JP2013158085A - High frequency current reduction device and detection transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency current reduction device and a detection transformer that effectively reduce common mode currents and normal mode noise currents.SOLUTION: A high frequency current reduction device 100 includes a detection transformer 1, a filter device 2, a voltage amplifier 3 and voltage application means 4. The detection transformer 1 has main windings 11-13, a common core 15 on which the main windings 11-13 are wound, a leakage flux core 16 arranged inside the common core 15 to separate the main windings 11-13, and a detection winding 14 wound evenly on the common core 15 to detect currents flowing through the main windings 11-13. Normal mode currents flowing through the main windings 11-13 generate magnetic fluxes in the leakage flux core 16 to provide inductances to the normal mode currents. The normal mode currents and common mode currents flowing through the main windings 11-13 generate a magnetic flux in the common core 15 to provide inductances to the common mode currents.

Description

  The present invention relates to a common mode current, which is a high-frequency current generated by a power converter connected to an AC power source and outputting an arbitrary AC voltage, and a high-frequency current reduction device for reducing normal mode noise current, and a detection transformer used therefor It is about.

  A conventional conductive noise filter detects a common mode voltage generated during a switching operation of a power semiconductor element via a ground capacitor connected to a line between an AC power source and a rectifier, and detects the common mode voltage Based on the common mode voltage, a canceling voltage with the same polarity as the common mode voltage is generated, and this canceling voltage is superimposed between the AC power source and the ground capacitor connection point on the route. (See, for example, Patent Document 1).

JP 2010-057268 A

Since the conventional conductive noise filter uses a ground capacitor as the common mode voltage detecting means, there is a problem that the impedance of the detection circuit becomes small and the detection value becomes small. When the detected value becomes small, the canceling voltage generated based on the detected value becomes small, and there is a case where the common mode voltage is not sufficiently canceled.
In the above conventional conductive noise filter, even if the common mode current can be reduced, the normal mode noise current is only reduced by the ground capacitor as the X capacitor, and the normal mode noise current is not sufficiently reduced. There was a problem. In order to enhance the reduction of the normal mode noise current, it is necessary to provide a filter reactor or the like corresponding to the normal mode noise current.
The present invention has been made to solve the above-described problems, and an object thereof is to obtain a high-frequency current reduction device and a detection transformer that can effectively reduce the common mode current and the normal mode noise current.

  The high-frequency current reduction device according to the present invention is inserted between the first electric device and the second electric device via a plurality of connection lines between the first and second electric devices, and the first electric device The high-frequency current reducing device reduces the high-frequency current flowing from the electrical device to the connection line. A detection transformer for detecting a current flowing from the first electric device to the connection line; a filter device for outputting a voltage in a desired frequency band by receiving an output of the detection transformer; and amplifying the output of the filter device. A voltage amplifier that outputs as an output voltage and the first and second electric devices are provided closer to the second electric device than the detection transformer. Based on the output voltage, the high frequency current is applied to the connection line. And a voltage applying means for applying a voltage in a predetermined direction. And the said detection transformer is arrange | positioned inside the said common iron core, the several common winding connected in series with each said connection line, the cyclic | annular common iron core around which the said main winding is wound, and the said common iron core A leakage magnetic flux core that separates the main windings together with the iron core, and a detection coil for current detection that is wound around the common iron core and detects a current flowing through the main winding to the connection line. Magnetic flux is generated in the iron core for leakage flux by the normal mode current flowing through each main winding, and each main winding acts as an inductance for the normal mode current. Magnetic flux is generated by the common mode current flowing through each main winding, and each main winding acts as an inductance for the common mode current.

  A detection transformer according to the present invention includes a plurality of main windings, an annular common iron core around which the main winding is wound, and the main iron core disposed between the main windings. It has an iron core for leakage magnetic flux that partitions, and a detection coil for detecting current that is wound around the common core and detects a current flowing through the main coil. A magnetic flux is generated by the normal mode current flowing through each main winding in the leakage magnetic flux core, and each main winding acts as an inductance with respect to the normal mode current. Magnetic flux is generated by the common mode current flowing through each main winding, and each main winding acts as an inductance for the common mode current.

  The high-frequency current reduction device according to the present invention is inserted between the first electric device and the second electric device via a plurality of connection lines between the first and second electric devices, and the first electric device The high-frequency current reducing device reduces the high-frequency current flowing from the electrical device to the connection line. A detection transformer for detecting a current flowing from the first electric device to the connection line; a filter device for outputting a voltage in a desired frequency band by receiving an output of the detection transformer; and amplifying the output of the filter device. A voltage amplifier that outputs as an output voltage and the first and second electric devices are provided closer to the second electric device than the detection transformer. Based on the output voltage, the high frequency current is applied to the connection line. And a voltage applying means for applying a voltage in a predetermined direction. And the said detection transformer is arrange | positioned inside the said common iron core, the several common winding connected in series with each said connection line, the cyclic | annular common iron core around which the said main winding is wound, and the said common iron core A leakage magnetic flux core that separates the main windings together with the iron core, and a detection coil for current detection that is wound around the common iron core and detects a current flowing through the main winding to the connection line. Magnetic flux is generated in the iron core for leakage flux by the normal mode current flowing through each main winding, and each main winding acts as an inductance for the normal mode current. Magnetic flux is generated by the common mode current flowing through each main winding, and each main winding acts as an inductance for the common mode current. Therefore, the current flowing through the connection line can be accurately detected by the detection transformer, and the detection transformer acts as an inductance of the common mode current and normal mode noise current, which are high-frequency currents. Both can be effectively reduced.

  A detection transformer according to the present invention includes a plurality of main windings, an annular common iron core around which the main winding is wound, and the main iron core disposed between the main windings. It has an iron core for leakage magnetic flux that partitions, and a detection coil for detecting current that is wound around the common core and detects a current flowing through the main coil. A magnetic flux is generated by the normal mode current flowing through each main winding in the leakage magnetic flux core, and each main winding acts as an inductance with respect to the normal mode current. Magnetic flux is generated by the common mode current flowing through each main winding, and each main winding acts as an inductance for the common mode current. For this reason, the current that flows in the main winding can be accurately detected by the detection winding, and each main winding acts as an inductance of the common mode current and normal mode noise current, which are high-frequency currents. Both mode noise currents can be effectively reduced.

