Application of Power Electronic Technology

Application of Power Electronic Technology

Power electronic technology is a modern industrial electronic technology whose main object is power processing and conversion. Modern industry, agriculture and other fields are inseparable from electric energy, and it is inseparable from the control and conversion of basic parameters such as voltage, current, frequency, waveform and phase that characterize electric energy. And power electronic technology can carry out precise control and efficient processing of these parameters, so power electronic technology is an important foundation for realizing the modernization of electrical engineering.

Application of Power Electronic Technology
Figure 1 – Application examples of power electronics technology

1. General industrial motor speed regulation

Various AC and DC motors are widely used in industry. Among them, the DC motor has good speed regulation performance, and the controllable rectifier power supply or the DC chopper power supply for its power supply are all power electronic devices. In recent years, due to the rapid development of power electronic frequency conversion technology, the speed regulation performance of AC motors can be comparable to DC motors. Therefore, AC speed regulation technology has been widely used and is gradually occupying a dominant position. As the main control method used in energy-saving control, the frequency conversion speed control of AC motors has brought huge energy-saving benefits. In all walks of life, fans and pumps are mostly driven by asynchronous motors, and their electricity consumption accounts for more than 50% of China’s industrial electricity consumption and 30% of the country’s electricity consumption. In the past, the air volume or water flow was controlled by controlling the air door or throttle valve, while the motor speed remained unchanged. As the angle of the air door or throttle valve was reduced, the resistance of the fluid was increased, so the power consumption changed very little. As a result, electrical energy is wasted when the air volume is small or the water flow is small. After China’s fans and water pumps adopt variable frequency speed regulation, it can save tens of billions of kilowatt-hours of electricity each year. Air conditioners in household appliances can save more than 30% of electricity after adopting frequency conversion speed regulation technology.

2. Transportation

Power electronic technology is widely used in electrified railways, DC locomotives in electric locomotives are powered by rectifier devices, and AC locomotives are powered by frequency conversion devices. For example, DC choppers are widely used in railway vehicles, and power electronics in maglev trains is a key technology. New environmentally friendly green electric vehicles and hybrid electric vehicles (EV/HEV) are actively developing. A car is a mechanical device developed by running on a gasoline engine. It emits a large amount of carbon dioxide and other exhaust gas, which seriously pollutes the environment. The motors of green electric vehicles use batteries as energy sources and rely on power electronic devices for power conversion and drive control. The charging of their batteries is also inseparable from power electronic technology. Obviously, electric vehicles will replace fuel vehicles in the future. Airplanes and ships require a variety of power supplies with different functional requirements, so aviation and navigation are inseparable from power electronic technology.

3. Power System

It is estimated that in developed countries, more than 60% of the electrical energy used by users has been processed by power electronic converters at least once. DC transmission has great advantages in long-distance and large-capacity transmission. The rectification at the transmission end and the inversion at the reception end use thyristor converter devices, while light-duty DC transmission mainly uses fully-controlled IGBT devices. The flexible alternating current transmission (FACTS) developed in recent years is also realized by relying on power electronic devices. Thyristor controlled reactor (TCR), static reactive power generator (SVG), active power filter (APF) and other power electronic devices are widely used for reactive power compensation or harmonic suppression of power systems. In the distribution network system, power electronic devices can also be used to prevent voltage drops and flicker during an instantaneous power failure of the power grid, so as to control power quality and improve the quality of power supply. In substations, power electronic devices are required to provide reliable AC and DC operating power to the operating system and to charge storage batteries.

4. Power supply for electronic devices

Various electronic devices generally need to be powered by DC power supplies of different voltage levels. The DC power supply used by the program-controlled switchboard in the communication equipment used to use thyristor to rectify the power supply, but now it has been changed to a high-frequency switching power supply with a fully-controlled device. The working power supply required by large computers and the power supply inside microcomputers now also use high-frequency switching power supplies. In applications such as large computers, uninterruptible power supply (UPS) is often required for power supply. Uninterruptible power supply is actually a typical power electronic device.

5. Household appliances

Power electronic lighting power supply is small in size, high in luminous efficiency, and can save a lot of energy. It is gradually replacing traditional incandescent lamps and fluorescent lamps. Electrical appliances such as air conditioners, televisions, audio equipment, home computers, washing machines, refrigerators, and microwave ovens also apply power electronic technology.

6. Other

Various electronic instruments in aerospace vehicles require power sources, and manned spacecraft cannot do without various power sources. All of these must use power electronic technology.

The large electric motors of pumped energy storage power stations need power electronic technology to start and adjust speed. Superconducting energy storage is a way of energy storage in the future. It needs a powerful DC power supply, which is also inseparable from power electronics technology.

New energy and renewable energy power generation, such as wind power generation and solar power generation, require power electronic technology to buffer energy and improve power quality. When it is necessary to connect to the power system, it is even more inseparable from power electronic technology.

When a nuclear fusion reactor generates a strong magnetic field and injects energy, it needs a large-capacity pulsed power source, which is a power electronic device. In scientific experiments or some special occasions, some special power sources are often needed, which is also the application of power electronic technology.

In short, power electronics technology is a relatively fast-developing subject, one of the main basic technologies for the development of high-tech industries, and an important means for the transformation of traditional industries. It can be predicted that with the development of new theories and technologies in various disciplines, the application of power electronics technology has a very broad prospect.