In 1922, German engineer Hermann Kemper proposed the principle of electromagnetic levitation and applied for a patent for a maglev train in 1934. Since then, with the development of world industrialization and the rapid growth of national economic strength, in order to meet the needs of people's convenient travel and economic development, developed countries such as Japan and Germany as well as China have begun to study maglev train technology and develop maglev transportation systems. Using the principle of electromagnets that "magnetic poles with the same name repel each other and magnetic poles with different names attract each other", the current in the coils on both sides of the maglev train track can turn the coils into electromagnets. It interacts with an electromagnet on the train, causing the train to start. The train moves forward because the electromagnet at the head of the train is attracted by the electromagnet installed on the track farther forward, and at the same time is repelled by the electromagnet installed on the track farther back. When the train starts to move forward, the direction of the current flowing in the coil is reversed. The result is that the polarity of the original current is reversed and vice versa.