It is a block diagram which shows the structure of the high frequency current reduction apparatus in Embodiment 1 of this invention. It is a top view which shows typically the structure of the detection transformer in Embodiment 1 of this invention. It is a connection diagram which shows the example of a connection of the high frequency current reduction apparatus in Embodiment 1 of this invention. It is a circuit diagram which shows the detail of the converter in Embodiment 1 of this invention. It is a circuit diagram which shows the detail of the inverter in Embodiment 1 of this invention. It is a top view which shows typically the structure of the detection transformer which has arrange | positioned the support member of the other example in Embodiment 1 of this invention. It is a block diagram which shows the structure of the high frequency current reduction apparatus in Embodiment 2 of this invention. It is a top view which shows typically the structure of the detection transformer in Embodiment 2 of this invention. It is a top view which shows typically the structure of the detection transformer in Embodiment 3 of this invention. It is a top view which shows typically the structure of the detection transformer in Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a configuration diagram showing a configuration of a high-frequency current reduction device 100 according to Embodiment 1 of the present invention, and FIG. 2 is a plan view schematically showing a configuration of a detection transformer 1 used in the high-frequency current reduction device 100.
The high-frequency current reduction device 100 includes a three-phase connection line R that connects the AC power source 101 and the converter 102 between an AC power source 101 as a first electric device and a converter 102 as a second electric device. The high-frequency current that is inserted through S and T and flows from the AC power supply 101 to the connection lines R, S, and T is reduced.
The high-frequency current reduction device 100 detects a current flowing through the connection lines R, S, and T from the AC power supply 101 as a detection voltage and outputs the voltage in a desired frequency band when the output of the detection transformer 1 is input. A filter device 2 that performs output, a voltage amplifier 3 that amplifies the output from the filter device 2 and outputs the output voltage as an output voltage, and a connection line that is provided on the converter 102 side of the detection transformer 1 and that is output from the voltage amplifier 3 And voltage applying means 4 for applying a voltage to R, S, and T. Hereinafter, each configuration of the high-frequency current reduction device 100 will be described in detail.

  The iron core of the detection transformer 1 includes a substantially cylindrical common iron core 15 as an annular common iron core and a leakage flux iron core 16 that is formed separately from the common iron core 15 and disposed inside the common iron core 15. . The magnetic flux leakage iron core 16 is an iron core having a substantially Y-shaped cross section formed from three leg portions 160, 161, 162. The material of the common iron core 15 is, for example, Ni—Zn ferrite, and the material of the leakage flux iron core 16 is a material having a higher magnetic flux saturation density than the material of the common iron core 15, for example, Mn—Zn ferrite. The lengths of the common iron core 15 and the leakage flux iron core 16 in the central axis direction are substantially the same, and the leakage flux iron core 16 is disposed inside the common iron core 15. The central axis direction is a direction in which the central axis of the cylindrical common iron core 15 extends, and is hereinafter referred to as an axial direction.

Three main windings 11, 12, and 13 are wound independently around the common iron core 15, and the three main windings 11, 12, and 13 are connected to three-phase connection lines R, S, and T, respectively. Connected in series. The winding directions of the main windings 11, 12, and 13 are the same. In the first embodiment, the number of turns is 4 turns. The main windings 11, 12, 13 inside the common iron core 15 are partitioned by the leg portions 160, 161, 162 of the leakage flux iron core 16. Cross sections of the main windings 11, 12, and 13 are indicated by marks in FIG.
Further, a detection winding 14 which is a current detection winding is wound around the common iron core 15. The detection winding 14 is a single winding and is wound 12 turns around the common iron core 15 at substantially equal intervals. Since the inside of the common iron core 15 is divided into three by the magnetic flux leakage iron core 16, four turns are wound in each space. A cross section of the detection winding 14 is indicated by a circle in FIG. When the detection winding 14 is wound around the common iron core 15, the current flowing through the connection lines R, S, T is detected as a detection voltage by the detection winding 14 via the main windings 11, 12, 13. One end of the detection winding 14 is connected to the filter device 2 and the other end is grounded. The polarities of the main windings 11, 12, 13 and the detection winding 14 are wound so as to have a polarity indicated by ● in FIG.

Between the common iron core 15 and the magnetic flux leakage iron core 16, a support member 17 formed by making a sheet of non-magnetic material into a cylindrical shape is disposed. By disposing the support member 17, the magnetic flux leakage in the common iron core 15 is maintained in a state where gaps with a uniform width are held between the common iron core 15 and the legs 160, 161, 162 of the magnetic flux leakage iron core 16. The iron core 16 is supported. What is necessary is just to determine the thickness of the supporting member 17 suitably according to the magnitude | size of the detection transformer 1 whole, and the width | variety of a required clearance gap.
In the first embodiment, the cylindrical support member 17 is used. However, the shape of the support member 17 is not limited to this. For example, the sheet-like support member 17 may be arranged only in a portion where the common iron core 15 and the leg portions 160, 161, 162 of the magnetic flux leakage iron core 16 are close to each other.
In the first embodiment, the substantially cylindrical common iron core 15 is used as the annular common iron core, but the shape of the common iron core is not limited to the substantially cylindrical shape. For example, it may be a polygonal cylinder such as a triangle or a hexagon, and it is only necessary to provide each space for winding the main windings 11, 12, and 13 inside.

The filter device 2 includes at least one filter circuit, and adjusts the constant of the filter circuit to adjust the pass frequency range to a desired value. In addition, the gain and phase are adjusted for each passing frequency, and the adjusted voltage is output.
The voltage amplifier 3 is composed of, for example, power supply terminals 30A and 30B and an operational amplifier 30C. The voltage input from the filter device 2 is amplified by the operational amplifier 30C and output.

  The voltage application means 4 includes three capacitors 41, 42, 43 for voltage application, and a ground resistor 44. Each capacitor 41, 42, 43 has one terminal connected to the three-phase connection lines R, S, T, respectively, and the other terminal connected in common at a common connection point 46. The output line from the operational amplifier 30C of the voltage amplifier 3 is connected to the common connection point 46. The common connection point 46 is grounded via the ground resistor 44.

The effects of the high-frequency current reduction device 100 having such a configuration will be described.
First, the detection transformer 1 will be described.
Of the configuration of the detection transformer 1, the main windings 11, 12, 13, the common iron core 15, and the magnetic flux leakage iron core 16 serve as a filter reactor that suppresses the passage of high-frequency current flowing through the connection lines R, S, T. Bear. Here, the current flowing through the connection lines R, S, and T includes a normal mode current and a common mode current. The normal mode current is a current including both a low frequency component such as a load current and a high frequency component which is a normal mode noise current, and the common mode current indicates only a current of a high frequency component which is a noise current to be reduced. Hereinafter, the low frequency component of the normal mode current is the load current, the high frequency component of the normal mode current is the normal mode noise current, the combination of the load current and the normal mode noise current is the normal mode current, and the common mode current is the high frequency component only. Therefore, it is simply a common mode current.

