1866, Siemens of Germany invented the self-excited DC generator.
1869, Belgium made a ring armature and invented a ring armature generator. This kind of generator uses water power to turn the rotor of the generator. After repeated improvement, 3. 2KW output power.
1882, Gordon of the United States made a two-phase giant generator with an output of 447KW, a height of 3 meters and a weight of 22 tons. Tesla of the United States was determined to develop AC motors when he was in Edison Company, but Edison insisted on DC mode only, so he sold the patent rights of two-phase AC generators and motors to Westinghouse Company.
1896, Tesla's two-phase alternator began to operate in Nyala Power Plant, and 3750KW and 5000V alternating current was sent to Buffalo, 40 kilometers away.
1889, Westinghouse built a power plant in Oregon, 1892, and it successfully sent the voltage of 15000 volts to Pittsfield.
In A.D. 183 1 year, Faraday passed a wire in a closed circuit through an electromagnetic field, and when the wire rotates, current flows through the wire. Faraday therefore realized that there is a close relationship between electricity and magnetic field, and he built the first prototype generator, including a copper disk rotating in the magnetic field, thus generating electricity. Before that, all the electricity was generated by electrostatic machines and batteries, and they could not generate much power. However, Faraday's generator finally changed everything.
The generator includes an electromagnet that can rotate rapidly between two or more magnetic fields. When two magnetic fields cross each other, electricity is generated and led out of the generator by wires. Electronic engineers get alternating current (AC) or direct current (DC) according to the winding mode of the generator and the arrangement of magnets. Most generators generate alternating current, which is easier to transmit over long distances through transmission lines than direct current.
Anyone who has studied physics will remember that Faraday, a British scientist, discovered the principle of electromagnetic induction in 183 1 year. This principle, which plays an important role in the development of human society, says: "When the magnetic field lines change, current will be induced in the wires around them."
Faraday painstakingly, through research and repeated experiments, finally discovered this influential scientific principle, and he was convinced that a generator that could really generate electricity could be made by using this principle.
In the second year after Faraday discovered the principle of electromagnetic induction, inspired by Faraday's discovery, the Frenchman Pisci made the first generator by applying the principle of electromagnetic induction.
Pixie's generator is close to the rotatable U-shaped magnet (driven by handwheel and gear), and two iron cores are wound on the wire coil, which are aligned with the N pole and S pole of the magnet respectively, and the wires of the coil are led out. In this way, when the handwheel is shaken to rotate the magnet, the magnetic field lines change, and as a result, current is generated in the coil conductor.
In the generator device, every time the magnet rotates for half a turn, the magnetic pole of the magnet corresponding to the coil changes once, so the direction of current also changes once. In order to change this situation and keep the current direction unchanged, Pixie came up with an ingenious method: two pieces of metal separated from each other are added to the rotating shaft of the magnet, and the two ends leading out of the coil are contacted with the two pieces of metal through spring pieces respectively. In addition, two wires are in contact with two metal sheets to draw current. This device, called commutator, was still used in later generators.
Why can the rectifier keep the current direction unchanged? This is because the current flows from the coil into the commutator, and the commutator rotates with the magnet. When the magnet turns half a turn, the direction of the current in the coil is reversed, and the commutator just turns half a turn and turns again, so the direction of the output current is always the same.
The generator invented by Pixie is the first in the world, but it also has some shortcomings. Need improvement. First of all, rotating magnets is not as convenient and flexible as rotating coils. Secondly, the directional current can be obtained through the rectifier, but the current intensity is still changing. In order to change this situation, people adopt the method of increasing the number of some magnets and coils, and leading out the changed current slightly staggered, so as to control the intensity change of the output current within a certain range.
In the more than 30 years since Pixie invented the generator, although some improvements have been made and some new inventions have appeared, the results are not great, and a generator that can output as much current as a battery and can be used in practice has never been developed.
