JP2003348818A - Power conversion system, and filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce enlargement and cost increase of a filter due to high voltage and high speed in switching of a power conversion system, by realizing the filter in a simple constitution having a small zero-phase current and a small leak current. <P>SOLUTION: As to the filter, a power line and a ground line are turned in a way that the power line is turned n times (n≥1) at one on a plurality of magnetic cores made up of second magnetic core, and the grounding line is turned n times on the second magnetic core so that the magnetic field at the second magnetic core when a current is caused to flow in the power line from a power conversion device to a load and the magnetic field at the second magnetic core when a current is caused to flow in the ground line from the frame of the load to the frame of power conversion device are canceled in the power conversion system. By forming the filter in the simple constitution for reducing both the zero-phase current and the leak current, enlargement and cost increase of the filter due to high voltage and high speed in switching of the power conversion system can be reduced. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion system and, more particularly, to a power conversion system using a filter for reducing a zero-phase current and a leakage current caused by a high withstand voltage of a semiconductor switching element and a high switching frequency. The present invention relates to a conversion system and a filter used for the conversion system.

[0002]

2. Description of the Related Art As the breakdown voltage and speed of switching elements such as IGBTs constituting a power converter have been increased, the switching voltage of the power converter has been increased and the switching frequency has been increased. Generally, switching of a power converter causes a zero-phase current, and causes a leakage current flowing to the ground via a load connected to the power converter, a power supply, and a parasitic capacitance between the power line connecting the power converter and the ground. It is known. For this reason, higher switching voltage,
Increasing the speed increases the zero-phase current and the leakage current, and has a problem of adversely affecting peripheral devices as electromagnetic induction noise and conduction noise.

In order to prevent such noise interference, conventionally,
A power line connecting the power converter, the load, and the power supply is wound around a magnetic core to form a choke coil filter. That is, an inductance that acts as high impedance at high frequency is inserted into the power line to reduce zero-phase current and leakage current. Methods have been used.

On the other hand, according to the prior art described in Japanese Patent Application Laid-Open No. 9-283350, it has been proposed to use a high magnetic permeability material called a nanocrystalline soft magnetic alloy ribbon for the magnetic material of the choke coil. ing.

Further, according to the prior art described in Japanese Patent Application Laid-Open No. Hei 7-22886, there has been proposed a method in which a ferrite material and an iron-based high magnetic permeability material are combined as the magnetic material of the choke coil.

According to the prior art described in Japanese Patent Application Laid-Open No. 2001-86734, a ground line connecting a load and a ground line of a power supply, which is called a common mode current return line, is provided with a magnetic line having a through hole together with a power line. There has been proposed a method of reducing leakage current by winding a material.

[0007]

However, in the prior art, when a choke coil is used, in order to prevent an increase in a zero-phase current and a leakage current accompanying a high voltage and a high speed switching, a large impedance such as a higher impedance is used. You have to make inductance. Therefore, a large number of magnetic cores must be used, and there is a problem that the size is increased. When a filter having a large inductance is made small with a high magnetic permeability material, if the current is large, the high magnetic permeability material is likely to be magnetically saturated, and may not function as a choke coil.

Further, in a filter in which both the ground line and the power line are wound around a magnetic material, although the leakage current is reduced, the filter has almost no effect on the reduction of the zero-phase current flowing between the power converter, the load, and the power supply. It is not possible to reduce noise caused by an induced magnetic field created by a circuit surrounded by a ground line and a power line. Therefore, it is necessary to separately add a choke coil, which causes a problem of an increase in size and an increase in cost.

According to the present invention, a filter for reducing both the zero-phase current and the leakage current is realized with a simple configuration, and the size and cost of the filter are increased due to a higher voltage and a higher switching speed of the power converter. The purpose is to control.

[0010]

One feature of the present invention is that
The power converter is wound around the power line n times (n ≧ 1) at a time around a plurality of magnetic cores including the first and second magnetic cores, and the ground line is wound m times around the second magnetic core (m ≧ 1). The magnetic field generated in the second magnetic core when the current is wound and the current flows from the power converter to the power line toward the load, and the current flows from the load housing to the ground line in the direction of the power converter to the housing. In this case, the power line and the ground line are wound in such a direction that the magnetic field generated in the second magnetic core cancels out.

