CN201229838Y - Dry type rectifier transformer - Google Patents

Abstract

The utility model relates to a dry type rectifier transformer, which comprises a primary winding and a secondary winding. The primary winding comprises a high-voltage winding, which adopts star connection; the secondary winding comprises a medium-voltage winding and a low-voltage winding, wherein, the medium-voltage winding adopts star connection and is connected with the branch circuit of a wave filter, and the low-voltage winding adopts delta connection and is connected with a rectifier. The dry type rectifier transformer can realize the effects of harmonic suppression and reactive compensation, and according to the magnetic motive force balance theory, magnetic motive force generated from the harmonic current of valve winding is basically balanced out by the harmonic magnetic motive force inducted by the medium-voltage winding, with corresponding frequency; compared with equivalent impedance of other windings, the equivalent impedance of the medium-voltage winding is smaller, and the smaller equivalent impedance of the medium-voltage winding is in favor of tuning the wave filter; the dry type rectifier transformer integrates the functions of the transformer and the wave filter into a whole, which has obvious effects for improving the performance of the transformer and reducing the loss of the transformer. The dry type rectifier transformer enhances the performance of the transformer, while the traditional rectifier transformer can not enhance the performance of the transformer.

Description

The dry rectifier transformer

Technical field

The utility model belongs to the rectifier transformer technical field, is specially a kind of dry rectifier transformer.

Background technology

The application of power electronic technology has been deep into the every field of industrial production and social life, and its negative effect is also obvious day by day, a large amount of harmonic waves and order harmonic components have been injected in the switch motion of power electronic equipment in electrical network, caused the serious distortion of voltage and current waveform in the AC network, thereby substituted the non-linear harmonic wave that causes of traditional ferromagnetic materials such as transformer, become topmost harmonic source.In traditional rectifying device, owing to the structural reason of rectifier transformer, can not play the harmonic wave inhibitory action, harmonic wave still enters electrical network by transformer, thereby influences electrical network.

Summary of the invention

Problem to be solved in the utility model is: have a large amount of Harmonic Interference in the electrical network, existing rectifier transformer can not play the harmonic wave inhibitory action, and harmonic wave still enters electrical network by transformer, thereby influences electrical network

The technical solution of the utility model is: the dry rectifier transformer, comprise former limit winding and secondary winding, and former limit winding is a high pressure winding, Y-connection; Secondary comprises presses winding and a low pressure winding in one, middle pressure winding is Y-connection, links to each other with filter branches, and the low pressure winding is that triangle connects, and connects rectifier.

The utility model adopts the single-column winding construction, and set three windings are arranged by low pressure-middle pressure-high pressure.

According to transformer magnetic potential balance law, establish high pressure umber of turn w1, electric current is i ₁, middle pressure umber of turn w2, electric current is i ₂, low pressure umber of turn w3, electric current are i ₃Since the unilateal conduction effect of rectifier, low pressure winding current i ₃Be nonsinusoidal waveform, the inside has comprised harmonic components, has 5,7 at perfect condition time-harmonic wave electric current, 11,13 times ... harmonic components, suc as formula shown in

$I_3=\frac{2\sqrt{3}}{\mathrm{\π}}{I}_d[\sin \mathrm{wt}+\underset{n=6k\±1}{\overset{\∞}{\mathrm{\Σ}}}{(-1)}^k\frac{1}{n}\sin \mathrm{nwt}],k=\mathrm{1,2,3}\·\·\·$

Like this can be i ₃Each harmonic be used as driving source, the main flux of harmonic current is just arranged in the magnetic circuit, do analysis with 5 subharmonic, i ₃₅Expression low pressure winding 5 subharmonic currents, F ₃₅Expression low pressure winding 5 subharmonic magnetic potentials, φ _5mRepresent 5 subharmonic magnetic fluxes, as Fig. 3.Ignore 5 subharmonic excitation magnetic potentials, the flat gesture equilibrium equation of magnetic potential can write out and be F ₃₅=F ₁₅+ F ₂₅, F then ₁₅=F ₃₅-F ₂₅, work as F ₃₅=F ₂₅The time, F ₁₅=0, i.e. net side 5 subharmonic current i ₃₅=0, structure of the present utility model can realize the interference of harmonic carcellation electric current.

As Fig. 4, the single-phase equiva lent impedance circuit diagram of the utility model, the harmonic current equivalence is a harmonic current source, three short-circuit impedances are Z _K12, Z _K13, Z _K23, be respectively between high pressure and the middle pressure between short-circuit impedance, high pressure and the low pressure short-circuit impedance between short-circuit impedance, middle pressure and the low pressure.Z ₁, Z ₂, Z ₃Be respectively the equivalent leakage impedance of high pressure winding, middle pressure winding and low pressure winding, satisfy following relationship between them:

Z ₁＝(Z _K12+Z _K13-Z _K23)/2 (1)

Z ₂＝(Z _K12+Z _K23-Z _K13)/2 (2)

Z ₃＝(Z _K13+Z _K12-Z _K12)/2 (3)

Make Z by design of transformer ₂Be close to 0, and Z ₁Much larger than Z ₂, the harmonic current overwhelming majority is through Z ₂Branch road passes through, Z ₁Flow harmonic current hardly, promptly harmonic current does not feed back to former limit, has so just played the harmonic shielding effect.