It is assumed that a normal mode current and a common mode current flow from the three-phase AC power source 101 to the main windings 11, 12, and 13 through connection lines R, S, and T.
First, the common mode current is examined. As described above, the main windings 11, 12, and 13 are all wound in the same direction. For this reason, the magnetic flux Φ1 due to the common mode current is generated in the closed magnetic circuit by the common iron core 15, and each main winding 11, 12, 13 acts as an inductance for the common mode current. Therefore, the common mode current can be reduced.
Consider normal mode current. The main windings 11, 12, and 13 are all wound in the same direction, and the normal mode currents of the respective phases are out of phase. It is. However, since the leakage magnetic paths of the main windings 11, 12, and 13 are provided by the leakage flux iron core 16, the magnetic fluxes Φ <b> 2 to Φ <b> 4 for each phase due to the normal mode current are supplied from the common iron core 15 to the leakage flux iron core. The main windings 11, 12, and 13 act as inductances with respect to the normal mode current. For this reason, the normal mode noise current which is a high frequency component among the normal mode current can be reduced. Note that arrows of magnetic fluxes Φ2 to Φ4 in FIG. 2 indicate the flow direction of the magnetic flux at a certain point in time, and the flow direction of the magnetic flux sequentially changes in accordance with the state of each phase current flowing from the AC power supply 101.

Next, the effect of providing a gap between the common iron core 15 and the leakage flux iron core 16 will be described.
First, the magnetic flux saturation iron core 16 is likely to cause magnetic flux saturation because of its structure. The reason for this will be described.
First, since the leakage flux iron core 16 is disposed inside the common iron core 15, the cross-sectional area of the leakage flux iron core 16 is greatly limited by the inner diameter of the common iron core 15 and the wire diameter of the winding used. . When the cross-sectional area of the leakage flux iron core 16 is limited, the leakage flux iron core 16 is likely to be saturated with the magnetic fluxes Φ2 to Φ4 caused by the normal mode current. The amount of magnetic flux generated in the common iron core 15 is larger than the amount of magnetic flux generated in the leakage flux iron core 16 by the amount of the magnetic flux Φ1 due to the common mode current. However, since the common mode current is a current having a small high-frequency component, the magnetomotive force is small, and the cross-sectional area of the common core 15 can be adjusted by increasing the outer diameter of the common core 15. Hard to occur.
Secondly, the magnetic fluxes Φ2 to Φ4 due to the normal mode current flowing through the legs 160, 161, 162 of the leakage flux iron core 16 are generated not only in the weakening direction but also in the strengthening direction. For example, in the example of FIG. 2, the magnetic flux is generated in the direction in which the magnetic flux is strengthened at the leg portion 161 and the leg portion 162 of the leakage flux iron core 16. When the magnetic flux is generated in the strengthening direction, the amount of the magnetic flux naturally increases. Therefore, the legs 160, 161, 162 of the leakage flux core 16 are likely to be saturated with magnetic flux.
If a gap is provided between the common iron core 15 and the leakage flux iron core 16, that is, if a gap is provided in the leakage magnetic path that passes through the leakage flux iron core 16, this gap acts as a magnetic resistance of the leakage magnetic path. By changing the width of the gap, the amount of magnetic flux Φ2 to Φ4 flowing through the leakage magnetic path can be adjusted. If the leakage flux core 16 is saturated, the inductance value with respect to the normal mode current decreases. However, by providing a gap having an appropriate width, the leakage flux core 16 is prevented from being saturated. be able to. Moreover, since the magnetic flux amount of the magnetic fluxes Φ2 to Φ4 can be adjusted by the width of the gap, the inductance value for the normal mode current can be adjusted. The width of the gap between the common iron core 15 and the leakage flux iron core 16 is determined based on a desired inductance value for the normal mode current.

Next, the effect obtained by forming the common iron core 15 and the leakage flux iron core 16 from different materials, in the first embodiment, the common iron core 15 made of Ni—Zn ferrite and the leakage flux iron core 16 made of Mn—Zn ferrite. Will be described. In general, Mn—Zn ferrite is a material having a higher magnetic flux saturation density than Ni—Zn ferrite.
As described above, the magnetic flux saturation iron core 16 is likely to cause magnetic flux saturation. However, the magnetic flux saturation of the magnetic flux leakage iron core 16 is prevented by making the material of the magnetic flux leakage iron core 16 a material having a high magnetic flux saturation density. Can do.
Moreover, as above-mentioned, it can prevent that the magnetic flux amount of magnetic flux (PHI) 2-Φ4 which flows through a leakage magnetic path becomes large too much by providing a clearance gap between the common iron core 15 and the iron core 16 for leakage magnetic flux. However, if the width of the gap is increased too much, the amount of magnetic flux decreases, and the inductance value with respect to the normal mode current decreases. When the inductance value decreases, the normal mode noise current cannot be effectively reduced. Therefore, if the material for the leakage flux core 16 is made of a material having a high magnetic flux saturation density as in the first embodiment, the amount of magnetic flux until the magnetic flux saturation of the leakage flux core 16 is reached increases. It is possible to prevent the inductance value from decreasing by keeping it small.
In the first embodiment, the material of the common core 15 is Ni—Zn ferrite and the material of the leakage flux core 16 is Mn—Zn ferrite. However, the material of the iron core is not limited to these, for example, An iron-based material can also be used.

  Thus, by inserting the detection transformer 1 including the main windings 11, 12 and 13, the common iron core 15, and the leakage flux iron core 16 between the AC power supply 101 and the converter 102, a filter reactor for the common mode current is obtained. And a role as a filter reactor with respect to the normal mode noise current, and the common mode current and the normal mode noise current flowing through the connection lines R, S, and T are suppressed.

Next, the effect of the detection winding 14 of the detection transformer 1 will be described.
In addition to the configuration of the main windings 11, 12, and 13 that function as a filter reactor with respect to the common mode current and the normal mode noise current, the common iron core 15, and the leakage flux iron core 16, the detection transformer 1 is configured as described above. The detection winding 14 is wound around the common iron core 15.
As described above, when a normal mode current and a common mode current flow from the three-phase AC power source 101 to the main windings 11, 12, and 13 through the connection lines R, S, and T, the common mode current flows in the common core 15. And Φ2 to Φ4 due to the normal mode current are generated. The detection winding 14 detects a current flowing through each of the main windings 11, 12, 13 as a detection voltage by interlinking these magnetic fluxes.
Here, in the first embodiment, one detection winding 14 is uniformly wound around the entire common iron core 15. Since the magnetic fluxes Φ2 to Φ4 due to the normal mode current are generated so as to be canceled by the common iron core 15 as a whole, the detection winding 14 is connected to the three-phase connection line R, by interlinking the magnetic flux Φ1 due to the common mode current. The common mode current J1 flowing through S and T can be detected as the common mode voltage V1 via the main windings 11, 12, and 13. The common mode current J1 is the sum of the common mode currents flowing through the three-phase connection lines R, S, and T.