Still another feature of the present invention is that a filter for reducing a zero-sequence current or the like includes three conductor wires n times (n
≧ 1) A first magnetic core and a second magnetic core are wound, and the conductor wire is wound m times (m ≧ 1) around the second magnetic core.

The other features of the present invention are as described in the claims of the present application.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a filter according to the present invention,
An embodiment of a power converter will be described with reference to the drawings.

FIG. 1 shows a first embodiment of a power conversion system to which the present invention is applied. AC power is supplied from a three-phase AC power supply 8 to a power converter 9 via a power line 1 ′ made of a conductor line, and the power converter 9 performs voltage switching to control a load 11 connected by the power line 1. ing.
The housing 10 of the power converter is connected to the housing 12 of the load, and a ground line 13 made of a conductor of an AC power supply by ground lines 3 and 3 'and grounded. In addition, the housing 10 and the housing 12
Are provided with ground wires 14 and 15 made of conductor wires for preventing electric shock. The filter 5 of the present invention is connected between the power line 1 and the ground line 3 connecting the power converter and the load.

Regarding the filter 5 according to the feature of the present invention,
FIG. 2 shows a configuration diagram of the first filter. In FIG. 2, the power line 1 and the ground line 3 are connected to the power converter on the left and connected to the load on the right. The three power lines 1 are wound on the first magnetic core 2 and the second magnetic core 2 'simultaneously by one turn. One ground wire 3 is connected to the second magnetic core 2 ′
It has the same number of one-turn windings as the power lines. The winding direction of each wire to the magnetic core is determined by the magnetic field generated in the magnetic core 2 ′ when a current flows from the power converter to the load on the power line 1, and from the load to the power converter on the ground line 3. The winding direction is set so that the magnetic field generated in the magnetic core 2 'when the current flows cancels out. With such a configuration, a large current flows through the filter, and the power line 1 having a large cross-sectional area can be wound in a single winding step, so that the number of manufacturing steps can be reduced and the size of the filter can be reduced.

The operation of FIG. 1 configured as described above will now be described. FIG. 11 shows an equivalent circuit when focusing on the zero-phase current and the leakage current of FIG. The power converter is modeled as a rectangular wave voltage source 9 ', the motor is a parasitic capacitance 11', the filter is an inductance connected in series with the power line, and the ground line and the power line are transformers having the same polarity. The inductance of the filter 5 'acts as a high impedance for both the zero-phase current and the leakage current, and the transformer acts as a high impedance for the leakage current. That is, with respect to the leakage current flowing to the ground, the inductance and the transformer work as high impedance, so that the leakage current is greatly reduced. The current flowing through the transformer is the sum of the zero-phase current flowing through the power line and the current flowing through the ground line 3 in the opposite direction, and is the same as the leakage current flowing through the ground. That is, the leakage current is smaller than the zero-phase current.

Here, for the filter 5, choke coil and transformer of the present invention, the inductance is kept constant (250
The effect of the filter configured as μH) was simulated. 12 and 13 show the results of the frequency characteristics of the zero-phase current and the leakage current. Since the frequency at which each current causes a problem in actual use is about 100 kHz, when compared in that frequency band, the zero-phase current of this filter is much lower than that of a transformer, and the choke coil It has dropped to the same extent. Also, the leakage current is
100kHz lower than choke coil at all frequencies
In the high frequency band of z or more, the frequency is significantly lower than that of the transformer or the choke coil. The reason for the drop is much lower than that of the transformer.Because the transformer tries to reduce only the leakage current while keeping the zero-layer current, the filter of the present invention first reduces the zero-phase current. This is because a certain leakage current can be further reduced. Therefore, the present filter configuration can efficiently reduce both the zero-phase current and the leakage current.

Under the condition of constant inductance, that is, the same material and volume of the magnetic core, it is better to use half of the magnetic core as the first magnetic core and the other half as the second magnetic core as in this structure. , Zero-phase current and leakage current can be reduced most efficiently.

100 kHz when the ratio of the inductance of the first and second magnetic cores (in this case, the ratio of the volume) is changed under the condition that the inductance sum of the first magnetic core and the second magnetic core is constant. , 150 kHz are shown in FIG. From the figure, the ratio is almost half (50
%), It can be seen that the leakage current is the lowest. Further, the ratio of the first magnetic core is set to 30.
It can be seen that a sufficient reduction effect can be obtained by setting the percentage to 70%.

