JP2022168680A - Magnetic field generator - Google Patents

Abstract

To provide a magnetic field generator capable of reducing magnetic field generated from a power transmission coil not only in the vicinity of, but also at a distance from the power transmission coil.SOLUTION: A magnetic field generator comprises: a main coil 10 for transmitting power by generating a magnetic field; cancel coils 20A and 20B arranged on the same plane as the main coil 10 around the main coil 10 to generate a magnetic field for cancelling or absorbing a leakage magnetic field generated by the main coil 10; and the other cancel coils 20A and 20B arranged spaced apart from the cancel coils 20A and 20B to generate a magnetic field for cancelling the leakage magnetic field generated by the main coil 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic field generator.

An electric vehicle that runs by converting electric power stored in a battery into driving force for a motor must be careful not to run out of electric power stored in the battery during running. There is also a method to charge the battery of the electric vehicle at the charging station, but there is also a possibility that the power will be exhausted by the time you reach the charging station.

Therefore, in order to prevent the power stored in the battery of an electric vehicle from being depleted, the development of in-running wireless power supply technology for charging the battery while the electric vehicle is running is underway. Wireless power supply technology while driving is concerned about the influence of leakage magnetic fields. This leakage magnetic field causes malfunction of electronic devices and adverse effects on the human body. Therefore, techniques have been proposed for suppressing leakage magnetic fields in the far vicinity. For example, Non-Patent Document 1 discloses a technique for reducing a nearby magnetic field by canceling a magnetic field generated by a power transmission coil with a magnetic field generated by a cancel coil.

T. Campi, S. Cruciani, F. Maradei and M. Feliziani, "Active Coil System for Magnetic Field Reduction in an Automotive Wireless Power Transfer System," 2019 IEEE International Symposium on Electromagnetic Compatibility, Signal & Power Integrity (EMC+SIPI) , New Orleans, LA, USA, 2019, pp. 189-192, doi: 10.1109/ISEMC.2019.8825202.

However, in the technique disclosed in Non-Patent Document 1, although the magnetic field near the power transmission coil can be reduced by the canceling coil, the magnetic field far away from the power transmission coil, for example, at a location about 10 meters away cannot be reduced. Can not.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic field generator capable of reducing the magnetic field generated by a power transmission coil not only in the vicinity of the power transmission coil but also at a distance from the power transmission coil. and

A magnetic field generator according to a first aspect of the present invention is arranged on the same plane as a first power transmission coil that transmits power by generating a magnetic field and the first power transmission coil around the first power transmission coil, and the a first cancel coil that generates or absorbs a magnetic field that cancels out a leakage magnetic field generated by a first power transmission coil; and at least one second canceling coil for generating a magnetic field.

A magnetic field generator according to a second aspect of the present invention is the magnetic field generator according to the first aspect, wherein at least one second cancel coil is arranged with a predetermined gap from the first power transmission coil. .

A magnetic field generating device according to a third aspect of the present invention is the magnetic field generating device according to the second aspect, wherein at least one pair of the second cancel coils is arranged at positions sandwiching the first power transmission coil at equal intervals. .

A magnetic field generating device according to a fourth aspect of the present invention is the magnetic field generating device according to any one of the first to third aspects, wherein the second cancel coils are arranged in the same direction as viewed from the first power transmission coil. At least one set is arranged in

A magnetic field generating device according to a fifth aspect of the present invention is the magnetic field generating device according to any one of the first to fourth aspects, wherein the second cancel coil is formed in the same shape as the first cancel coil. be done.

A magnetic field generating device according to a sixth aspect of the present invention is the magnetic field generating device according to any one of the first to fifth aspects, is arranged around the second cancel coil, and transmits electric power by generating a magnetic field. and a second transmitting coil for performing

A magnetic field generator according to a seventh aspect of the present invention is the magnetic field generator according to the sixth aspect, wherein the second power transmission coil does not generate a magnetic field while the first power transmission coil is generating the magnetic field. .

A magnetic field generating device according to an eighth aspect of the present invention is the magnetic field generating device according to any one of the first to seventh aspects, wherein the first cancel coil is arranged to sandwich the first power transmission coil. .