  If a capacitor is used to detect common mode current, the impedance of the detection circuit will be small when detecting high frequency common mode current, and almost no common mode voltage will be generated. It is difficult to detect the common mode current of the band. In the first embodiment, since the common mode current J1 is detected by the detection transformer 1, it is possible to detect the voltage in a state where the impedance of the detection circuit is high and the common mode voltage is generated. Therefore, the detection accuracy of the common mode current J1 is improved.

Next, functions and effects of the filter device 2, the voltage amplifier 3, and the voltage applying unit 4 will be described.
As described above, the filter device 2 adjusts the pass frequency range to a desired value, and adjusts the gain and phase for each passing frequency. For example, the gain may be reduced for frequency components such as the carrier frequency of the inverter 104, which will be described later, the frequency range outside the frequency range defined by the standard, and the frequency at which the voltage amplifier 3 resonates due to the impedance of the system. For example, the gain of the frequency to be increased is increased. The common mode voltage V1 detected by the detection winding 14 of the detection transformer 1 is input to the filter device 2, and the input common mode voltage V1 passes through the filter circuit to be converted into a voltage V2 in a desired frequency band. 2 is output.
The voltage amplifier 3 has a gain set to G1, for example, and outputs an output voltage V3 obtained by amplifying the voltage V2 from the filter device 2 by a gain G1. Note that the input impedance of the voltage amplifier 3 is set to a large value in order to detect the voltage across the detection winding 14 with higher accuracy.
Then, the output voltage V3 from the voltage amplifier 3 is applied to the common connection point 46 of the voltage application means 4 to change the voltage across the capacitors 41, 42 and 43. This output voltage V3 is generated so as to be in substantially the same direction as the common mode voltage V1, and a current J3 having substantially the same magnitude in the same direction as the common mode current J1, which is a high-frequency current, is passed through the capacitors 41, 42, and 43. The voltage amplifier 3 adjusts the output voltage V3 so as to be supplied to the connection lines R, S, T. By supplying the current J3 to the connection lines R, S, and T, most of the common mode current J2 that flows from the connection lines R, S, and T to the converter 102 flows through a path from the voltage amplifier 3 via the voltage application unit 4. Therefore, the common mode current J1 flowing from the AC power supply 101 to the connection lines R, S, and T can be reduced. By adjusting the output voltage V3 so that the common mode current J1 approaches zero by the voltage amplifier 3, the common mode current J1 can be reduced to almost zero.
In the case of the first embodiment, the capacitors 41, 42 and 43 of the voltage applying means 4 are low-frequency impedances between the connection lines R, S and T as X capacitors, so that the normal mode noise current is the capacitor 41. , 42, 43, and normal mode noise current is reduced.

The above is the description of the high-frequency current reduction device 100. Next, a connection example of such a high-frequency current reduction device 100 will be described. 3 is a connection diagram illustrating a connection example of the high-frequency current reduction device 100, FIG. 4 is a circuit diagram illustrating details of the converter 102, and FIG. 5 is a circuit diagram illustrating details of the inverter 104.
As shown in FIG. 3, the high-frequency current reduction device 100 is, for example, a system that supplies power from an AC power source 101 to a three-phase motor 106 as a load via a converter 102, an intermediate filter 103, an inverter 104, and an output filter 105. Applied.
As shown in FIG. 4, the converter 102 is configured by connecting a IGBT 102A as a semiconductor switching element in a three-phase full bridge connection, and converts the three-phase alternating current to a variable voltage direct current by controlling the opening and closing of the IGBT 102A. The output of the converter 102 is input to the inverter 104 through the intermediate filter 103 having a capacitor through connection lines P and N which are DC buses.
As shown in FIG. 5, the inverter 104 is configured by connecting a three-phase full-bridge IGBT 104A as a semiconductor switching element, and converts the direct current into a three-phase alternating current of variable voltage and variable frequency by controlling the opening and closing of the IGBT 104A. The output of the inverter 104 is supplied to the load 106 via the output filter 105 by R1, S1, and T1, which are AC output lines.
Here, as an example, the high-frequency current reduction device 100 is inserted between the AC power source 101 as the first electric device and the converter 102 as the second electric device. Examples are not limited to this. For example, in FIG. 3, the first electric device is the inverter 104, the second electric device is the load 106, and the high-frequency current reduction device 100 is inserted between the inverter 104 and the load 106 instead of the output filter 105. Good. The high-frequency current reduction device can be inserted between various electrical devices and can reduce the high-frequency current.

As described above, since the high-frequency current reduction device 100 according to the first embodiment detects the high-frequency current flowing through the connection lines R, S, and T as a voltage by the detection transformer 1, the impedance of the detection circuit is high, and the connection The detection accuracy of the high-frequency current (common mode current J1 in the first embodiment) flowing through the lines R, S, and T can be improved. Therefore, a small common mode current or a common mode current in a high frequency band can be reliably detected as the common mode current J1, and the current is supplied to the connection lines R, S, T by the voltage applying means 4 based on the detected current. The common mode current J1 can be effectively reduced.
Further, since the detection transformer 1 acts as an inductance of the common mode current and the normal mode noise current by the main windings 11, 12 and 13, the common iron core 15 and the leakage flux iron core 16, the common mode current and the normal mode noise current are generated. Both can be effectively reduced.
Therefore, although the detection transformer 1 is a simple component, it serves as a detection means for detecting high-frequency current flowing through the connection lines R, S, and T with high accuracy, and serves as a filter reactor for reducing common mode current. It can serve as a filter reactor for reducing normal mode noise current, and can reduce the size of the high-frequency current reduction device 100 and improve the high-frequency current reduction efficiency.
In the first embodiment, the detection of the high-frequency current flowing through the connection lines R, S, and T is detected as a voltage by the detection transformer 1, but it is not always necessary to detect the voltage by the detection transformer 1. If the detection transformer detects the high-frequency current flowing through the connection lines R, S, and T as a current, the filter device 2 is configured to output a voltage in a desired frequency band with the detection current from the detection transformer as an input. That's fine. However, if the detection transformer 1 detects the high frequency current flowing through the connection lines R, S, and T as a voltage as in the first embodiment, the detection transformer is more effective than the detection transformer. The impedance to the high-frequency current generated by 1 is increased, and a further high-frequency current reduction effect is achieved.

