Rapidly developing computer technology has led humanity into the information society, while also promoting the rapid development of power module technology. In the 1980s, computers fully adopted switch-mode power supplies, completing the upgrade of computer power supplies. Subsequently, switch-mode power supply technology entered the fields of electronics and electrical equipment one after another.
The development of computer technology has proposed green computers and green power modules. Green computers refer to personal computers and related products that are harmless to the environment, while green power refers to efficient and power-saving power supplies associated with green computers. According to the “Energy Star” program established by the U.S. Environmental Protection Agency on June 17, 1992, desktop personal computers or related peripheral devices that consume less than 30 watts in sleep mode meet the requirements for green computers. Improving power supply efficiency is the fundamental way to reduce power consumption. For a 200-watt switch-mode power supply with an efficiency of 75%, the power supply itself consumes 50 watts of energy.
The rapid development of the telecommunications industry has greatly promoted the development of communication power supplies. High-frequency, miniaturized switch-mode power supplies and their technologies have become mainstream in modern communication power supply systems. In the communication field, rectifiers are usually referred to as primary power supplies, while DC-DC converters are referred to as secondary power supplies. The role of the primary power supply is to convert single-phase or three-phase AC power grids into DC power supplies with a nominal value of 48V. Currently, traditional phase-controlled voltage stabilizers have been replaced by high-frequency switch-mode power supplies in primary power supplies for program-controlled switches. High-frequency switch-mode power supplies (also known as switch-mode rectifiers, SMR) achieve high efficiency and miniaturization through high-frequency operation of MOSFETs or IGBTs, with switching frequencies generally controlled in the range of 50-100kHz. In recent years, the power capacity of switch-mode rectifiers has continuously expanded, with single-machine capacities increasing from 48V/12.5A, 48V/20A to 48V/200A, 48V/400A.
Due to the variety of integrated circuits used in communication equipment, their power supply voltages also vary. In communication power supply systems, high-power-density high-frequency DC-DC isolated power modules are used to convert the bus voltage (generally 48V DC) into various required DC voltages, which can greatly reduce losses, facilitate maintenance, and allow for easy installation and expansion. They can generally be directly mounted on standard control boards, and the requirements for secondary power supplies are high power density. As communication capacity continues to increase, communication power supply capacity will also continue to grow.
DC-DC converters convert a fixed DC voltage into a variable DC voltage. This technology is widely used in the smooth speed control of trolleybuses, subway trains, and electric vehicles, providing smooth acceleration, fast response performance, and energy-saving effects. Replacing variable resistors with DC choppers can save 20%-30% of electrical energy. DC choppers not only serve the purpose of voltage regulation (switch-mode power supply) but also effectively suppress harmonic current noise on the grid side.
The secondary power supply DC-DC converters for communication power supplies have been commercialized, with modules using high-frequency PWM technology, switching frequencies around 500kHz, and power densities of 5W-20W/in3. With the development of large-scale integrated circuits, there is a demand for power modules to achieve miniaturization, which requires continuously increasing switching frequencies and adopting new circuit topologies. Some companies have already developed secondary power modules using zero-current switching and zero-voltage switching technologies, resulting in significant improvements in power density.
An uninterruptible power supply (UPS) is a high-reliability, high-performance power supply that is essential for computers, communication systems, and situations requiring uninterrupted power. The AC mains input is rectified into DC, with part of the energy charging the battery pack and another part being converted back to AC via an inverter, which is then sent to the load through a transfer switch. To ensure energy supply to the load even in the event of inverter failure, an alternative backup power source is provided through the power transfer switch.
Modern UPS systems commonly use pulse width modulation technology and modern power electronic devices such as MOSFETs and IGBTs, which reduce noise while improving efficiency and reliability. The introduction of microprocessor hardware and software technology enables intelligent management of UPS systems, allowing for remote maintenance and diagnostics.