A magnetic field generating device according to a ninth aspect of the present invention is the magnetic field generating device according to any one of the first to seventh aspects, wherein the first cancellation coil is arranged to surround the first power transmission coil. .

A magnetic field generator according to a tenth aspect of the present invention is the magnetic field generator according to any one of the first to ninth aspects, wherein the first power transmission coil transmits power to an electrically driven moving body. .

A magnetic field generating device according to an eleventh aspect of the present invention is the magnetic field generating device according to the tenth aspect, wherein the second cancel coil is spaced apart from the first cancel coil along the running direction of the moving object. are placed.

A magnetic field generating device according to a twelfth aspect of the present invention is the magnetic field generating device according to the eleventh aspect, wherein at least one of the second cancel coils is arranged on a traveling route adjacent to the traveling route of the moving body. It is

A magnetic field generating device according to a thirteenth aspect of the present invention is the magnetic field generating device according to any one of the first to twelfth aspects, wherein the moving body is an electrically driven electric vehicle.

A magnetic field generator according to a fourteenth aspect of the present invention includes a plurality of power transmission coils arranged at predetermined intervals and configured to transmit electric power by generating a magnetic field, and one power transmission coil among the plurality of power transmission coils. is transmitting power, at least one other power transmitting coil generates a magnetic field that cancels the leakage magnetic field generated by the one power transmitting coil during power transmission.

A magnetic field generator according to a fifteenth aspect of the present invention is the magnetic field generator according to the fourteenth aspect, wherein the other power transmission coil is arranged next to the one power transmission coil.

A magnetic field generator according to a sixteenth aspect of the present invention is the magnetic field generator according to the fourteenth aspect or the fifteenth aspect, wherein the plurality of power transmission coils transmits power to an electrically driven moving body.

According to the present invention, by canceling the magnetic field generated by the power transmission coil with at least two cancel coils, the magnetic field generated by the power transmission coil can be reduced not only in the vicinity of the power transmission coil but also in the distance. Equipment can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline|summary of the magnetic field generator which concerns on embodiment of this invention. 3 is a perspective view showing structures of a main coil and a canceling coil; FIG. FIG. 4 is a diagram schematically showing power supply to an electric vehicle by a magnetic field generator; FIG. 4 is a diagram schematically showing power supply to an electric vehicle by a magnetic field generator; It is a figure which shows the measurement point of the leakage magnetic field of a main coil. It is the figure which showed the graph which simulated and compared the leakage magnetic field. It is a figure which shows the example of selection of a cancellation coil. FIG. 10 is a diagram showing another selection example of canceling coils; FIG. 10 is a diagram showing another selection example of canceling coils; It is a figure which shows the modification of the shape of a cancellation coil. It is a figure which shows the modification of a magnetic field generator. It is a figure which shows the modification of a magnetic field generator.

An example of an embodiment of the present invention will be described below with reference to the drawings. In each drawing, the same or equivalent components and portions are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

FIG. 1 is a diagram showing an overview of a magnetic field generator according to an embodiment of the invention.

The magnetic field generating device shown in FIG. 1 is a device used in a running wireless power supply system for wirelessly supplying power to a battery of an electric vehicle 1, which is an example of a moving body of the present invention, while the vehicle is running. . In FIG. 1, a plurality of pairs of main coils 10 and cancellation coils 20A and 20B provided near the main coils 10 are embedded on the road along the running direction of the electric vehicle 1. A generator is shown. FIG. 1 shows three sets of main coils 10 and canceling coils 20A and 20B indicated by (A) to (C) embedded in a road.

The main coil 10 generates a magnetic field at a predetermined frequency for wirelessly powering the electric vehicle 1 . The main coil 10 is an example of the first power transmission coil of the present invention. Although not shown in FIG. Coils are provided that generate a current in response to the generated magnetic field. The current generated by the coil is used to charge the battery provided in the electric vehicle 1 . That is, the magnetic field generated by the main coil 10 allows the electric vehicle 1 to charge the battery while the vehicle is running.