FIG. 3 shows an equivalent circuit of the filter of the present invention. In FIG. 2, the power converter is connected to the right and the load is connected to the left. However, the same effect can be obtained from FIG. 3 even if the connection direction is reversed.

FIG. 17 shows a second filter configuration diagram. From FIG. 3, it can be seen that even if power lines are separately wound around the first and second magnetic cores, they become electrically equivalent and have an effect. In FIG. 2, the magnetic material 2 is circular, but an elliptical magnetic material obtained by combining two U-shaped magnetic materials may be used.
Further, a material in which E-type or I-type magnetic materials are opposed to each other and a hole for winding is formed may be used.

FIG. 18 shows a third filter configuration diagram. A single core can be formed by drilling a hole in the center of one core and projecting a ground wire from the hole so that the single core plays the role of the first and second magnetic cores.

In this embodiment, the power line is wound once on the first magnetic core and the second magnetic body at the same time, and the ground wire is wound once on the second magnetic core. It may be passed through or wound twice or more. The number of turns may be such that it is physically wound around the magnetic material and the magnetic core is not saturated.

FIG. 4 shows a second embodiment of the power conversion system to which the present invention is applied. The difference from FIG. 1 is that the ground wire of the filter is connected not to the housing 10 of the power converter, but to the ground portion 13 of the power supply. This is effective when the parasitic capacitance between the power converter and the ground is smaller than the parasitic capacitance between the power line, the power supply, the load, and the ground. At this time,
The leakage current returns to the power converter through the parasitic capacitance of the power supply 8. With this configuration, both the zero-phase current and the leakage current can be reduced as described above.

FIG. 5 shows a third embodiment of the power conversion system to which the present invention is applied. The difference from FIG. 1 is that the filter is connected between the power supply 8 and the power converter 10. This is due to the leakage current between the power supply and the power converter,
This is effective when zero-phase current is a problem. At this time, the leakage current returns to the power converter through the power converter 10 and the parasitic capacitance of the ground, the ground, the power supply 8 and the parasitic capacitance of the ground, and the power supply line. With this configuration, the zero-phase current,
Leakage current can be reduced.

FIG. 6 shows a configuration diagram of a fourth filter according to the feature of the present invention. The difference from FIG. 2 is that a second magnetic core 2 ′ around which a ground wire 3 of the filter is wound uses a magnetic core 2 ″ made of a material having a higher permeability than the first magnetic core material wound only with a power line. Since the zero-phase current flows through the power line 1 and most of the zero-phase current flows through the ground line 3 in the opposite direction to the power line, the current penetrating through the magnetic material through which both the power line 1 and the ground line 3 pass. Apparently cancel each other out and become smaller.
This current is a leakage current and is smaller than the zero-phase current. For this reason, the material and the core size of the magnetic core are selected in consideration of the saturation with respect to the peak value of the current waveform passing through the magnetic core. Since the peak value of the leakage current waveform is smaller than the peak value of the zero-phase current waveform, the saturation current value is small. For this reason, a high magnetic permeability material can be used as the material of the second magnetic core, and the inductance can be realized in a small volume. As a numerical example, when a ferrite having a relative magnetic permeability of 1000 to 2000 is used for the first magnetic core, a relative magnetic permeability of 1 is used for the second magnetic core.
Than when using 2,000 to 2,000 ferrites,
Using an iron-based high magnetic permeability material having a relative magnetic permeability of 10,000 to 100,000 can ideally achieve the same inductance with a small volume of about 10%. However, since the high permeability material is deteriorated by the frequency, it is actually 3
The volume is about 0%.

FIG. 14 is a schematic diagram of an embodiment using the ferrite cut core and the ring-shaped iron-based high magnetic permeability material of the present invention.
Shown in Using a ferrite cut core 18 and a ring-shaped high magnetic permeability material 19,
4 and a high-permeability core fixing stand 25. The power line bus bar 20 is fixed by a power line bus bar fixing stand 23. By fixing them separately, the distance between the magnetic core and the busbar is maintained, preventing damage and dielectric breakdown due to vibration. The number of turns is 3 and the connection between turns is
The connection bus bar 22 is used.

Ferrite has a low magnetic permeability, and even if a cut core is used, the influence on the inductance of the core gap is small. FIG. 15 shows a cross-sectional view of the ferrite core. By using the ferrite cut core, the bus bar occupancy inside the two U-shaped ferrite cores can be increased and the size can be reduced.

