CN102005291B

CN102005291B - Mutual inductor in current transformer

Info

Publication number: CN102005291B
Application number: CN200910171622A
Authority: CN
Inventors: 杜峰; 张先刚; 卓越
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2009-08-31
Filing date: 2009-08-31
Publication date: 2012-10-03
Anticipated expiration: 2029-08-31
Also published as: CN102005291A

Abstract

The invention provides a mutual inductor in a current transformer, which is a polygon coil formed by end-to-end connection of at least three independent coils, wherein two ends of two adjacent independent coils are mutually overlapped, and the winding density of the overlapped part of each independent coil with other independent coils is less than that of the non-overlapped part. The invention can reduce the influence from external interference and the sensibility to the position of a measured conductor, improves the measurement precision of the current transformer, lowers the winding difficulty, and has more remarkable advantages especially when the volume of the current transformer is smaller.

Description

Mutual inductor in a kind of current transformer

Technical field

The present invention relates to the current measurement techniques field, the mutual inductor in particularly a kind of current transformer.

Background technology

At present; To breaker of plastic casing (MCCB; Molded Case Circuit Breaker) requirement develops towards economize on electricity and high-precision direction gradually; Can not satisfy the fast-developing market demand for the MCCB with single defencive function, the MCCB that novel MCCB possesses defencive function and electric current quality analysis simultaneously possesses stronger competitiveness.

For the electric current mass analysis function, it is necessary that current with high accuracy is measured for MCCB, in existing MCCB product; Iron core current transformer is the main flow of carrying out current measurement; It has simple in structure and advantage cheaply, and is as shown in Figure 1, this iron core current transformer by four independently the square coil that surrounds of coil constitute; These coils are that lead is wrapped on the iron core and forms, and measured conductor is positioned in the middle of the square coil.But to be current measuring range little and certainty of measurement is low for its shortcoming.Wherein, certainty of measurement is low is mainly reflected in two aspects: anti-external interference ability and to the sensitiveness of measured conductor position.

To the low problem of certainty of measurement; Propose in current transformer, to adopt closed fully circular coil in the prior art; Because certainty of measurement is low is that discontinuity between the absolute coil two ends causes; When only adopting the circular coil of a closure, can improve anti-external interference ability and to the sensitiveness of measured conductor position, thereby improve certainty of measurement.But closed circular coil has brought bigger difficulty for wire winding, and difficulty is more outstanding when the volume that requires current transformer is very little especially.

Summary of the invention

In view of this, the invention provides the mutual inductor in a kind of current transformer, so that improve the certainty of measurement of current transformer.

The serve as reasons polygon coil of at least three end to end formations of absolute coil of mutual inductor in a kind of current transformer, this mutual inductor;

Wherein, the two ends of adjacent two absolute coils are overlapped, in each absolute coil with the coiling density of other absolute coil overlaid part coiling density less than non-overlapped part.

More excellent ground, but said absolute coil is sieve Paderewski coil.

In addition, in each absolute coil with the coiling density constant of other absolute coil overlaid part, the coiling density constant of non-overlapped part.

In said structure, the symmetrical configuration of said polygon coil.

Further, when said mutual inductor was made up of the even number absolute coil, said absolute coil was separately positioned on the both sides of printed circuit board (PCB), and any two absolute coils of every side are non-conterminous mutually in said polygon coil.

More excellent ground, in each absolute coil and the coiling density of other absolute coil overlaid part and the coiling density ratio of non-overlapped part be the value between 0.43 and 0.54.

Especially, be specially 0.5 with the coiling density of other absolute coil overlaid part and the coiling density ratio of non-overlapped part in each absolute coil.

Can find out by above description; Mutual inductor provided by the invention constitutes the polygon coil by at least three absolute coils are end to end; The two ends of wherein adjacent two absolute coils are overlapped; The continuity of the coil loop that guarantee to constitute, and in each absolute coil with the coiling density of other absolute coil overlaid part coiling density less than non-overlapped part, guarantee the coiling uniformity of coil loop; Reduce the influence that receives external interference and to the sensitiveness of the position of measured lead, thereby improved the certainty of measurement of current transformer.

