Magnetoelectric machine with improved rotation uniformity

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.

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 magnetoelectric machine there is the effect of "sticking" of the rotor, which significantly affects the smooth operation of the actuator at low frequencies of rotation of the rotor, thus reducing the range of the speed control actuator and limiting the scope of its application [1, p.45].

The main reason for the violation smooth movement of the rotor ("sticking" of the rotor) is the reactive torque, which reduces the starting torque magneto-electric machine, causes the stop of the rotor in certain positions and increases the irregularity of rotation of the magneto-electric machines [2, ñ.38].

Under reactive torque magneto-electric machines understand the time, resulting in an electric car due to the timing structure of the anchor, the asymmetry of its magnetic circuit and uneven working gap [2, ñ.38].

The reactive torque, which is one of the components of the ripple torque, not dependent on the shape of the supply current and supply voltage, as maintained in the de-energized state of the electromagnetic machine.

Due to the timing structure of the stator curve reactive moment is different from the sine wave and is otlozhenii it in Fourier series obtained spectrum of harmonics, called subcommi [5, s-457].

The slant grooves is the most effective way of dealing with subcommi harmonics.

Closest to the claimed technical solution is an electric machine with the bevel grooves of the stator on the pole arc, equal to the whole number Zubovich divisions stator [5, s-459]. The disadvantage of this technical solution is the most discrete accept the bevel grooves and, as a consequence, the decrease of the coefficient of skewness and EMF, which leads to a decrease in the energy parameters of the electric machine.

The objective of the invention is to minimize torque reaction, which is the reason for reducing the uniformity of rotation of the rotor of the magneto-electric machine.

The technical result, which directed the proposed solution is to reduce the ripple torque reaction magnetoelectric machine containing the armature winding, arranged in grooves z, and neravnopolochny rotor with permanent magnets, the execution of the bevel grooves anchors on the angle α, corresponding to a whole number of periods of the sockets harmonics.

Theoretical analysis and calculation of the reactive moment is very difficult. In General, the expression for the reactive moment M_pmagneto-electric machine can be written as follows [2, ñ.38]

$$M_p=k\cdot F\cdot \frac{d\lambda (\theta )}{d\theta },\text{(1)}$$

where k is a constructive factor;

F is the magnetic flux of the permanent magnet, WB;

λ is the conductivity of the magnetic circuit, GN;

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

The dependence of conductivity λ of the angle of rotation θ is due to the influence of serration anchors and can be written in the form [3, s]

$$\lambda (\theta )={\lambda }_0+{\displaystyle \underset{n=1}{\overset{\infty }{\sum }}{\lambda }_p\cdot \cos \left(z\cdot \theta \cdot n\right)},(2)$$

where n is the number of harmonics;

λ₀- constant component of the magnetic conductance, GN;

λ_p- the variable component of the magnetic conductance, GN;

z - number of teeth.

Then

From the formula (3) shows that the moment M_pchanged according to the law of cosine, which is undesirable ripple, thus, the number of pulsations of the reactive torque per rotation is a multiple of the number of teeth of the armature z is [4, p.12]

$$N=2\cdot z\text{(4)}$$

Because the ripple have zubtsovy procedure, it is useful to consider subcool harmonica with sequence number n corresponding to the number of teeth z

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

where p is the number of pairs of poles of the magneto-electric machine.

Ripple caused by other harmonics will be of significantly less value and can be neglected [5, s].

In the literature [5, s] a method of reducing the accordion is subcatego order consisting in the execution of the bevel grooves on the pole arc, equal to the whole number Zubovich divisions anchor.

In one subzone division, which runs the slant grooves can be placed several periods the sockets harmonics. A significant weakening of the ripple can be obtained by the slant grooves at an angle corresponding to one period of the sockets harmonics, since the average value of the amplitude A_zone period of the sockets harmonics is zero [6, s]

$$<A_z>=\underset{T_z\to \infty }{\lim }\frac{1}{2\cdot T_z}{\displaystyle \underset{0}{\overset{T_z}{\int }}\cos (t)dt=\mathrm{0,}}\text{(6)}$$

where T_z- period of the sockets harmonics, al. the hail.

