JPH10233316A - Biased magnetization detecting device and its evaluating device for transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the influence of a magnetic flux leaked from an iron core of a transformer which may be exerted upon a biased magnetization detecting device for detecting d.c. biased magnetization amount of the iron core. SOLUTION: A detecting coil 8 is wound around a magnetic core 7 of magnetic material. Both ends (7a and 7b) of the magnetic core 7 are extended in parallel and in the opposite direction to each other inside or on the surface of an iron core 5 of a transformer. A part (7c) around which the detecting coil 8 is wound crosses orthogonally to both of the ends. The part of the magnetic core around which the detecting coil 8 is wound is placed in the orthogonal direction to the main magnetic flux of the iron core of the transformer. The leakage flux from the iron core is prevented from crossing the detecting coil 8 or minimized to avoid its influence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting the amount of direct current bias of a transformer, and more specifically, a bias detection element, a transformer having the same, a transformer and a bias evaluation device, and a device including the same. Belongs to the technology of power conversion systems.

[0002]

2. Description of the Related Art Along with advances in power electronics technology, a self-excited power converter using a self-extinguishing semiconductor device such as a GTO has been applied to the electric power field. Generally, when a self-excited power converter is connected to an AC power system, it is connected via a conversion transformer. In such a transformer for conversion, a DC component is added to the excitation voltage due to variations in the firing of the semiconductor switch elements, etc., so that a DC bias phenomenon in which the magnetic flux passing through the core is biased to either positive or negative. Get up. If the core of the transformer is DC-polarized, the loss of the transformer and the noise increase. Further, depending on the degree of the magnetic bias, the iron core is magnetically saturated and an excessive current flows through the winding, which may cause damage to the semiconductor switch element of the power converter connected to the winding.

Conventionally, in order to prevent magnetic saturation due to DC bias of the core of such a transformer for conversion, the output voltage of the power converter is adjusted so as to detect the amount of bias of the core and to cancel this. Is performed. For example,
Japanese Patent Publication No. 50-33213 proposes a method in which a magnetic field detecting element is installed in a laminated iron core of a transformer, and a magnetic flux in the iron core is directly monitored to detect an amount of magnetic demagnetization. According to this, a detection coil is wound around a magnetic core having an extremely high initial magnetic permeability to form a magnetic field detecting element, and the legs of the magnetic core of the magnetic field detecting element are attached in close contact with the laminated steel sheet of the transformer core, Dividing a part of the main magnetic flux passing through the iron core to a magnetic core with high permeability,
This is to detect the amount of magnetization by observing the voltage induced in the detection coil. That is, since the magnetic core has a lower saturation magnetic flux density than the laminated steel plate and is magnetically saturated, even if the main magnetic flux changes in a sine wave shape, the magnetic flux passing through the core (magnetic flux linked to the detection coil) has a sine wave wave height. A trapezoidal positive / negative waveform suppressed by saturation is obtained. Therefore, a steep pulse-like induced voltage is generated in the detection coil near the zero point where the polarity of the magnetic flux changes. The time interval at which this pulse-like voltage appears depends on the positive and negative excitation amounts, so that by observing the time interval of the pulse-like voltage, the DC bias amount and the polarization polarity are detected. You can do it.

[0004]

When the magnetic flux density of the main magnetic flux passing through the laminated steel sheet of the transformer becomes high to some extent, the magnetic flux leaking from the steel sheet and passing outside the steel sheet (hereinafter referred to as leakage magnetic flux) increases. The leakage magnetic flux is
No. 0-33213), the induced voltage is affected when the detection coil of the demagnetization detecting element is linked and the leakage magnetic flux increases. In other words, the magnetic core of the bias detection element has a phase range in which the magnetic flux is magnetically saturated by the shunt magnetic flux of the main magnetic flux.
It acts on the leakage magnetic flux substantially in the same manner as the air core. Therefore, the number of magnetic flux linkages near the center (phase angles 90 ° and 270 °) of the trapezoidal saturated magnetic flux corresponding to the vicinity of the peak value of the leakage magnetic flux linked to the detection coil increases, and the pulse changes due to the change in the magnetic flux. Induced voltage may occur. The pulse-like voltage generated by this leakage magnetic flux is a so-called disturbance that may or may not be generated depending on the magnitude of the leakage magnetic flux, and an error in detecting the amount of DC bias by observing the time interval of the pulse-like voltage. And there is a problem in accuracy and reliability. As a result, when such a polarization detection element is applied to a polarization evaluation device of a power conversion system, there is a possibility that the control of the polarization suppression of the transformer may fail.