And this mutual inductor constitutes by a plurality of absolute coils are end to end, when coiling, carries out respectively to each absolute coil, has reduced the coiling difficulty, realizes easily, and special when the volume that requires current transformer is very little, advantage is more outstanding.

Description of drawings

Fig. 1 is the mutual inductor sketch map in the current transformer in the prior art.

Fig. 2 is a mutual inductor sketch map provided by the invention.

Fig. 3 is the sketch map that is provided with of mutual inductor provided by the invention.

The sketch map that Fig. 4 discharges for three mutual inductors that provide among the present invention side by side.

The Error Simulation figure influenced by external interference of Fig. 5 for providing among the present invention.

Another Error Simulation figure that influenced by external interference of Fig. 6 for providing among the present invention.

The Error Simulation figure influenced by measured conductor position of Fig. 7 for providing among the present invention.

Another Error Simulation figure that influenced by measured conductor position of Fig. 8 for providing among the present invention.

Embodiment

In order to make the object of the invention, technical scheme and advantage clearer, invention is described in detail below in conjunction with accompanying drawing and specific embodiment.

The serve as reasons polygon coil of at least three end to end formations of absolute coil of mutual inductor in the current transformer provided by the invention; Wherein, the two ends of adjacent two absolute coils are overlapped, in each absolute coil with the coiling density of other absolute coil overlaid part coiling density less than non-overlapped part.

Because the saturation characteristic of iron core under big current conditions can make the measurement range of current transformer be affected; In order to enlarge the measurement range of current transformer; Bobbin can adopt insulating material, but promptly each independently coil all adopt sieve Paderewski coil (Rogowski coil).

For the structure that makes above-mentioned mutual inductor is clearer, be that example is described in detail with four the end to end formation quadrangle of absolute coil coils below.

The measuring principle of current transformer is based on Ampere circuit law, and promptly magnetic flux density is proportional to the algebraical sum of passing these all current strength of loop along the line integral of any loop.Therefore can find out; The shape of loop, any electric current that passes the spatial distribution of loop current and do not pass loop all can not exert an influence in current measurement; But in order to guarantee certainty of measurement, need mutual inductor to constitute loop, non-continuous event can not appear in promptly adjacent absolute coil; And the winding density that needs loop keeps constant as far as possible, and the number of turns of mutual inductor unit length that promptly constitutes loop is constant as far as possible.

In order to satisfy the requirement of measuring principle, can be with four the end to end formation quadrangle of absolute coil coils as mutual inductor, and very close to each other between each absolute coil of the overlapped assurance in the two ends of adjacent two coils, promptly guarantee continuity, as shown in Figure 2.

In addition; In order to keep the winding density constant of whole mutual inductor as far as possible; Coil-winding density for lap need be less than the coiling density of non-overlapped part; If the accurate degree of wire winding reaches desired level; Then in each absolute coil the coiling density of lap should be non-overlapped part coiling density

still; Because the wire winding in the reality can not reach desired level; Therefore, the coiling density ratio of coiling density and non-overlapped part that can keep lap in the absolute coil usually is between 0.43 and 0.54, and experiment records the measure error of ratio between this and still can remain in 0.1%.

Particularly, can adopt identical four absolute coils, but this alone absolute coil can be sieve Paderewski coil, the quadrangle of its formation preferably satisfies symmetry.In addition, when winding the line, guarantee the coiling density constant of lap in each absolute coil, the coiling density constant of non-overlapped part as far as possible.

In order to guarantee that adjacent two absolute coil two ends can overlapping assurance not have gap physically, when carrying out coil stationary, can absolute coil be separately positioned on the both sides of printed circuit board (PCB) (PCB), any two absolute coils are non-conterminous mutually on every side.Still be example with four, as shown in Figure 3, wherein two absolute coils are positioned at the side of PCB, and two other absolute coil is positioned at the opposite side of PCB, that is to say, adjacent two absolute coils lay respectively at the both sides of PCB, and are overlapping in the both sides of PCB.