The utility model can reach the effect of harmonic shielding and reactive power compensation, and according to the magnetomotive force balance theory, the magnetomotive force that valve side winding harmonic current produces is offseted by the harmonic wave magnetomotive force of the corresponding number of times of middle pressure winding induction basically; The equiva lent impedance of middle pressure winding is compared very little with other winding equiva lent impedances, help the tuning of filter; Integrate transformer function and filter function, to improving transformer performance, reducing transformer loss all has obvious effects.The utility model has improved the performance of transformer, and this is that traditional in the past rectifier transformer is not available.

Description of drawings

Fig. 1 is the utility model single-column winding construction figure.

Fig. 2 is the utility model external circuits schematic diagram.

Fig. 3 is single-phase three the winding magnetomotive force schematic diagrames of the utility model.

Fig. 4 is single-phase three the winding equiva lent impedance circuit diagrams of the utility model.

Fig. 5 is a three-phase bridge rectifier circuit.

Fig. 6 is the single tuned filter group schematic diagram that middle pressure winding connects.

Fig. 7 is the utility model system emulation circuit.

Direct current Id waveform when Fig. 8 is the utility model system emulation load.

Fig. 9 is a current on line side waveform when not throwing filter under the utility model system emulation.

Current on line side waveform when Figure 10 drops into single tuned filter for the utility model.

Embodiment

As Fig. 1, the dry rectifier transformer comprises former limit winding and secondary winding, the single-column winding construction, and set winding is arranged by low pressure-middle pressure-high pressure, and former limit winding is a high pressure winding, Y-connection; Secondary is to press winding and a low pressure winding in one, and middle pressure winding is Y-connection, links to each other with filter branches, and the low pressure winding is that triangle connects, and connects rectifier, as Fig. 2.

Industrial extensive use three-phase bridge rectifier circuit illustrates the utility model to connect bridge rectifier below.

As Fig. 5, the trigger angle in bridge rectifier $0\&le;\&PartialD;\&le;\mathrm{\&pi;}/3$ The time, direct current output average voltage $U_d=1.35U_{2L}\cos \&PartialD;;$ Work as trigger angle $\mathrm{\&pi;}/3<\&PartialD;<2\mathrm{\&pi;}/3$ The time, direct current output average voltage $U_d=2.34U_2[1+\cos (\mathrm{\&pi;}/3+\&PartialD;)],$ U wherein _2LBe valve side line voltage, U ₂Be valve side phase voltage.For inductive load, because electric current is continuous, the angle of flow of thyristor is 2 π/3 always, $U_d=1.35U_{2L}\cos \&PartialD;,$ I ₂=0.816 I _d, I ₂Be Circuit Fault on Secondary Transformer current effective value, I _dBe direct current.When $\&PartialD;=0$ The time, I ₂Under perfect condition, decompose according to fourier series, $I_3=\frac{2\sqrt{3}}{\mathrm{\&pi;}}{I}_d[\sin \mathrm{wt}+\underset{n=6k\&PlusMinus;1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{(-1)}^k\frac{1}{n}\sin \mathrm{nwt}],$ K=1,2,3 ..., I as can be seen ₂In contain the bigger main subharmonic currents of amplitude such as 5,7,11,13.For power factor (PF), do not consider the influence of angle of overlap, λ=ν λ ₁, ν is a fundamental factor in the formula, ν=0.955; λ ₁Be displacement factor, ${\mathrm{\&lambda;}}_1=\cos \&PartialD;.$

Middle LC filter of pressing winding to connect 5,7,11 and 13 principal character harmonic waves of elimination is as Fig. 6.The LC filter is also referred to as passive filter, is the filter that is formed by filtering capacitor, reactor and resistor appropriate combination, and is in parallel with harmonic source, also takes into account the needs of reactive power compensation except that strobing.The LC filter is divided into single tuned filter again, high pass filter is several with double-tuned filter etc.The middle pressure winding filter of present embodiment has adopted the single tuning scheme, as table 2.

Table 1 single tuned filter parameter

Single tuning	5 times tuning	7 times tuning	11 times tuning	13 times tuning
					C(μF)	26	26	26	26
L(mh)	15.6	7.9	3.2	2.3

The utility model is carried out system emulation,, comprise the input power supply as Fig. 7, novel dry rectifier transformer model, rectifier model and load, the checking transformer has the harmonic shielding effect after dropping into filter.Simulation result such as table 2 and Fig. 8-10.Table 2 is when throwing filter and drops into the single tuned filter side harmonics relatively, can find out drop into single tuned filter after harmonic wave obtain very big inhibition.

Table 2 side harmonics relatively

	THD(％)	First-harmonic (%)	5 times (%)	7 times (%)	11 times (%)	13 times (%)
							Do not throw	24.1	100	18.6	11.8	6.89	5.36
Dull	4.6	100	2.23	1.5	0.62	0.43

Fig. 8 is the oscillogram of a DC side, can find out that from figure the electric current of bridge rectifier is pulsed, and is the source of valve side harmonic current.Filter has an of short duration transient process as can be seen from Figure 10, and in this course, the current on line side waveform is unstable, after the stable operation, does not contrast when throwing filter with Fig. 9, and the filter effect of single tuned filter is fine.

Claims (3)

1, dry rectifier transformer comprises former limit winding and secondary winding, it is characterized in that former limit winding is a high pressure winding, Y-connection; Secondary comprises presses winding and a low pressure winding in one, middle pressure winding is Y-connection, links to each other with filter branches, and the low pressure winding is that triangle connects, and connects rectifier.

2, dry rectifier transformer according to claim 1 is characterized in that being the single-column winding construction, and set three windings are arranged by low pressure-middle pressure-high pressure.

3, dry rectifier transformer according to claim 1 and 2 presses winding to connect single tuned filter in it is characterized in that.

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