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Power Electronics
Power electronics is the application of electronics to the control and conversion of electric power. The first high-power electronic devices were made using mercury-arc valves. In modern systems, the conversion is performed with semiconductor switching devices such as diodes, thyristors, and power transistors such as the power MOSFET and IGBT. In contrast to electronic systems concerned with the transmission and processing of signals and data, substantial amounts of electrical energy are processed in power electronics. An AC/DC converter (rectifier) is the most typical power electronics device found in many consumer electronic devices, e.g. television sets, personal computers, battery chargers, etc. The power range is typically from tens of watts to several hundred watts. In industry, a common application is the Adjustable-speed drive, variable speed drive (VSD) that is used to control an induction motor. The power range of VSDs starts from a few hundred watts and ends at ten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltic Cable Thyristorturm
Baltic may refer to: Peoples and languages *Baltic languages, a subfamily of Indo-European languages, including Lithuanian, Latvian and extinct Old Prussian *Balts (or Baltic peoples), ethnic groups speaking the Baltic languages and/or originating from the Baltic countries *Baltic Germans, historical ethnic German minority in Latvia and Estonia *Baltic Finnic peoples, the Finnic peoples historically inhabiting the area on the northeastern side of the Baltic sea Places Northern Europe * Baltic Sea, in Europe * Baltic region, an ambiguous term referring to the general area surrounding the Baltic Sea * Baltic states (also Baltic countries, Baltic nations, Baltics), a geopolitical term, currently referring to Estonia, Latvia and Lithuania * Baltic Provinces or governorates, former parts of the Swedish Empire and then Russian Empire (in modern Latvia, Estonia) * Baltic Shield, the exposed Precambrian northwest segment of the East European Craton * Baltic Plate, an ancient tectonic pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adjustable-speed Drive
A motor drive is a physical system that includes a motor. An adjustable speed motor drive is a system that includes a motor that has multiple operating speeds. A variable speed motor drive is a system that includes a motor that is continuously variable in speed. If the motor is generating electrical energy rather than using it, the motor drive could be called a generator drive but is often still referred to as a motor drive. A variable frequency drive (VFD) or variable speed drive (VSD) describes the electronic portion of the system that controls the speed of the motor. More generally, the term ''drive'', describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control. Where speeds may be selected from several diff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter H
Walter may refer to: People and fictional characters * Walter (name), including a list of people and fictional and mythical characters with the given name or surname * Little Walter, American blues harmonica player Marion Walter Jacobs (1930–1968) * Gunther (wrestler), Austrian professional wrestler and trainer Walter Hahn (born 1987), who previously wrestled as "Walter" * Walter, standard author abbreviation for Thomas Walter (botanist) ( – 1789) * "Agent Walter", an early codename of Josip Broz Tito * Walter, pseudonym of the anonymous writer of '' My Secret Life'' * Walter Plinge, British theatre pseudonym used when the original actor's name is unknown or not wished to be included * John Walter (businessman), Canadian business entrepreneur Companies * American Chocolate, later called Walter, an American automobile manufactured from 1902 to 1906 * Walter Energy, a metallurgical coal producer for the global steel industry * Walter Aircraft Engines, Czech manufacturer of aero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point-contact Transistor
The point-contact transistor was the first type of transistor to be successfully demonstrated. It was developed by research scientists John Bardeen and Walter Brattain at Bell Laboratories in December 1947. They worked in a group led by physicist William Shockley. The group had been working together on experiments and theories of electric field effects in solid state materials, with the aim of replacing vacuum tubes with a smaller device that consumed less power. The critical experiment, carried out on December 16, 1947, consisted of a block of germanium, a semiconductor, with two very closely spaced gold contacts held against it by a spring. Brattain attached a small strip of gold foil over the point of a plastic triangle—a configuration which is essentially a point-contact diode. He then carefully sliced through the gold at the tip of the triangle. This produced two electrically isolated gold contacts very close to each other. The piece of germanium used a surface laye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field-effect Transistor
The field-effect transistor (FET) is a type of transistor that uses an electric field to control the current through a semiconductor. It comes in two types: junction FET (JFET) and metal-oxide-semiconductor FET (MOSFET). FETs have three terminals: ''source'', ''gate'', and ''drain''. FETs control the current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source. FETs are also known as unipolar transistors since they involve single-carrier-type operation. That is, FETs use either electrons (n-channel) or holes (p-channel) as charge carriers in their operation, but not both. Many different types of field effect transistors exist. Field effect transistors generally display very high input impedance at low frequencies. The most widely used field-effect transistor is the MOSFET (metal–oxide–semiconductor field-effect transistor). History The concept of a field-effect transistor (FET) was first patented by the Austr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julius Edgar Lilienfeld
