RU2231194C2 - Nine-phase fractional (q=4/7) winding of a c electrical machine - Google Patents

Abstract

FIELD: electrical engineering, electrical machine manufacture.

SUBSTANCE: invention refers to 12-phase asynchronous motors with short-circuited rotor fed from semiconductor frequency converter in frequency-controlled A C electric drive. Technical result consists in manufacture of double-layer m=9-phase, m'=18 zone fractional winding with q=4/7 and p=7in z=18pq=72 slots with removal of highly expressed harmonic of fractional order from its magnetomotive force to reduce differential scattering. Winding is double-layer lap 2p=14-pole winding with number of slot per pole and phase q=4/7 and grouping in row 1 1 01 0 1 0 in z=72 slots made of 72 coils carrying numbers from 1K to 72 K and pitch

by slots. When number of phases m=9, phase zones m'=2m=18 coils 1K=4(k) and 2+4(K) have (1-x)

turns and coils 3K=4(k), 4K+(k) have (1+x)

turns. In first phase there are connected in series 1K, 22K,-27K, 32K, -37K,-59K,63K,-68K with start of phase from start 1K and its finish from start of coil 68K. Coils of each next phase alternate with interval of 32 numbers within limits of 72 coils relative to coils of first phase where

is number of turns in each slot, x=0.08 and value k in numbers of coils changes within limits from 0 to 2 m-1=17. Sign (-) by number of coil designates its connection in phase in opposition.

EFFECT: reduced labor input to manufacture of winding.

3 dwg

Description

The invention relates to the windings of electrical AC machines and can be used, for example, on a stator of asynchronous motors (HELL) with a squirrel-cage rotor, powered by semiconductor frequency converters (IF).

Known are m≥3-phase, m '= 2m-zone AC symmetrical loop windings made by two-layer 2p-pole from 2pm coil groups with equal-step or concentric coils with a fractional number q = z / 2pm = b + c / d = Nd grooves z per pole and phase when grouping coils in coil groups, depending on the fractional part c / d of q [1-2].

With the denominator of fractionality d≥4, the windings are characterized by a high content of harmonic MDS with a significant deterioration in the performance of electric machines with such windings; with an increase in the number of phases m and phase zones m ’, the harmonic composition of the winding MDS improves.

Closest to the proposed one is the fractional m = 3-phase, m '= 6-zone, 2p = 14-pole winding at q = 4/7, performed two-layer in z = 6pq grooves with a grouping of coils in a series of 1101010 [1] for c / d = 4/7 and b = 0.

The invention aims to perform a two-layer m = 9-phase, m '= 2m = 18-zone fractional winding at q = 4/7 and p = 7 in z = 18pq = 72 grooves while eliminating the most pronounced fractional harmonic for reduction of differential scattering [3].

The solution of this problem is achieved by the fact that for a two-layer fractional 2p = 14-pole winding with the number of grooves per pole and phase q = 4/7 and grouping in a row 1101010, performed in z = 72 grooves m = 9-phase, m '= 18 -zone of K = 72 coils with numbers from 1K to 72K and pitch in grooves at _p : 1K + 4 (k) and 2K + 4 (k) coils contain (1-x) w _k turns, and 3K + 4 coils (k) and 4K + 4 (k) - along (1 + x) w _k turns, in the first phase, coils 1K, 22K, -27K, 32K, -37K, -58K, 63K, -68K are connected with the beginning of the phase from the beginning of 1K and its end from the beginning of 68K, and the groups of each subsequent phase alternate with an interval of 32 numbers per limit ax 72 coils relative to the coils of the first phase, where y _p = 6, 2w _k is the number of turns of each groove, x = 0.08 and the value of k in the numbers of coils varies from 0 to 2m-1 = 17, and the sign (-) when the coil number means its counter inclusion in phase.

Figure 1 shows the recessed grooves of the grooved layers with alternations of m '= 18 phase zones A-A'-A''-Z-Z'-Z''-B-B'-B''-X-X'- X '' - C-C'-C '' - Y-Y'-Y '' of the proposed 2p = 14-pole, m = 9-phase, m '= 2m = 18-zone double layer fractional winding with z = 72 grooves , K = 72 coils and q = z / 18р = 4/7 (N = 4, d = 7) with markings on top of the numbers of coils 1K, 22K, 27K, 32K, 37K, 58K, 63K, 68K of the first phase (zones A and X) and the bottom of the groove numbers (from 1 to z = 72); figure 2 - diagrams of the shift of the coils of the first phase for the pole p = 7 (top) of harmonic MDS (EMF) ν = 1 and the pole pν = νp = 11 of the fractional harmonic MDS ν = 11/7 (in the center) at angles α _p = 360 ° / z = 5 ° and γ = α _n / 2d = 2.5 ° / 7; figure 3 - the construction of the part of the polygon MDS according to [3] of the winding of figure 1 at x = 0, where the center shows the vectors of the symmetric m '= 18-phase system of phase currents of the zone A-A'-A''- Z-Z '-Z''-B-B'-B''-X-X'-X''-S-C'-C''-Y-Y'-Y''.

The winding of Fig. 1 at 2p = 14 poles, z = 72 grooves, m = 9 phases, m '= 2m = 18 phase zones is made of a two-layer of K = 72 coils with numbers from 1K to 72K and pitch in the grooves y _p = 6 has a fractional number of grooves per pole and phase q = 4/7 at N = 4 and d = 7, i.e. according to the grouping [1] 1101010 from each N = 4 coils d = 7 groups are formed. For this, a series of 2m = 18 groups 1101010 is compiled, phase zones are marked under it in the sequence A-A'-A '' - Z-Z'-Z '' - B-B'-B '' - X-X'- X '' - С-С'-С '' - Y-Y'-Y '' and the zones under the zero numbers of the row are crossed out, after which the number of grooves are sequentially marked under the remaining numbers, and the scan according to Fig. 1 is obtained. The winding at m '= 18 phase zones and d = 7 creates a rotating MDS with harmonic series [2] ν = 18k / d ± 1 = 18k / 7 ± 1 = 1 (+), 11/7 (-), 25 / 7 (+), ..., where ± k is any integer such that ν> 0 (k = 0 for the fundamental harmonic ν = 1), the sign (+) corresponds to harmonic straight lines and (-) to the opposite.