Currently, the maximum capacity of online UPS systems has reached 600kVA. The development of ultra-compact UPS systems is also rapid, with products available in various specifications such as 0.5kVA, 1kVA, 2kVA, and 3kVA.
Inverter power supplies are primarily used for variable speed control of AC motors, playing an increasingly important role in electrical drive systems and achieving significant energy-saving effects. The main circuit of inverter power supplies adopts an AC-DC-AC scheme. The mains frequency power is rectified into a fixed DC voltage, which is then inverted into a variable voltage and frequency AC output using a PWM high-frequency inverter composed of high-power transistors or IGBTs. The output waveform of the power supply approximates a sine wave, used to drive AC asynchronous motors for stepless speed regulation.
Internationally, series products of inverter power supplies below 400kVA have already been launched. In the early 1980s, Toshiba was the first to apply AC variable speed control technology to air conditioners. By 1997, its market share reached over 70% in Japanese household air conditioning. Inverter air conditioners offer comfort and energy-saving advantages. Domestic research on inverter air conditioners began in the early 1990s, with production lines introduced in 1996, gradually forming a hotspot for the development and production of inverter air conditioners. It is expected that around 2000, a climax will be reached. In addition to inverter power supplies, inverter air conditioners also require compressors suitable for variable speed control. Optimizing control strategies and selecting functional components is the further development direction for inverter power supply research for air conditioning.
The high-frequency inverter rectifier welding machine power supply is a new type of welding machine power supply characterized by high performance, high efficiency, and material savings, representing the current development direction of welding machine power supplies. With the commercialization of large-capacity IGBT modules, this power supply has a broad application prospect.
Inverter welding machine power supplies generally adopt the AC-DC-AC-DC conversion method. The 50Hz AC power is rectified into DC by a full-bridge rectifier, and the PWM high-frequency conversion section composed of IGBTs inverts the DC voltage into a high-frequency rectangular wave of 20kHz, which is then coupled through a high-frequency transformer, rectified, and filtered to become stable DC for arc power supply.
Due to the harsh working conditions of welding machine power supplies, which frequently alternate between short circuit, arc ignition, and open circuit, the reliability of high-frequency inverter rectifier welding machine power supplies becomes the most critical issue and the primary concern for users. By using microprocessors as controllers for pulse width modulation (PWM), various working states of the system can be predicted through the extraction and analysis of multiple parameters and information, allowing for timely adjustments and handling of the system, thus addressing the reliability issues of large-capacity IGBT inverter power supplies.
Foreign inverter welding machines have already achieved rated welding currents of 300A, a duty cycle of 60%, full-load voltages of 60-75V, and current adjustment ranges of 5-300A, with a weight of 29kg.
High-power switch-type high-voltage DC power supplies are widely used in electrostatic dust removal, water quality improvement, medical X-ray machines, CT machines, and other large equipment. The voltage can reach up to 50-159kV, with currents exceeding 0.5A and power reaching up to 100kW.
Since the 1970s, some companies in Japan have begun to adopt inverter technology to convert mains electricity into medium frequency around 3kHz after rectification, followed by voltage boosting. In the 1980s, high-frequency switch-mode power supply technology developed rapidly. Siemens in Germany used power transistors as the main switching elements, increasing the switching frequency of power supplies to over 20kHz. They successfully applied dry-type transformer technology to high-frequency high-voltage power supplies, eliminating the need for oil tanks in high-voltage transformers, further reducing the size of transformer systems.
Research on high-voltage DC power supplies for electrostatic dust removal has been conducted domestically, where mains electricity is rectified into DC, and a full-bridge zero-current switching series resonant inverter circuit is used to invert the DC voltage into high-frequency voltage, which is then boosted by a high-frequency transformer and finally rectified into high-voltage DC. Under resistive load conditions, the output DC voltage can reach 55kV, with currents reaching 15mA and a working frequency of 25.6kHz.
