Paper Keywords: electrical engineering technology; Electrical major; phylogeny
First, the development history of electrical engineering technology
Electrical engineering is one of the core disciplines in modern science and technology. Traditionally, electrical engineering has been defined as the sum of related disciplines used to create and produce electrical and electronic systems. The concept of electrotechnics in 2 1 century has gone far beyond this category, and now electrotechnics covers almost all engineering behaviors related to electrons and photons. The development degree of electrical engineering directly reflects the level of national scientific and technological progress. Therefore, the education and scientific research of electrical engineering has always played an important role in universities in developed countries.
1. Establishment of electromagnetic theory and development of communication technology
The thunder and lightning in nature made human beings have the earliest and simplest understanding of electricity, and natural magnets attracted iron as the earliest observation of magnetic phenomena. However, human research on electromagnetic phenomena began in Britain in the 6th century/kloc-0. In 1663, German scientist gleeck invented a triboelectrification instrument, and in 1729, British scientists discovered that charge can be conducted through metal, which was an early experiment of human electricity.
(1) Coulomb's law. 1785, the French physicist Coulomb concluded that the acting force between two charges is inversely proportional to the square of the distance between them and directly proportional to the product of the charges they carry, which is the famous Coulomb's law. The historical significance of this discovery lies in that it marks that electromagnetic phenomena's research has entered the quantitative stage from the qualitative stage.
(2)? Volt battery? . 1799, the Italian physicist Volt found through repeated experiments that putting any wet object between two different metals will produce current. A year later, Volt invented the world's first battery. Since then, the study of electricity has expanded from static electricity to dynamic electricity, opening up a new field of electrical research.
(3) Oster discovered the magnetic effect of current and Ampere's right hand rule. 1820, Oster happened to find that the small magnetic needle around the electrified platinum wire was slightly shaking, and then he confirmed this discovery through repeated experiments. Later, Ampere further studied and put forward the right-handed rule, and found the relationship between the current direction and the rotation direction of the magnetic needle. Ampere also discovered the law of interaction between two charged conductors and two charged coils through experiments, thus laying the foundation of electrodynamics.
(4) Faraday discovered electromagnetic induction. Faraday, a British scientist, was the first person to successfully complete the experiment of magnetic energy power generation. He summarized five situations of induced current: one is to change the current; The second is the changing magnetic field; The third is the steady flow of movement; The fourth is the moving magnetic field; The fifth is the wire moving in the magnetic field. Faraday called this phenomenon? Electromagnetic induction? . The discovery of electromagnetic induction made it possible to generate electricity. So far, generators, motors and transformers all work by using the principle of electromagnetic induction.
(5) Maxwell established the electromagnetic field theory. Maxwell, a British mathematician and physicist, summed up a series of previous achievements, expressed electromagnetic fields with mathematical equations, established a complete electromagnetic theoretical system, revealed the essential unity of light, electricity and magnetism, and predicted the existence of electromagnetic waves. 1873, he published the classic work of electromagnetic field theory, General Theory of Electromagnetism, which is a landmark masterpiece of natural science theory.
Any scientific invention and discovery is the result of unremitting efforts of many scientists. German physicists Ohm, Gauss, Hertz, American physicist Henry, Russian physicist Lengqi, etc. Both contribute to the formation of electromagnetic theory. This article is not listed in a category.
The establishment of electromagnetic theory laid the foundation for the development of radio communication. /kloc-in the 20th century, communication technology made a breakthrough, and wired telegraph, wired telephone and wireless communication were invented one after another.
2. The initial development of electrical technology
The development of human society has experienced three industrial revolutions, which have played a great role in human progress. The first industrial revolution, from the middle of18th century to the middle of19th century, was marked by the steam engine invented by Watt and characterized by mechanization, with its center in Britain. /kloc-from the second half of the 0/9th century to the middle of the 20th century, the second industrial revolution marked by the electrification of industrial production made achievements in electricity, steel and chemical industry. Three technologies? Communication by car, plane and radio? Three civilizations? , its center is in the United States and Germany; From the middle of the 20th century to the beginning of the 20th century, the third industrial revolution, characterized by the informationization of social production and life, was also called the new technological revolution. The second industrial revolution began with the start and application of electrical technology.