To determine the angle of shift of the coils of the first of m = 9 symmetrical phases for the poles p = 7 (ν = 1) and pν = νp = 11 (ν = 11/7) in Fig. 1 (bottom), the shifts are marked in grooves between the coils 1K, 22K, 32K, 63K of zones A, the axis of their symmetry O lies in the middle between 1K, 22K and relative to it, the shift angles are equal: for p = 7-O → 22K-10.5α _n p = 10.5 · 35 ° = 360 ° + 7.5 ° = + 1.5α _p and O → 1K = -1.5α _n , O → 32K → 20.5α _p p = 720 ° -2.5 ° = -0.5 · α _p and O → 63K = + 0.5α _p , according to which the upper diagram of Fig. 2 is constructed at an angle α _p = 5 ° (the coils of zones X - 37K, 58K, 68K, 27K are 180 ° offset from the coils of zones A); for pν = 11: O → _n → 10,5α 22K pν = 11 · 360 ° / 7 + 82,5 ° / 7 = 4 · 360 ° / 7 + 33γ, O → 1K = 3 · 360 ° / 7-33γ ; O-32K → 22 · 360 ° / 7-27.5 ° / 7 = 360 ° / 7-11γ, O → 63K = 6 · 360 ° / 7 + 11γ, according to which the diagram of Fig. 2 (in the center) is constructed at the circle is divided into p = 7 parts (360 ° / 7) taking into account the oncoming rotation of the harmonic MDS ν = 11/7, where γ = α _n / 2d = 2.5 ° / 7. _Using the shortening coefficients K _yν = sin (ν90 ° y _p / τ _p ) of the coils (for pole division τ _p = z / 2p = 36/7) and Fig. 2, the projections of the EMF of the coils on the vertical axis of symmetry are calculated and winding coefficients are determined taking into account unequal coils: for pν = 11 (ν = _11/7 ) -K _obν = ([1 + x) cos (360 ° / 7-11γ) - (1-x) cos (180 ° / 7 + 33γ)] K _yν / 2 = -0.01524 + х0.1901 (at K _yν = 0.2588), whence, by the condition К _obν = 0, the value х = 0.08 is determined, at which the harmonic from the EMF of the winding of Fig. 1 is eliminated ν = 11/7 with pν11;

for p = 7 (ν = 1) -K _ob = [sin (10 °) / sin (2.5 °) + 2xcos (0.5α _n ) -2xcos (1.5α _n )] K _y / 4 = 0 , 961335 + х0.00367 (at K _y = 0.96593), i.e. for an equal-turn winding (x = 0), the amplitude of the harmonic MDS ν = 11/7 has a relative value Fν / F = K _revν / νK _rev = 0.0152 (11/7) 0.9613 = 0.0101 or 1.01%, and at x = 0.08 - Fν / F = 0. The differential scattering of the winding, determined from its MDS polygon of FIG. 3 according to [3], by calculating the squares of radii i = N = 4 of the groove points of one repeating part of the winding relative to the center, for non-uniform winding at x = 0.08 decreases by ≈40%.

Thus, the proposed winding has the same filling of each groove with a wire of the same cross section, is characterized by reduced differential scattering due to the elimination of the fractional harmonic order ν = 11/7 from the MDS (EMF), is symmetric m = 9-phase, m '= 2m = 18 -zone, each of its phase shifted by an electrical angle of 40 ° (since the interval in the coil 32 corresponds to electrical shift angle phase began 32α _n p = 32 · 35 ° = 1120 ° -1080 ° = 40 °). Its application in a squirrel-cage rotor HELL powered by a 9-phase current inverter allows a three-fold reduction in phase current compared to 3-phase inverters, which significantly reduces the cost of controlled valves and the entire inverter when simplifying its circuit.

Sources of information

1. Livshits-Garik M. Windings of AC machines / Per. from English M.-L.: SEI, 1959, p.224 - prototype.

2. Voldek A.I. Electric cars: Textbook for high schools. L .: Energy, 1978.

3. Popov V.I. Determination of differential scattering of multiphase windings // Electricity, 1987, No. 6, pp. 50-53.

Claims (1)

Nine-phase fractional (q = 4/7) winding of AC electric machines, 2p = 14-pole, two-layer with the number of grooves per pole and phase q = 4/7 and grouping in a row 1 1 0 1 0 1 0, performed in z = 72 grooves from K = 72 coils with numbers from 1K to 72K and pitch in grooves y _p , characterized in that for the number of phases m = 9 and phase zones m '= 2m = 18 coils 1K + 4 (k) and 2K + 4 (k) contain (1-x) w _k turns, and 3K + 4 (k) and 4K + 4 (k) coils (1 + x) w _k turns, in the first phase, 1K, 22K coils are connected in series –27K, 32K, –37K, –59K, 63K, –68K with the beginning of the phase from the beginning of 1K and its end from the beginning of 68K, and the coils of each subsequent the phases alternate with an interval of 32 numbers within 72 coils relative to the coils of the first phase, where y _n = 6, 2w _k is the number of turns of each groove, x = 0.08 and the value of k in the numbers of coils varies from 0 to 2m – 1 = 17, and the sign (-) at the number of the coil means its counter-inclusion in phase.

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