CN2641908Y - Low excitation inrush current, low operation overvoltage phase-shifting transformer - Google Patents

Abstract

The utility model provides an input phase-shifting transformer which is matched to multilevel high-pressure large-power inverter with series units. An inner winding is arranged with a structure of multilevel cylinder loop or that of axial twin bundled cylinder loop. The inner winding is provided with double electrostatic shields, which can be grounded, or connected with the inlet or the outlet terminal of a high pressure coil simultaneously or separately. The outer winding is arranged with a single-pie style or a plurality of pies in parallel style or a multilevel cylinder style. The outer winding is arranged with a vertical airway which is formed by a corrugated metal sheet. The transformer costs low and the corrugated metal airway has a good effect of heat dissipation. The utility model is a novel phase-shifting transformer with low magnetizing inrush current and low switching overvoltage.

Description

Low magnetizing inrush current, low switching overvoltage phase shifting transformer

Technical field:

The utility model relates to a critical component supporting with unit cascade type multi-level high-voltage big-power transducer (hereinafter to be referred as frequency converter)---(input) phase shifting transformer, particularly be low magnetizing inrush current, low switching overvoltage phase shifting transformer.

Background technology:

In unit cascade type multi-level high-voltage big-power transducer, (input) phase shifting transformer is indispensable parts, and this from following analysis as can be known.

Do high voltage converter with the low-voltage power electronic component two kinds of methods are arranged usually: the one, directly to connect with low voltage component, another kind of method is to use independently power unit cascade, the latter becomes the main flow of high-voltage high-power frequency transformator because of than the former more advantage being arranged.

Below be the principle explanation and the transformer effect therein of this frequency converter.Fig. 1-1, Fig. 1-2, Fig. 1-3 represent the typical voltage stack of 3KV, 6KV and 10KV system schematic diagram respectively, are example with the 6KV frequency converter.

It every by 6 independently, rated voltage is that the low pressure and low power units in series of 577V (peak value is 816V) forms, the output phase voltage is that 3462V line voltage can reach about 6000V.Each power cell bears whole output currents but the power output of 1/6 phase voltage and 1/8 only is provided.

Each power cell is respectively by one group of secondary winding power supply of transformer, mutually insulated between the power cell and between the transformer secondary winding.Its electrical structure principle schematic as shown in Figure 2, for constituting the circuit theory schematic diagram of 6 grades of frequency converters, Fig. 3 is power cell figure.

The phase shifting transformer electrical schematic diagram is as shown in Figure 4: transformer (is example with 6KV frequency converter input transformer) former limit winding is 6KV, and totally ten eight windings of secondary is divided into three-phase.Each winding is the extend-triangle connection, have respectively ± 5 °, ± 15 °, ± phase shift angles such as 25 °, each winding connects a power cell.This phase shift connection can be eliminated the harmonic wave below 35 times effectively, can not cause Harmonic Interference above national standard to electrical network, and realize the electrical isolation step-down.

Clearly phase shifting transformer has played two keys in this frequency converter: the one, thus the electrical isolation effect just can make the series connection of the separate realization of each frequency conversion power unit voltage superposition, and the 2nd, the phase shift connection can be eliminated the harmonic wave below 35 times effectively.(can eliminate following harmonic wave in theory 6n-1 time, n is a unit progression).

Phase shifting transformer operation the time must be with up-conversion unit operations switch to power on and descend electric, so the switching overvoltage that produces because of transient process of transformer safety that will inevitably jeopardize electronic component in the converter unit.Usually the switching overvoltage of the phase shifting transformer of 10KV level and following electric pressure generation can not cause danger to transformer itself, but is fatal concerning electronic component.The switching overvoltage of therefore managing to reduce transformer is one of emphasis of this transformer of design; The magnetizing inrush current of this transformer also very big (the excessive reason of shoving be the coil of transformer energising in inside near iron core) in addition, excessive magnetizing inrush current can cause the power switch tripping operation, the cut-off overvoltage that produce this moment higher (in the past the phase shifting transformer of design principle design transformer often takes place cause that in the moment of closing a floodgate switch trip also causes the over-voltage breakdown phenomenon of element simultaneously) routinely, the magnetizing inrush current that reduces transformer be this transformer of design main points two.

