SU70335A1 - Asynchronous motor - Google Patents

Description

In order to obtain high speeds (above 3000 rpm) with an electric drive with an asynchronous motor, it is necessary to power the motor from a network of increased frequency, or use a multi-machine drive, or use electrical machines of complex design.

The high-speed asynchronous motor proposed according to the invention, which is simpler in design than the known ones, permits a high-speed single-machine electric drive with a normal frequency (50 Hz) supply from the mains.

In the proposed engine, the magnetic circuit of the stator is composed of an open ring forming the working part and a U-shaped non-working element closing this ring. An auxiliary magnetic core is placed in the air gap of the latter to prevent short-circuiting of this part of the machine.

The foregoing is illustrated in the drawing, which shows a sketch of the magnetic system of the proposed engine. Here / is the working (ring) part of the stator, 2 is a non-working stator element, 5 is a rotor, 4 is an auxiliary magnetic circuit.

This embodiment of an asynchronous motor is based on the following considerations.

Linear speed field in an induction machine, as you know, is equal to с 2m /, where m is the pole division, and / is the frequency of the current of the supply network. The magnitude of the floor field can thus be obtained any for any number of poles of the machine, varying only by the geometric dimensions of the pole division, i.e. the diameter of the machine at a constant frequency of the supply network current.

Denote by D the diameter of the bore of the stator of a conventional asynchronous motor and I - the number of revolutions per minute of its rotor, and d and P2 - respectively the diameter of the bore of the ring element / proposed engine and the number of revolutions per minute of its rotor.

Since the linear velocities of the fields of both machines (with the same pole division lengths) are the same, then, neglecting the slip, the peripheral rotor speeds of rotors can be considered identical.

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And since these peripheral speeds are determined by the expressions cipw Ci - nDn-i and C2p 7ruf ' 2, the ratio of the rotor revolutions of both

n, d

machines will be equal to -, t. e. The rotor speed of the proposed rotor; the capacity of the motor exceeds the speed of a conventional asynchronous machine by the number of times corresponding to the ratio of the bore diameters of the stators of the machines.

The stator appendage 2 of the stator must be filled with iron, forming an auxiliary marnite 4, so that this part of the stator is not in a state of short circuit.

Subject invention

Claims (2)

1. An asynchronous motor for operation at speeds above 3000 rpm when powered from a 50-period network is different in that the magnetic circuit is made up of an open ring that forms the working part and the closing ring is a U-shaped non-working ring. 2. The motor according to claim 1 is different from the fact that an auxiliary magnetic conductor is interposed in the air gap of the non-working element to prevent this part of the machine from short-circuiting.