Modern power supply technology is a multidisciplinary edge crossing technology which applies power electronic semiconductor devices and integrates automatic control, computer (microprocessor) technology and electromagnetic technology. It plays a key role in various high-quality, high-efficiency and high-reliability power supplies, and is a concrete application of modern power electronics technology. At present, power electronics, as the basis of energy saving, talent saving, automation, intelligence and mechatronics, is developing towards high-frequency application technology, modular hardware structure and green product performance. In the near future, power electronics technology will make power technology more mature, economical and practical, and realize the combination of high efficiency and high quality electricity consumption.
3.2 Modularization
Modularity has two meanings, one is modularity of power devices, and the other is modularity of power supply units. Our common device modules, including one unit, two units, six units to seven units, including switching devices and anti-parallel free-wheeling diodes, are essentially "standard" power modules (SPM). In recent years, some companies also put the driving and protection circuits of switching devices into power modules to form an "intelligent" power module (IPM), which not only reduces the volume of the whole machine, but also facilitates the design and manufacture of the whole machine. In fact, due to the continuous improvement of frequency, the influence of lead parasitic inductance and parasitic capacitance is more and more serious, which causes greater electrical stress (such as overvoltage and overcurrent burr) to the device. In order to improve the reliability of the system, some manufacturers have developed "user-specific" power module (ASPM), which installs almost all the hardware of the whole machine in a module in the form of chips, so that there is no traditional lead connection between components. This module has been designed strictly and reasonably in the aspects of heat, electricity and machinery, and has reached a perfect position. It is similar to the user-specific integrated circuit (ASIC) in microelectronics. As long as the control software is written into the microprocessor chip in the module, and then the whole module is fixed on the corresponding radiator, a new switching power supply device is formed. It can be seen that the purpose of modularization is not only to facilitate the use and reduce the volume of the whole machine, but also to cancel the traditional connection and minimize the parasitic parameters, so as to minimize the electrical stress borne by the device and improve the reliability of the system. In addition, due to the limitation of device capacity and the consideration of increasing redundancy and improving reliability, high-power switching power supply generally adopts multiple independent module units working in parallel and adopts current sharing technology. All modules share the load current. Once one module fails, other modules will share the load current equally. This not only improves the power capacity, but also meets the requirements of large current output under the condition of limited device capacity. Moreover, the reliability of the system is greatly improved by adding redundant power modules with less power than the whole system. Even if a single module fails, it will not affect the normal work of the system and will provide sufficient time for repair.
3.3 Digitization
In the traditional power electronics technology, the control part is designed and operated according to analog signals. In the 1960s and 1970s, power electronics technology was based entirely on analog circuits. However, digital signals and digital circuits are becoming more and more important, and digital signal processing technology is becoming more and more mature, showing more and more advantages: it is convenient for computer processing and control, avoiding analog signal distortion, reducing the interference of stray signals (improving anti-interference ability), facilitating software package debugging and remote sensing and telemetry, and facilitating the implantation of technologies such as self-diagnosis and fault tolerance. Therefore, in the 1980s and 1990s, analog technology is still useful for the design of various circuits and systems, especially for the solution of PCB layout, electromagnetic compatibility (EMC) and power factor correction (PFC), but for intelligent switching power supply, digital technology is indispensable when computer control is needed.
3.4 Greening
The greening of power supply system has two meanings: first, it saves electricity significantly, that is, it saves power generation capacity, and power generation is an important cause of environmental pollution, so saving electricity can reduce environmental pollution; Secondly, these power sources can't (or less) pollute the power grid. The International Electrotechnical Commission (IEC) has formulated a series of standards, such as IEC555, IEC9 17, IECl000 and so on. In fact, many power electronic energy-saving devices often become the pollution sources of the power grid: injecting serious high-order harmonic current into the power grid, reducing the total power factor, multi-peak voltage coupling of the power grid, and even missing corners and distortion. At the end of the 20th century, various schemes of active filter and active compensator were born, and there were many methods to correct power factor. These laid the foundation for mass production of various green switching power supply products in 2 1 century.
Modern power electronics technology is the basis of the development of switching power supply technology. With the continuous emergence of new power electronic devices and circuit topologies suitable for higher switching frequency, modern power supply technology will develop rapidly under the impetus of practical needs. Under the traditional application technology, the performance of switching power supply is affected by the performance limitation of power devices. In order to give full play to the characteristics of various power devices and minimize the influence of device performance on the performance of switching power supply, new power supply circuit topology and new control technology can make the power switch work in zero voltage or zero current state, thus greatly improving the working frequency, improving the working efficiency of switching power supply and designing a switching power supply with excellent performance.
In a word, power electronics and switching power supply technologies are constantly developing due to application requirements, and the emergence of new technologies will update many application products and open up more updated application fields. The realization of high frequency, modularization, digitalization and greening of switching power supply will mark the maturity of these technologies and realize the combination of high efficiency and high quality electricity consumption. In recent years, with the development of communication industry, the domestic market demand of switching power supply for communication with switching power supply technology as the core exceeds 2 billion RMB, attracting a large number of domestic and foreign scientific and technological personnel to carry out research and development. It is the general trend that switching power supply replaces linear power supply and phased power supply. Therefore, the domestic market of electric power supply system, which also has a demand of 10 billion output value, is starting and will soon develop. There are many other special power supplies and industrial power supplies with switching power supply technology as the core waiting for people to develop.