in p>1834, Jacoby of Germany invented the DC motor. In 1888, Tesla of Yugoslavia invented the AC motor. In 1821, Faraday, a British scientist, first proved that electricity could be converted into rotary motion. The first person to make an electric motor is said to be Jacoby of Germany. Around 1834, he became a simple device: a six-arm wheel was installed between two U-shaped electromagnets, and each arm was equipped with two bar magnets. After electrifying, the mutual attraction and repulsion between the bar magnet and the U-shaped magnet drive the wheel shaft to rotate. Later, Jacoby made a large device. Installed in a small boat, powered by 32 Daniel batteries, the boat sailed on the Elbe River for the first time in 1838, with a speed of only 2.2 kilometers per hour. At the same time, Davenport of the United States also successfully made a motor to drive the printing machine and printed Electromagnetic and Mechanical Information, an American electricity semester sentence. However, these two kinds of motors have little commercial value, and using batteries as power supply is too expensive and impractical. It was not until the first practical DC engine came out that the motor was widely used. In 187, the Belgian engineer Gram invented the DC generator, which is very similar to the motor in design. Later, Gram proved that the rotor of a DC engine would rotate like a motor when current was input. As a result, this kind of Gram motor was produced in large quantities. Efficiency is also constantly improving. At the same time, Siemens in Germany made better generators and began to study vehicles driven by electric motors, so Siemens made the world tram. In 1879, at the Berlin Industrial Exhibition, Siemens' smokeless tram won applause from the audience. Siemens electric locomotive was only 3 horsepower at that time. Later, the electric locomotive tested by American inventor Edison reached 12-15 horsepower. But the motors at that time were all DC motors, which were limited to driving trams. In 1888, the Yugoslav-born American inventor Tesla invented the AC motor. It is made according to the principle of electromagnetic induction, also known as induction motor. This kind of motor has simple structure, uses alternating current, does not need rectification and has no spark, so it is widely used in industrial household appliances. The alternating current motor is usually powered by three-phase alternating current. In 192, Swedish engineer danielson first put forward the idea of synchronous motor. The working principle of synchronous motor is the same as that of induction motor. The stator generates a rotating magnetic field, so the rotor winding is powered by DC, and the speed is fixed, which is not affected by the load. Therefore, synchronous motors are especially suitable for clocks, record players and tape recorders. The DC motor is DC excited, and its working characteristics are different depending on the wiring mode of its excitation winding. Series motor has a large starting torque, which is suitable for traction and hoisting. The speed of parallel motor changes little with the load and can be adjusted, which can be used for constant speed or speed regulation. Compound motor has the characteristics of the above two excitation engines. AC commutator motor, that is, AC motor with commutator rotor. Because it can be used for both AC and DC, it is called AC-DC dual-purpose motor or universal motor, which is mostly used in household appliances.
Reference: Light of Science.