On the other hand, the high magnetic susceptibility material has a large influence on the inductance of the gap, so that a cut core cannot be used.
Therefore, a structure for passing the power line bus bar 20 through the ring-shaped high magnetic permeability core 19 is required. FIG. 16 shows a set diagram of the ring-shaped high magnetic permeability core 19 and the power line bus bar 20. With a structure in which there is a gap through which the core passes above the power line bus bar, the power line bus bar can be passed through the ring-shaped high permeability core.

FIG. 7 shows a configuration diagram of a fifth filter according to the feature of the present invention. The difference from FIG. 2 is that a low-impedance resistor 6 is connected in series to the ground line 3 of the filter so that the current due to the potential fluctuation of the ground does not saturate the magnetic material. The value R of the resistor 6 may be determined so as to satisfy Expression (1) from the frequency f of the leakage current to be reduced and the inductance L of the magnetic core around which both the power line and the ground line are wound.

[0031]

R≪2πfL (1) To reduce the leakage current to 1/10 of the zero-phase current,
What is necessary is just to determine the resistance value R as in the equation (2).

[0032]

(Equation 2)

FIG. 8 shows a configuration diagram of a fifth filter according to the feature of the present invention. The difference from FIG. 2 is that instead of resistors,
That is, a capacitor is connected to the ground line 3. The value of the capacitor 7 may be determined so as to satisfy Expression (3) from the frequency f of the leakage current to be reduced and the inductance L of the magnetic core around which both the power line and the ground line are wound.

[0034]

(Equation 3)

If it is desired to reduce the leakage current to one-tenth of the zero-phase current, the value R of the resistor may be determined as in equation (4).

[0036]

(Equation 4)

In FIG. 5, the present invention is applied to the three-phase power supply line of the power converter, but can also be applied to a three-wire power cord of general electric equipment and a signal line for connecting electric equipment. FIG. 9 shows an example in which the present invention is used for a three-wire power cord, and FIG.

In each of the above-described embodiments, an example has been described in which the present invention is applied to a three-phase power conversion system. However, the present invention is not limited to a power conversion device but can be applied to a device that involves load control by switching. In each embodiment, the case where each housing is grounded to the ground has been described. However, the present invention can be applied to a system in which the housing is not grounded to the ground and has only a ground wire connecting between the housings.

[0039]

As described above, according to the present invention, a filter for reducing both the zero-phase current and the leakage current can be realized with a simple configuration, and the switching of the power converter can be performed at a higher voltage and at a higher speed. An increase in size and cost of the filter can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram of a power conversion system according to a first embodiment to which the present invention is applied.

FIG. 2 is a configuration diagram of a first filter according to a feature of the present invention.

FIG. 3 is an equivalent circuit diagram of a filter according to a feature of the present invention.

FIG. 4 is a diagram of a power conversion system according to a second embodiment to which the present invention is applied.

FIG. 5 is a diagram of a power conversion system according to a third embodiment to which the present invention is applied.

FIG. 6 is a configuration diagram of a fourth filter according to a feature of the present invention.

FIG. 7 is a configuration diagram of a fifth filter according to a feature of the present invention.

FIG. 8 is a configuration diagram of a sixth filter according to a feature of the present invention.

FIG. 9 is a diagram of a power cord using a filter according to a feature of the present invention.

FIG. 10 is a diagram of a signal cable using a filter according to a feature of the present invention.

FIG. 11 is a diagram showing FIG. 1 as a simple equivalent circuit for explaining the operation.

FIG. 12 is a simulation result of a zero-sequence current as compared with a conventional example to explain the effect of the present invention.

FIG. 13 is a simulation result of a leakage current compared with a conventional example in order to explain the effect of the present invention.

FIG. 14 is an embodiment (drawing) using a ferrite cut core and a ring-shaped iron-based high magnetic permeability material.

FIG. 15 is a cross-sectional view of the ferrite core part of FIG.

FIG. 16 is a set diagram of FIG. 14;

FIG. 17 is a configuration diagram of a second filter according to a feature of the present invention.

FIG. 18 is a configuration diagram of a third filter according to a feature of the present invention.

FIG. 19 is a diagram showing a relationship between a ratio of inductance between a first core and a second core and a leakage current reduction effect.

