RU2518489C2 - Magnetoelectric machine with improved rotation uniformity - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is related to the area of electric engineering and namely to electric machines with permanent-magnet excitation, and it may be used in electric machine engineering. At that the invention ensures improved rotation uniformity, enhanced energy indicators, reduction of noise and vibration level for the magnetoelectric machine. In the suggested magnetoelectric machine including armature with winding laid in z slots and non-salient pole rotor with permanent magnets the armature slots are bevelled at the angle α corresponding to an integer number of tooth harmonic periods.

EFFECT: decreasing reactive moment pulsation for the magnetoelectric machine.

Description

The invention relates to the field of electrical engineering, namely to electric machines with excitation from permanent magnets, and can be used in electrical engineering.

It is known that in the magnetoelectric machine the effect of “sticking” of the rotor is observed, which significantly worsens the smooth operation of the drive at low rotor speeds, thereby reducing the range of control of the speed of the drive and limiting its scope [1, p. 45].

The main reason for the violation of the smooth movement of the rotor (“sticking” of the rotor) is the reactive moment, which reduces the starting torque of the magnetoelectric machine, causes the rotor to stop in certain positions and increases the uneven rotation of the magnetoelectric machine [2, p. 38].

By the reactive moment of a magnetoelectric machine is understood the moment arising in an electric machine due to the gear structure of the armature, the asymmetry of its magnetic circuit and the uneven working gap [2, p. 38].

The reactive moment, which is one of the constituents of the pulsations of the torque, does not depend on the shape of the current consumed and the supply voltage, since it remains in the de-energized state of the magnetoelectric machine.

Due to the tooth structure of the stator, the curve of the reactive moment differs from the sinusoid and when it is expanded into the Fourier series, a spectrum of harmonics is obtained, which are called tooth harmonics [5, p. 456-457].

Slanting is the most effective way to deal with tooth harmonics.

Closest to the claimed technical solution is an electric machine with a bevel groove of the stator into a pole arc equal to an integer number of tooth divisions of the stator [5, p. 457-459]. The disadvantage of this technical solution is the large discreteness of the received bevel grooves and, as a consequence, a decrease in the coefficient of bevel and EMF, which leads to a decrease in the energy performance of an electric machine.

The objective of the invention is to minimize the reactive moment, which is the reason for reducing the uniformity of rotation of the rotor of the magnetoelectric machine.

The technical result, the proposed solution is aimed at, is to reduce the ripple of the reactive moment of a magnetoelectric machine containing an armature with a winding laid in z grooves and an implicit pole rotor with permanent magnets; .

Theoretical analysis and calculation of the reactive moment presents significant difficulties. In general terms, the expression for the reactive moment M _{r of a} magnetoelectric machine can be written as follows [2, p. 38]

$$M_R=k\cdot F\cdot \frac{d\lambda (\theta )}{d\theta },\text{(one)}$$

where k is the design coefficient;

Ф - magnetic flux of a permanent magnet, Wb;

λ is the conductivity of the magnetic circuit, GN;

θ is the angle of rotation of the rotor, el. hail.

The dependence of the conductivity λ on the angle of rotation θ is due to the influence of the gearing of the armature and can be written in the form [3, p.201]

$$\lambda (\theta )={\lambda }_0+{\displaystyle \sum _{n=\mathrm{one}}^{\infty }{\lambda }_P\cdot \cos \left(z\cdot \theta \cdot n\right)},(2)$$

where n is the number of harmonics;

λ ₀ is the constant component of magnetic conductivity, H;

λ _p - a variable component of magnetic conductivity, GN;

z is the number of teeth.

Then

$$M_R=k\cdot F\cdot \frac{d}{d\theta }\cdot \left({\lambda }_0+{\displaystyle \sum _{n=\mathrm{one}}^{\infty }{\lambda }_P\cdot \cos \left(z\cdot \theta \cdot n\right)}\right)\text{(3)}$$

From the formula (3) it is seen that the moment M _p varies according to the law of cosine and is an undesirable pulsation, thus, the number of pulsations of the reactive moment per revolution is a multiple of the number of teeth of the armature z and is [4, p.12]

$$N=2\cdot z\text{(four)}$$

Since the pulsations are in the tooth order, it is advisable to consider the tooth harmonic with serial number n corresponding to the number of teeth z

$$n=\frac{N}{p}\text{(5)}$$

where p is the number of pole pairs of the magnetoelectric machine.

Ripples caused by other harmonics will have significantly lower values and they can be neglected [5, p. 457].

In the literature [5, p.459] a method for reducing harmonics of the tooth order is presented, which consists in performing bevel grooves on a pole arc equal to an integer number of tooth divisions of the anchor.

