What is the principle of suspended magnetic levitation?

Maglev train is a high-tech means of transportation that uses the attraction and repulsion of magnetic poles. Simply put, repulsion makes the train suspended, and gravity makes the train move.

The maglev train is equipped with electromagnets and the bottom of the railway is equipped with coils. After electrification, the polarity of the magnetic field generated by the ground coil is always the same as that of the electromagnet on the train, and they are "like poles repel each other", which makes the train suspend. Coils are also installed on both sides of the rail, and alternating current turns the coils into electromagnets. It interacts with the electromagnet on the train to make the train move forward. The electromagnet (N pole) at the head of the train is attracted by the electromagnet (S pole) at the front of the track and repelled by the electromagnet (N pole) at the back of the track-the result is a "push" and a "pull". The maglev train keeps a certain gap (generally1-10 cm) with the track during operation, so it runs safely, smoothly and comfortably, without noise, and can realize full-automatic operation. The service life of maglev train can reach 35 years, while that of ordinary wheel-rail train is only 20-25 years. The service life of maglev train track is 80 years, while that of ordinary track is only 60 years. In addition, the maglev train reached its maximum speed within 39 seconds after its start, and the current maximum speed is 552 kilometers per hour. According to the prediction of German scientists, by 20 14 years, the speed of maglev train will reach 1000 km/h after adopting new technology. The maximum speed of ordinary wheel-rail trains is 300 kilometers per hour.

Based on the principle of "like-sex repulsion and opposite-sex attraction", the maglev train makes the magnet have the ability of defying gravity, which makes the car body completely off the track, suspended at a distance of about 1 cm from the track, and flew in the air, creating a miracle of space flight with almost zero height.

Shanghai maglev train is the first demonstration operation line of maglev train in the world. After completion, it only takes 6-7 minutes from Longyang Road Station in Pudong to Pudong International Airport.

Shanghai maglev train is a kind of "constant magnetic attraction type" (referred to as "constant conductivity type"), which is designed according to the principle of "opposites attract" and is a suction suspension system. The suspension electromagnets installed on the bogies on both sides of the train and the magnets laid on the track are used, and the vehicle is suspended by the suction generated by the magnetic field.

Electromagnets are installed at the bottom of the train and at the top of bogies on both sides. The induction plate and the induction steel plate are respectively installed above the I-beam track and below the upper arm. Control the current of electromagnet to keep a gap of 65,438 0 cm between electromagnet and track, and balance the attraction between bogie and train with the gravity of train. By the attraction of magnets, the train can float about 65,438+0 cm, and the train can be suspended on the rails. This must accurately control the current of the electromagnet.

The driving principle of suspension train is exactly the same as that of synchronous linear motor. Generally speaking, the alternating current flowing in the coils on both sides of the track can turn the coils into electromagnets, and the train will start because of the interaction with the electromagnets on the train.

The N pole of the electromagnet at the head of the train is attracted by the S pole of the electromagnet installed on the front track and repelled by the N pole of the electromagnet installed on the back track. When the train moves forward, the current in the coil flows in the opposite direction, that is, the original S pole becomes the N pole, and the N pole becomes the S pole. When the cycles alternate, the train will run forward.

Stability is controlled by the navigation system. The "constant magnetic attraction" guiding system is a group of electromagnets installed on the side of the train for guiding. When the train deviates from the left and right, the guide electromagnet on the train interacts with the side of the guide rail to produce repulsive force, which makes the vehicle return to the normal position. When the train runs on a curve or ramp, the control system can control the operation by controlling the current in the guide magnet.

The idea of "normal guidance" maglev train was put forward by German engineer Herman Corpster in 1922.

"Normal-oriented" maglev train, the working principle of track and motor is exactly the same. Just arrange the "rotor" of the motor on the train and lay the "stator" of the motor on the track. Through the interaction between "rotor" and "stator", electric energy is converted into positive kinetic energy. We know that when the "stator" of the motor is electrified, the "rotor" can be driven to rotate through electromagnetic induction. When the power is transmitted to the "stator" of the track, the train is driven to move linearly like the "rotor" of the motor through electromagnetic induction.

Shanghai maglev train runs at a speed of 430 kilometers per hour, and only one train can run in one power supply area. There are isolation nets at 25 meters on both sides of the track and protective equipment on both sides. The radius of the bend is 8000 meters, and the naked eye is almost a straight line; The minimum radius is1300m. Passengers will not feel uncomfortable. The most advanced isolation devices in the world are installed within 50 meters on both sides of the whole track.

Advantages of maglev train:

The train is suspended above the rail, and the rail is not in contact with the vehicle, so the running speed is fast, which can exceed 500 km/h, running smoothly and comfortably, and it is easy to realize automatic control; No noise and harmful waste gas, which is beneficial to environmental protection; Can save construction funds; Low operation, maintenance and energy consumption costs.