SU11025A1 - Device for leveling longitudinal and transverse fields of a multi-phase synchronous machine - Google Patents

Description

The present invention relates to a device for leveling the longitudinal and transverse fields of a multiphase synchronous machine and has the goal of obtaining current symmetry in the phase windings of the core during asynchronous start.

In FIG. Figure 1 shows devices for reducing the magnetic resistance of the transverse field, in the case of a machine with pronounced poles, by dividing the inter-iron space into two parts; FIG. 2 and 3, devices for increasing the magnetic resistance of the transverse field, in the case of a machine with clearly and implicitly expressed poles, by introducing into its circuit an additional air gap; FIG. 4 devices for asynchronous start-up of a synchronous machine under load.

As is known, at the time of starting a synchronous motor as asynchronous, the currents in the phases of the core winding are different in strength, as a result of which the starting torque of the motor depends on the position taken by the rotor at the time of starting. Indeed, if we assume that the currents in the cortex are symmetrical, then they will create along the axis of the poles of the inductor and neutral pulsating magnetomotive forces equal in magnitude and shifted in phase by 90 °. If the longitudinal and transverse pulsating fields created by these magnetomotive forces were also equal in magnitude, they would induce symmetrical electromotive forces in the winding of the core and would take symmetrical currents from the network. But in synchronous machines with clearly expressed poles, the magnetic resistance for a transversely pulsating field is greater than for a longitudinally pulsating due to the gap between the poles, and therefore the amplitude of the main harmonic of the transversely pulsating field is less than that of the longitudinal pulsating field and the electromotive forces induced in the core, and therefore currents taken from the network will be asymmetrical.

According to the present invention, this disadvantage is eliminated by reducing the magnetic resistance of the transverse field with constant longitudinal magnetic resistance. This is achieved by dividing the interglacial space into two parts: the usual gap between the pole tips and the iron core, pierced by both the longitudinal and transverse fields, and the gap in the pole core itself, or between the pole core and the sleeve, pierced only by a longitudinal flow (Fig . one).

For machines with solid poles and a rear frame, it may appear that the magnetic resistance for the longitudinal field is greater than for the transverse, which will require an increase in the magnetic resistance for the transverse field. For this purpose, in the present invention, pole pieces made of sheet iron are supplied with a radial slot, which increases the magnetic resistance only for the transverse field (Fig 2). Similar to the described device for machines with not clearly expressed poles is shown in FIG. 3, depicting a rotor provided with respectively spaced radial slits.

In the present invention for asynchronous motor starting under load, the pole pieces are supplied with two windings already known for their device (FIG. 4), connected in between. P.

contact rings to start-up: resistances and closable in a synchronous mode. The first distributed winding D dampens the transverse field, and the second concentrated winding E is the longitudinal field. In this case, the entire magnetic circuit is made of sheet iron, the individual sheets of which are insulated from each other and from the tightening bolts. If, for constructive reasons, it is impossible to dispense with a solid rome, the latter is supplied with a magnetic shunt of sheet iron. The inter-iron space, as in FIG. 1, is made of two parts, the total magnetic resistance of which is equal to the magnetic resistance of the air gap between pole tips and iron core used in ordinary cases, and the gap between pole cores B and rum C is made by inserts and G of non-magnetic material.

The subject of the patent.

A device for leveling the longitudinal and transverse fields of a multi-phase synchronous machine to obtain current symmetry in the phase windings of the core during asynchronous start-up, characterized in that to align the longitudinal and transverse fields the junction between the cores of the inductors made of sheet metal and the rim is made through inserts F and G is made of a non-magnetic material; in order to weaken only the transverse field, the pole shoes of the inductors are provided with a soothing winding D distributed over their arc, and to weaken to the longitudinal floor under the shoes is located, coaxially with the winding of a collision, concentrated winding E, at start-up can be connected in the same way as winding D through contact rings with starting resistances (Fig. 4). to the patent of the foreign electricity company Universal Company No. 11025