  Further, if a gap is provided between the common iron core 15 and the magnetic flux leakage core 16 of the detection transformer 1, the gap acts as a magnetic resistance of the leakage magnetic path passing through the magnetic flux leakage iron core 16, so that By providing a gap with a sufficient width, the magnetic flux saturation of the leakage flux core 16 can be prevented. Therefore, it is possible to prevent a decrease in inductance due to the magnetic flux saturation of the leakage flux iron core 16 and reliably reduce the normal mode noise current.

  Further, the common iron core 15 and the leakage flux iron core 16 are formed separately, and the annular support member 17 is disposed between the common iron core 15 and the leakage flux iron core 16, so that a gap having a uniform width is maintained. In this state, the magnetic flux leakage iron core 16 is supported by the common iron core 15. For this reason, a uniform gap can be easily provided in each leakage magnetic path by the common iron core 15 and the magnetic flux leakage iron core 16 having a simple shape. Accordingly, the magnetic resistances of the leakage magnetic paths of the main windings 11, 12, and 13 are all kept uniform, and the detection transformer 1 is formed without any three-phase imbalance.

Moreover, the magnetic flux saturation of the magnetic flux leakage iron core 16 can be suppressed by making the material of the magnetic flux leakage iron core 16 a material having a high magnetic flux saturation density. And even if the cross-sectional area of the leakage flux iron core 16 is small, the amount of magnetic flux until the magnetic flux saturation is reached can be increased, so that the width of the gap can be reduced to prevent the inductance value from decreasing. Therefore, the normal mode noise current can be effectively reduced.
Further, since the cross-sectional area of the leakage flux iron core 16 can be reduced, the overall size of the detection transformer 1 can be reduced.
In addition, since the common iron core 15 and the leakage flux iron core 16 are separate members, the common iron core 15 and the leakage flux iron core 16 can be easily made of different materials. The material of the leakage flux iron core 16 can be set freely.

The configuration of the support member provided in the gap between the common iron core 15 and the leakage flux iron core 16 is not limited to the sheet-like support member as described above. FIG. 6 is a plan view of a detection transformer in which another example support member is arranged.
As shown in FIG. 6, a rod-like support rod 17 </ b> A such as a pin is arranged as another support member between the common iron core 15 and the leakage flux iron core 16. The support rod 17A is formed of a magnetic material, and one end is fixed to the common iron core 15 and the other end is fixed to the leakage magnetic flux core 16. Thus, the leakage magnetic flux iron core 16 is provided in the common iron core 15 with a uniform width. Hold and support.

By using the support rod 17A as the support member, the following operational effects are obtained.
When a normal mode current flows through the main windings 11, 12, and 13, magnetic fluxes Φ <b> 2 to Φ <b> 4 are generated in the leakage magnetic path that passes through the leakage magnetic flux core 16. When the flowing normal mode current is small, the amount of generated magnetic flux is small, and the magnetic fluxes Φ2 to Φ4 flow so as to pass through the support rod 17A that is a magnetic body. Therefore, the magnetic resistance of the leakage magnetic path is small. When the flowing normal mode current increases, the amount of generated magnetic flux increases, and magnetic flux saturation of the support rod 17A having a small cross-sectional area occurs. After the magnetic flux saturation of the support rod 17A, the magnetic fluxes Φ2 to Φ4 pass through the gap between the common iron core 15 and the leakage flux iron core 16, and the magnetic resistance of the leakage magnetic path is increased by the gap.
That is, when the support rod 17A is used as a support member, when the flowing normal mode current is large and the magnetic flux saturation of the support rod 17A occurs, the gap acts as the magnetic resistance of the leakage magnetic path via the leakage flux iron core 16, This has the same effect as when a non-magnetic sheet-like support member 17 is used as the support member.
The detection transformer using the magnetic support rod 17A can be used effectively when the normal mode current flowing through the main windings 11, 12, and 13 is large enough to cause the magnetic flux saturation of the support rod 17A. The mode noise current can be reduced.

In addition, although the rod-shaped support rod 17A like a pin was used as a support rod here, the shape of a support rod is not restricted to this. The support bar only needs to have a shape that can uniformly maintain the width of the gap between the common iron core 15 and the magnetic flux leakage core 16, and the support bar made of a magnetic material includes the common iron core 15 and the magnetic flux leakage iron core 16. In order to exhibit the effect of the gap between the cross sections, the cross section may be an elongated cross section line.
Further, instead of the magnetic support rod, a nonmagnetic support rod having the same shape may be used. In that case, since no magnetic flux flows in the support rod, the magnetic flux passes through the gap between the common iron core 15 and the leakage flux iron core 16 regardless of the magnitude of the normal mode current flowing through the main windings 11, 12, 13. Therefore, it has the same effect as the case where the non-magnetic sheet-like support member 17 is used as the support member.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing the configuration of the high-frequency current reduction device 100A according to Embodiment 2 of the present invention, and FIG. 8 is a plan view schematically showing the configuration of the detection transformer 1A used in the high-frequency current reduction device 100A. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in the figure, in the detection transformer 1A of the high-frequency current reduction device 100A of the second embodiment, the same number of detection windings 18, 19, and 20 as the main windings 11, 12, and 13 are wound around the common core 15. Has been. Filter devices 2A, 2B and 2C, voltage amplifiers 3A, 3B and 3C, and voltage applying means 4A, 4B and 4C are provided for each of the detection windings 18, 19 and 20. In FIG. 7, each of the voltage amplifiers 3A, 3B, and 3C has the same configuration as that of the voltage amplifier 3 shown in FIG. 1, and only the operational amplifier is shown and the display of the power supply terminal is omitted.

  The detection windings 18, 19, and 20 of the detection transformer 1 </ b> A are respectively wound around the sections partitioned by the common iron core 15 and the leakage flux iron core 16, similarly to the main windings 11, 12, and 13. Here, the main winding 11 and the detection winding 18, the main winding 12 and the detection winding 19, and the main winding 13 and the detection winding 20 are wound in the same section. The number of turns of each of the detection windings 18, 19 and 20 is 4 turns. In FIG. 8, the cross section of the detection winding 18 is marked with a circle, the cross section of the detection winding 19 is marked with a circle, and the cross section of the detection winding 20 is shaded. This is indicated by a circle. By winding the detection windings 18, 19, 20 corresponding to the main windings 11, 12, 13 in each section, the current flowing through the connection line R is detected via the main winding 11. The current flowing through the connection line S is detected by the detection winding 19 via the main winding 12, and the current flowing through the connection line T is detected by the detection winding 20 via the main winding 13. To detect. One ends of the detection windings 18, 19, and 20 are connected to the filter devices 2A, 2B, and 2C, respectively, and the other ends are grounded. The polarities of the main windings 11, 12, 13 and the detection windings 18, 19, 20 are wound so as to have a polarity indicated by ● in FIG.