Existing phase shifting transformer exists switching overvoltage that the fatal harm and the excessive magnetizing inrush current of electronic component are caused two big shortcomings such as power switch tripping operation.And the high pressure of transformer and low-voltage coil structure are continous ways.

Summary of the invention:

The purpose of this utility model is to shift to transformer in order to overcome the existing transformer generation switching overvoltage of shifting to the low magnetizing inrush current that the ad hoc meter of magnetizing inrush current that reduces transformer is a kind of and unit cascade type multi-level high-voltage big-power transducer is supporting, low switching overvoltage.

Feature of the present utility model is that interior loop (high-tension coil) is multilayer garden cartridge type loop construction, and big capacity adopts the garden cartridge type loop construction of axially two division formulas; Interior loop (high-tension coil) is provided with the structure of two electrostatic shieldings, and electrostatic shielding can be simultaneously or independent grounding, connect high-tension coil inlet wire or outlet terminal, and exterior loop (low-voltage coil) adopts single cake formula or a plurality of single cake parallel.Exterior loop (low-voltage coil) adopts the short garden of multilayer cartridge type.Exterior loop (low-voltage coil) adopts the uptake ventilator that is formed by corrugated metal sheet.

The measure of restriction switching overvoltage is:

1. strengthen the excitation impedance Z of transformer _mAnd interior loop (high-tension coil) direct-to-ground capacitance C

After deliberation: the cut-off overvoltage U that produces during the no-load transformer outage _CmWith rated voltage U _oRatio K _vBe that the overvoltage multiple is determined by following formula:

$K_v=\frac{U_{\mathrm{cm}}}{U_o}=\frac{I_o{Z}_o}{2\mathrm{\&pi;}{\mathrm{fL}}_m{I}_o}=\frac{\sqrt{L_m/\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y0323349000142.png,Y0323349000151.png"\; state="\{\{state\}\}">C</figure-callout>}}}{2\mathrm{\&pi;}{\mathrm{fL}}_m}=\frac{\frac{1}{2\mathrm{\&pi;}\sqrt{L_{m}C}}}{f}=\frac{f_o}{f}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;1$

Wherein:

$U_{\mathrm{cm}}=\sqrt{{\left(I_{\mathrm{ch}}{Z}_o\right)}^2+U_o^2}\&ap;I_{\mathrm{ch}}{Z}_o=I_o{Z}_o=I_o\sqrt{\frac{\mathrm{Lm}}{C}}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;2$

I _Ch---the switch shut off value

I _o---the no-load transformer electric current

Z _o---the transformer characteristic impedance $Z_o=\sqrt{\frac{\mathrm{Lm}}{c}}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;3$

L _m---static exciter inductance L m ≈ Zm/ ω ... 4

Z _m---the static exciter impedance

C---transformer interior loop (elementary) direct-to-ground capacitance

f _o---the frequency of oscillation after damming $f_o=\frac{1}{2\mathrm{\&pi;}\sqrt{L_{m}C}}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;5$

F---electrical network power frequency

Clearly strengthening excitation impedance has also just strengthened magnetizing inductance and interior loop direct-to-ground capacitance this all can reduce the overvoltage multiple.

2. interior loop adopts multilayer garden tube double shield formula structure; The ectonexine that two electrostatic shieldings are placed on coil respectively with the starting and receive head and be connected of coil as Fig. 5.

By traditional design principle: the 6-10kV level capacity surpasses the high-tension coil structure continous way normally of the transformer of 630kVA, the transformer in this patent design, and the high-tension coil of 300-6300kVA all adopts multilayer garden core structure.