At the same time, several periods of the tooth harmonic can fit into one tooth division, on which the beveling of the grooves is performed. Significant weakening of pulsations can be obtained by performing bevel grooves at an angle corresponding to one period of the tooth harmonic, since the average value of the amplitude A _{z of} one period of the tooth harmonic has a zero value [6, p. 526]

$$<A_z>=\underset{T_z\to \infty }{\lim }\frac{\mathrm{one}}{2\cdot T_z}{\displaystyle \underset{0}{\overset{T_z}{\int }}\cos (t)dt=0}\text{(6)}$$

where T _z - period of the tooth harmonic, el. hail.

Therefore, the value of the slanting of the grooves must be selected from the condition of multiplicity to the period of the tooth harmonic T _z in el. hail.

$$\alpha =T_z\cdot i,(7)$$

where i = 1, 2, 3, ... is the serial number of the harmonic;

$$T_z=\frac{360}{n}(8)$$

Based on formulas (4) - (8), we obtain

$$\alpha =\frac{360\cdot p}{2\cdot z}\cdot \text{i}(9)$$

Determination of the bevel angle of the grooves by the formula (9) for various i allows one to obtain a number of values at which the ripple of the reactive moment will be minimal.

When choosing the number i, it is necessary to take into account that large values of the slots correspond to a large slope of the grooves and a smaller amplitude of pulsations, which is preserved due to the presence of other higher-order harmonics in the curve of the reactive moment.

The beveling of the grooves is carried out in a known manner in the manufacture of an anchor package [7, p. 84-85].

For example, mowing of grooves can be carried out after packing, isolation and filling of the anchor with wound coils using a special device with a hydraulic drive that rotates the anchor to the desired bevel angle, using either a special groove or a bulge on the outer diameter of the anchor. There are no recommendations on the size of this groove, since its depth and width are determined by the size of the anchor and depend on the bevel angle of the smallest of the cores. After this operation, beveled anchors can be fastened or glued. During welding of the anchor, it is recommended that the welding seam be parallel to the bevel and extend along the axis of the teeth along the outer diameter of the armature to ensure the optimum cross section of the magnetic circuit in this part of the armature magnetic circuit.

Thus, the task is solved to minimize the reactive moment, which consists in reducing the ripple of the reactive moment, and therefore, improving the uniformity of rotation of the magnetoelectric machine.

The proposed technical solution, in addition to improving the uniformity of rotation, allows you to increase energy performance (efficiency, cos (φ)), reduce noise and vibration of the magnetoelectric machine.

An example of the implementation of the proposed magnetoelectric machine with improved uniformity of rotation can serve as a DCB valve DCM142-18-3 with permanent magnets developed by the applicant company OJSC "Electric Drive". The DBM 142-18-3 electric motor has z = 45; p = 3.

, $$\alpha =\frac{360\cdot p}{2\cdot z}\cdot \text{i}=\frac{360\cdot 3}{2\cdot 45}\cdot \mathrm{four}=48\mathrm{uh}l.gR\mathrm{but}d.$$

,

the pulsation of the reactive moment is 0.27% (experimental value) of the nominal torque, which provides improved uniformity of rotation.

When creating the proposed magnetoelectric machine at the applicant company OAO Elektroprivod, the task of developing a series of DC direct current motors with permanent magnets for precision electric drives of metalworking equipment (technological robots) was practically solved, one of the requirements of which is high uniformity of rotation and positioning accuracy.

Information sources

[1] Luzin M.I. Magnetoelectric valve motor with improved overall dimensions and a small value of the moment of “sticking” of the rotor [Text] / M.I. Luzin // Electricity. - 2010. - No. 6. - p. 45-48.

[2] Dubensky A.A. Contactless DC motors [Text] / A.A.Dubensky. - M .: Energy, 1967. - 144 p.

[3] Osin I.L. Electric machines of automatic devices [Text]: textbook. manual for universities / I.L. Osin, F.M. Yuferov. - M.: Publishing House MPEI, 2003. - 424 p.

[4] Efimov V.V. Numerical and experimental modeling of electromechanical components of auto-electronic systems [Text]: Abstract of the dissertation Cand. tech. Sciences / V.V.Efimov. - Cheboksary: ChSU, 2011 .-- 23 p.

[5] Yuferov F.М. Electric machines of automatic devices [Text]: a textbook for university students enrolled in special. "Electromechanics" / F.M. Yuferov. - 2nd ed., Revised. and add. - M.: Higher School, 1988 .-- 479 p.

[6] Korn G. Handbook of mathematics for scientists and engineers [Text] / G. Korn, T. Korn; under the editorship of I.G. Aramanovich; trans. from English - M .: Nauka, 1968 .-- 720 p.

[7] Vinogradov N.V. Production of electrical machines [Text]: a manual for technical colleges / N.V. Vinogradov. - 2nd ed., Revised. - M., Energy, 1970. - 288 p., With silt.

Claims (1)

A magnetoelectric machine containing an armature with a winding laid in z grooves and an implicit pole rotor with permanent magnets, made with a bevel of the armature grooves and characterized in that the bevel of the grooves is made at an angle α corresponding to an integer number of tooth harmonic periods.