Therefore, the amount of slant grooves are selected from the conditions of the ratio of the period of the sockets harmonic T_zin El. the hail.

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

where i=1, 2, 3, ... is the sequence number of harmonics;

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

On the basis of the formulas (4)to(8), we obtain

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

Determination of the angle of slant grooves by the formula (9) for various i allows you to get the number of values in which the pulsation of the torque reaction will be minimal.

When choosing the number i should note that large values of i correspond to the large value of the bevel grooves and lower ripple amplitude, persistent due to the presence in the curve of the torque reaction of the other harmonics of the highest order.

The slant grooves is performed in a known manner in the manufacture of the package anchors [7, p.84-85].

For example, mowing the grooves can be performed after packaging, isolation, and fill the wound coils of the armature using special is the first device with a hydraulic drive, which turn mow the anchor to the desired bevel angle using either a groove or bulge at the outer diameter of the armature. Recommendations for the size of this slot does not exist, because its depth and width are determined by the size of the anchor and depend on the angle of bevel of the least of cores. After this operation the beveled anchor can be stapled or glued. During welding of anchors, it is recommended that the welding seam is parallel to the bevel and passed along the axis of teeth on the outer diameter of the anchor, to ensure optimal cross-section of the magnetic circuit in this part of the magnetic circuit of the armature.

Thus, solved the task is to minimize torque reaction, which was to reduce the pulsations of the reactive torque, and therefore, improving the uniformity of rotation of the magneto-electric machine.

The proposed technical solution, in addition to improve the uniformity of rotation, allows to improve the energy performance indicators (KPI, cos(φ)), to reduce noise and vibration magnetoelectric machine.

An example of the implementation of the proposed magneto-electric machine with improved uniformity of rotation can serve as a brushless direct current motor DBM-18-3 with permanent magnets development of the company-applicant JSC "Electric". The motor DBM 142-18-3 has z=45; p=3.

$$\alpha =\frac{360\cdot p}{2\cdot z}\cdot \text{i}=\frac{360\cdot 3}{2\cdot 45}\cdot 4=48el.gp\mathrm{and}d.$$,

this ripple torque reaction is 0,27% (experimental value) of the nominal torque, which provides improved uniformity of rotation.

With the establishment of the proposed magneto-electric machine on the enterprise-applicant JSC "Electric" was practically solved the problem of the development of a number of brushless DC motors with permanent magnets for precision actuators Metalworking equipment (technological robots), one of the requirements to which is the high uniformity of rotation and positioning accuracy.

Sources of information

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[2] Dubno A.A. brushless DC [Text] / ASI. - M.: Energy, 1967. - 144 S.

[3] aspens IN Electric m the tires automatic devices [Text]: textbook. manual for schools / Ilasin, Fmodern. - M.: MPEI Publishing house, 2003. - 424 S.

[4] Efimov V.V. Numerical and experimental simulation of the Electromechanical components of field systems [Text]: abstract of thesis Cand. technology. Sciences / Web. - Cheboksary: CSU, 2011. - 23 S.

[5] yuferov F.M. Electric machine automatic devices [Text]: textbook for students enrolled in special. "Electrician" / Fmodern. - 2nd ed., revised and enlarged extra - M.: Vysshaya SHKOLA, 1988. - 479 C.

[6] Korn, Handbook of mathematics for scientists and engineers [Text] / Garn, Tarn; edited Igirimbabazi; Per. s angl. - M.: Nauka, 1968. - 720 S.

[7] Vinogradov, NV Manufacture of electrical machinery [Text]: textbook for Colleges / Nikolai Vinogradov. - 2nd ed., Rev.), Energy, 1970. - 288 S., Il.

Magnetoelectric machine containing the armature winding, arranged in grooves z, and neravnopolochny rotor with permanent magnets made with the bevel grooves anchors and characterized in that the bevel grooves made on the angle α, corresponding to a whole number of periods of the sockets harmonics.