Inventor:
Nikola tesla is an American inventor, mechanical engineer and Serbian electrical engineer. He is regarded as one of the important promoters of power commercialization and is famous for presiding over the design of modern communication systems.
Based on the electromagnetic field theory discovered by michael faraday, Tesla has made many revolutionary inventions in the field of electromagnetic field. Induction motor was invented in 1887, and its related patents and electromagnetic theory research work are the cornerstones of modern wireless communication and radio.
Extended data:
Braking mode
There are three kinds of electric braking methods for three-phase induction motors: energy consumption braking, reverse braking and regenerative braking.
1. When braking with energy consumption, cut off the three-phase AC power supply of the motor and deliver DC power to the stator winding. At the moment when the AC power supply is cut off, the motor still rotates in the original direction due to inertia. This mode is characterized by smooth braking, but it needs DC power supply and high-power motor, which requires high cost of DC equipment and low braking force at low speed.
2. Reverse braking is divided into load reverse braking and power reverse braking.
(1), load reverse braking is also called load reverse braking. This torque makes the weight slowly descend at a steady speed. The characteristic of this kind of braking is that the power supply does not need reverse connection and special braking equipment, and the braking speed is adjustable, but it is only suitable for wound motor, and its rotor circuit needs a large resistor in series to make the slip ratio greater than 1.
(2) Power Reverse Braking When the motor needs to be braked, it can be braked quickly as long as the two-phase power lines are arbitrarily switched to make the rotating magnetic field opposite. When the motor speed is equal to zero, immediately cut off the power supply.
This kind of braking is characterized by fast stopping, strong braking force and no need for braking equipment. However, due to the large current and impact force during braking, it is easy to overheat the motor or damage the parts of the transmission part.
3. Regenerative braking is also called feedback braking. Under the action of heavy objects (when the crane motor lowers the heavy objects), the speed of the motor is higher than the synchronous speed of the rotating magnetic field. At this time, the rotor conductor produces induced current, which generates torque in the opposite direction under the action of rotating magnetic field, but the motor speed is high, so it is necessary to use a speed change device to slow down.
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Reference source: Tesla official website -mode3.