RU2224346C2 - Multiphase fractional-slot winding of ac machine - 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 frequency converter incorporated in variable-speed ac drive is m = 12-phase, m' = 12-section double-layer fractional-slot winding with pole per phase number q = 6/5 and p = 5 placed in z = 12 pq = 72 slots with most conspicuous fractional harmonic component removed from its magnetomotive force. It has ten pole pairs and is assembled of 12p = 60 coil groups numbered from 1G to 60C and slot pitch y_s of coils grouped in line 2 1 1 1 1. Each double-coil group 1G + 5(c) has (1-x)w_c turns per coil and (1-x)w_c turns for groups 3G + 5(c) and 4G + 5()c). Connected in series opposition in first phase are groups 1G, 13G, 25G, 37G, 49G with starting phase lead tapped from starting lead of 1G and its finishing lead, from finishing lead of 49G; groups of each next of m = 12 phases are alternating at intervals of 25 numbers within 60 groups relative to first-phase group, where y_s = 9; 2w_c is turn number in each slot; x = 0.13; c in coil group numbers varies between 0 and m' - 1 = 11 at number of phase sections m' = m = 12. 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 are 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 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, 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 for q = 1 + 1/5 = 6/5 and p = 5, performed by a two-layer in z = 6pq grooves with a grouping of coils in a row 2 1 1 1 1 (for c / d = 1/5 and b = 1), repeated 2m = 6 times [1].

 The invention aims at performing a two-layer m = 12-phase, m '= 12-zone fractional winding at q = 6/5 and p = 5 in z = 12pq = 72 grooves while eliminating the most pronounced fractional harmonic from its MDS to reduce the differential scattering [3].

The solution of this problem is achieved by the fact that for a two-layer fractional 2p = 10-pole winding with the number of grooves per pole and phase q = 6/5 and grouping in a row 2 1 1 1 1, performed in z = 72 grooves m = 12-phase, m '= 12-band of 12p = 60 coil groups numbered from 1G to 60G when the coils step along the grooves y _n: dvuhkatushechnye group 1D + 5 (k) comprise (1-x) w _{to the} windings in the coils, the single-coil - of w _to turns for groups 2G + 5 (k), 5G + 5 (k) and according to (1 + x) w _to turns for groups 3G + 5 (k) and 4G + 5 (k), in the first phase are connected in series - according to group 1G, 13G, 25G, 37G, 49G with the beginning of the phase from the beginning of 1G and its end from ontsa 49G, and each successive group phase alternated at intervals of 25 within the room 60 groups regarding groups of the first phase, wherein y _n = 9; 2w _k is the number of turns of each groove, x = 0.13, and the value of k in the numbers of groups varies from 0 to m'-1 = 11.

Figure 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 = 10- pole, m = 12-phase, m '= 12-zone double-layer fractional winding at z = 72 grooves and q = z / 12p = 6/5 (N = 6, d = 5) with marking on top of the numbers of groups 1G, 13G, 25G, 37G, 49G of the first phase (zone A) and the bottom of the groove numbers (from 1 to z = 72); figure 2 - diagram of the shift of the axes of the coil groups of the first phase for the polarities p = 5 (top) harmonic MDS (EMF) ν = 1 and p _ν = 7 harmonic MDS fractional order ν = 7/5 (in the center) at angles α _p = 360 ^° / z = 5 ^° and γ = α _n / 2d = 0.5 ^° ; figure 3 - the construction of the polygon MDS according to [3] of the winding of figure 1 at x = 0, where the vectors m '= 12-phase system of currents of phase zones A-A'-Z-Z'-B-B are shown in the center '-X-X'-C-C'-Y-Y'.

и 1Г-->49Г=7•72^o-7γ 1Г-->25Г-->28,5•35^o= 14•72^o-21γ и 1Г-->37Г=14•72^o+21γ, по которым построена диаграмма фиг.2 (в центре) при разбивке окружности на р=5 частей (360^o/5=72^o) с учетом встречного вращения гармонической МДС ν=7/5, где γ = α_п/2d = 0,5^°. 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=9 и полюсного деления τ_п = z/2p = 7,2) затем определяется обмоточный коэффициент K_обν: для p_ν = 7 (ν=7/5)

(при K_уν = 0,3827), откуда по условию K_обν = 0 определяется значение х=0,13, при котором из ЭДС (МДС) обмотки фиг.1 устраняется гармоническая ν=7/5 с p_ν = 7; для р= 5 (ν=1)

(К_у=0,92388), т.е. для равновитковой обмотки (х=0) амплитуда МДС гармонической ν=7/5 имеет относительное значение