The benefit that primary coil adopts multilayer garden cartridge type to add two electrostatic shieldings is:

The garden vertical electric capacity of cartridge type coil is big, has increased the anti overvoltage impact capacity of transformer coil itself;

The heat radiation air flue of interior loop is a uptake ventilator, and its heat dispersion is better than the horizontal air flue of continuous winding greatly.

The effect of electrostatic shielding has 2 points:

(1) increases the direct-to-ground capacitance C of coil, thereby also reduced the overvoltage multiple.

(2) reduced the electrostatic component that impulse overvoltage is delivered to secondary;

When the surge voltage ripple intrudes into a certain winding of transformer, because the electromagnetic coupled between winding also overvoltage can occur on other windings of this transformer.The voltage transmission has two components basically between winding, and first Electrostatic Coupling produces, and it two is that electromagnetic coupled produces.Only study the former herein---electrostatic component.

Intrude into moment of Transformer Winding at the surge voltage ripple, because electric current can not suddenly change in the inductance, so the transmission of voltage is carried out with the Electrostatic Coupling form between the initial time winding.Fig. 6 is the equivalent line map of the capacitive coupling between two windings of transformer:

When surge voltage invasion winding 1-1, winding 1-1 above earth potential is U _o, because electrostatic component u appears in the electrostatic capacitance coupling on winding 2-2 ₂As shown in the formula:

${\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="Y0323349000142.png,Y0323349000151.png"\; state="\{\{state\}\}">u</figure-callout>}}_2=\frac{C12}{C12+C2}{U}_o\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;6$

C12, C2 are respectively coupling capacitance between winding 1-1 and winding 2-2 and the direct-to-ground capacitance of winding 2-2 in the formula.Winding 2-2 is a secondary valve side winding in phase shifting transformer, is placed on the outside of net side winding 1-1, and is far away apart from iron core.When not adding electrostatic shielding, direct-to-ground capacitance C2 is less, and coupling capacitance C12 is bigger, the surge voltage u that is coupled the winding 2-2 as can be known from formula 6 ₂Higher.

After having added electrostatic shielding, by two capacitances in series, numerical value reduces coupling capacitance C12 as shown in dotted line garden, Fig. 6 middle and upper part, and the direct-to-ground capacitance C2 of winding 2-2 increases, the surge voltage u that is coupled among the winding 2-2 as can be known from formula 6 ₂Reduce.

3. low-voltage coil adopts multiple version: 1) continuous cake formula (traditional structure), 2) single cake formula or a plurality of single cake parallel (imitative Luo Binkangshi), 3) short garden cartridge type and increase the corrugation air flue that forms with pressing metal plates at interlayer, the art of this patent introduction be back two kinds of versions.

The version great majority sections of being of domestic and international each unit winding of phase shifting transformer secondary are pie winding continuously, the coiling characteristics be between positive section circle and circle be in order the width of cloth to accumulation, must " fall to coil " in the time of anti-section, the total number of turns of each unit be a several sections line cake number of turn sums, complex process.Its outward appearance such as coiled mosquito-repellent incense.Electromagnetic wire is that glass fibre or insulation film hold.Each unit winding of the phase shifting transformer secondary of U.S. sieve guest Kanggong department is pressed the winding method coiling of continous way winding with bare copper strip, need not " fall to coil ", each unit is with regard to only one section, be called single cake formula, start to weld from air flue between cake with lead wire and draw, turn-to-turn pad insulation board is owing to be bare copper strip, creepage for preventing turn-to-turn, the necessary every hem width of turn-to-turn pad insulation board is in about bare copper strip 10mm.

One of version of present technique transformer secondary simplex winding is used for big current unit winding for many single cakes parallel (imitative Luo Binkangshi).

Winding current is excessive when the unit, adopts multiple conducting wires to come coiling technology just very complicated by the winding method of continous way winding, even is difficult to moulding.

