DE2612787A1 - INVERTER DEVICE WITH N-PHASE OUTPUT - Google Patents

Description

MANITZ. FINSTERWALD & GRÄMKOW

! • Einhen, the 25th MSZ. t97ß P / 3 / t> - K

THE MAECÖHI COHPMT LIMIiEED Marconi House, Hew Street Chelmsford, Essex, England

Inverter device with n-phase output

The invention relates to inverter devices, i.e. devices for generating alternating wave trains from direct current sources

For several years inverter devices were generally in the form of square wave generators, followed by an LC (inductance / capacitance) Filter "known. With large inverter facilities, bulky and heavy filters had to be used can be used for this purpose. Often times the weight of the filter was half the weight of the entire apparatus.

Recently, inverter devices have been developed which have a multi-pulse "waveform to generate a required alternating waveform. Also such inverter devices require the installation of output filters, although the filtering requirements in the case of an inverter device according to the patent application filed at the same time "Inverter with logic switching elements" (our file number M 3II5) be a little less annoying than it is commonly used could.

DR. G. MANtTZ · DtPL.-rNG. M. FINSTERWALD DIPL- [MC. W. G R. AMKOW ZENTRALKASSE BAYER. FOLK BANKS

β MÖNCHEN 23, ROBERT-KOCH-STRASSE I 7 STUTTGART SO CBAD CANNSTATT) MÖNCHEN. ACCOUNT NUMBER 72TO

TEL. f 089) 22 * 2 «. TELEX 5-29673 PATMF SEELBERGSTR.23 / 25.TEL. {O7 «) 56r2; 6l POSTSCHECKr MÖNCHEN 7700 2-BOS

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The invention is intended to provide an inverter device which avoids the use of large, bulky LG piIter vj he can.

In accordance with this invention, an inverting device comprises yields an output with a given number of η phases, a facility to use a polyphase waveform to generate a number of _g_ symmetrical phases, facilities, to convert these generated polyphase waveforms to a static transformer that converts phases and facilities for deriving an n-phase output from that transformer.

Static, phase changing transformers are described by J.E. Parton in the I.E.E. Monograph No. 13, published November 15, 1951 (Proc. I.E.E. Volume 99, Part N, 1952, pages 12 to 23).

The invention uses the cancellation of the harmonic waves, which is a by-product of such static phase transformers to a sufficiently low proportion to generate harmonic harmonics in an inverter direction, the bulky ones usually required for this and weighty LC-3 filters can be avoided.

The number £ should not be equal to the number η, and normally is £ greater than n. Typically, when a three-phase output is required (i.e. when η is equal to is), the means for generating the above-mentioned waveform are chosen so that this waveform is five symmetrical Has phases. Usually, but not necessarily, £ and η are odd numbers.

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The static phase converter transformer preferably has as many legs as there are phases from the generator device and it has as many secondary windings around each leg as there are phases from the output waveform are required.

The invention is particularly applicable to an inverter according to the patent application filed at the same time
"Inverter with logic switching elements" (our file number M 3115) described invention. The combined effect of the two inventions is to provide an inverter device that is relatively very compact and that stands out from the crowd
characterized from the outset with a very low content of harmonic waves in their output waveform.

The invention is explained in more detail below with reference to the drawing, for example. In the drawing shows:

Figure 1 is a schematic drawing of a three-phase inverter device according to the invention,

Figures 2 and 3 cti-e synthesis of two of the phases of the initial Vellenzuges the inverter device! ig. 1 and

FIG. 4 shows the representation of individual phase vector diagrams.

J.E. Parton proved that with a static phase change transformer, as he had described it in his monograph mentioned above, a compensatory transformation takes place, when the number of turns form a matrix of values which corresponds to the cosine values of the phase angles involved.

From symmetry considerations it follows that in a three-phase system the third, sixth and ninth harmonic waves have the same phase position for all three input phases,

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i.e. they have a zero phase sequence. It follows that each Connection that cancels out zero-phase sequence parts, what e.g. a delta or a star connection does, these harmonic waves with an ordinal number divisible by three. The extinction in the more general case occurs when the phase vectors for the harmonic waves concerned form a closed polygon. In the special one In the case of a three-phase system, the polygon has an area of zero. It can be shown that in a system of K phases the polygon will always close, except for harmonic harmonics of ordinal number 2ES + _ 1, where S is an integer or Is zero.

