high frequency, the major foreign switching power supply manufacturers are committed to simultaneously developing new and intelligent meta equipment, especially improving the loss of secondary rectifier equipment, and making great scientific and technological innovations in power ferrite (Mn Zn) materials, so as to improve the high magnetic properties under high frequency and large magnetic flux density (BS), The miniaturization of capacitors is also a key skill. The use of SMT skills has made great progress in switching power supply. Meta equipment is 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 must innovate the traditional PWM switching skills. The soft switching skills of ZVS and ZCS have become the mainstream skills of switching power supply, and the working power of switching power supply has been greatly improved. For the goal of high reliability, American switching power supply manufacturers have taken measures such as reducing the operating current and junction temperature to reduce the stress of equipment, so as to greatly improve the reliability of goods
