RU2224347C2 - Multiphase fractional-slot winding for ac machines - Google Patents

Abstract

FIELD: electrical and electromechanical engineering; twelve-phase squirrel-cage induction motors. SUBSTANCE: proposed winding used for induction motors supplied with power from semiconductor voltage converters in variable-speed ac drives is double-layer m = 12-phase, m' = 12-section fractional-slot lap winding with number of slots per pole per phase q = 6/7, p = 7, 2p = 14 poles, placed in z = 12 pq = 72 slots with most conspicuous fractional harmonic component removed from its magnetomotive force. It has C = 72 coil groups numbered from 1C through 72C at slot pitch y_s grouped in row 1 1 1 1 1 1 0. Each coil 1C + 6(c) and 6C + 6(c) has (1+x)w_c turns; each coil 2C + 6(c) and 5C + 6(c), w_c turns, and each coil 3C + 4(c) and 4C + 4(c), (1+x)w_c turns. Connected in series opposition in first phase are coils 1C, 12C, 22C, 32C, 53C, 63C with starting phase lead tapped from starting lead of 1C and its finishing lead, from finishing lead of 63K; coils of each next phase are alternating at interval of 42 numbers within C = 72 relative to first-phase coils, where y_s = 2; 2w_c is turn number in each slot; x = 0.17; c varies in coil numbers between 0 and 11. EFFECT: reduced differential dissipation. 1 cl, 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 m≤3-phase, m '= 2m-zone loop symmetrical AC windings, performed by two-layer of 2pm coil groups with equal-step or concentric coils with a fractional number q = z / 2pm = b + c / d = N / d grooves z per pole p and phase when the coils are grouped into coil groups, which depends on the fractional part c / d of the number q [1-2]. With a fractionality denominator of d≥4, such windings are characterized by a high content of harmonic MDS, including fractional orders, which are especially pronounced at q <1 (b = 0), which significantly worsens the performance of electric machines with such windings; as the number of winding phases increases, the harmonic composition of its MDS improves.

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

 The invention aims at performing a two-layer m = 12-phase. m '= 12-zone fractional winding at q = 6/7 and p = 7 in z = 12pq = 72 grooves while eliminating the most pronounced fractional harmonic from its MDF to reduce 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 = 6/7 and grouping in a series of 1 1 1 1 1 1 0, performed in z = 72 grooves m '= 12 -phase, m '= 12-zone of K = 72 coils with numbers from 1K to 72K at groove pitch y _p : coils 1K + 6 (k) and 6K + 6 (k) contain (1 + x) w _k coils 2K + 6 (k) and 5K + 6 (k) in w _k turns, and coils 3K + 6 (k) and 4K + 6 (k) in (1-x) w _k turns, in the first phase are connected in series - according to the coil 1K, 12K, 22K, 32K, 53K, 63K with the beginning of the phase from the beginning of 1K and its end from the end of 63K, and the coils of each subsequent phase are in turn are at intervals of 42 numbers within K = 72 relative to the coils of the first phase, wherein y _n = 3; w _to - the number of turns of each groove, x = 0.17 and the value of k in the numbers of coils varies from 0 to m'-1 = 11.

In FIG. 1 shows a scan along the grooves of the grooved layers with alternations of m: = 12-phase zones A-A'-Z-Z'-B-B'-X-X'-C-C'-YY 'of the proposed 2p = 14-pole, m = 12-phase, m '= 12-zone double-layer fractional winding at z = 72 grooves and q = z / 12p = 6/7 (N = 6, d = 7) with marking on top of the numbers of coils 1K, 12K, 22K, 32K, 53K, 63K of the first phase (zone A) and from 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 poles p = 7 (top) harmonic MDS (EMF) ν = 1 and p _ν = 5 harmonic MDS fractional order ν = 5/7 (in the center) at angles α _p = 360 ^° / z = 5 ^° and γ = α _n / 2d = 2.5 ^° / 7; figure 3 - construction of a part of the polygon MDS according to [3] of the winding of figure 1 at x = 0, where the center vectors of the currents of phase zones A-A'-Z-Z'-B-B'-X-X'- are shown C-C'-Y-Y '.

The winding of Fig. 1 at 2p = 14 poles, z = 72 grooves, m = 12 phases, m '= 12-phase zones is made of a two-layer of K = 72 coils with groove step at _n = 3 and has a fractional number of grooves per pole and phase q = 6/7 at N = 6, d = 7, i.e. according to the grouping [1] 1 1 1 1 1 1 0 from each N = 6 coils d = 7 coils are formed. To form the winding, a series of 12 groups 1 1 1 1 1 1 0 is written, phase zones in the sequence A-A'-Z-Z'-B-B'-X-X'-C-C'- are marked below it YY 'and the zones corresponding to the zeros of the series are crossed out, after which the grooves under the remaining numbers of the series are numbered sequentially, resulting in the alternation of phase zones along the grooves of Fig. 1.