Are on the transformer K-legs, each with the same Number of turns, and with a K-phase, balanced source, an in-phase system can be obtained, infdem the windings in the through the The following matrix must be attached in the given proportions

cos O cos 2π cos 2 * 2π

K ~ K

cos 2% cos

(Z% + 2%) cos (2% + 2 * 2%)

(S "K") (n K)

cos 2i 2it cos (2 * 2% + 2%) cos (2 jp 2% + 2 * 2%)

ΪΓ (, η Κ) (η K)

The expression in the pth row and the qth column is then [(p - 1) 22S + (q - 1) ψ

The primary voltage in the qth column can be expressed as V sin m (wt + (q - 1) ψί) , where m is the harmonic ordinal number .

The secondary voltage is therefore

V sin ra (wt + (q - 1) 2π) cos ((p - Ί) 2π +

K ⁿ

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at any turn. · · '■ ·' ^: ·.

The sum of the voltages for the pth phase is therefore m (wt ₊ (q-1) 2x) cos ((p - 1) 2 * ₊ (q - 1) ψ)

v £ sin m wt cos (q - 1) | ™ 'cos ((p - D ψ * (q - 1) | s

₊ V ^ cos m wt sin (q - 1) ρ cos ((p - 1) & +. H "1) | S

V sin m wtXcos (q - 1) 2 ^ m cos (p - 1) 2π cos. (q - 1) ψ

V sin mwtScos (q - 1) ^ m sin (p - 1) ψ sin (q - 1) ψ

₊ V cos m wtSsin (q - 1) 2 * n · cos (p - 1) 2 * cos (q - 1) ψ

Λ K ⁿ

-fV COS m wt> ^ in (q - 1) 2 £ η sin (ρ - 1) 2 * sin (q - 1)

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V sin m wt cos (ρ - 1) 2π / cos (q - 1) 2πΐη cos (q - 1) _2_π

ίρ ^{κ κ}

V sin ra wt sin (p - 1) 27t ^ cos (q - 1) 2-rcm sin (q - 1) 2%

"^ ^KK

+ V cos m wt cos (p - 1) 2π, / sin (q - 1) 2ππι cos (q - 1) 2tc

ⁿ «μ ^KK

- V cos m wt sin (p - 1) 2π> sin (q - 1) 2-rcm sin (q - 1) 2it

f K K "

= V sin m wt cos (ρ - 1) ^ 2? Cos (q - 1) (m + 1) 2 / n. ₊ cos (q - 1) (m - 1) ifj

+ V sin m wt sin (p - 1) 2x / (sin (q - 1) (m + 1) 2 π _- sin (q - 1) (nv - 1) 2 £ J 2 η r ^ KK /

+ V cos m wt cos (p - 1) 2 - ^^ fine (q - 1) (m + 1) 2tc ₊ sin (q - 1) (m - 1)

nf * K K

+ V _- COS m wt sin (p - 1) 2i £ / (cos (q - 1) (m + 1) 27t_cos (q _ 1) ( _m - 1) 2π \ ^ 2 u η λΓ ^ Ι Κ Κ /

Now represents ^ acos (g - 1) (m + 1) ^ - the sum of the projections of the Sides of a closed polygon and is = zero, if not

m + 1 is equal to a multiple of K. Then the sum is simply ■

Ic

The same applies to ^ cos (q.-1) (m-1) fü-, only this time the Sum = zero except when m = 1.

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similarly, the sine expressions also result in zero, only there there are no exceptions here if m = 1 or K - 1.

The value of the output is therefore equal to lull, unless m = 1 or K - 1, or to be more precise 2SK + _ 1, where S is an integer or zero. The output voltage is then:

VK sin (m wt + (p - 1) 2i *).
2 "n ~

The output value is therefore composed of a balanced set of η phases, each of which is only the fundamental frequency and contain harmonic waves whose ordinal numbers are adjacent to integer multiples of double the phase number are.

