RU2779449C1 - Inductor for magnetization of multi-pole rotor magnets - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to devices for magnetizing multi-pole rotor magnets. Inductor for magnetization of multipole rotor magnets contains a body made of non-magnetic and non-conductive material and conductive bars connected in series. Tires in the radial section have the shape of crescents. The inner boundaries of the tire section are arcs of circles, the radius of which coincides with the radius of the working area of ​​the inductor, and the outer boundaries are arcs of circles with centers coinciding with the midpoints of the inner boundaries of the tires and radii equal to the chords drawn from the middle of the inner boundaries to their edges.

EFFECT: increasing the efficiency of magnetization of multi-pole rotor magnets.

1 cl, 3 dwg, 1 tbl

Description

The invention relates to electrical engineering, in particular to devices for magnetizing multi-pole magnets used in electrical machines, radial magnetic couplings and magnetic gearboxes.

Multi-pole rotor magnets must create the maximum possible magnetic field in the working gap of the electric machine. The deviation of the normal component of the field in the radial section of the working gap of the electrical machine from the sinusoid leads to a decrease in the efficiency of its operation, which is expressed in an increase in losses due to eddy currents and hysteresis (a decrease in efficiency), an increase in the pulsations of the engine torque and generator EMF, mechanical loads on the machine elements, vibrations and the noise generated by the machine. In this regard, it is advisable to magnetize multipole rotor magnets in such a way that the fields they create have a normal component distributed according to a sinusoidal law in the working gap of the machine.

A device for magnetization and thermomagnetic processing of multi-pole magnets containing conductive rods installed parallel to the axis of the processed magnet [Inductor for magnetization and thermomagnetic processing of n-pole with an even number of poles of the rotors of electrical machines: and.with. 1334193 A USSR, No. 3871024 / 24-07 / Stadnik I.P., Klevets N.I., Baev A.V. and Gridnev A.I.; dec. 03/21/85; publ. 08/30/87. Bull. 32. 3 p.].

This device is designed to magnetize multi-pole magnets in a direction that provides maximum magnetic flux to the stator poles. With such an orientation of the magnetization of multi-pole magnets, a sinusoidal distribution of the magnet field in the working gap of the machine is not ensured.

Known inductor for magnetizing multi-pole rotary magnets [Multipolar magnetizing device for permanent magnets: p. 4470031 US / Steingroever et al.; filed Sep. 28, 1982. 8 p.], consisting of conductive rods of circular cross section, installed parallel to the axis of the inductor and evenly distributed around the circumference. The inductor also contains cylindrical rods of soft magnetic material located between the conductive rods to enhance the magnetic flux created by the currents flowing in the conductors of the device.

This device does not provide magnetization of multipole magnets in the direction in which the magnet creates a field with a sinusoidally distributed normal component in the working gap of the electric machine.

Known inductor for thermomagnetic processing and magnetization of multi-pole rotor magnets, consisting of conductive rods installed parallel to the axis of the inductor at the same distance from it [Inductor for magnetization and thermomagnetic processing of multi-pole magnets: a.s. 1791858 A1 USSR, No. 4671380/07 / Stadnik I.P., Gorskaya I.Yu.; dec. 02/28/89; publ. 30.01.93, Bull. 4. 4 p.], chosen as a prototype.

This inductor does not effectively magnetize multipole rotor magnets in the direction in which the magnet creates a field with a sinusoidally distributed normal component in the working gap of the electric machine.

The purpose of the invention is to increase the efficiency of magnetization of multi-pole rotor magnets that create a field distributed according to a sinusoidal law.

The technical problem solved by the invention is to reduce the deviation of the orientation of the magnetization of multi-pole rotor magnets from the direction that provides a sinusoidal distribution of the normal component of the magnet field in the working gap of the machine.

The solution of the problem is achieved by the fact that the inductor contains N conductive tires, the cross-sectional shape of which is a crescent. In this case, the inner boundary of the section of each tire has the shape of a circular arc of length πD/N (D is the diameter of the working area of the inductor), the center of which coincides with the center of the section of the inductor; the outer boundaries of the tire section are in the form of an arc of a circle, the center of which coincides with the center of the inner boundary, and the radius is equal to the chord connecting the center of the inner arc with its end. The tires are evenly distributed around the circumference with little clearance for insulation.

In FIG. 1 shows a radial section of a four-pole inductor, where the following designations are used: 1 - conductive tires, 2 - an inductor case made of non-magnetic electrical insulating material, for example, textolite, designed to fix the position of the tires, 3 - a magnetizable sample (four-pole magnet, N = 4). Dots and crosses show the direction of the current in the inductor tires in working condition.

In all tires of the inductor at the time of its operation, currents of the same magnitude must flow. The simplest way to meet this requirement is to connect tires in series with a "snake". In this case, the ends of the two tires should be used to connect the power source of the inductor.

The busbars of the inductor must be distributed around the circumference at regular intervals to ensure symmetrical N-pole magnetization of the magnet.

