This article is mainly about the introduction of pulse power technology, and focuses on the concept and application of pulse power technology.
Pulse power technologyPulsed power technology is an electro-physical technology that quickly compresses, converts, or directly releases energy that is stored slowly and has a higher density to the load. It is widely used in many fields such as national defense scientific research, high-tech research and civil industry.
Overview of pulse power system development
1. The composition of pulse power device.
Pulsed power technology is an electro-physical technology that quickly compresses, converts, or directly releases energy that is stored slowly with a higher density to the load. Its essence is to compress the pulse energy on the time scale to obtain high peak power output in a very short time. This technology is an emerging science and technology developed to meet the needs of national defense scientific research. It is an important means to obtain high-current relative electron beams or ion beams. It is widely used in defense scientific research, high-tech research, civil industry and many other fields. in.
The primary energy sources commonly used at this stage mainly include: capacitors or Marx generators that store energy in the form of electric fields, inductors or pulse transformers with magnetic energy, various mechanical energy generators with a certain moment of inertia, chemical energy devices, and nuclear energy devices. Commonly used intermediate energy storage systems and pulse shaping systems include: pulse transformers, capacitive transmission lines (forming lines), inductive energy storage, magnetic flux compressors (magnetic amplifiers), channel power generation systems of magnetic fluid generators, and those that use mechanical energy Induction power generation system, etc. The conversion system includes various conversion switches in the power supply, including two types of close switches and disconnect switches. Various switches can be distributed in different positions of the pulse power supply according to their different application methods. The high-power pulse power supply first stores energy in the primary energy source, then charges through the intermediate energy storage and pulse forming system, and finally discharges to the load quickly after compression, pulse forming or conversion processes.
2. The development history and research status of power pulse technology at home and abroad.
In the 1930s, people began to try to use capacitor discharge to generate X-rays. This is the origin of power pulse technology. Since the successful development of the world’s first strong current electron beam accelerator SMOG (3MV, 50kA, 30ns) in 1964, major laboratories in the United States, Japan, the Soviet Union and many advanced countries in Europe have successively built numerous high-power pulse devices. .
The pulse power device PBFA-II (12MV, 8.4MA, 40ns) developed by Sandia Lab in 1986 is the first pulse power device in the world to pass the 100TW mark. my country’s high-pulse power technology started relatively late. In the 1970s, the research team led by Professor Wang Ganchang officially started the research on high-power pulsed electron beam generators. In 1979, the Beijing Institute of High Energy Physics built my country's largest high-current pulsed electron beam accelerator flash-I, which was used as a γ-ray simulation source. After the completion of a series of high-current pulsed electron beam accelerators, my country has created better conditions for research in high-tech fields such as collective ion acceleration, excimer lasers, electromagnetic railguns, flash X-ray photography, and high-power microwaves.
Application of Pulsed Power Technology in the Field of Environmental Engineering
1. Electrostatic dust removal.
The traditional DC high voltage electrostatic dust removal method is severely limited by the specific resistance of the dust in practical applications, especially the high specific resistance dust has a low conductivity and is easy to accumulate on the dust collecting electrode. When it accumulates to a certain extent, a large amount of charge is difficult Achieve orderly release, leading to the appearance of anti-corona, which seriously affects the dust collection rate. At the same time, dust particles with a smaller specific resistance have higher electrical conductivity, which can easily release negative charges to the dust collector and carry positive charges. Under the action of the electric field force of the motor, the dust particles are pushed into the air flow again. This situation shows that the electrostatic precipitator is difficult to effectively remove dust particles with a small specific resistance. The pulse power technology can promote the effective solution of the above problems. The high-voltage pulse generates a certain corona current, which directly penetrates between the electrodes and gradually extends to the dust layer. After the high specific resistance dust layer breaks down, the accumulated charge on the layer is released. Thereby effectively improving the dust removal efficiency. At the same time, pulse corona can generate a certain number of high-energy electrons. These electrons are large in number and evenly distributed, which can produce more active particles. While electrostatically adsorbing dust ions, plasma eliminates the entrained dust in the dust. Organic matter analysis and sulfur dioxide, etc., so as to promote the effective realization of desulfurization and denitrification. Compared with the traditional DC high voltage electrostatic dust removal method, the pulse electrostatic dust removal method saves energy and improves the dust removal efficiency.