[0005] An object of the present invention is to eliminate the influence of leakage magnetic flux interlinked with a polarization detecting element for detecting the amount of magnetic polarization of a transformer.

[0006]

The object of the present invention can be solved by the following means. The solution principle of the present invention is:
(1) Make sure that the leakage magnetic flux, which is a disturbance, does not interlink with the detection coil of the magnetic deflector detection element, or (2) Provide a compensation element that detects only the disturbance magnetic flux to interlink the detection coil of the magnetic deflector detection element. Thus, the induced voltage component due to the disturbance magnetic flux is removed.

As a specific means of the principle (1), a detection coil is wound around a magnetic core made of a magnetic material, and is disposed inside or on a surface of a transformer core to detect a magnetic bias of the transformer. The magnetic recording medium is characterized in that both ends of the magnetic core extend in parallel and in opposite directions to each other, and a portion around which the detection coil is wound is formed to be orthogonal to both ends. When both ends of the magnetic core are installed in parallel with the main magnetic flux in the transformer core, the core portion around which the detection coil is wound is arranged in a direction orthogonal to the main magnetic flux of the transformer core. As a result, it is possible to prevent or minimize the leakage magnetic flux parallel to the main magnetic flux to the detection coil, so that the influence of the leakage magnetic flux can be eliminated.

[0008] Alternatively, the magnetic flux or the non-magnetic material may be covered with a shield member made of a magnetic material or a non-magnetic material except for a portion of the periphery of the magnetic field detecting element which is in contact with the transformer core, so that the leakage magnetic flux links to the detecting coil. Can be prevented or minimized. Alternatively, the part where the detection coil is wound is separated from the surface of the laminated core forming the transformer core by a certain dimension, and is disposed at a position where the leakage magnetic flux is sufficiently reduced, so that the leakage magnetic flux links to the detection coil. It can be prevented or minimized.

As a specific means of the principle (2), a compensating element formed by winding a compensating coil around an air core or a non-magnetic material winding frame is arranged in the same manner as the magnetic flux detecting element, By forming the coils of the elements in the same shape and connecting them so that the induced voltage of the compensating element is subtracted from the induced voltage of the magnetic field detecting element, the induced voltage component due to disturbance magnetic flux can be removed. Even if the coils of the bias detecting element and the compensating element are different, the induced voltage component due to the disturbance magnetic flux can be removed by the arithmetic processing.

Further, the change rate of the output of the demagnetizing coil is detected by focusing on the difference between the pulse voltage corresponding to the vicinity of the zero cross of the shunt magnetic flux of the main magnetic flux and the pulse voltage corresponding to the peak of the leakage magnetic flux. However, the problem of the present invention can also be solved by determining a time interval at which the rate of change becomes equal to or greater than a set value, and evaluating the magnetization of the transformer based on the obtained change in the time interval.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given based on an embodiment of the present invention. (First Embodiment) FIG. 1 shows an overall configuration diagram of a power conversion system according to an embodiment of the present invention, and FIGS. As shown in FIG. 1, an AC side winding 2 of a conversion transformer 1 is connected to an AC system (not shown), and a converter side winding 3 is a power converter 4 formed by using a semiconductor switch element. It is connected to the. The iron core 5 of the transformer for conversion 1 is formed by laminating steel plates, and the magnetic field detecting element 6 is attached to the iron core 5. The bias detection element 6 is formed by winding a detection coil 8 around a plate-shaped magnetic core 7 formed in a crank shape. Both ends of the detection coil 8 are connected to an arithmetic unit 9. The polarization detecting element 6 and the arithmetic unit 9 form a polarization evaluation device 10. Arithmetic unit 9
Captures the induced voltage of the detection coil 8, calculates the amount of magnetization of the conversion transformer 1 based on the voltage, and outputs it to the control device 11. The control device 11 controls the ignition timing of the semiconductor switch element of the power converter 4 based on the input amount of polarization and its polarity to eliminate the polarization of the conversion transformer 1. .