  The filter devices 2A, 2B, and 2C have the same configuration as the filter device 2 of the first embodiment, and the voltage amplifiers 3A, 3B, and 3C have the same configuration as the voltage amplifier 3 of the first embodiment. The voltage application means 4A includes a voltage application capacitor 410 and a ground resistor 44A. One terminal of the capacitor 410 is connected to the connection line R, and the other terminal is connected to the output line of the voltage amplifier 3A. A connection point between the other terminal of the capacitor 410 and the output line of the voltage amplifier 3A is grounded via a ground resistor 44A. A current is supplied to the connection line R through the capacitor 410 by the voltage applying means 4A. The voltage application unit 4B and the voltage application unit 4C have the same configuration as the voltage application unit 4A, and include capacitors 420 and 430 for voltage application and ground resistors 44B and 44C, respectively. A current is supplied to the connection line S by the voltage application means 4B, and a current is supplied to the connection line T by the voltage application means 4C.

Since the high-frequency current reduction device 100A having such a configuration includes the three detection windings 18, 19, and 20 in the detection transformer 1A, the following effects are obtained.
As described in the first embodiment, when a normal mode current and a common mode current flow from the three-phase AC power supply 101 to the main windings 11, 12, and 13 via the connection lines R, S, and T, the common Magnetic flux Φ1 due to common mode current and magnetic fluxes Φ2 to Φ4 due to normal mode current are generated in the iron core 15. The detection windings 18, 19, and 20 detect currents flowing through the main windings 11, 12, and 13 as detection voltages by interlinking these magnetic fluxes.

The detection winding 18 wound in the same section as the main winding 11 has a common mode current flowing through the connection line R and a normal mode by interlinking the magnetic flux Φ1 caused by the common mode current and the magnetic flux Φ2 caused by the normal mode current. A current J1A combined with the current is detected as a voltage V1A via the main winding 11. That is, the voltage V1A is a voltage obtained by combining the common mode voltage and the normal mode voltage.
Similarly, the detection winding 19 wound in the same section as the main winding 12 has a common mode current flowing in the connection line S due to the linkage of the magnetic flux Φ1 due to the common mode current and the magnetic flux Φ3 due to the normal mode current. Current J1B that is the sum of the normal mode current and the normal mode current is detected as a voltage V1B that is the sum of the common mode voltage and the normal mode voltage.
Similarly, the detection winding 20 wound in the same section as the main winding 13 has a common mode current flowing in the connection line T by the linkage of the magnetic flux Φ1 caused by the common mode current and the magnetic flux Φ4 caused by the normal mode current. Current J1C that is the sum of the normal mode current and the normal mode voltage is detected as a voltage V1C that is the sum of the common mode voltage and the normal mode voltage.
In this way, the currents J1A, J1B, and J1C flowing through the connection lines R, S, and T are respectively detected by the detection windings 18, 19, and 20 through the main windings 11, 12, and 13, respectively. , V1B, and V1C, respectively.
The ratio between the common mode current and the normal mode current to be detected can be set to a desired ratio by adjusting the width and material of the gap between the common iron core 15 and the leakage flux iron core 16. As described in the first embodiment, the amount of magnetic fluxes Φ2 to Φ4 flowing in the leakage magnetic path can be adjusted by changing the width of the gap between the common iron core 15 and the magnetic flux leakage iron core 16. It is.

The voltages V1A, V1B, and V1C detected by the detection windings 18, 19, and 20 are input to the filter devices 2A, 2B, and 2C, respectively, and the input voltages V1A, V1B, and V1C pass through the filter circuit. The voltages V2A, V2B, and V2C in desired frequency bands are output from the filter devices 2A, 2B, and 2C, respectively.
Here, the normal mode voltage included in the voltages V1A, V1B, and V1C detected by the detection windings 18, 19, and 20 includes not only a normal mode noise current of a high frequency component but also a load of a low frequency component that is not a reduction target. Includes voltage due to current. The filter devices 2A, 2B, and 2C remove the voltage caused by the low-frequency component load current, and extract only the voltage caused by the high-frequency component normal mode noise current and common mode current. Further, gain and phase are also adjusted by the filter devices 2A, 2B, and 2C.

The voltages V2A, V2B, and V2C output from the filter devices 2A, 2B, and 2C are input to the voltage amplifiers 3A, 3B, and 3C, respectively. The gains of the voltage amplifiers 3A, 3B, and 3C are set to substantially the same value (here, G1), and the output voltages obtained by amplifying the voltages V2A, V2B, and V2C from the filter devices 2A, 2B, and 2C by a gain G1 times, respectively. V3A, V3B, and V3C are output. Here, by setting the gains of the voltage amplifiers 3A, 3B, and 3C to substantially the same value, a large imbalance is not caused in the voltages caused by the common mode currents in the output voltages V3A, V3B, and V3C.
Note that if the common mode current and the normal mode noise current of each phase are unbalanced due to the imbalance of the three-phase loads, the gains may be set to different values.

The output voltages V3A, V3B, and V3C from the voltage amplifiers 3A, 3B, and 3C are applied to the capacitor 410 of the voltage applying unit 4A, the capacitor 420 of the voltage applying unit 4B, and the capacitor 430 of the voltage applying unit 4C, respectively. , 420, and 430 are changed. The connection lines R, S, and T are supplied with currents J3A, J3B, and J3C by the voltages across the capacitors 410, 420, and 430, respectively. Here, the output voltages V3A, V3B, and V3C that change the voltage across the capacitors 410, 420, and 430 are obtained by removing the voltage due to the low-frequency component load current. That is, since the common mode voltage and the normal mode noise voltage are combined, the currents J3A, J3B, and J3C based on the output voltages V3A, V3B, and V3C are the high-frequency component currents of the currents J1A, J1B, and J1C, respectively ( The current is almost the same magnitude in the same direction as the current obtained by combining the common mode current and the normal mode noise current.
By supplying the currents J3A, J3B, and J3C to the connection lines R, S, and T, respectively, most of the high-frequency component currents of the currents J2A, J2B, and J2C flowing from the connection lines R, S, and T to the converter 102 are reduced. Since the current flows from the voltage amplifiers 3A, 3B, and 3C through the voltage application means 4A, 4B, and 4C, the currents J1A, J1B, and J1C flowing from the AC power source 101 to the connection lines R, S, and T are selected. High frequency components, that is, common mode current and normal mode noise current can be reduced. By adjusting the output voltages V3A, V3B, and V3C so that the common mode current and the normal mode noise current of the currents J1A, J1B, and J1C approach zero by the voltage amplifiers 3A, 3B, and 3C, respectively, the current J1A, The common mode current and the normal mode noise current of J1B and J1C can be reduced to almost zero.