Julius Edgar Lilienfeld (April 18, 1882 – August 28, 1963) was an American electrical engineer and physicist who has been credited with the first patent on the field-effect transistor in 1925. He was never able to build a working practical semiconductor device based on his concept. Additionally, because he didn't publish articles in learned journals and since high-purity semiconductor materials were not available to him, his FET patent never achieved fame, causing confusion for later inventors. Early life Lilienfeld was born to a Jewish family in Lemberg (present-day Lviv) in the Austrian part of the Austro-Hungarian Empire. Lilienfeld's father was the lawyer Sigmund Lilienfeld, his mother Sarah Jampoler Lilienfeld. Education After graduating high school in 1899, between 1900 and 1904, Lilienfeld studied at the Friedrich-Wilhelms-Universität (renamed Humboldt University in 1949), in Berlin, where he received his Ph.D. on February 18, 1905. In 1905, he started work at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Voltage Direct Current
A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages between 100 kV and 800 kV. HVDC lines are commonly used for long-distance power transmission, since they require fewer conductors and incur less power loss than equivalent AC lines. HVDC also allows power transmission between AC transmission systems that are not synchronized. Since the power flow through an HVDC link can be controlled independently of the phase angle between source and load, it can stabilize a network against disturbances due to rapid changes in power. HVDC also allows the transfer of power between grid systems running at different frequencies, such as 50 and 60 Hz. This improves the stability and economy of each grid, by allowing the exchange of power between previously incompatible networks. The modern form o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uno Lamm
August Uno Lamm (May 22, 1904 – June 1, 1989) was a Swedish electrical engineer and inventor. He was sometimes called "The Father of High Voltage Direct Current" power transmission. During his career, Lamm obtained 150 patents. In 1980 the Institute of Electrical and Electronics Engineers (IEEE) developed the Uno Lamm High Voltage Direct Current Award for contributions to the field of high voltage electrical engineering. Biography Lamm was born in Gothenburg, Sweden to Fredrik Hjalmar Lamm and Aino Maria Lovisa Wilhelmina Wijkander. He obtained his master's degree at KTH Royal Institute of Technology in Stockholm in 1927. After a short time in compulsory military service he joined ASEA, the Swedish electrical conglomerate, initially working in their training program. In 1929 he was made manager of the project to develop a high-voltage mercury arc valve. Valves at the time operated only up to about 2500 volts, and if higher-voltage valves were available they could hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyratron
A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, producing a phenomenon known as a Townsend discharge. Gases used include mercury vapor, xenon, neon, and (in special high-voltage applications or applications requiring very short switching times) hydrogen. Unlike a vacuum tube (valve), a thyratron cannot be used to amplify signals linearly. In the 1920s, thyratrons were derived from early vacuum tubes such as the UV-200, which contained a small amount of argon gas to increase its sensitivity as a radio signal detector, and the German LRS relay tube, which also contained argon gas. Gas rectifiers, which predated vacuum tubes, such as the argon-filled General Electric " Tungar bulb" and the Cooper-Hewitt mercury-pool rectifier, also provided an influence. Irving Langmuir and G. S. Meikle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Cooper Hewitt
Peter Cooper Hewitt (May 5, 1861 – August 25, 1921) was an American electrical engineer and inventor, who invented the first mercury-vapor lamp in 1901. Hewitt was issued on September 17, 1901. In 1903, Hewitt created an improved version that possessed higher color qualities which eventually found widespread industrial use. Early life Hewitt was born in New York City, the son of New York City Mayor Abram Hewitt and the grandson of Business magnate, industrialist Peter Cooper. He was educated at the Stevens Institute of Technology and the Columbia School of Engineering and Applied Science, Columbia University School of Mines. Career In 1901, Hewitt invented and patented a mercury-vapor lamp that was the forerunner of the fluorescent lamp. A gas-discharge lamp, Hewitt's invention used Mercury (element), mercury vapor produced by passing current through liquid mercury. His first lamps had to be started by tilting the tube to make contact between the two electrodes and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AC/AC Converter
A solid-state AC-to-AC converter converts an AC waveform to another AC waveform, where the output voltage and frequency can be set arbitrarily. Categories Referring to Fig 1, AC-AC converters can be categorized as follows: * Indirect AC-AC (or AC/DC-AC) converters (i.e., with rectifier, DC link and inverter), such as those used in variable frequency drives * Cycloconverters * Hybrid matrix converters * Matrix converters (MC) * AC voltage controllers DC link converters There are two types of converters with DC link: * Voltage-source inverter (VSI) converters (Fig. 2): In VSI converters, the rectifier consists of a diode-bridge and the DC link consists of a shunt capacitor. * Current-source inverter (CSI) converters (Fig. 3): In CSI converters, the rectifier consists of a phase-controlled switching device bridge and the DC link consists of 1 or 2 series inductors between one or both legs of the connection between rectifier and inverter. Any dynamic braking operation required ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DC-to-DC Converter
A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of Electric power conversion, electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission). History Before the development of power semiconductors, one way to convert the voltage of a DC supply to a higher voltage, for low-power applications, was to convert it to AC by using a vibrator (electronic), vibrator, then by a step-up transformer, and finally a rectifier. Where higher power was needed, a motor–generator unit was often used, in which an electric motor drove a generator that produced the desired voltage. (The motor and generator could be separate devices, or they could be combined into a single "dynamotor" unit with no external power shaft.) These relatively inefficient and expensive designs were used only when there was no alternative, as to po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