In the case of a five-phase system, the output consists of:

G round frequency, 11th, 21st, 31st ... harmonics with

positive sign

9th, 19th, 2 ° / be ... harmonics with negative sign.

The closing of the polygon depends on whether the phase sequence of the harmonic waves appears in normal order, as a zero phase sequence, or jumping. The consequences for the harmonic waves ^ related to the transformer input, are:

Basic frequency ^ 11th etc. 1 2 3 ² I- 5

3rd, 13th ... etc. 14 2 5 3

5th, 15th ... etc. 11111

7th, 17th ... etc. 13 5 2 4

9th, 19th ... etc. 1 5 4 3 2

will be eliminated

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If an input wave train, which consists of a symmetrical multiphase system, is fed into a phase-changing transformer, the harmonic harmonics in between disappear. This is true regardless of the harmonic spectrum of the input, provided that symmetry is maintained. Even in the worst possible case, a square wave output, are the first harmonic waves that are encountered in the output, those of the 9th and 11th order, theoretically respectively 11.1% and 9.1% _? based on the fundamental wave.

Use is made of this characteristic in the invention.

In Figure 1, 1 represents a five-phase inverter which provides a five-phase output waveform which is not smoothed for any other than the naturally occurring harmonic cancellation when the inverter 1 in accordance with the invention is at the same time as mentioned above filed patent application is. The five phases supplied by the inverter 1 are symmetrical. In order to provide a symmetry of the phases, the inverter 1 contains five identical power stages, which are driven by a Johnson counter and are switched five times faster than the output frequency prescribes. Two of the outputs are inverted to produce the required symmetrical phase pattern.

The static phase transformer 2 contains as many legs as there are phases at the output of the inverter 1, that is to say five, and these are _{denoted by 3 5} 4- »5 ₅ 6 and 7, respectively. Each leg contains a primary winding, each named 8, 9, _5, 10, 11 or "12. Each phase of the inverter 1 is connected to one of the primary windings 8 to 12.

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The three output phases, each at the output terminals 13? 14 and 15 appear, are represented by the three secondary windings, each between one of the output terminals 13, 14bzw. I5 and a common line connection 16 extend, generated. As can be easily seen, each secondary winding has turns around each of the legs 3, 4, 5, 6 and 7.

The numbers of turns are summarized below, where A denotes the beginning and E the end of the winding;

Schen
kel 3 Schen
kel 4- E. Schen
kel 5 E. Schen
kel 6 fencing
skel 7 Primary A 100 E A 100 E. A 100 A. A 100 SjA 100 E Secondary to the off
input terminal 13 A 200 E A 62 A. E 162 A. E 162 a'a 62 E.
j
r
} Secondary to the off
gang ski emme 15 E 100 A E 196 E. E 20 E. A 182 E'A 134 E.
!
t Secondary to the off
input terminal 14 E 100 A A 134 A 182 E 20 Af E 196 A
I.
i

The synthesis of the output phases appearing at the output terminals 12 and I3 are shown in FIGS. 2 and 3, respectively. Both in Fig. 1 and in Fig. 2, a. the output voltage appearing at the terminal in question and b_, £, el, e_ and f_ represent the contributions resulting from the windings on legs 3, 4, 5, 6 and 7, respectively.

existing at the outputs

With such an arrangement, the percentages are harmonics Measure harmonics (up to the 2nd harmonic) as follows:

Phase A - symmetrical

Phase B - asymmetrical

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Order of A. B. Order of A. B. Harmonics 100 100 See harmonies 0.5 0.4 Fundamental frequency 0.4 0.2 12th 0.5 0.1 2. 1.5 2.1 15th 0.25 0.2 5. 0.5 0.1 14th 0.2 0.5 4th 1.0 1.9 15th 0.1 0.2 5. 0.5 0.2 16. 0.1 0.1 6th 0.9 0.6 17th 0.45 0.55 7th 0.5 0.4 18th 6.5 5.25 8th. 15.0 10.8 19th 0.55 0.5 9. 0.6 0.1 20th 5.5 4.5 10. 9.8 8.8 21. 11.

that only the 9 «» 11 · »19 and 21st harmonic harmonics are present in a significant proportion. Some other components are likely to come from a light one Asymmetry in the phases given to the transformer or in the residual magnetism in its core or in the rounding up the number of turns to whole numbers.

