SU655036A1 - Induction electric motor - Google Patents

Description

The invention relates to electrical engineering, in particular to three-phase asynchronous electric motors with a short-circuited or phase-wound rotor having an increased value of efficiency.

Asynchronous electric motors are known, comprising a stator and a rotor with windings for windings I.

However, such engines have insufficient IEDs.

Also known asynchronous motor, containing the magnetic stator and rotor with grooves for the windings 2.

This engine is the closest to the technical essence and the achieved result to the invention. An increase in the efficiency of this engine as compared to the engines of the main performance is achieved by s & by increasing the consumption of active materials.

The purpose of the invention is to reduce the consumption of active materials while maintaining the efficiency of the engine.

For this purpose, in the sections (0.25-0.6) of the total length of the magnetic cores, the grooves are made with a relative bevel, the value of which is determined by the formula

Be (0.014-0.07),

where D is the diameter of the bore of the stator;

P is the number of pairs of poles. FIG. I shows the distribution of the maximum value of induction in the gap along the axis of the electric motor without beveling the grooves (curve 1) and with a partial bevel (curve 2); in fig. 2 shows one of the examples of the sweep of the magnetic circuit of an electric motor of the device described, dotted

the lines show the axes of the slots 3 of the rotor, the solid axes of the slots 4 of the stator; in fig. 3 given a spatial vector diagram of an asynchronous motor; in fig. 4 - a variant of the device with a partial bevel

grooves along the edges of the rotor; in fig. 5-8 are versions of the device with a bevel of the slots of the rotor and the stator.

Increasing the efficiency of an asynchronous electric motor of this device is based on the following.

It is known that in the nominal slip zone of asynchronous motors, in which the axes of the stator and rotor slots are parallel along the entire length of the steel package (electric motors without slot grooves), the maximum induction value of the resulting flow in the gap of the Som machine does not change along the axis of the machine within the steel package ( Fig. 1, curve 1).

It is also known that in asynchronous electric motors with groove beveling (the axes of the stator and rotor slots are crossed along the entire length of the steel package of the machine) in the zone of the nominal slip, the value Here along the axis of the machine is variable. At the same time, in the center of the package, the values of Вцт became. in the gap of a machine without a bevel and with a bevel of grooves, they are almost equal from this point along the axis of the induction machine to one of the edges of the steel package and descend to the other. From this it follows that in the zone of nominal slip, the flow in the gap of the machine with the slope of the grooves is almost equal to the flow of the same machine without the slope of the slots.

In an engine in that area of the machine for which a flow attenuation is formed in an engine with bevel slots, stator and rotor grooves are proposed to be mutually parallel (Fig. 2), which will increase the Bosch value in this area to approximately the value occurring in the car without beveling grooves. As a result, the flow of the machine as a whole increases and turns out to be greater than the flow of the engine without or with a bevel of the grooves with the same slip (Fig. 1, curve 2). As the analysis shows, the flow of the machine increases by 2-3% in general for the machine, which leads to an increase in the torque of the electric motor.

From the spatial vector diagram (Fig. 3) it follows that an increase in the resulting MDS FQ leads to a decrease in the angle 2 and. consequently, to a greater moment increase. However, this reserve of moment increase is small due to the high value of cos-fg in modern electric motors.

An increase in the motor torque causes a decrease in slip (at a constant torque on the shaft). As a result of the slip reduction, the copper loss of the machine is reduced. All these factors lead to an increase in the efficiency of the machine of the proposed device or to a reduction in the consumption of active materials while maintaining efficiency. From FIG. 3 it follows that the increase in the MDS FO of the machine corresponds to an increase in the angle c.

The analysis shows that the maximum increase in magnetic flux is observed with a total length of the slope of the grooves equal to (0.25-0.6) the length of the magnetic cores, and with a total slope of the slots

6s (0.014 - 0.07) -.

The foregoing is valid for the direction of rotation of the rotor, which coincides with the direction of the bevel of its grooves 3 (if the bevel is made on the stator, then when rotating in the direction opposite to this bevel).

Studies show that when the rotor rotates in the opposite direction, the efficiency of the engine also increases slightly compared to a machine of the usual design.

When the machine bevels, the axial force arises, which, in particular, depends on the difference in the inductions of the resulting flow along the edges of the steel package. In the engines of the proposed device, this force is less than in engines with a conventional groove slope, since the bevel is performed only on a part of the length of the steel package and the difference between the inductions on the edges of the steel package is less.

However, for engines with loaded bearing assemblies, it may be advisable to reduce this effort due to additional measures. In the design of FIG. 4, in the case of equalization of the grooves 3 of the rotor along the edges of the pack L cr, all components of the axial forces caused by the slope of the grooves fully balance and do not affect the bearing assembly of the machines.

Perform a modification of FIG. 4, it is also advisable to reduce the influence of the bevel of the tips 3 on the cross-sectional area of the groove.

Despite the increasing complexity of the technology, this design may be useful for machines with a high degree of steel magnetic circuit.

For this modification

be - be, + be,

for any ratio b and & c,.

The bevel is produced in one direction from the section with parallel axes of the stator and rotor slots.

The greatest effect of increasing efficiency is with the direction of rotation along the groove bevel.

For motors larger than 10 kW, it is advisable to slant the slots on the stator.

In the devices of FIG. 5-8 Providing the bevel of the slots 3 and 4 both on the stator and on the rotor, it is used in cases when it is desirable to reduce the value of b for one of the parts of the machine. The directions of the slope of the slots of the stator and the rotor must be opposite. The preferred direction of rotation is in the slope of the slots 3 of the rotor. The magnitude of the total skew in FIG. 5, 7, 8 o & c, and FIG. 6

Bc, + 6c. + & NW + JS ,,

where 6ci, lcr, be,, bc are partial bevels. The preferred direction of rotation is the slope of the rotor slots.

In the case when the technological capabilities for beveling the rotor slots are larger than the stator (although also limited), the design of FIG. 7

If, technologically, the stator has great opportunities for beveling the slots, and the rotor is smaller, then a larger bevel is performed on the stator, but preferably

the direction of rotation is in the bevel of the rotor slots.

FIG. 8, an example is considered when the axes of the stator slots are chamfered in one direction. In this case

be 6ci Cj.

If, then the preferred direction of rotation is against the slope of the slots, with - along the slope of the slots.

The general rule when performing the groove mowing is the following: on the scan of the magnetic circuit of the machine, the axes of the stator and rotor slots should not simultaneously have central symmetry within the steel package.

As follows from the above and field test data, the proposed device of three-phase asynchronous electric motors with a squirrel-cage or phase-wound rotor provides an increase in the level of efficiency in the same range as the series of asynchronous electric motors with an increased efficiency value (series AOT2) specially produced. However, the electric motor of the proposed device does not require additional consumption of active and other materials, as well as changes in production technology.

Claims (2)

1.Sergeev P.S. Design of electrical machines. M., “Energie, 1969, p. 422- 423. 2. Directory Directory. Asynchronous electric motors of a single series A2 and AO2 with a capacity from 0.6 to 100 kW, publishing house "Informelectro. M., 1969, p. 45-47. the sun  L tg.g