  As described above, the high-frequency current reduction device 100A according to the second embodiment is provided with the same number of detection windings 18, 19, and 20 as the main windings 11, 12, and 13 in the detection transformer 1A. In addition to the effect of 1, the current can be detected for each of the main windings 11, 12, and 13, thereby having the effect that not only the common mode current but also the normal mode current can be detected as a voltage. By applying a voltage to each connection line R, S, T based on each detection voltage, both common mode current and normal mode noise current flowing from the AC power supply 101 to the connection lines R, S, T are reduced. Can do.

Embodiment 3 FIG.
In the third embodiment of the present invention, a modified example of the iron core shape of the detection transformer shown in the first embodiment will be described. The configuration other than the iron core shape of the detection transformer is the same as that of the first embodiment, and the description thereof is omitted.
FIG. 9 is a plan view schematically showing the configuration of the detection transformers 1B to 1E according to the third embodiment of the present invention. The common iron cores of the detection transformers 1B to 1E are the common iron cores 15B to 15E and the magnetic flux leakage iron cores, respectively. The magnetic flux leakage iron cores 16B to 16E are used. As in the first embodiment, the main windings 11, 12, 13 and the detection winding 14 are wound around the common iron cores 15B to 15E, but the main windings 11 outside the common iron cores 15B to 15E, Illustration of the arrangement of 12, 13 and the detection winding 14 is omitted. In the first embodiment, the number of turns of each of the main windings 11, 12, 13 is 4 turns, and the number of turns of the detection winding 14 is 12 turns. The number of turns of 12 and 13 is 3 turns each, and the number of turns of the detection winding 14 is 9 turns. Since the inner side of the common iron core 15B is divided into three by the magnetic flux leakage iron core 16B, the detection winding 14 is wound three turns in each space. The detection transformers 1B and 1C are provided with the support rod 17A described in the first embodiment as an example, and the detection transformer 1D is provided with the sheet-like cylindrical support member 17 described in the first embodiment as an example. In the detection transformer 1E, as an example, a sheet-like support member 17 is disposed which is disposed only in the vicinity of the common iron core described in the first embodiment and the magnetic flux leakage core.

For example, in the detection transformer 1B, the shape of the common iron core 15B is the same as that of the common iron core 15 of the first embodiment, but the shape of the leakage flux iron core 16B is different from that of the leakage flux iron core 16 of the first embodiment. The shape of the leakage flux iron core 16B is such that each apex portion having a substantially triangular cross section is chamfered, and each of the main windings 11, 12 inside the common iron core 15B by the common iron core 15B and the leakage flux iron core 16B. 13 are partitioned.
Magnetic resistance of the leakage magnetic path in which gaps of uniform width are provided between the chamfered portions 160B, 161B, 162B of the common iron core 15B and the leakage flux iron core 16B, and the magnetic fluxes Φ2 to Φ4 generated by the normal mode current flow. Are adjusted to be even. This gap acts as a magnetic resistance of the leakage magnetic path passing through the leakage flux iron core 16B, and the amount of magnetic flux generated by the normal mode current can be adjusted. The magnetic flux Φ1 due to the common mode current generated in the detection transformer 1B is omitted.

  The detection transformers 1C and 1D are the same as in the case of the detection transformer 1B. The shape of the common iron cores 15C and 15D is the same as that of the common iron core 15 of the first embodiment, and the shape of the leakage flux iron cores 16C and 16D is the embodiment. 1 different from the magnetic flux leakage iron core 16. In any of the shapes of the leakage flux iron cores 16C and 16D, the main windings 11, 12, and 13 are partitioned by arranging the leakage flux iron cores 16C and 16D inside the common iron cores 15C and 15D. Shape. A gap having a uniform width is provided between the common cores 15C and 15D and the leakage flux cores 16C and 16D, and the magnetic resistances of the leakage magnetic paths through which the magnetic fluxes Φ2 to Φ4 generated by the normal mode current flow are all equal. It has been adjusted to become. Note that the magnetic fluxes Φ1 to Φ4 are not shown for the detection transformers 1C and 1D.

In the detection transformer 1E, both the common iron core 15E and the leakage flux iron core 16E are different from the shapes of the common iron core 15 and the leakage flux iron core 16 of the first embodiment.
In the detection transformer 1E, the magnetic flux leakage iron core 16E has a circular cross section, and the common iron core 15E is provided with legs 150E, 151E, and 152E protruding from the inside of the cylindrical iron core toward the magnetic flux leakage iron core 16E. Cylindrical shape. The main windings 11, 12, and 13 are partitioned by the legs 150E, 151E, and 152E of the common iron core 15E and the leakage flux iron core 16E. A gap having a uniform width is provided between each leg portion 150E, 151E, 152E of the common iron core 15E and the iron core 16E for leakage flux, and the leakage magnetic path of each magnetic flux Φ2 to Φ4 generated by the normal mode current flows. The magnetic resistances are all adjusted to be equal. Note that the magnetic flux Φ1 due to the common mode current generated in the detection transformer 1E is omitted.

As described above, the detection transformers 1B to 1E have different shapes, but the main windings 11, 12, and 13 are partitioned by the common iron cores 15B to 15E and the leakage flux iron cores 16B to 16E. A gap having a uniform width is provided between the iron cores 15B to 15E and the leakage flux iron cores 16B to 16E. For this reason, this gap acts as the magnetic resistance of the leakage magnetic path passing through the leakage flux iron cores 16B to 16E, and has the same effect as in the first embodiment.
The detection transformers 1B to 1E, which are modifications of the iron core shape described in the third embodiment, can also be applied to the high-frequency current reduction device 100A of the second embodiment.