When the two phases appearing at output terminals 12 and 15 are recorded, it should be noted that although both are good approximations of sine waves, they are not identical to one another. The reason for this is that the 9th and 11th, as the harmonic components which play the greatest role, have negative and positive phase sequences and are therefore not in the same phase relationship to the fundamental wave in all three outputs. The outputs of the three phases at the nth harmonic are:

sin (n wt ₊ 120 °), 5_ ^s * ⁿ ( ^{n wt} ~ ¹²⁰ °)

5 sin η wt, 1_ (

2n "2n 2n

5 sin η (wt + 120 °), ^. sin η (wt - 120 °). 2n ²ⁿ

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The neutral point on the primary side has a voltage measured relative to the midpoint of the supply rails, which has the shape of a square wave with the frequency of fifth harmonic and the amplitude of one fifth of the supply voltage accepts. This point can be traced back to the midpoint of the "supply voltages" without change the output waveform.

The initial connection of the five phases results in a severely torn waveform on every single turn. Around to reduce the eddy current losses, it seems better to use a waveform with fewer discontinuities that can be obtained when the phases are as wide as possible be connected away from each other. The result is one

the
"Five-star" connection, with / the windings a closed one

Form a loop with the following sequence:

End 1 at beginning 3
End 3 at beginning 5
End of 5 at the beginning of 2
End 2 at beginning 4
End 4 at beginning 1

Will have the same matrix of number of turns ratios

will

If a three-legged transformer is wound and / three individual windings with the same number of turns are connected as a three-phase output, a three-to-five phase converter system is formed. Can this be shown to work and cancel the harmonics in the same way _? like the five-legged transformer in FIG. 1. If the connection is reversed, the power is transformed in the opposite direction. The waveform observed between phases is similar to that generated with the five-legged transformer, but the system gives

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M ■

now a short circuit instead of an open circuit for the harmonic components. This design could be used in a system which operates from a constant current source, such as a high voltage DC link. Since there are only individual windings on the three-phase side, there is no cancellation of the zero-phase sequence components in the connection to the neutral voltage. With a compensating winding of two turns around the middle leg and one reverse turn each on the side legs, the components of the zero phase sequence disappear. So an equalizing output winding should be used when a neutral point is required.

In Fig. 4- the phase vector diagram shows how the entire output voltage is built up from the five secondary windings. The ratio of the output voltages to the Number of turns related to the leg in phase is:

1 + 2 cos ² 72 ° + 2 cos ² 144 ° = 0.7725 1 + 2 cos 72 ° - 2 cos 144 °

For a winding with three legs it is:

1 + 2 cos ² 120 ° = 0.75
1 - 2 cos 120 °

As the number of turns increases, the ratio approaches

The current waveforms in the windings, both in the primary and secondary, are approximately sinusoidal and become completely sinusoidal with a small amount of filtering.

- patent claims -

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Claims (4)

Claims 1. / inverter arrangement that has an output with a given Number of η phases, thus g e k e η η indicates that a device (1) for generating a polyphase waveform with a number g of symmetrical Phases and devices (8, 9 »10, 11, 12) for feeding this generated polyphase waveform to a static transformer (2) which converts g to η phases Means (13, 14-, 15) for deriving the η phases of the Output from this transformer are present. 2. Inverter arrangement according to claim 1, characterized in that £ and η are odd numbers and £ _ is greater than η. 3. Inverter arrangement according to claim 2, characterized in that g is equal to five and η is equal to three. 4. Inverter arrangement according to any one of the above claims, characterized in that the static, phase-changing transformer (2) has a number of legs (3j 4-, 5 * 6) 7) which is equal to the number £ of through the generator (1) generated phases and a number of secondary windings (13, 14, 15) »each leg (3, 4, 5, 6, 7), which is equal to the number η of phases of the Output waveform. 5 · Inverter arrangement according to one of the above claims, characterized characterized in that the generator device (1) an inverter according to the simultaneous patent application "Inverter with logic switching elements" (file number M 3115) is. 709825/0590 ORIGINAL INSPECTEP