[Explanation of symbols]

1, 1 ', 1 "... power line, 2, 2', 2" ... magnetic core,
3, 3 ', 13, 14, 15 ... ground wire, 4 ... magnetic core with high magnetic permeability, 5, 5' ... filter according to the present invention, 6
... Resistance, 7 ... Capacitor, 8 ... AC power supply, 9,9 '... Power conversion device, 10,12 ... Housing, 11,11' ... Motor, 16 ... 3-wire power cord connector, 17 ... Signal cable connector, 18 ... ferrite cut core, 19 ... ring-shaped high magnetic permeability core, 20 ... power line busbar, 21
... Grounding cable, 22 ... Busbar for inter-turn connection,
23: Power line bus bar fixing stand, 24: Ferrite cut core fixing stand, 25: High magnetic permeability core fixing stand, 26: Insulating portion of power line bus bar, 27: Conducting portion of power line bus bar, 28: One turn of power line bus bar , 29 ... 2 turns of the power line bus bar, 30 ... 3 turns of the power line bus bar.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Asako Koyanagi             Hitachi, Ibaraki Pref.             Hitachi, Ltd., Hitachi Laboratory (72) Inventor Satoshi Inarida             1070 Ma, Hitachinaka City, Ibaraki Pref.             Mito Transport Co., Ltd., Transportation Systems Division, Hitachi, Ltd.             Inside the system headquarters (72) Inventor Shoichi Hisada             1070 Ma, Hitachinaka City, Ibaraki Pref.             Mito Transport Co., Ltd., Transportation Systems Division, Hitachi, Ltd.             Inside the system headquarters (72) Inventor Toshihiko Sekizawa             1070 Ma, Hitachinaka City, Ibaraki Pref.             Mito Transport Co., Ltd., Transportation Systems Division, Hitachi, Ltd.             Inside the system headquarters (72) Inventor Takashi Kaneko             1070 Ma, Hitachinaka City, Ibaraki Pref.             Mito Transport Co., Ltd., Transportation Systems Division, Hitachi, Ltd.             Inside the system headquarters F term (reference) 5H007 AA01 AA05 AA08 AA17 BB06                       CA01 CB04 CB05 CC23 HA02                 5H740 BA11 BA15 BB05 BB09 BB10                       NN02 PP10

Claims (20)