FIG. 2 is an enlarged perspective view showing a portion of the iron core 5 to which the magnetic field detecting element 6 is attached, and FIG.
FIG. 3 is a sectional view taken along line III-III in FIG. 2. As shown in FIG. 2, the magnetic core 7 of the outgoing polarized磁検element 6 is formed in a crank-type plate, both end portions 7a, 7b are parallel to the direction of the magnetic flux [Phi ₁ of the iron core 5, and opposite to each other It is formed so as to extend in the direction, and is attached in close contact with the surface of the laminated steel sheet 12 constituting the iron core 5. Then, the portion of the magnetic core 7 around which the detection coil 8 is wound (the central portion of the crank type) 7
c is formed so as to float at least by the thickness of the coil from the surface of the laminated steel plate of the iron core 5, and is perpendicular to the direction of the magnetic flux Φ ₁ of the iron core, that is, the axis of the detection coil 8 has the magnetic flux Φ ₁
Are arranged at right angles to the direction of. Magnetic core 7
Is preferably formed of a magnetic material having an extremely high initial magnetic permeability, for example, an iron-nickel alloy or an amorphous magnetic material. Further, in FIG. 2, the bias detection element 6 is shown to be inserted into the lamination gap (0.2 to 0.3 mm) of the laminated steel sheet, but may be attached to the surface of the outermost laminated steel sheet. .

The operation of the embodiment thus formed will be described below. As shown in FIG. 2, a portion of the main magnetic flux [Phi ₁ through core 5 of the transformer 1 is split into high permeability magnetic core 7, the shunt magnetic flux [Phi ₂ again passes through the magnetic core 7a-7c-7b Return to iron core 5. A voltage is induced in the detection coil 8 by the shunt magnetic flux Φ ₂ . 4 (a),
(B) and (c) show the waveform of the time change of the main magnetic flux Φ ₁ in the laminated steel sheet, the waveform of the time change of the shunt magnetic flux Φ ₂ linked to the detection coil 8, and the output voltage V of the detection coil 8. And waveforms. As shown in the figure, the main magnetic flux Φ ₁ changes in a sine wave shape, but since the magnetic core 7 has a lower saturation magnetic density than the laminated steel sheet, it is magnetically saturated and the shunt magnetic flux Φ ₂ has a trapezoidal waveform as shown in the figure. Become. Therefore, the terminals 8a,
The waveform of the output voltage V appearing at 8b is when the shunt magnetic flux [Phi ₂ is suddenly changed, i.e. steep pulse appears near the zero point of the main magnetic flux [Phi _1. Since this pulse-like voltage alternates between the positive and negative polarities, the time interval Δt ₁ between the maximum value and the minimum value,
By measuring Δt ₂ and determining the difference, the amount of polarization and the polarity can be detected.

Here, the fact that the influence of the leakage magnetic flux can be eliminated by the embodiment of FIG. 1 will be described. The leakage flux is
A magnetic flux passing through the steel plate external leaks from the steel sheet near the peak of the main magnetic flux [Phi _1, shown in Φa in FIG. As is apparent from the figure, since the axis of the detection coil 8 is arranged at right angles to the leakage magnetic flux Φa, the leakage magnetic flux Φa does not interlink with the detection coil 8. Therefore, as shown in FIGS. 4B and 4C, since the magnetic flux linked to the detection coil 8 does not change, the leakage magnetic flux Φ
No pulse is generated by a.

[0015] In contrast, as in the prior art, formed into a straight shape without a magnetic core 7 to the crank type, if this was mounted parallel to the main magnetic flux [Phi _1, leakage axis of the detection coil 8 flux Φa And the leakage magnetic flux Φa is
Interlink with As a result, the effects shown in FIGS. In other words, the increase in leakage flux .PHI.a becomes a problem is near the peak of the main magnetic flux [Phi _1, when it reaches a level that can not be ignored, as shown in (Φ ₁ + Φa) in FIG. (A), platform The magnetic flux in the shaded portion is applied to the center of the shape waveform, and a disturbance pulse appears in the output voltage V accordingly. As a result, the time intervals Δt ₁ and Δt ₂ of the pulse cannot be specified or may be specified erroneously, and the amount of demagnetization cannot be accurately and reliably evaluated. Therefore, there is a possibility that the control of the transformer to be demagnetized may fail.
FIG. 6B is a waveform diagram of each part showing the influence of the leakage magnetic flux in a state in which the amount of magnetization Φdc is DC-polarized.