According to the specification of a standard above-mentioned mutual inductor provided by the invention is verified below.If there are three above-mentioned mutual inductors in the current transformer; As shown in Figure 4; Distance between the measured conductor in each mutual inductor is 35mm; The mobile range of measured conductor is ± 1.5mm within, it is as shown in Figure 5 that the mutual inductor that is designated A is designated the influence of mutual inductor of B, the maximum error of absolute method of measurement is less than 0.003%; It is as shown in Figure 6 that the mutual inductor that is designated A is designated the influence of mutual inductor of C, and the maximum error of absolute method of measurement is less than 0.001%; It is 0.003%+0.001%=0.004% that the mutual inductor that is designated A receives the overall error of ectocine.

If the mobile range of measured conductor is at 3 * 3mm ²Within, then mutual inductor receives the position influence of measured conductor can be as shown in Figure 7, and the maximum error of absolute method of measurement is less than 0.0042%; If the mobile range of measured conductor is at 9 * 9mm ²Within, then mutual inductor receives the position influence of measured conductor can be as shown in Figure 8, and the maximum error of absolute method of measurement is less than 0.05%.

Can find out that by above description mutual inductor provided by the invention possesses following advantage:

1) this mutual inductor constitutes the polygon coil by at least three absolute coils are end to end; The two ends of wherein adjacent two absolute coils are overlapped; Guarantee the continuity of the coil loop of formation; And with the coiling density of other absolute coil overlaid coiling density partly, guarantee the coiling uniformity of coil loop in each absolute coil, thereby improve the certainty of measurement of current transformer less than non-overlapped part.This advantage has obtained checking from above-mentioned experimental data, the position influence that receives external interference and measured lead is less.

2) this mutual inductor constitutes by a plurality of absolute coils are end to end, when coiling, carries out respectively to each absolute coil, has reduced the coiling difficulty, realizes easily, and special when the volume that requires current transformer is very little, advantage is more outstanding.

3) because the reduction of technology difficulty, and can adopt a plurality of absolute coils commonly used, therefore, also reduce the cost of manufacture of current transformer.

4) but each absolute coil in this mutual inductor can adopt sieve Paderewski coil, avoided that the saturation characteristic of iron core under big current conditions bring to measuring the restriction of range, improved the measurement range of current transformer greatly.

The above is merely preferred embodiment of the present invention, and is in order to restriction the present invention, not all within spirit of the present invention and principle, any modification of being made, is equal to replacement, improvement etc., all should be included within the scope that the present invention protects.

Claims

1. the mutual inductor in the current transformer is characterized in that, the serve as reasons polygon coil of at least three end to end formations of absolute coil of this mutual inductor;

2. mutual inductor according to claim 1 is characterized in that, but said absolute coil is sieve Paderewski coil.

3. mutual inductor according to claim 1 is characterized in that, in each absolute coil with the coiling density constant of other absolute coil overlaid part, the coiling density constant of non-overlapped part.

4. mutual inductor according to claim 1 is characterized in that, the symmetrical configuration of said polygon coil.

5. mutual inductor according to claim 1; It is characterized in that; When said mutual inductor was made up of the even number absolute coil, said absolute coil was separately positioned on the both sides of printed circuit board (PCB), and any two absolute coils of every side are non-conterminous mutually in said polygon coil.

6. according to the described mutual inductor of the arbitrary claim of claim 1 to 5, it is characterized in that, in each absolute coil and the coiling density of other absolute coil overlaid part and the coiling density ratio of non-overlapped part be the value between 0.43 and 0.54.

7. mutual inductor according to claim 6 is characterized in that, is specially 0.5 with the coiling density of other absolute coil overlaid part and the coiling density ratio of non-overlapped part in each absolute coil.