Present technique adopts many parallel structures of single cake for the transformer secondary unit winding of big electric current; See Fig. 7 design feature: (with continuous cake formula and Luo Binkangshi difference)

1) turn to single cake formula line segment with single electromagnetic wire, each line segment has comprised whole wire turns of a phase-shifting unit, (with continuous pie winding dissimilarity)

2) according to the size of electric current and the manufacturing dimension of electromagnetism wire gauge permission, select the mode (with continuous pie winding dissimilarity) of several line segment parallel connections for use

3) lead be insulating bag around electromagnetic wire, and without bare copper strip, thereby technology is simple, the line segment end is neat, good looking appearance (with Luo Binkangshi winding dissimilarity)

4) according to the heat generating spot temperature rise of coil itself, can in the middle of line segment, set up the uptake ventilator (with continuous pie winding dissimilarity) that forms by corrugated metal sheet

Two of the version of present technique transformer secondary unit winding is short garden cartridge type: see Fig. 8

Its winding method is pressed the coiling rule of laminar winding, be by axially-aligned between circle and the circle both, but outward appearance is similar to pie winding.This version is applicable to that the unit winding current is less, electromagnetic wire cross section smaller transformer.

The advantage of short garden cartridge type winding is simple except technology, the flakiness ratio of electromagnetic wire wire gauge is required unlike pie winding the harshness, also have its unique advantage: vertically electric capacity and direct-to-ground capacitance are big, winding withstand shocks the electricity ability strong, also reduced auxiliary winding Electrostatic Coupling voltage; The uptake ventilator that is formed by corrugated metal sheet is also set up in the winding heat radiation except horizontal air flue, the latter's heat-sinking capability is better than the former greatly, the temperature rise of winding is low, thereby can reduce conductor cross-section, the material cost employing metal corrugation air flue that reduces transformer also is the important breakthrough in the art of this patent:

Traditional coil heat radiation air flue all is to form by placing insulation palm bar or cross-over block.Do air flue with metal material, as deal with improperly and can insulate by the damage electromagnetic wire, cause turn-to-turn short circuit, consequence is hardly imaginable.The metal corrugation air flue that uses in this patent is through special PROCESS FOR TREATMENT, and it is perfectly safe to have accomplished.

The advantage of metal corrugation air flue is: metal material good heat conductivity, thereby good heat dissipation effect; Vertical electric capacity of coil is big, narrates before its benefit.

Present technique is mainly calculated by electromagnetism in order to the measure of restriction magnetizing inrush current and the structural design of magnet exciting coil is controlled; The instantaneous several times that surpass its load current value of magnetizing inrush current that common no-load transformer closes a floodgate and produces; promptly surpass hundreds of times of stable state no-load current; so big magnetizing inrush current just be should give consideration owing to very shortly in fact the coil of transformer is safe from danger its action time when adjusting relay protection.If not, after the no-load transformer combined floodgate causes switch protection tripping operation excision transformer, may think it is that transformer is out of order by mistake.For with the supporting phase shifting transformer of frequency converter: switch protection tripping operation when fundamentally just not allowing Transformer Close, when load transformer close a floodgate cause switch protection tripping operation excision transformer after because the switch excision is inductive current, shut off value I _ChGreatly, the cut-off overvoltage of generation also very high (seeing formula 2), therefore the electronic component in the as easy as rolling off a log damage frequency converter must be enough little with the supporting phase shifting transformer magnetizing inrush current of frequency converter.

According to theory analysis: the maximum I of its magnetizing inrush current behind the three-phase transformer idle-loaded switching-on _OmComputing formula is as follows:

$I_{\mathrm{om}}\&equiv;B_m{\mathrm{HD}}_t^2\left({\mathrm{WD}}_x^2\right)$

Wherein: B _mMagnetic unshakable in one's determination is close

D _tCore-diameter

H closing coil height

The W closing coil number of turn

Dx closing coil diameter

Reduce magnetizing inrush current, can set about from the following aspect: fall low magnetic density, reduce the closing coil height, reduce the number of turn and the diameter of core-diameter or increase closing coil.