2. Ozone production.
Ozone is a strong oxidizing gas, which plays an important role in sterilization, oxidation, and bleaching. Ozone is colorless, odorless, and non-corrosive. It uses air as the main raw material for preparation. Under the action of mutation power plants, there is a small amount of gas molecules. Carriers obtain energy from the external electric field, and through collision and ionization with gas molecules, the decomposition of oxygen molecules and the instantaneous combination of oxygen atoms are realized to form ozone. Pulsed power technology plays an important role in ozone production and helps to improve ozone production efficiency. In the power supply for the ozone reactor to provide the bipolar narrow pulse spark gap high voltage switch, through the effective use of the mutually perpendicular rotating ball gaps, the realization of positive and negative DC high voltage chopping is promoted. After the pulse capacitor is charged, the Another pair of mutually perpendicular rotating spherical gaps supplies power to the reactor. After proper adjustment of the pulse capacitor and reactor matching situation, the front and width of the voltage pulse are realized, and the pulse frequency is adjusted at the speed of the rotating ball gap to promote the successful production of ozone.
3. Wastewater treatment.
Due to the narrow pulse characteristics of the output voltage waveform, under the action of the high-voltage pulse power supply, the molecular structure of the object to be processed between the unbalanced electrodes in the liquid phase will change to a certain extent, prompting the lighter electrons to gradually become high-energy free electrons and move After colliding with other molecules in the process, the water phase is formed by a chemical reaction. Under the action of the active substance, the organic matter in the water is explained, so as to realize the effective treatment of wastewater.
About the development trend of pulse power technology
1. From a single pulse to a repetitive high-average power pulse.
In the past, pulsed power technology was mainly used for national defense scientific research services, and most of them were operated in a single operation. However, the pulsed power technology for industrial and civilian use requires a certain average power and must be operated at a repetitive frequency.
2. Energy storage technology-develop a power source with high energy storage density.
In many applications, the size and weight of the pulse power system are decisive factors. For example, aircraft detection underwater object technology, shipborne electromagnetic guns, etc., require a large pulse power, and the system should not be too large and heavy. .
3. Switching technology---discuss new high-power switches and develop high-repetition frequency switches.
The parameters of the switching element directly affect the performance of the entire pulse power system, which is an important key technology in the pulse power technology. The development of various types of switching elements that can withstand high voltage and strong current, short breakdown time delay, small dispersion, small inductance and resistance, less electrode burnout, and stable operation under repeated pulses, is the current pulse power technology at home and abroad Another highly valued research topic in China.
4. Actively develop new application areas.
In recent years, the application of pulsed power technology in semiconductors, integrated circuits, chemical engineering, environmental engineering, medical and other fields has attracted wide attention from all walks of life, and gratifying progress has been made in some application research. With the experience of successful application, pulsed power technology will be more applied to civilian technology. Civilian use is a huge market, and the promotion of the market will bring new vitality to the development of pulsed power technology. Pulsed power technology is an important content in modern power electronics technology. As an important method in non-equilibrium plasma, it has gradually been widely used in the field of environmental engineering in recent years. In the process of dealing with environmental pollution, it has high efficiency, The advantages of energy saving, cleanliness and convenience have broad application prospects.
Architecture of Pulsed Power TechnologyThe essence of pulsed power is to compress pulse energy on the time scale to obtain high peak power output in a very short time (20~100ns).
Pulsed power systems generally use initial energy storage technologies (capacitor energy storage, inductor energy storage, superconducting energy storage, mechanical energy storage, chemical energy storage, nuclear energy, etc.) to generate the required primary pulse waveforms (on the order of milliseconds to microseconds) , And then use pulse shaping and switching technology to compress and reshape the energy pulse on the time scale to achieve the amplification of the peak power of the output pulse and output it to the load to provide high-tech devices and new concept weapons with strong electrical pulse power source. The following article mainly introduces the related content of the main energy storage system and pulse compression forming system based on the development of current pulse power technology.
Figure 1: Topological diagram of pulsed power system
1. Energy storage or pulse generation system
At present, the energy storage methods of pulse power technology include: capacitive energy storage, inductive energy storage, chemical energy storage, mechanical energy storage, etc.