(Second Embodiment) FIG. 6 is a cross-sectional view of a main part of a conversion transformer to which another embodiment of the magnetic field detecting element according to the present invention is applied. The present embodiment is an example in which the magnetic field detecting element is magnetically shielded so as not to link the leakage magnetic flux. That is, as shown, the core 13 of the outgoing polarized磁検element 6 is formed in a straight shape, and the parallel portion and both end portions of the detection coil 8 is wound around the main magnetic flux [Phi ₁ of the core, the laminated steel plate 12 It is arranged in contact with the surface. Then, the demagnetization detecting element 6
Is the shield member 1 except for the side in contact with the laminated steel sheet 12.
4 is covered. For the shield member 14, it is preferable to use a nonmagnetic conductive foil such as copper or aluminum whose surface is insulated. Alternatively, a magnetic foil whose surface is insulated may be used.

By providing such a shield member 14, the leakage magnetic flux Φa leaking from the laminated steel plate 12 and passing through the external gap is not blocked by the shield member 14 and linked to the detection coil 8. No induced voltage due to the leakage magnetic flux Φa occurs. Therefore, the disturbance pulse as shown in FIG. 5 does not appear in the output voltage V. That is, near the peak of the main magnetic flux [Phi ₁ (middle part of the trapezoidal waveform)
Does not appear due to the addition of the magnetic flux in the shaded area. Thereby, similarly to the embodiment of FIG.
Since the output voltage V of FIG. 4 can be obtained, the present invention can be applied to a converter evaluation device or a power conversion system to accurately and reliably evaluate the amount of magnetization of the transformer. The bias control can be stably performed.

(Third Embodiment) FIGS. 7 and 8 are a plan view and a cross-sectional view of a main part of a conversion transformer to which another embodiment of a magnetic field detecting element according to the present invention is applied. FIG. 8 is a sectional view taken along line VIII-VIII in FIG. The present embodiment is to eliminate the influence of the leakage magnetic flux by detecting and compensating for a disturbance pulse component generated in the bias detection element by the leakage magnetic flux. The bias detection element 6 is formed in the same manner as in FIG. 6 and is attached to the surface of the laminated core 12 in close contact.
The compensating element 20 is attached to the laminated iron core 12 such that the coil axis of the compensating element 20 matches the coil axis. Compensation element 20
Is formed by winding a compensating coil 22 around a winding frame 21 formed in the same shape as the magnetic core 13. The winding frame 21 is formed of a non-magnetic insulator. The detecting coil 8 and the compensating coil 22 have the same number of turns, with the winding directions being opposite to each other. Then, the detection coil 8 and the compensation coil 2
The terminal 2 is connected in series with the terminal 8a and the terminal 22b connected so that the induced voltages cancel each other, and the remaining terminals 8b and 22a are used as output terminals.

With this configuration, the main magnetic flux Φ
Part ₁ is a magnetic core 13 provided in close contact with the surface of the iron core 5.
And a voltage corresponding to the magnitude and polarity of the main magnetic flux Φ ₁ is induced in the detection coil 8 by the divided magnetic flux Φ ₂ . On the other hand, since the magnetic core 21 of the compensating element 20 is formed of a non-magnetic material, a part of the main magnetic flux Φ ₁ does not flow to the compensating element 20. Then, the leakage magnetic flux Φa through core external leaks from the laminated steel 12 near the peak of the main magnetic flux [Phi ₁ is detected through the air-core substantially equivalent to the core 13 by the magnetic saturation coil 8
Interlink with However, the leakage magnetic flux Φa, on the other hand, links with the compensation coil 22 through a non-magnetic bobbin 21 substantially equivalent to the air core. Thereby, those coils 8, 2
2, an induced voltage component corresponding to the leakage magnetic flux Φa is generated,
They are canceled because they are equal in size and opposite in direction. Therefore, the output voltage V output between the terminal 8b and the terminal 22a includes the leakage flux Φ
The disturbance pulse due to a is not included.

As a result, the output voltage V of FIG. 4 is obtained in the same manner as in the above-described embodiment. The evaluation can be performed accurately and with reliability, and the control of suppressing the magnetization of the transformer can be stably performed.