The cancel coils 20A and 20B provided near the main coil 10 generate a magnetic field that cancels the leakage magnetic field associated with the magnetic field generated by the main coil 10, or absorb the leakage magnetic field associated with the magnetic field generated by the main coil 10. is a coil. The cancel coils 20A and 20B at the position (B) are an example of the first cancel coil of the present invention.

FIG. 2 is a perspective view showing the structure of the main coil 10 and cancel coils 20A and 20B. The main coil 10 is composed of a conductive wire wound a predetermined number of times on an aluminum plate 40 and a ferrite 30 . Further, the cancel coils 20A and 20B are provided at positions separated from the main coil 10 by a predetermined distance. Similar to the main coil 10, the cancel coils 20A and 20B are composed of conductive wires wound a predetermined number of times on the aluminum plate 40 and the ferrite 30, respectively.

FIG. 3 is a diagram schematically showing power supply to the electric vehicle 1 by the magnetic field generator. (A) to (C) in FIG. 3 correspond to (A) to (C) in FIG.

As shown in FIG. 3 , wireless power feeding to the electric vehicle 1 is realized by switching the main coil 10 that generates the magnetic field according to the passage of the electric vehicle 1 . The method of detecting passage of the electric vehicle 1 is not limited to a specific method, and may be performed by, for example, burying a sensor in the road.

In the example shown in FIG. 3, the main coil 10 of (B) is turned ON to generate a magnetic field while the electric vehicle 1 is at the position of (B), and the main coils 10 of (A) and (C) are turned on. It is OFF. That is, the battery of the electric vehicle 1 is charged by the magnetic field generated by the main coil 10 of (B).

However, with the main coil 10 alone, there is concern about the influence of the leakage magnetic field as described above. Therefore, the magnetic field generator according to this embodiment is characterized by reducing the leakage magnetic field by combining with the cancel coils 20A and 20B.

FIG. 4 is a diagram schematically showing power supply to the electric vehicle 1 by the magnetic field generator. FIG. 4 schematically shows five sets of main coils 10 and canceling coils 20A and 20B (A) to (E).

In the example shown in FIG. 4, with the electric vehicle 1 at the position (C), the main coil 10 (C) is turned ON to generate a magnetic field, and (A), (B), (D) and (E) The main coil 10 is turned off. Then, in the state where the electric vehicle 1 is at the position (C), the cancel coils 20A and 20B of (B), (C) and (D) are turned ON to generate magnetic fields, and (A) and (E) cancel coils 20A and 20B are turned off. The cancel coils 20A and 20B at positions (B) and (D) are examples of the second cancel coils of the present invention.

The magnetic field generator according to this embodiment generates a magnetic field from the same set of cancel coils 20A and 20B as the main coil 10 that generates the magnetic field, and the same set of cancel coils as the main coil 10 that does not generate the magnetic field. A magnetic field is generated from 20A and 20B. The magnetic field generator according to the present embodiment generates a magnetic field from the main coil 10 and the cancel coils 20A and 20B in this way, so that the leakage magnetic field accompanying the magnetic field generated by the main coil 10 is generated only in the vicinity of the main coil 10. Not only that, but it can also be reduced at a distance.

In addition, by using a plurality of sets of cancel coils 20A and 20B in this manner, the voltage required for the cancel coils can be reduced compared to the case where the plurality of sets of cancel coils 20A and 20B are not used, and the cancellation coils consume less voltage. power can be reduced.

Here, the effects of the magnetic field generator according to this embodiment will be described. FIG. 5 is a diagram showing measurement points of the leakage magnetic field of the main coil 10. As shown in FIG. As shown in FIG. 5, the effect of the magnetic field generator according to the present embodiment is shown by simulating the leakage magnetic field at a location 10 meters away from the center of the main coil 10 in the horizontal direction. Here, a case where a plurality of sets of cancel coils 20A and 20B are not used (Case 1) and a case where two sets of cancel coils 20A and 20B shown in FIGS. 4B and 4C are used (Case 2) ) and the case (case 3) using the three sets of cancel coils 20A and 20B shown in FIGS. 4B, 4C and 4D.

