What Is a Drag Conveyor?

Traction motors on main railway electric locomotives, industrial and mining electric locomotives, electric drive diesel locomotives, and various electric vehicles (such as battery cars, urban trams, and underground electric vehicles).

Tractor

Railway locomotive electric locomotive, industrial and mining electric locomotive,

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In order to solve the "steering" problem of DC and pulse traction motors, some countries have used thyristor-less commutator traction motors and three-phase AC asynchronous variable frequency traction motors, and are testing magnetically levitated high-speed vehicles powered by linear asynchronous motors. Thyristor-less commutator traction motor is composed of a synchronous motor and a group of thyristor inverters.

Thyristor and rotor position detector to replace the commutator and carbon brush structure of DC traction motor. This motor has the advantages of a DC motor without the difficult "commutation" problem. However, the thyristor and its control system are quite complicated, so the electronic components directly affect the running reliability of the motor. The three-phase AC asynchronous variable frequency traction motor has a simple structure, reliable operation and low cost, and is an ideal traction motor. However, due to the need for frequency control, its development and application were once limited. In the 1960s, the development of high-power thyristor frequency conversion devices enabled asynchronous motors to achieve variable frequency speed regulation. Many countries have already adopted three-phase AC asynchronous variable frequency traction motors for locomotives and motor vehicles. The Federal Republic of Germany and Japan used linear asynchronous motors on the tested maglev high-speed vehicles. Its primary winding is laid on the ground guide rail, and is powered by a variable frequency power supply on the ground to generate a traveling wave magnetic field. The speed of a magnetically levitated high-speed vehicle can be changed by adjusting the power supply frequency. The secondary winding is the reaction plate, which is mounted on the frame of the vehicle. The interaction of the primary traveling wave magnetic field and the secondary induced current not only generates a thrust force that moves the vehicle forward, but also generates a magnetic pull force to levitate the vehicle, and plays a role of dynamic braking during braking conditions.