(Fourth Embodiment) FIGS. 9 and 10 show a plan view and a cross-sectional view of a main part of a conversion transformer to which another embodiment of a magnetic field detecting element of the present invention is applied. In the present embodiment, similarly to the embodiments shown in FIGS. 7 and 8, the influence of the leakage magnetic flux is eliminated by detecting and compensating for a disturbance pulse component generated in the demagnetization detecting element by the leakage magnetic flux. It is in. FIG. 9 is a plan view showing a state of attachment of the magnetic field detecting element 6 and the compensating element 23, and FIG. 10 is a line XX of FIG.
FIG. As shown in these figures, the magnetic field detecting element 6 is formed in the same manner as in FIG. 7, and is attached to the surface of the laminated iron core 12 in close contact. The compensating element 23
It is attached to the laminated core 12 with the coil axis coincident with the magnetic field detecting element 6. The compensating element 23 is formed by winding a compensating coil 24 around a winding frame 21 formed in the same shape as the magnetic core 13. The winding frame 21 is formed of a non-magnetic insulator. Then, the induced voltages of the detection coil 8 and the compensation coil 24 are respectively connected to the terminals 8a and 8b and the terminals 22a and 22a.
22b is input to the calculating means 25.

With this configuration, similarly to the embodiment shown in FIG. 7, the bias detecting element 6 has a voltage corresponding to the magnitude and polarity of the shunt magnetic flux Φ ₂ and a voltage corresponding to the leakage magnetic flux Φa. There while voltages V ₁ obtained by superimposing is induced, the compensation element 20
, A voltage V ₂ corresponding to the leakage magnetic flux Φa is induced. The arithmetic unit 25 takes in these voltages V ₁ and V ₂ , and obtains a voltage V according to the magnitude and polarity of the shunt magnetic flux Φ ₂ by the following equation (1).

V = V ₁ −k · V ₂ (1) Here, k is an adjustment coefficient for completely canceling the induced voltage due to the leakage magnetic flux Φa, and the number of turns of the detection coil 8 and the compensation coil 24 is effective. This is for adjusting a difference in cross-sectional area or the like.

As a result, the output voltage V shown in FIG. 4 is obtained for the voltage V output from the arithmetic unit 25 in the same manner as in the above-described embodiment. In this case, the amount of magnetization of the transformer can be accurately and reliably evaluated, and the control of suppressing the magnetization of the transformer can be stably performed.

(Fifth Embodiment) Although this embodiment is not shown, a voltage component corresponding to the leakage magnetic flux Φa is removed by calculation from the output voltage V _{1 of the} magnetic field detecting element 6 shown in FIG. It is. In other words, in the waveform diagrams of the output voltage V shown in FIGS. 5A and 5B, the time gradient dv ₁ / dt of the pulse-like voltage appearing near the zero point of the main magnetic flux Φ ₁ is such that the leakage magnetic flux Φa interlinks. Gradient dv of the disturbance pulse induced by
_It is considered to be larger than ₂ / dt. The reason is that near the zero point of the main magnetic flux Φ ₁ , the shunting magnetic flux Φ ₁ is not saturated because the magnetic polarization detecting element 6 is not saturated and the magnetic permeability of the magnetic core 13 is high.
₂ is concentrated and sharply increases, whereas the magnetic flux detecting element 6 is saturated near the peak of the main magnetic flux Φ ₁ and the magnetic permeability is considerably small, so that the leakage magnetic flux Φa is not concentrated. This is because the increase is gradual.

The output voltage V is calculated by the arithmetic unit 25.
Is determined, and if this is smaller than a predetermined value, it is regarded as a disturbance, and the voltage pulse in that portion is forcibly set to zero. Thereby, the same effect as that of the embodiment of FIG. 9 can be obtained.

(Sixth Embodiment) FIGS. 11 and 12 show embodiments of the shape of the magnetic core of the magnetic field detecting element according to the present invention. 11, shunt the magnetic flux but the legs of the magnetic core 27 (portion surrounded by oblique lines) is mounted in contact with the laminated steel 12, the contact area of this portion is large and diverted from the main magnetic flux [Phi ₁ it is preferable to reduce the magnetic resistance to the [Phi _2. These can be applied to the embodiments shown in FIGS. In the case of the embodiment shown in FIG. 1, it is preferable to form the leg portions 28a and 28b large as in the magnetic core 28 shown in FIG. In addition, the shape is not limited to these, and any shape that can increase the contact area between the magnetic core and the iron core can be applied.