The power transmission distance of the main coil 10 is assumed to be 15 cm, and the resonance frequency is assumed to be 85 kHz. The size of the main coil 10 is 400×400 mm, the number of turns is 15, the pitch is 1.8 mm, the inductance at resonance is 251.82 μH, the capacitance is 139.23 μF, and the Q value is 551.04. The size of the cancel coils 20A and 20B is 100×400 mm, the number of turns is 8, the pitch is 2 mm, the inductance at resonance is 40.765 μH, the capacitance is 245.31 μF, and the Q value is 73.004.

FIG. 6 is a diagram showing graphs in which the leakage magnetic fields in the above three cases are simulated and compared. The horizontal axis of the graph shown in FIG. 6 is the cancel voltage applied to the cancel coils 20A and 20B, and the vertical axis is the magnetic field intensity (leakage magnetic field) 10 meters ahead from the main coil 10. In FIG. Reference numeral 101 indicates the relationship between the cancel voltage and the magnetic field strength when there is no magnetic field generated by the cancel coils 20A and 20B. Reference numeral 102 indicates the regulation value of the magnetic field strength (2.66 mA/m, from the Ministry of Internal Affairs and Communications Notification No. 207, item 4). Reference numeral 103 indicates the relationship between the cancellation voltage and the magnetic field strength in Case 1. FIG. Reference numeral 104 indicates the relationship between the cancellation voltage and the magnetic field strength in Case 2. FIG. Reference numeral 105 indicates the relationship between the cancellation voltage and the magnetic field strength in case 3. FIG. The voltage of the main coil 10 was fixed at 1000 V in order to make it easier to understand the effect of suppressing the leakage magnetic field.

According to the graph shown in FIG. 6, in case 1, even when the cancel voltage was 800 V, the leakage magnetic field did not fall below the regulation value. On the other hand, in Case 2, when the cancel voltage exceeded approximately 610 V, the leakage magnetic field fell below the regulation value. Furthermore, in case 3, the leakage magnetic field fell below the regulation value when it exceeded about 470V.

From the simulation results shown in FIG. 6, by increasing the number of cancel coils, the leakage magnetic field can be made smaller than the regulation value at a low cancel voltage. Therefore, by increasing the number of cancel coils, it is possible to reduce the power required to reduce the leakage magnetic field.

The location and number of cancel coils to be used can be selected. FIG. 7 is a diagram showing an example of selection of cancel coils. For example, as shown in FIG. 7, only the cancel coil 20A may be used in Case 3 above. Note that FIG. 7 does not show the main coil 10 that does not generate a magnetic field and the same set of cancel coils 20B.

FIG. 8 is a diagram showing another selection example of cancel coils. FIG. 8 shows an example of using the cancel coils 20A and 20B of the pairs (A) and (E), instead of the pairs (B) and (D) next to the main coil 10 generating the magnetic field. there is Even if the cancel coil is selected in this way, it is possible to similarly reduce the leakage magnetic field at a distance.

FIG. 9 is a diagram showing another selection example of cancel coils. FIG. 9 shows an example in which coils are embedded in a plurality of lanes. FIG. 9 shows an example in which a plurality of cancel coils 20B of adjacent lanes are selected instead of groups adjacent to the main coil 10. In FIG. Even if the cancel coil is selected in this way, it is possible to similarly reduce the leakage magnetic field generated by the main coil 10 at a distance.

Also, the shape of the cancel coil can be changed. For example, a cancellation coil may be formed so as to surround the main coil.

FIG. 10 is a diagram showing a modification of the shape of the cancel coil. The magnetic field generator may form a canceling coil 20 surrounding the main coil 10 and have a plurality of sets of the main coil 10 and the canceling coil 20, as shown in FIG. FIG. 10 shows an example in which the canceling coils 20 of the adjacent pairs (A) and (E) are used instead of the pairs (B) and (D) adjacent to the main coils 10 generating the magnetic field. . Even if the cancellation coil is formed in this way and the cancellation coil is selected, it is possible to reduce the leakage magnetic field generated by the main coil 10 at a distance.

So far, an example in which a cancel coil is provided in addition to the main coil has been shown, but the present invention is not limited to such an example. For example, a main coil that does not generate a magnetic field for supplying power to the electric vehicle 1 may be used as the cancel coil described above without providing a cancel coil.