Embodiment 4 FIG.
In the detection transformer configured as shown in the first to third embodiments, the temperature of the common iron core and the magnetic flux leakage iron core rises due to iron loss and copper loss of each winding. In particular, the magnetic flux leakage iron core is surrounded by the common iron core, windings, and support members, so that the area in contact with the outside air is small and the temperature is likely to rise. When the temperature rises, the magnetism of the magnetic flux leakage core is lost, and normal mode noise current may not be effectively reduced.
In the fourth embodiment, a description will be given of a detection transformer in which a leakage magnetic flux core is provided with a cooling hole for heat dissipation in order to reduce the temperature rise of the leakage magnetic flux core disposed inside the common core.

FIG. 10 is a plan view schematically showing the configuration of the detection transformer according to the fourth embodiment of the present invention, and each leakage of the detection transformers 1B to 1E described in the third embodiment that refers to the first embodiment. The magnetic flux cores 16B to 16E are provided with cooling holes 21 extending in the axial direction. The number of the cooling holes 21 can be appropriately provided according to the shape and cross-sectional area of the leakage flux iron cores 16B to 16E. The configuration other than the provision of the cooling holes 21 in the magnetic flux leakage iron cores 16B to 16E is the same as that of the third embodiment that refers to the first embodiment, and the description thereof is omitted.
10, the illustration of the arrangement of the main windings 11, 12, 13 and the detection windings 14 outside the common iron cores 15B to 15E is omitted as in FIG. 9 for explaining the third embodiment. Yes. Further, the number of turns of each of the main windings 11, 12, and 13 is set to 3 turns, and the number of turns of the detection winding 14 is set to 9 turns and wound around the common iron core 15 at substantially equal intervals. The detection transformers 1B and 1C are provided with the support rod 17A described in the first embodiment as an example, and the detection transformer 1D is provided with the sheet-like cylindrical support member 17 described in the first embodiment as an example. In the detection transformer 1E, as an example, a sheet-like support member 17 is disposed which is disposed only in the vicinity of the common iron core described in the first embodiment and the magnetic flux leakage core.

As described above, in the fourth embodiment, since the cooling hole 21 is provided in the leakage flux iron cores 16B to 16E, the area where the leakage flux iron cores 16B to 16E are in contact with the outside air is increased. Therefore, in addition to the effects of the first embodiment and the third embodiment, the temperature rise of the leakage flux iron cores 16B to 16E is reduced, and the magnetic deterioration of the leakage flux iron cores 16B to 16E is suppressed. Thereby, the normal mode noise current is effectively reduced.
The detection transformers 1B to 1E in which the cooling flux 21 is provided in the leakage flux cores 16B to 16E described in the fourth embodiment can be applied to the high-frequency current reduction device 100A of the second embodiment, and the leakage flux core 16B. It has the effect of reducing the temperature rise of ~ 16E and suppressing the magnetic deterioration of the leakage flux cores 16B-16E.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

1,1A-1E detection transformer, 2,2A-2C filter device,
3, 3A-3C voltage amplifier, 4, 4A-4C voltage application means, 11-13 main winding,
14 detection winding, 15, 15B-15E common iron core,
16, 16B-16E Iron core for leakage flux, 17 support member,
17A Support rod as a support member, 18-20 detection winding, 41-43 capacitor,
100, 100A high-frequency current reduction device, 101 AC power supply as a first electrical device,
102 Converter as second electric device, 410, 420, 430 capacitor,
R, S, T connecting line, Φ1 to Φ4 magnetic flux.

Claims (8)

A high frequency wave inserted between the first electric device and the second electric device via a plurality of connection lines between the first and second electric devices and flowing from the first electric device to the connection line. A high-frequency current reduction device for reducing current,
A detection transformer for detecting a current flowing from the first electric device to the connection line;
A filter device that receives the output of the detection transformer and outputs a voltage in a desired frequency band;
A voltage amplifier that amplifies the output of the filter device and outputs it as an output voltage;
A voltage provided between the first and second electric devices on the second electric device side of the detection transformer and applying a voltage in a predetermined direction based on the high-frequency current to the connection line based on the output voltage Applying means,
The detection transformer includes a plurality of main windings connected in series with the connection lines, an annular common iron core around which the main winding is wound, and the common iron core disposed inside the common iron core. A leakage magnetic flux core that separates the main windings; and a detection winding for current detection that detects a current that is wound around the common core and flows to the connection line via the main winding; Magnetic flux is generated in the leakage flux core by the normal mode current flowing through the main windings, and the main windings act as inductances for the normal mode current. A high-frequency current reduction device, wherein a magnetic flux is generated by a common mode current flowing through a main winding, and each main winding acts as an inductance for the common mode current. 2. The high-frequency current reduction device according to claim 1, wherein a gap is provided between the common iron core and the leakage flux iron core. The support member is provided between the common iron core and the leakage flux iron core, and supports the leakage flux iron core while holding the gap width uniform on the common iron core. 2. The high-frequency current reduction device according to 2. The width of the gap between the common iron core and the iron core for leakage magnetic flux is determined based on a desired inductance value with respect to the normal mode current. High frequency current reduction device. The voltage application means includes a plurality of capacitors, one terminal connected to the connection line and the other terminal connected in common at a common connection point, and applying the output voltage to the common connection point. 5. The high-frequency current reduction device according to claim 1, wherein a current substantially in the same direction as a high-frequency current flowing through the connection line is supplied from the capacitor to the connection line. 6. The detection winding of the detection transformer is wound around each section partitioned by the common iron core and the leakage flux iron core in the same number as each of the plurality of main windings,
The currents flowing through the main windings are detected by the detection windings, respectively, and a voltage in a desired frequency band for each output of the detection windings is output by the filter device. An output is amplified by the voltage amplifier and output as an output voltage, and a voltage based on the output voltage is applied to the corresponding connection line by the voltage application means. Item 5. The high-frequency current reduction device according to any one of items 4 to 4. The voltage applying means includes a plurality of capacitors having one terminal connected to each connection line, and a high frequency current flowing through each connection line by applying each output voltage to the other terminal of each capacitor. 7. The high-frequency current reduction device according to claim 6, wherein a current substantially in the same direction as the current is supplied from each capacitor to each connection line. A plurality of main windings, an annular common core around which the main winding is wound, a leakage magnetic flux core disposed inside the common core and partitioning the main windings together with the common core, and And a current detection detection coil that is wound around a common iron core and detects a current flowing through the main winding. Magnetic flux is generated in the leakage magnetic flux core by a normal mode current flowing through each main winding. The main windings act as inductances for the normal mode current, and magnetic flux is generated in the common iron core by the normal mode current and the common mode current flowing through the main windings. A detection transformer that acts as an inductance for a mode current.

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