As the material of the magnetic core of the magnetic field detecting element, for example, permalloy which is an iron or nickel alloy can be used, and an amorphous magnetic material (amorphous) can also be used. Further, the thickness, dimensions, etc. of the magnetic core are not particularly specified, and for example, thin plates can be used in a laminated state.

Further, the magnetic field detecting element can be installed not only between the laminated steel plates of the transformer core but also on the surface of the iron core. The transformer may be attached to the upper and lower yokes in addition to the iron core main legs and side legs.

(Seventh Embodiment) FIG. 13 shows a configuration diagram of an embodiment of an apparatus for evaluating the amount of magnetization according to the present invention. In this example,
The amount of demagnetization is evaluated based on an output voltage obtained by removing a disturbance pulse component due to the leakage magnetic flux Φa from the output of the demagnetization detecting element. As shown in the figure, the demagnetization amount evaluation device includes a demagnetization detection element 6 and a calculation device 9. The calculation device 9 includes an amplifier 30 that amplifies the output voltage V of the demagnetization detection device 6 to a predetermined level, and an amplifier. An A / D converter 31 for performing analog / digital conversion of the output of the A / D converter 30;
And an operation unit 32 for evaluating the amount of magnetic polarization of the transformer core 5 based on the output signal of the transformer core 5.

The operation unit 32 calculates the Δt ₁ shown in FIG. 14 from the output voltage V of the magnetic field detecting element 6 converted into a digital value.
And Δt ₂ are obtained, and for example, the amount of bias Φdc is calculated by the following equation (2).
Ask for.

Φdc = Φmax · sin {(Δt ₁ −Δt ₂ ) / (Δt ₁ + Δt ₂ )} (2) Alternatively, as shown in the waveform at the bottom of FIG. The converted output voltage V of the magnetic field detecting element 6 is integrated, thereby obtaining a magnetic flux ∫Vdt linking to the magnetic field detecting element 6, and the interval Δt ₁ ′ between the points where the waveform of the magnetic flux crosses the zero level is obtained. From Δt ₂ ′, the amount of bias Φdc can be obtained in the same manner as in equation (2). This method is effective when the exciting voltage of the conversion transformer is a non-sine wave such as a PWM waveform. That is, in the case of a PWM waveform or the like,
Since the flux linkage of the polarization磁検detecting element there is a sudden change other than the vicinity of zero of the main magnetic flux, there is a possibility that the pulsed voltage other than the vicinity of the zero point of the main magnetic flux is generated, Delta] t ₁ from the waveform of the output voltage V And Δt ₂ cannot be uniquely determined. However, even in such a case, the magnetic flux ∫Vdt is uniquely determined. Therefore, even when the excitation voltage is distorted, the amount of magnetization can be determined.

In FIG. 13, when the output voltage V of the magnetic field detecting element 6 is sufficiently large, the amplifier 30 may be omitted. Further, the method of calculating the amount of magnetization in the arithmetic unit 32 is not limited to the above-described method.

(Eighth to tenth embodiments) FIGS. 15, 16, and 1
FIG. 7 shows an application example of a power conversion system to which the demagnetization amount evaluation device according to the present invention is applied. FIG. 15 is a conceptual configuration diagram when applied to a DC power transmission system. In the figure, AC / DC converters 41 and 42 are converters for converting alternating current to direct current or direct current to alternating current. Connected to the AC system via The transformers for conversion 44, 45 are provided with magnetic polarization evaluation devices 46, 47, respectively.
Is connected. Any of the above-described embodiments is applied to the magnetic polarization evaluation devices 46 and 47.
9 is output. The control devices 48 and 49 correct the firing timing of the semiconductor switch elements constituting the AC / DC converters 41 and 42 so as to cancel the input magnetic flux Φdc, and send commands to the AC / DC converters 41 and 42.
As a result, the DC bias of the conversion transformers 44 and 45 is eliminated, and the inconvenience associated with the DC bias can be prevented.

FIG. 16 is a conceptual configuration diagram when applied to a reactive power compensation system. The power converter 51 is connected to a power system 53 via a conversion transformer 52. The power converter 51 is connected to a start-up power supply 54 such as a capacitor. A polarization evaluation device 55 is connected to the conversion transformer 52. Any one of the above-described embodiments is applied to the magnetic bias evaluation device 55, and the conversion transformer 5
Then, the DC bias amount Φdc is obtained and output to the control device 56.
The control device 56 corrects and controls the ignition timing of the semiconductor switch element included in the power converter 51 so as to cancel the input amount of bias Φdc. As a result, the DC bias of the conversion transformers 44 and 45 is eliminated, the inconvenience associated with the DC bias is prevented, and the desired reactive power compensation can be stably performed.