The birth of (1) DC generator. 183 1 year, British entrepreneurs developed the first steam-powered permanent magnet generator in history; 1832 French scientist Pixar invented the world's first DC engine; 1866, Siemens invented the self-excited DC generator; 1870, Gram invented a practical self-excited DC generator with reliable structure, stable current and high output power, which was widely used as lighting power supply in various countries.
(2) Long-distance transmission and preliminary establishment of technical system of power industry. 1875, the world's earliest coal-fired power plant was built in Paris, France. Edison not only invented the light bulb, but also established the first DC power plant in the United States in 1882, equipped with six DC generators, which transmitted lighting electricity through cables, but the maximum transmission distance at that time was only 1.6km. Edison also built a hydropower station, forming the embryonic form of the power industry system.
(3) The birth of alternator charging motor. From 1876 to 1878, Russian yabulo Chekhov successfully experimented with single-phase AC transmission technology. 1885, the first AC single-phase power station designed by British engineer Phil Anji was built. In the same year, the team led by Westinghouse completed the AC power generation and power supply system and created the AC distribution network. 1883, American electrical engineer Tesla invented the world's first induction motor, and five years later he invented two-phase asynchronous motor and AC drive system. 1888, Russian engineering teachers Burovski and Delvaux invented the three-phase communication system. 189 1 year, Germany installed the world's first three-phase alternator and built the first three-phase AC transmission line. Since then, three-phase asynchronous motors have been widely used, and electric energy has gradually replaced steam as the power source, and the power industry has developed rapidly.
3. Establishment of electrical theory
The establishment of (1) loop theory. The early researches on the circuit are as follows: 1778 volts put forward the concept of capacitance, and gave the calculation method of the stored charge Q=CU on the conductor; Ohm published Ohm's law in 1826; Faraday put forward the law of electromagnetic induction in 183 1 year; 1832, Henry proposed a formula for calculating magnetic flux.
1845, the German physicist Kirchhoff put forward the basic law about the relationship between current and voltage in any circuit: the current law (the algebraic sum of currents in each branch at any node at any time in the circuit is zero); The law of voltage (the algebraic sum of the voltages of each element at any time in any closed circuit is zero). These two laws develop Ohm's law and lay a foundation for the analysis of circuit system.
1853, the British physicist Thomson deduced the circuit oscillation equation, and reached the conclusion that the current oscillates repeatedly and decays continuously during the power generation process of Leiden bottle, and calculated the relationship between the oscillation frequency and the parameters of R, L and C, which laid the foundation for the dynamic circuit analysis. In 1855, Thomson also established the equivalent circuit model of long-distance cable.
1893, steinmetz, an American electrician, proposed a method for calculating AC circuits? Phasor method? In fact, it is very practical and easy to understand, and it is still used in the analysis of sinusoidal AC circuits.
In the meantime, the principle of Helmholtz equivalent generator, the circuit model of Kirchhoff releasing the parameters of long-distance overhead lines, the calculation method of Heweside to solve the transient process of circuits, and the law of heat conduction established by Fourier's mathematical method have all played an important role in enriching and perfecting the electrician theory.
(2) Establishment of electric network theory. The rise of communication technology promotes the development of electric network theory. In 1924, Foster gave the reactance theorem of two-terminal network of inductance and capacitance, and established the theory of electric network for designing circuits with given frequency characteristics.
1945, American scientist Byrd summed up the frequency domain analysis method for analyzing linear circuits and control systems. In 1953, Mei Sen established the method of analyzing complex feedback system with signal flow graph, which has been widely used. In 1950s, American scientist Dammer made the first batch of integrated circuits, from which circuit analysis and synthesis with source devices were added. In 1970s, with the efforts of scientists such as L.O.Chua, the theory of device modeling gradually improved. The appearance of computers in the mid-20th century made computer-aided analysis and design of electrical networks a basic means of circuit theory research.