Traditional AC-DC converters inject a large amount of harmonic current into the grid during operation, causing harmonic losses and interference, and also leading to a deterioration in the power factor on the grid side, known as “power pollution.” For example, when uncontrolled rectification is combined with capacitive filtering, the grid-side third harmonic content can reach 70%-80%, with a grid-side power factor of only 0.5-0.6.
Power active filters are a new type of power electronic device that can dynamically suppress harmonics, overcoming the shortcomings of traditional LC filters, and are a promising means of harmonic suppression. The filter consists of a bridge-type switching power converter and a specific control circuit. The difference from traditional switch-mode power supplies is that: (1) it not only feeds back the output voltage but also feeds back the average input current; (2) the reference signal for the current loop is the product of the error signal of the voltage loop and the sampled full-wave rectified voltage signal.
Distributed power supply systems use small power modules and large-scale integrated circuit control as basic components, utilizing the latest theoretical and technological achievements to form modular, intelligent high-power supply systems, thus tightly integrating strong and weak electricity, reducing the development pressure of large power components and devices (centralized), and improving production efficiency.
In the early 1980s, research on distributed high-frequency switch power supply systems mainly focused on converter parallel technology. In the mid to late 1980s, with the rapid development of high-frequency power conversion technology, various converter topologies emerged one after another. Combining large-scale integrated circuits and power component technologies made the integration of medium and small power devices possible, rapidly promoting the research of distributed high-frequency switch power supply systems. Since the late 1980s, this direction has become a research hotspot in the international power electronics community, with the number of papers increasing year by year and the application fields continuously expanding.
The distributed power supply method has advantages such as energy saving, reliability, efficiency, economy, and ease of maintenance. It has gradually been adopted by large computers, communication equipment, aerospace, industrial control, and other systems, and is also the most ideal power supply method for low-voltage power supplies (3.3V) for ultra-high-speed integrated circuits. In high-power applications such as electroplating, electrolysis power supplies, electric locomotive traction power supplies, medium-frequency induction heating power supplies, and motor drive power supplies, there is also a broad application prospect.
Modern power electronics technology is the foundation for the development of switch-mode power supply technology. With the continuous emergence of new power electronic devices and circuit topologies suitable for higher switching frequencies, modern power supply technology will rapidly develop under the push of practical needs. Under traditional application technologies, the performance of switch-mode power supplies is affected due to the limitations of power device performance. To maximize the characteristics of various power devices and minimize the impact of device performance on switch-mode power supply performance, new power supply circuit topologies and control technologies can allow power switches to operate in zero-voltage or zero-current states, significantly improving working frequency and efficiency, and designing excellent performance switch-mode power supplies. Power electronics and switch-mode power supply technology are constantly advancing due to application demands, and the emergence of new technologies will lead to the renewal of many application products and open up more new application fields. The realization of high-frequency, modular, digital, and green switch-mode power supplies will mark the maturity of these technologies, achieving a combination of high-efficiency power consumption and high-quality power consumption. In recent years, with the development of the communication industry, the market demand for communication switch-mode power supplies centered on switch-mode power supply technology has reached over 2 billion RMB in China, attracting a large number of domestic and foreign scientific and technological personnel to develop and research it. The replacement of linear power supplies and phase-controlled power supplies with switch-mode power supplies is an inevitable trend, thus the domestic market for power operation power supply systems with a demand worth tens of billions is being activated and will soon develop. Many other specialized power supplies and industrial power supplies centered on switch-mode power supply technology are also waiting for development.
Challenges and Opportunities in Data Center Infrastructure Construction (Part 2)
Challenges and Opportunities in Data Center Infrastructure Construction (Part 1)
Introduction to High-Voltage Generator Sets
Common Faults and Mechanism Analysis of Lead-Acid Batteries (Part 2)
Common Faults and Mechanism Analysis of Lead-Acid Batteries (Part 1)
If you have valuable insights related to data center infrastructure, feel free to submit your articles.
If you have any questions, please feel free to ask, and experts will provide answers.Email: [email protected]
WeChat ID: UPS Application
English ID: upsapp