[Claims] 1. A power conversion system comprising: a power conversion device; a load connected to the power conversion device via a power line; and a ground line connecting a housing of the power conversion device and a housing of the load. The power line is wound l times (l ≧ 1) around the first magnetic core, and n times (n ≧ 1) around the second magnetic core, and the ground wire is wound m times around the second magnetic core ( m ≧ 1) wound, and a magnetic field generated in the second magnetic core when a current flows through the power line from the power converter to the load.
The magnetic field generated in the second magnetic core when a current flows through the ground line in the direction from the housing of the load to the housing of the power converter, the power line and the ground line in a winding direction such that they cancel each other out. Is wound around the power conversion system. 2. A power converter, a load connected to the power converter by a power line, a power supply for supplying power to the power converter, and a ground portion of the power supply and a housing of the load. In a power conversion system having a ground line, the power line is wound l times (l ≧ 1) around a first magnetic core and n times (n ≧ 1) around a second magnetic core. A magnetic field generated in the second magnetic core when a current flows from the power converter to the power line in the direction of the load m times (m ≧ 1) around the second magnetic core;
The magnetic field generated in the second magnetic core when a current flows through the ground line in the direction from the housing of the load to the housing of the power converter, the power line and the ground line in a winding direction such that they cancel each other out. Is wound around the power conversion system. 3. A power conversion system comprising: a power conversion device; a power supply connected to the power conversion device via a power line; and a ground line connecting a grounding part of the power supply and a housing of the power conversion device. Is applied to the first magnetic core once (l
≧ 1) wound and n times around the second magnetic core (n ≧ 1)
The ground wire is wound m times (m ≧ 1) around the second magnetic core. When a current flows from the power converter to the power line in the direction of the load, the ground wire is wound around the second magnetic core. The resulting magnetic field,
The magnetic field generated in the second magnetic core when a current flows through the ground line in the direction from the housing of the load to the housing of the power converter, the power line and the ground line in a winding direction such that they cancel each other out. Is wound around the power conversion system. 4. A power conversion system comprising: a power conversion device; a load connected to the power conversion device via a power line; and a ground line connecting a housing of the power conversion device and a housing of the load. The power line is wound n times (n ≧ 1) at a time around a plurality of magnetic cores including the first and second magnetic cores, and the ground wire is wound m times (m ≧ 1) around the second magnetic core. A magnetic field generated in the second magnetic core when a current flows from the power converter to the power line in the direction of the load;
The magnetic field generated in the second magnetic core when a current flows through the ground line in the direction from the housing of the load to the housing of the power converter, the power line and the ground line in a winding direction such that they cancel each other out. Is wound around the power conversion system. 5. A power converter, a load connected to the power converter by a power line, a power supply for supplying power to the power converter, and a ground portion of the power supply and a housing of the load. In a power conversion system having a ground line, the power line is wound around the first magnetic core and the second magnetic core n times (n ≧ 1) at a time, and the ground line is wound m times on the second magnetic core. (M ≧ 1), and a magnetic field generated in the second magnetic core when a current flows through the power line from the power converter to the load.
A magnetic field generated in the second magnetic core when a current flows through the ground line from the load housing toward the power grounding region winds the power line and the ground line in a winding direction such that they cancel each other. A power conversion system. 6. A power conversion system comprising: a power conversion device, a power supply connected to the power conversion device via a power line, and a ground line connecting a grounding part of the power supply and a housing of the power conversion device. Is applied to the first and second magnetic cores n times at a time (n ≧
1) the ground wire is wound m times (m ≧ 1) around the second magnetic core; and when a current flows from the power source to the power line in the direction of the power converter, the second magnetic core is wound. The magnetic field generated in the core,
The power line and the ground line are wound in a winding direction such that a magnetic field generated in the second magnetic core when a current flows through the ground line from the housing of the power conversion device toward the ground portion of the power supply cancels out. A power conversion system characterized by being turned. 7. The power conversion system according to claim 1, wherein the number of turns n of the power line and the number of turns m of the ground line are the same. 8. The material according to claim 1, wherein a relative magnetic permeability of a material used for the second magnetic core is higher than a relative magnetic permeability of a material used for the first magnetic core. A power conversion system, characterized in that: 9. The power conversion system according to claim 1, wherein a ferrite is used as a material of the first magnetic core, and an iron-based material is used as a material of the second magnetic core. . 10. The relative magnetic permeability of the material used for the first magnetic core according to claim 1,
The relative magnetic permeability of the material used for the second magnetic core is 10 to 2000.
A power conversion system, wherein the power conversion system is 000 to 100,000. 11. The power conversion system according to claim 1, wherein a resistor is connected to the ground line. 12. The power conversion system according to claim 1, wherein a capacitor is connected to the ground line. 13. A magnetic head comprising a first magnetic core and a second magnetic core, wherein three conductor wires are wound n times (n ≧ 1) at a time, and wherein the second magnetic core has a conductor wire of m A filter characterized by being wound one turn (m ≧ 1). 14. A conductor wire according to claim 12, wherein the conductor wire wound n times around the first magnetic core and the second magnetic core is a power line, and the conductor wire wound m times is a ground wire. And filter. 15. The filter according to claim 12, wherein the number of turns m and the number of turns n are the same. 16. A power conversion device, comprising: a load connected to the power conversion device via a power line; and a ground line connecting a housing of the power conversion device and a housing of the load. The ground wire is wound around the magnetic core having a hole once (l ≧ 1), the ground wire is passed through the hole in the magnetic core, and the magnetic field is generated when a current flows from the power converter to the load in the direction of the load. A magnetic field generated in the core, and a magnetic field generated in the magnetic core when a current flows through the ground wire in a direction from the load housing to the power conversion device housing,
A power conversion system, wherein the power line and the ground line are wound in such a direction that they cancel each other. 17. The method according to claim 1, wherein the ratio of the inductance of the first magnetic core to the sum of the inductance of the first magnetic core and the inductance of the second magnetic core is 30% to 70%. %. 18. The method according to claim 1, wherein an inductance ratio of said first magnetic core is approximately 50%.
%. 19. The method according to claim 1, wherein the ratio of the volume of the first magnetic core to the sum of the volume of the first magnetic core and the volume of the second magnetic core is 30%.
A power conversion system characterized by being at least 70%. 20. The power conversion system according to claim 18, wherein the volume ratio of the first magnetic core is approximately 50%.