1867, the German inventor Werner von Siemens made a major improvement on the generator. He believes that using electromagnets instead of magnets (that is, permanent magnets) can enhance the magnetic force and generate powerful current.
The principle that Siemens uses electromagnets instead of permanent magnets to generate electricity is that the iron core of electromagnets still has weak magnetism in the absence of current. When the coil rotates, the weak remanence is used to generate current, which is then fed back to the electromagnet to enhance its magnetic force, so that the electromagnet can also generate strong magnetism. Then, Siemens began to study electromagnetic generators. This new type of generator was soon made, which can generate a powerful current far exceeding that of Pique generator. At the same time, this kind of generator is much more convenient than connecting many batteries to power on, so it is widely used as a practical generator.
Shortly after Siemens' new generator came out, Italian physicist Pachinuti invented the ring generator armature in 1865. This armature replaces the coil wound on the iron core bar with the coil wound on the iron ring, which improves the efficiency of the generator.
In fact, Pasnuti put forward the idea of generator armature as early as 1860, but it failed to attract people's attention. 1865 he published this original view in a magazine, which has not been recognized by the society so far.
1869, when Belgian scholar Guram was studying electricity in Paris, he saw an article published by Pachinuti and thought that this invention had its advantages. So he developed a generator with excellent performance at 1870 according to Pachinuti's design scheme and the principle of electromagnetic generator adopted by Siemens.
In Pachinuti's invention, the commutator part of the generator was improved significantly, so that the current intensity generated by the generator changed little. However, the current intensity of Guram generator manufactured by Pachinutian design scheme has little change. This is one of the excellent performances of Guram generator.
Guram's generators have good performance, so they are widely sold. Not only did he make a fortune, but he was also known as the "father of generators".
Some people saw the success of Guram's invention of the generator, and also wanted to improve the generator and make a more advanced generator. Among these people, there is an engineer Artney who studies generators in Siemens. He invented different winding modes of Guram generator and made a generator with good performance.
The armature of Guram generator is made of iron wire wound in circles, and the circles are insulated by paper. Then, the circles are tied together as iron cores, and coils are wound on them, and then some wires in different parts of the coils are led to the commutator. The armature of Artney generator is made of many thin circular iron sheets which are insulated with paper and then stacked to make an iron core, and then a coil is wound on it. People call this method "drum", which means drum-like shape. After this improvement, the appearance and performance of the generator are much better than before.
Because of this invention, Siemens has become more and more famous. As a result, Germany, with Siemens as the core, vigorously developed various generators, thus making the power industry develop rapidly.
With the gradual enlargement of the generator, the power of the rotating generator has also changed. Among them, water power is more interesting. This is because it is more convenient to rotate large generators by hydraulic power, without consuming fuel and with low cost. Therefore, Siemens invested in the research of hydropower generation.
Hydropower is different from hydropower. In the former, the generator must be installed in a fast-flowing place, that is, where the water flow gap is large. In this way, it is necessary to generate electricity in the upper reaches of rivers in mountainous areas and then transport it to distant cities.
In order to transmit electricity over a long distance, it is necessary to set up a long transmission line. However, when strong current passes through the transmission line, the conductor will heat up. In this way, the final generated electric energy is lost on the way to a distant place because of the heating of the wires.
In order to reduce the heating loss of electric energy in long-distance transmission, there are two methods: one is to increase the cross-sectional area of voltage, that is, to thicken the wires and reduce the resistance; The second is to increase the voltage and reduce the current.
The former method is difficult to adopt because it requires a lot of metal wires and it is difficult to erect thick wires. Comparatively speaking, the latter method is more practical. However, it is difficult to increase or decrease the voltage of the direct current used at that time. Therefore, people have to start to consider using alternating current, and the voltage of alternating current is easy to change.
It seems that it is easier to change a DC generator into an alternator, mainly by removing the commutator. Therefore, Artne of Siemens Company invented the alternator in 1873. Since then, the research on alternator has become popular, which has also led to the rapid development of this kind of generator.