In FIG. 2 shows a general view of the inductor.

The inductor is made as follows. A conductive system consisting of N busbars is made from a material with a high electrical conductivity, such as copper. The tires are connected by a "snake", and the beginning of the first bus and the end of the last are connected to the power source of the inductor.

A non-magnetic and non-conductive durable material, for example, an epoxy resin compound, is used to make an inductor housing, which is necessary to fix the busbars in the desired position, because. when current flows through the tires, electromagnetic forces arise between them, which tend to change the position of the tires relative to each other. The axial length of the inductor must be greater than the axial size of the magnetizable multi-pole magnet.

The inductor works as follows. A magnetizable sample is inserted into the hole. Between the sample and the body of the inductor there must be a technological gap that is necessary and sufficient for placing and removing the sample, which must fit tightly into the working area of the inductor. A current pulse is passed through the conductors of the inductor, the required value and duration of which depend on the material of the magnetized sample, the number of poles and the volume of the sample. Typically, a pulse duration of the order of several milliseconds is required [Nesterin V.A. Equipment for impulse magnetization and control of permanent magnets. M.: Energoatomizdat, 1986. 88 p.].

The magnetized multi-pole magnet is removed from the inductor.

Due to the fact that the inductor busbars are continuous current conductors of a relatively large size, in the pulsed mode of operation, a pronounced uneven current distribution over the busbar cross section (skin effect) can be observed. This will lead to the fact that the distribution of the magnetizing field in the working area of the inductor will deviate from the required one. To eliminate this effect and ensure high-quality magnetization of multi-pole magnets, tires are made from conductors of the same size connected in parallel. Tires can also be made from braided wire.

The magnetization of multi-pole permanent magnets in the proposed inductor provides the orientation of the magnetization vector of the magnets close to the orientation given by the following formula [Multi-pole magnet: a.s. 662979 USSR, No. 2302336/24-07 / Rabinovich Ya.D.; dec. 12/23/75; publ. 05/15/79, Bull. 18. 2 p.]:

where α is the angular coordinate of the observation point in the radial section of the multipole magnet. When the magnetization is oriented at an angle β, the multipole magnet creates a field in the working area of the machine, the normal component of which is distributed over the pole according to a sinusoidal law.

To quantify the deviation of the magnetizing field of the inductor from that given by formula (1), you can use the relative root-mean-square deviation of the inductor field from the ideal field, calculated by the formula:

where S is the cross-sectional area of the magnet,

Jxo, Jyo - components of the magnetization vector of a perfectly magnetized magnet, calculated by the formulas:

Jxi, Jyi - components of the magnetization vector of the magnet, magnetized in the proposed inductor. These magnetization components are calculated using the following formulas:

- поле индуктора в радиальном сечении рабочей области (магнита),where

- field of the inductor in the radial section of the working area (magnet),

μ ₀ - magnetic constant,

S _T - cross-sectional area of conductive tires,

- вектор плотности тока в шинах индуктора.

is the current density vector in the inductor busbars.

In formula (2), the magnetization vector in both cases must be normalized to unity so that the difference between the components is determined only by the orientation of the vectors. Formulas (3), (4) ensure that this requirement is met. When calculating the field of the inductor, the current density in the tires can be set equal to 1 A/m ² .

Table 1 shows the results of calculating the relative standard deviation of the field of the prototype and the proposed inductor from the ideal (by orientation) for different values of the poles according to formulas (2)-(4). The prototype corresponds to indices 1, the proposed invention - 2.

From the data of Table 1 it follows that the proposed inductor with the number of poles N=2, 4, 6 creates a magnetizing field in the working area, which deviates from the required orientation, significantly less than the field of the prototype (see Table 1, Δ ₁ and Δ ₂ ). This leads to a much smaller deviation of the normal component of the magnet field from the sinusoidal than the prototype (see Table 1, ΔB ₁ and ΔB ₂ ). Moreover, the positive effect in the case of magnets with a small number of poles, which are most often used in practice, is most pronounced.

In FIG. 3 shows the normal components of the field of a solitary four-pole rotor magnet magnetized in accordance with formula (1) (solid line - sinusoid), prototype inductor (dashed line) and the proposed inductor (dashed line). The relative root-mean-square deviations of the magnet fields from the sinusoid are 12.0% for the magnetized prototype, and 2.8% for the magnetized by the proposed inductor.

Thus, the use of the proposed inductor provides significantly better than the prototype, the quality of the magnetization of multi-pole rotor magnets.

Claims (1)

An inductor for magnetizing multipole rotor magnets, comprising a body made of a non-magnetic and non-conductive material, and conductive tires connected in series, characterized in that, in order to increase the efficiency of magnetization of the magnets, the tires in the radial section have the shape of crescents, the inner boundaries of which are arcs of circles, radius which coincides with the radius of the working area of the inductor, and the outer boundaries are arcs of circles with centers coinciding with the midpoints of the inner boundaries of the tires and radii equal to the chords drawn from the middle of the inner boundaries to their edges.

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