или 2,40%, а при х=0,13 - F_ν/F = 0. Дифференциальное рассеяние обмотки, определяемое из ее многоугольника МДС фиг. 3 по [3] путем вычисления квадратов радиусов i=N=6 пазовых точек одной повторяющейся части обмотки относительно центра, для неравновитковой обмотки при х=0,13 снижается на ≈30%.The winding of Fig. 1 at 2p = 10 poles, z = 72 grooves, m = 12 phases, m '= 12 phase zones is made of two layers of 12p = 60 groups with coil spacing along the grooves y _p = 9 and has a fractional number of grooves per pole and phase q = 6/5 at N = 6 and d = 5, i.e. according to the grouping [1] 2 1 1 1 1 from every N = 6 coils d = 5 coils are formed. The winding at m '= 12 phase zones and d = 5 creates a rotating MDS with harmonic series [2] ν = 12k / d ± 1 = 1 (+), 7/5 (-), 17/5 (+), 19 / 5 (-), ..., 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 (-) inverse. To determine the angles of shift of the axes of the coil groups of the first of m '= 12 symmetric phases for the poles p = 5 (ν = 1) and p _ν = νp = 7 (ν = 7/5) in Fig. 1 (bottom), the grooves are marked between axes groups 1D, 13D, 25G, 37g, 49G, their axis of symmetry lies and 1D relative to its axis groups have angles axis for p = 5 - 1D → 13D → 14,5α _n p = 14,5 • 25 ^° = 362.5 ^° -360 ^° = + 0.5α _p and 1Г → 49Г = -0.5α _p , 1Г → 25Г → 28.5 • 25 ^° = 712.5 ^° -720 ^° = -1.5α _p and 1Г → 37Г = + 1,5α _p , according to which the diagram of figure 2 (upper) is constructed at an angle α _p = 5 ^° ; for

and 1G -> 49G = 7 • 72 ^o -7γ 1G -> 25G -> 28.5 • 35 ^o = 14 • 72 ^o -21γ and 1G -> 37G = 14 • 72 ^o + 21γ, according to which the diagram of Fig. 2 is constructed (in the center) when the circle is divided into p = 5 parts (360 ^o / 5 = 72 ^o ) taking into account the oncoming rotation of the harmonic MDS ν = 7/5, where γ = α _n / 2d = 0.5 ^° . Figure 2 determines the distribution coefficient, taking into account the unequal coils by calculating the projection of the emf of the coils on the axis of symmetry (vertical); with the coefficient K _yν = sin (ν90 ^° у _п / τ _п ) shortening the coils (for step y _п = 9 and pole division τ _п = z / 2p = 7,2) then the winding coefficient K _{obν is determined} : for p _ν = 7 (ν = 7/5)

(when K _уν = 0.3827), whence, by the condition K _obν = 0, the value x = 0.13 is determined, in which the harmonic ν = _7/5 with p _ν = 7 is eliminated from the EMF of the winding of Fig. 1; for p = 5 (ν = 1)

(K _y = 0.92388), i.e. for an equal-turn winding (x = 0), the amplitude of the MDS harmonic ν = 7/5 has a relative value

or 2.40%, and at x = 0.13 - F _ν / F = 0. The differential scattering of the winding, determined from its polygon MDS Fig. 3 by [3] by calculating squares of radii i = N = 6 of the groove points of one repeating part of the winding relative to the center, for a non-turn winding at x = 0.13 it decreases by ≈30%.

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 = 7/5 from the MDS (EMF), is symmetric m = 12-phase, m '= 12-zone and each of its phases is formed by coil groups of zones, respectively, A, A ', Z, Z', B, B ', X, X', C, C ', Y, Y' with a shift of the phases on an electric angle of 30 ^o (since interval 25 corresponds groups electrical phase-shift angle started 25α _n pq = 25 • 25 ^° 6/5 = 750 ^° -2 • 360 ^° = 30 ^°). Its application in a squirrel-cage rotor HELL powered by a 12-phase current drive allows you to reduce the phase current by four times compared to a 3-phase drive, which significantly reduces the cost of controlled valves and the entire drive if 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, 6, p. 50-53.

Claims (1)

Multiphase fractional (q = 6/5) winding of AC electric machines, made of 2p = 10-pole double-layer in z = 72 grooves with the number of grooves per pole and phase q = 6/5 of 12p = 60 coil groups with numbers from 1G to 60G with the step of the coils in the grooves in _p and their grouping in a series of 2 1 1 1 1, characterized in that when the number of phases m = 12 and phase zones m '= 12, two-coil groups 1G + 5 (k) contain (1 - x ) w _for turns in coils, single-coil for w _for turns for groups 2G + 5 (k), 5G + 5 (k) and for (1 + x) w _for turns for groups 3G + 5 (k) and 4G + 5 (k), while in the first phase they are connected in series – according to groups 1G, 13G, 25G , 37g, 49G with the beginning of the start phase 1G and 49G end of its end, and each successive group phase are alternated at intervals of 25 within the room 60 groups regarding groups of the first phase, where _n = 9; 2w _k is the number of turns of each groove, x = 0.13, and the value of k in the numbers of groups varies from 0 to m '- 1 = 11.

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