01Capacitor energy storage system
Capacitive energy storage is the earliest energy storage method that has been studied, and it is also the most widely used energy storage method currently. Its technology is mature and can be used in millisecond, microsecond, and nanosecond pulse power devices. As an energy storage device, it has the characteristics of large capacity, extremely small internal inductance, and high withstand voltage. The energy storage can reach thousands of joules to several megajoules. The disadvantage is that the energy storage density is low, and it is not economical to use on devices above 107J.
02Inductive energy storage type power supply system
Compared with capacitive energy storage, inductive energy storage has high energy storage density, small size, light weight, and lower cost. Therefore, the application of inductive energy storage has the potential to obtain higher energy utilization and pulse power, and the insulation of inductive energy storage systems The problem is relatively easy to solve. At present, it is widely used in the research fields of plasma physics, strong laser, electromagnetic radiation and so on.
03Chemical Energy Storage Power System
Chemical energy storage is actually the use of chemical reactions that occur when energy storage materials are in contact, and energy is stored through the conversion of thermal energy and chemical energy. It has a high energy storage density (for example, the energy storage density of TNT explosive is 5.25*10^3J/cm³). And they can be released and converted into electric pulses quickly, so modern pulse power technology often uses chemical energy pulse generators. In addition to high energy storage density electrochemical power sources (such as batteries), there are also various forms commonly used. Magnetic flux compression generators (generators), pulse magnetic fluid generators and magnetic fluid capacitors.
04 Mechanical energy storage power system
The most common mechanical energy storage devices are pulse generators and stand-alone generators, and most of them use a turbine or electric motor to drive a large mass flywheel to a high speed, so that the flywheel inertially stores kinetic energy, and then suddenly transfers to pulse On the rotor shaft of the generator, it generates electrical pulse output, and the flywheel is decelerated or stopped due to the discharge of energy.
2. Pulse compression or forming system
The pulse shaping system uses energy or time compression methods to shape and narrow the power pulse output by the energy storage or generation system to meet the required pulse power value, pulse shape and pulse width. There are mainly the following types:
01Pulse power transformer
The pulse power transformer is different from the general pulse transformer. It has a large pulse power capacity. It is mainly used to change the voltage and current amplitude, as well as to compress and change the pulse shape. There are mainly four types: â‘ Double resonance pulse transformer; â‘¡Cable winding pulse Transformers (air-core and iron-core); â‘¢Nanosecond pulse converter; â‘£Special pulse transformers, including Martin type, HPG feed type, auto-coupling three-section type, non-uniform transmission line type, cascade type pulse transformer.
02High-power short-circuit switch
The high-power short-circuit switch can isolate or close the pulse power device, convert energy, shorten the pulse front and compress the pulse, thereby changing the pulse shape. There are many types of high-power short-circuit switches, mainly: ①gas discharge switches triggered by electrodes (including three-electrode discharger and four-electrode short-circuit switches); ② laser-triggered short-circuit switches; ③ trigger vacuum switches (including planar electrode type, coaxial Electrode type, rod electrode type, cylindrical anode type and metal plasma arc switch); ④ solid switch (including controllable solid switch, semiconductor power device and photoelectric conduction pulse power switch); ⑤ surface discharge switch; ⑥ self-strike Through switch (including two-electrode self-breakdown switch and multi-switch rectifier); ⑦High-power gas and liquid field distortion switch; ⑧Continuous-repetitive pulse switch; ⑨Magnetic switch.
High-power circuit breakers are often used in inductive energy storage pulse power devices. Their functions are to cut off the circuit, increase the voltage and time compression pulses. They mainly include: ①Electric explosive conductor circuit breaker (wire or foil); ②Plasma ablation circuit breaker (Melt erosion model and snow plow model); ③Mechanical interrupter (including vacuum interrupter, corrugated interrupter and controlled solid circuit breaker); ④Metal plasma arc switch; ⑤Cross field tube; ⑥Plasma Body gun or DPF switch; ⑦ thermally driven disconnect switch; ⑧ superconducting disconnect switch; ⑨ non-linear resistance solid switch; ⑩ reflection switch; electron beam control switch (including closing function); explosive explosion disconnect switch (one-way fragmentation and Non-inductive).
ConclusionThis is the end of the related introduction about pulse power technology. If you have any deficiencies, please correct me.
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