FIG. 11 is a diagram showing a modification of the magnetic field generator. FIG. 11 shows an example in which a plurality of main coils 10 constituting the magnetic field generator are embedded in the road along the running direction of the vehicle.

In FIG. 11, the main coil 10 at position (C) is a coil that generates a magnetic field for supplying power to the electric vehicle 1, and the main coils 10 at positions (B) and (D) are This coil generates a magnetic field that cancels out the leakage magnetic field generated by the main coil 10 at the position (C). That is, the main coil 10 at position (C) and the main coils 10 at positions (B) and (D) are applied with voltages that generate different magnetic fields.

Thus, even if no cancel coil is provided, it is possible to reduce the leakage magnetic field generated by the main coil 10 at a distance.

FIG. 12 is a diagram showing a modification of the magnetic field generator. As shown in FIG. 12, a plurality of main coils 10 constituting the magnetic field generator are embedded in the road along the running direction of the vehicle, and a plurality of canceling coils 20 are arranged adjacent to the rows of the main coils 10 . This is an example of being buried in the road along the running direction of the vehicle.

In FIG. 12, one main coil 10 generates a magnetic field for supplying electric power to the electric vehicle 1, and three cancel coils 20 generate magnetic fields that cancel the leakage magnetic field generated by the main coil 10. . Thus, even when the row of the main coil 10 and the row of the cancel coil 20 are separated, it is possible to reduce the leakage magnetic field generated by the main coil 10 at a distance.

1 electric vehicle 10 main coils 20, 20A, 20B cancel coils

Claims (16)

a first power transmission coil that transmits power by generating a magnetic field;
a first cancellation coil arranged on the same plane as the first power transmission coil around the first power transmission coil and generating or absorbing a magnetic field that cancels a leakage magnetic field generated by the first power transmission coil;
at least one second cancel coil that is spaced apart from the first cancel coil and generates a magnetic field that cancels a leakage magnetic field generated by the first power transmission coil;
A magnetic field generator. 2. The magnetic field generator according to claim 1, wherein at least one of said second cancel coils is arranged with a predetermined gap from said first power transmission coil. 3. The magnetic field generator according to claim 2, wherein at least one set of said second cancel coils is arranged at positions sandwiching said first power transmitting coil at equal intervals. 4. The magnetic field generator according to claim 1, wherein at least one set of said second cancel coils is arranged in the same direction as viewed from said first power transmitting coil. 5. The magnetic field generator according to claim 1, wherein said second cancel coil is formed in the same shape as said first cancel coil. 6. The magnetic field generating device according to claim 1, further comprising a second power transmitting coil arranged around said second canceling coil for transmitting electric power by generating a magnetic field. The magnetic field generator according to claim 6, wherein said second power transmission coil does not generate a magnetic field while said first power transmission coil is generating a magnetic field. The magnetic field generator according to any one of claims 1 to 7, wherein the first cancel coils are arranged with the first power transmission coil interposed therebetween. The magnetic field generator according to any one of claims 1 to 7, wherein the first cancellation coil is arranged to surround the first power transmission coil. The magnetic field generator according to any one of claims 1 to 9, wherein the first power transmission coil transmits power to an electrically driven moving object. 11. The magnetic field generator according to claim 10, wherein said second cancel coil is spaced apart from said first cancel coil along the running direction of said moving body. 12. The magnetic field generator according to claim 11, wherein at least one of said second cancel coils is further arranged on a traveling path adjacent to said moving body's traveling path. The magnetic field generating device according to any one of claims 10 to 12, wherein said mobile body is an electric vehicle driven by electricity. Equipped with a plurality of power transmission coils arranged with a predetermined gap and transmitting power by generating a magnetic field,
While one of the plurality of power transmitting coils is transmitting power, at least one other power transmitting coil generates a magnetic field that cancels a leakage magnetic field generated by the one power transmitting coil during power transmission. Generator. 15. The magnetic field generator according to claim 14, wherein said another power transmission coil is arranged next to said one power transmission coil. 16. The magnetic field generator according to claim 14, wherein said plurality of power transmission coils transmit power to an electrically driven moving object.

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