In FIG. 16, if a power storage device such as a battery or SMES is used in place of the starting power supply 54, it can be used as a power storage system and can be used for load leveling.

FIG. 17 is a conceptual configuration diagram when applied to a phase adjustment system. In the figure, a power converter 61 has a function of forward conversion and reverse conversion, and is connected to an AC system 63 via a transformer 62 for adjustment.
Are connected to a series transformer 64 connected in series. The series transformer 64 is connected to a magnetic bias evaluation device 65. Any one of the above-described embodiments is applied to the magnetic polarization evaluation device 65, and the DC magnetic polarization amount Φdc of the series transformer 65 is obtained and output to the control device 66. The control device 66 corrects and controls the ignition timing of the semiconductor switch element included in the power converter 61 so as to cancel the input amount of bias Φdc.

According to the phase adjuster configured as described above, the power converter 61 applies an arbitrary phase difference to the ground voltages V ₁₁ and V ₁₂ at both ends of the power system 63 via the series transformer 64. Is applied to the power system 63, and V ₁₁
It is possible to arbitrarily adjust the phase difference between V ₁₂ and. Then, the DC bias of the series transformer 65 is eliminated by the action of the bias evaluation device 65 and the control device 66, and the inconvenience associated with the DC bias can be prevented, and the desired phase adjustment can be stably performed. .

[0039]

According to the present invention, it is possible to eliminate the influence of the leakage magnetic flux interlinked with the polarization detecting element for detecting the amount of magnetic polarization of the transformer.

[Brief description of the drawings]

FIG. 1 shows an overall configuration diagram of a power conversion system according to an embodiment to which a magnetic field evaluation device of the present invention is applied.

FIG. 2 is an enlarged perspective view of a magnetic field detecting element according to FIG. 1;

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

4 is an operation waveform diagram of each section in the embodiment of FIG.

FIG. 5 is an example of an operation waveform diagram of each unit of the related art shown for comparison with FIG.

FIG. 6 shows a sectional view of an embodiment of a shield type magnetic field detecting element according to the present invention.

FIG. 7 is a mounting plan view of an embodiment of a compensation type magnetic field detecting element according to the present invention.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7;

FIG. 9 is a mounting plan view of another embodiment of the compensation type magnetic field detecting element according to the present invention.

FIG. 10 is a sectional view taken along line XX in FIG. 9;

FIG. 11 is a plan view showing an embodiment of a magnetic core of the magnetic field detecting element according to the present invention.

FIG. 12 is a plan view showing another embodiment of the magnetic core of the bias detecting element according to the present invention.

FIG. 13 is an overall configuration diagram of an embodiment of a magnetic polarization evaluation device of the present invention.

FIG. 14 is a waveform chart for explaining the operation of the bias evaluation apparatus of FIG. 13;

FIG. 15 is a conceptual configuration diagram of an embodiment of a DC power transmission system to which the magnetic polarization evaluation device of the present invention is applied.

FIG. 16 is a conceptual configuration diagram of an embodiment of a reactive power compensation system to which the magnetic field evaluation device of the present invention is applied.

FIG. 17 is a conceptual configuration diagram of an embodiment of a phase adjustment system to which the magnetic polarization evaluation device of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transformer for conversion 4 Power converter 5 Iron core 6 Magnetic polarization detecting element 7 Magnetic core 8 Detecting coil 9 Computing device 10 Magnetic polarization evaluating device 11 Controller 12 Laminated steel plate 13 Magnetic core 14 Shield member 15 Magnetic core 20, 23 Compensating element 21 Reel frame 22, 24 Compensation coil 27, 28 Magnetic core 30 Amplifier 31 A / D converter 32 Operation unit

Claims (11)