и О-->32К=10•360^o/7+15γ, О-->63К-->20,5•35^o=10•/7-5γ
и О-->22К= 10•360^o/7+15γ, О-->1K-->30,5•35^o= 15•360^o/7-25γ и О-->12К= 15•360^o/7+25γ,
по которым построена диаграмма фиг.2 (в центре) при разбивке окружности на р=7 частей (360^o/7) с учетом встречного вращения гармонической МДС ν=5/7, где γ = α_п/2d = 2,5^°/7. По фиг.2 определяется коэффициент распределения с учетом неравновитковости катушек путем вычисления проекций ЭДС катушек на ось их симметрии (вертикальную), при коэффициенте K_yν = sin(ν90^°у_п/τ_п) укорочения катушек (для шага y_п=3, полюсного деления τ_п = z/2p = 36/7) затем определяется обмоточный коэффициент K_обν:
для

(при K_уν = 0,60876), откуда по условию K_обν = 0 определяется значение х= 0,17, при котором из ЭДС (МДС) обмотки фиг.1 устраняется гармоническая ν=5/7 с p_ν/= 5;
для

,
т. е. для равновитковой обмотки (х=0) амплитуда МДС гармонической ν=5/7 имеет относительное значение

или 10,15%,
а при x = 0,17-F_ν/F = 0. Дифференциальное рассеяние обмотки, определяемое из многоугольника МДС фиг.3 по [3] путем вычисления квадратов радиусов i=6 пазовых точек одной повторяющейся части обмотки относительно центра, для неравновитковой обмотки при х=0,17 снижается на ≈60%.The winding at m '= 12-phase zones and q = 6/7 (d = 7) creates a rotating MDF with harmonic in the series [2] ν = 12k / d ± 1 = 1 (+), 5/7 (-), 17/7 (-), 19/7 (+), ..., where ± k is any integer such that ν => 0 (k = 0 for the fundamental harmonic ν = +1), the sign (+) corresponds to harmonic direct and (-) inverse. To determine the shear angles of the coils of the first of the m '= 12 symmetric phases for the poles p = 7 (ν = 1) and p _ν = νp = 5 (ν = 5/7) in Fig. 1 (bottom), the shifts in the grooves between the coils 1K, 12K, 22K, 32K, 53K, 63K and the axis of their symmetry lies in the middle O between the coils 32K and 53K, then the coils are shifted to the angles relative to this axis:
for p = 7-1O → 53K → 10.5α _p p = 10.5 • 35 ^° = 367.5 ^° -360 ^° = + 1.5α _p
and O → 32K = -1.5α _p , O → 63K → 20.5 • 35 ^° = 717.5 ^° -720 ^° = -0.5α _p ,
and O → 22K = + 0.5α _p ,
and O → 1K → 30.5 • 35 ^° = 1067.5 ^° -1080 ^° = -2.5α _p
and O → 12K = + 2.5α _p ,
on which the diagram of figure 2 (upper) is constructed at an angle α _p = 5 ^° ;
for

and O -> 32K = 10 • 360 ^o / 7 + 15γ, O -> 63K -> 20.5 • 35 ^o = 10 • / 7-5γ
and O -> 22K = 10 • 360 ^o / 7 + 15γ, O -> 1K -> 30.5 • 35 ^o = 15 • 360 ^o / 7-25γ and O -> 12K = 15 • 360 ^o / 7 + 25γ,
according to which the diagram of Fig. 2 is plotted (in the center) when the circle is divided into p = 7 parts (360 ^o / 7) taking into account the oncoming rotation of the harmonic MDS ν = 5/7, where γ = α _n / 2d = 2.5 ^° / 7. Figure 2 determines the distribution coefficient, taking into account the unevenness of the coils by calculating the projection of the emf of the coils on the axis of symmetry (vertical), with the coefficient K _yν = sin (ν90 ^° _p / τ _p ) shortening the coils (for step y _p = 3, pole division τ _p = z / 2p = 36/7) then the winding coefficient K _{obν is determined} :
for

(at K _уν = 0.60876), whence, by the condition K _obν = 0, the value x = 0.17 is determined, in which the harmonic ν = _5/7 with p _{ν /} = 5 is eliminated from the EMF of the winding of Fig. 1;
for

,
i.e., for an equal-turn winding (x = 0), the amplitude of the MDS harmonic ν = 5/7 has a relative value

or 10.15%,
and at x = 0.17-F _ν / F = 0. Differential scattering of the winding, determined from the polygon MDS of Fig.3 according to [3] by calculating squares of radii i = 6 of the groove points of one repeating part of the winding relative to the center, for non-uniform winding at x = 0.17 decreases by ≈60%.

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 fractional harmonic order ν = 5/7 from the MDS, is symmetric m = 12-phase, m '= 12-zone and each phase is formed by coils of zones, respectively, A, A '; Z, Z '; B, B '; X, X '; C (42α since p = _n 5 • 42 7 = 1470 ^° -4 ^° • 360 ^° = 30 ^°). Its application in AD with short-C ', Y, Y' (from the displacement of the phases at the electrical angle of 30 ^o with a rotor when powered by a 12-phase current drive, it allows fourfold reduction of the phase current compared to 3-phase drives, which significantly reduces the cost of both controlled valves and the entire drive if the circuit is simplified.

Sources of information
1. Livshits-Garik M. Windings of AC machines / trans. from English M-L .: SEI, 1989, p.224 - prototype.

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

 3. Popov V. I. Determination of differential scattering of multiphase windings // Electricity, 1987, 6, pp. 50-53.

Claims (1)

Multiphase fractional (q = 6/7) winding of AC electric machines, made of 2p = 14-pole two-layer in z = 72 grooves with the number of grooves per pole and phase q = 6/7 of K = 72 coils with numbers from 1K to 72K and in increments of grooves y _p when they are grouped in a series 1 1 1 1 1 1 1 0, characterized in that for the number of phases m = 12, the coils 1K + 6 (k) and 6K + 6 (k) contain (1 + x) w _to turns, coils 2K + 6 (k) and 5K + 6 (k) - along w _to turns, and coils 3K + 6 (k) and 4K + 6 (k) - along (1) w _to turns, in the first phase are connected in series - according to the coil 1K, 12K, 22K, 32K, 53K, 63K with the beginning of the phase from the beginning of 1K and its end from the end of 63K, and the coils oh subsequent phases alternate with intervals of 42 numbers within K = 72 relative to the coils of the first phase, where _n = 3; 2w _k is the number of turns of each groove, x = 0.17, and the value of k in the numbers of coils varies from 0 to 11.

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