The urban trams with a low floor are more convenient for the passengers, and with a high floor - more cheaply and more technologically during manufacturing and operation. The combined advantages those and others in themselves are trams with average height of a floor, but for this purpose it is necessary to lower height of tram carriages, that is reached by application of electric motors with a small stator external diameter.
It is offered in this the perspective electric drive on the base of the synchronous motor with independent excitation. The salient rotor poles of the motor do not contain windings. The motors stator is carried out on the base of the stator body of regular AC electric motor. The multiphase winding is located in the stator. A winding section, which conductors settle down above the between rotor poles, carry out a role of the excitation winding, and others, which conductors lay above poles, - a role of the armature winding. Together they create the electro-magnetic torque.
The stator windings of the motor are fed by the frequency converter. Field of an excitation and field of a armature reaction are adjusted independently. The switching of currents in the stator phases is fulfilled by the frequency converter in the function of the rotor position.
The control system of the electric drive is similar to DC electric drive, the control systems can be realized in different ways, for example, two-zoned speed control with the subordinated control, etc.
This electric drive can be recommended as the electric drive of a tram, and also for other mechanisms with heavy and highly heavy conditions of operation.