Clearly: the transformer of low magnetizing inrush current also has some defectives: far above cost unshakable in one's determination, total cost can increase to some extent as the electromagnetic wire cost; (one of transformer optimal design principle: copper valency=iron valency) transformer is pyknic, and is not attractive in appearance; Floor space is big.

So the selection of magnetizing inrush current is low and suitable.

The beneficial effects of the utility model are: reduce the switching overvoltage that phase shifting transformer produces 1.; Increase the safety of electronic component in the converter unit.2. reduce the magnetizing inrush current of transformer, but accurate Calculation inrush phenomenon and choose reasonable inrush phenomenon multiple.3. metal corrugation air flue, metal heat-conducting is good, good heat dissipation effect, vertical electric capacity of coil is big, reduces auxiliary winding Electrostatic Coupling voltage.

Description of drawings:

Fig. 1-1 3KV frequency converter voltage stack schematic diagram

Fig. 1-2 6KV frequency converter voltage stack schematic diagram

Fig. 1-3 10KV frequency converter voltage stack schematic diagram

6 grades of 6KV frequency changer circuits of Fig. 2 principle schematic

Fig. 3 transducer power unit figure

Fig. 4 phase shifting transformer electrical schematic diagram

Fig. 5 transformer coil schematic diagram

Fig. 5-1 axial split high-tension coil schematic diagram

Electrostatic Coupling and equivalent circuit diagram between Fig. 6 winding

The a plurality of single cake formulas of Fig. 7 low pressure winding construction in parallel

The short garden of Fig. 8 low pressure cartridge type winding construction

Sequence number explanation among the figure: (1) is unshakable in one's determination, (2) high pressure interior loop is received head, (3) high pressure interior loop is started, (4) interior electrostatic shielding terminal, (5) outer electrostatic shielding terminal, (6) interior electrostatic shielding, (7) outer electrostatic shielding, (8) high pressure (interior) coil, (9) low voltage unit coil, (10) electromagnetic wire, (11) corrugation air flue, (13) asynchronous electric work machine, (14) high-performance microprocessor.(15) insulating cylinder of cross-over block, (16) band stay.

Embodiment:

According to Fig. 5, the interior electrostatic shielding (6) that electrostatic shielding (6) makes at Volume in the Volume system on special core is gone up and is placed the air flue stay, then on stay with multilayer garden core structure mode Nomex ^Paper bag electromagnetic wire coiling high-tension coil (8) go up to be placed the air flue stay at the high-tension coil that winds (8), and then on stay electrostatic shielding (7) outside the Volume system.So far the two electrostatic shielding high-tension coils of band are made and are finished; Low voltage unit coil (9) is used Nomex ^The paper bag electromagnetic wire is wound on the insulating cylinder (16) of band stay, and the version of coil can be divided into following three kinds:

1. traditional continuous cake formula structure.

2. by the parallel structure of single or multiple single cakes shown in Figure 7, be used for the unit coil of big electric current, as required, set up metal corrugation air flue.

3. by the short garden core structure of band metal corrugation air flue shown in Figure 8, be used for the unit coil of the 10KV level of little electric current.

Separate the horizontal air flue that is formed with enough creepage distances with cross-over block (15) between the intersegmental or cake of above letterweight unit coil.

Claims (3)

1. One kind with the supporting phase shifting transformer of frequency converter, it is characterized in that:

   A. high-tension coil is a multilayer garden cartridge type loop construction, and big capacity adopts the garden cartridge type loop construction of axially two division formulas;

   B. high-tension coil is provided with two electrostatic shielding structures, and electrostatic shielding can be simultaneously or independent grounding, connect high-tension coil inlet wire or outlet terminal;

   C. low-voltage coil adopts single cake formula or a plurality of single cake parallel.
2. 2. by the described phase shifting transformer of claim 1, it is characterized in that low-voltage coil adopts the short garden of multilayer cartridge type.
3. 3. by claim 1,2 described phase shifting transformers, it is characterized in that low-voltage coil adopts the uptake ventilator that is formed by corrugated metal sheet.

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