[Claims] 1. A magnetic field detecting element for detecting a DC magnetic field of a transformer by arranging a detecting coil around a magnetic core of a magnetic material and arranging the detecting coil inside or on a surface of a transformer core, wherein both ends of the magnetic core are parallel to each other. A magnetic field detecting element for a transformer, wherein the detecting coil extends in opposite directions, and a portion formed by winding the detection coil is formed to be orthogonal to the both ends. 2. A transformer in which a detection element formed by winding a detection coil around a magnetic core of a magnetic material is disposed inside or on a surface of a transformer core, wherein both ends of the magnetic core of the detection element are connected to each other. It extends parallel to the direction of magnetic flux of the transformer core and in the opposite direction to each other, and a portion formed by winding the detection coil is formed perpendicular to the direction of magnetic flux of the transformer core. Transformer. 3. A transformer in which a detection element formed by winding a detection coil around a magnetic core of a magnetic material is disposed inside or on a surface of a transformer core. The wound portion and both ends are arranged in parallel with the magnetic flux of the transformer core, and both ends thereof are arranged in contact with the transformer core, and are in contact with the transformer core in the periphery of the magnetic flux detecting element. A transformer characterized by being covered with a shield member made of a magnetic material or a non-magnetic material except for a surface. 4. A transformer in which a detection element formed by winding a detection coil around a magnetic core made of a magnetic material is disposed inside or on a surface of a transformer core, wherein a compensating coil is provided on an air core or a non-magnetic material winding frame. The wound compensating element is arranged in the same manner as the magnetic deflector detecting element, and the magnetic core and the winding frame have the wound portions and both ends of each coil parallel to the magnetic flux of the transformer core, and The two ends are disposed in contact with the transformer core,
The transformer, wherein the detection coil and the compensation coil are formed in the same shape, and are connected so that the induced voltage of the compensation coil is subtracted from the induced voltage of the detection coil. 5. A polarized magnetic field detecting element, which is formed by winding a detecting coil around a magnetic core made of a magnetic material, is disposed inside or on the surface of an iron core of a transformer. In the magnetic flux evaluation device for calculating the magnetic flux and the polarization of the magnetic flux passing therethrough, the detection coil is arranged so that the magnetic flux passing outside the laminated steel sheet forming the iron core does not interlink with the detection coil. Magnetic deflection amount evaluation device. 6. An apparatus for evaluating the amount of magnetic polarization according to claim 5, wherein both ends of a magnetic core of said magnetic field detecting element extend in a direction parallel to a magnetic flux direction of said transformer core and in directions opposite to each other,
A magnetic flux evaluation device, wherein a portion formed by winding the detection coil is formed to be orthogonal to a magnetic flux direction of the transformer core. 7. The device for evaluating the amount of magnetic polarization according to claim 5, wherein the magnetic field detecting element is covered with a shield member made of a magnetic material or a non-magnetic material except for a surface in contact with the transformer core. DC bias amount evaluation device characterized by the above-mentioned. 8. A magnetism detecting element formed by winding a detection coil around a magnetic core of a magnetic material is disposed inside or on a surface of an iron core of a transformer, and evaluates the magnetism of the transformer based on an output of the detection coil. In the biased magnetic field evaluation device, a compensating element formed by winding a compensating coil around a non-magnetic material winding frame is arranged in the same manner as the biased magnetic field detecting element, and the magnetic core and the winding frame are each wound with the respective coils. Parts and both ends thereof are arranged in parallel with the magnetic flux of the transformer core, and both ends thereof are arranged in contact with the transformer core, and demagnetize the transformer based on outputs of the detection coil and the compensation coil. An evaluation apparatus for magnetic declination characterized by performing evaluation. 9. A polarization detecting element, which is formed by winding a detection coil around a magnetic core of a magnetic material, is disposed inside or on the surface of an iron core of a transformer, and evaluates the polarization of the transformer based on the output of the detection coil. The change rate of the output of the detection coil is detected, a time interval at which the change rate becomes equal to or more than a set value is obtained, and the magnetic bias of the transformer is determined based on the change of the obtained time interval. A magnetic polarization evaluation device characterized by evaluating the following. 10. The magnetic deflecting evaluation device according to claim 5, wherein the magnetic core of the magnetic deflecting detecting element is made of iron.
An apparatus for evaluating magnetic polarization, comprising a nickel alloy or an amorphous magnetic material. 11. A power converter using a semiconductor switching element, a conversion transformer connected to the AC side of the power converter, and a magnetic polarization evaluation device for evaluating magnetic polarization of the conversion transformer. A depolarization suppression control unit that controls the power converter so as to cancel the depolarization of the conversion transformer based on the evaluation of the depolarization evaluation device. A power conversion system, characterized in that the device is the polarization evaluation device according to any one of claims 5 to 9.