Research On The Influence Of The Airgap Change On The Performance Of Linear Induction Motor

Along with speeding up the developmental advancement of the world urbanization, the transportation becomes the difficult problem of the urban development day by day. The traditional metro system is droved by rotating induction motor, and the power is transferred to the wheels and axles through the corresponding mechanical gearing equipment, and its force of traction or brake, which is formed through the function of wriggling between the wheel and track, drives or stops the vehicles. Once the force between wheel and track surpasses the biggest adhesive power that the track's permission, it will bring the idle turn and slide of wheels and the vehicles can't be droved or braked. Therefore the traditional metro system is a kind of driving type that is restricted with the track adherence. And this driving type results in the disadvantages of metro project such as the high cost of construction and maintenance, the big noise of vibration.The linear metro, which is droved by linear induction motor (LIM), needn't intermediate gearing and is droved to advance directly by the electromagnetic thrust between primary and secondary of LIM. Its force of traction is no longer restricted with the track adherence and the wheel only plays the support and guidance role. Compared with the traditional metro, the linear metro has many remarkable features: it has excellent power capacity, the smaller tunnel area and less pollution; it can go through steep gradients and small curve radius safely, smoothly and quietly.The primary of linear induction motor which drives the metro is installed on the chassis bogie, and because it is quite strict with laying down railway rail to use flat linear induction motor to drive metro, its secondary----reaction board (called induction board), which is a kind of compound board of aluminum and steel, is fixed on the rail sleeper between the track. It is the airgap which is a gap between the primary and secondary of LIM. The electromagnetic airgap is a very important parameter of LIM. The transverse traction force and vertical electromagnetic attraction consist in the interspaces between primary and secondary of LIM when...