Power Supply Device

Abstract

To reduce leakage magnetic flux of a power supply device.SOLUTION: A power supply device 1 includes: a power supply coil 11; a power receiving coil 13; a first core 12 around which the power supply coil 11 is wound; a second core 14 around which the power receiving coil 13 is wound; and shield members 15a, 15b for covering the entire periphery of the power supply coil 11 and the entire periphery of the power receiving coil 13. The shield members 15a, 15b include a conductor 20 and an insulator 21. The conductor 20 has a first end 20a and a second end 20b disposed so as to face with each other. The insulator 21 is disposed between the first end 20a and the second end 20b of the conductor 20.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power supply device that supplies power wirelessly. [Background technology]

[0002] In recent years, wireless power supply (non-contact power supply) that does not use power cords or power transmission cables has been adopted as a system for supplying power to batteries installed in electric vehicles (EVs) and automated guided vehicles (AGVs).

[0003] For example, a power supply device that utilizes electromagnetic resonance is disclosed in Patent Document 1. The power supply device includes a power supply unit provided in a power supply facility and a power receiving unit mounted on a vehicle.

[0004] The power supply unit includes a power supply coil unit to which high frequency power is supplied from a power source. The power supply coil unit includes a power supply coil, a power supply core around which the power supply coil is wound, and a power supply shield case that houses the power supply coil and the power supply core.

[0005] The power supply side shield case is made of a metal shield using copper or aluminum. The power supply side shield case has a bottom wall that covers a part of the power supply side core around which the power supply side coil is wound, and a standing wall that stands from the periphery of the bottom wall, and is configured in a box shape with a part open (see paragraph 0021 of the same document).

[0006] The power receiving section includes a power receiving coil unit including a power receiving coil that electromagnetically resonates with the power feeding coil, a power receiving core around which the power receiving coil is wound, and a power receiving shield case that houses the power receiving coil and the power receiving core.

[0007] The power-receiving-side shield case is made of a metal shield, like the power-feeding-side shield case, and has a bottom wall that covers a part of the power-receiving-side coil and a standing wall that stands upright from the periphery of the bottom wall, and is configured in a box shape with a part open (see paragraph 0027 of the same document). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2014-179438 A Summary of the Invention [Problem to be solved by the invention]

[0009] In a conventional power supply device, the power supply shield case and the power receiving shield case are configured to have a portion open, so that a portion of the power supply coil and a portion of the power receiving coil are exposed from each shield case, which causes leakage magnetic flux from the exposed portions of the coils, resulting in a decrease in power transmission efficiency.

[0010] The present invention has been made in view of the above circumstances, and has as its technical object to reduce leakage magnetic flux in a power supply device. [Means for solving the problem]

[0011] The present invention is intended to solve the above-mentioned problems, and provides a power supply device comprising a power supply coil, a power receiving coil, a first core around which the power supply coil is wound, a second core around which the power receiving coil is wound, and a shielding member covering the entire circumference of the power supply coil and the entire circumference of the power receiving coil, wherein the shielding member comprises a conductor and an insulator, the conductor has a first end and a second end arranged opposite to each other, and the insulator is disposed between the first end and the second end.

[0012] According to this configuration, the entire circumference of the power supply coil wound around the first core and the entire circumference of the power receiving coil wound around the second core are covered with a shielding material, thereby preventing exposure of each coil and each core, and reducing leakage flux of the power supply device. In addition, by insulating the first end and the second end of the shielding material with an insulator so as not to be conductive, eddy currents generated in the conductor during power supply can be suppressed. As a result, it is possible to improve the power transmission efficiency of the power supply device.

[0013] The power supply device may further include a guide portion for guiding the first core or the second core to a position where power can be supplied. The guide portion allows each coil and each core to be accurately positioned at a position where power can be supplied. Effect of the Invention

[0014] According to the present invention, leakage magnetic flux of a power supply device can be reduced. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a circuit diagram of a power supply device. [Diagram 2] FIG. 2 is a plan view showing a magnetic field coupling portion of the power supply device. [Diagram 3] 3 is a cross-sectional view taken along the line of arrows III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view taken along the line IV-IV of FIG. 2. [Diagram 5] FIG. [Figure 6] FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of FIG. 6. [Figure 8] FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 9] FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 10]FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 11] FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 12] FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. [Figure 13] 13 is a graph showing measurement results of leakage inductance. [Figure 14] 13 is a graph showing measurement results of excitation inductance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 to 5 show an embodiment of a power supply device according to the present invention. In this embodiment, a magnetic field coupling type power supply device is exemplified.

[0017] The power supply device can be used in a charging system for an electric vehicle (EV), an automatic guided vehicle (AGV), etc. The power supply device can also be used in other power supply systems. In this embodiment, as an example, a case where the power supply device is used in a charging system for an automatic guided vehicle will be described.

[0018] As shown in FIG. 1, the power supply device 1 includes a power supply unit 2 as a primary circuit provided in a charging station, a power receiving unit 3 as a secondary circuit provided in an automated guided vehicle, and a magnetic field coupling unit 4 that enables the transmission of power from the power supply unit 2 to the power receiving unit 3 by magnetic field coupling.

[0019] The power supply unit 2 includes, for example, a power source 5 and a switching circuit 6. The switching circuit 6 includes, for example, an H-bridge circuit including four switching elements 7a and a diode 7b, and a capacitor 7c. The power supply unit 2 converts a DC voltage applied by the power source 5 into a square wave AC voltage by the switching circuit 6.

[0020] The power receiving unit 3 includes, for example, a rectifier circuit 8 and a battery 10 as a secondary battery. The rectifier circuit 8 includes four diodes 9b each having a resonant capacitor 9a connected in parallel, and a smoothing capacitor 9c. The power receiving unit 3 converts the AC voltage transmitted from the power supply unit 2 to a DC voltage using the rectifier circuit 8, and charges the battery 10.

[0021] As shown in Figures 2 to 4, the magnetic field coupling unit 4 includes a power supply coil 11 connected to the power supply unit 2, a first core 12 around which the power supply coil 11 is wound, a power receiving coil 13 connected to the power receiving unit 3, a second core 14 around which the power receiving coil 13 is wound, and shield members 15a, 15b for suppressing leakage magnetic flux.

[0022] The power supply coil 11 and the power receiving coil 13 are made of insulated wire and are wound around the cores 12 and 14 with a predetermined number of turns.

[0023] The first core 12 and the second core 14 are made of a magnetic material such as ferrite. Each of the cores 12, 14 is U-shaped in a plan view. The first core 12 has a pair of straight portions 16 and a connecting portion 17 connecting the straight portions 16. Similarly, the second core 14 has a pair of straight portions 18 and a connecting portion 19 connecting the straight portions 18. Each of the straight portions 16, 18 of the cores 12, 14 has an end surface 16a, 18a at its protruding end.

[0024] 4, the cross section of each of the cores 12 and 14 is rectangular, but is not limited to this shape. Each of the cores 12 and 14 has a first surface 12a, 14a, a second surface 12b, 14b, a third surface 12c, 14c, and a fourth surface 12d, 14d, which correspond to each side of the rectangle.

[0025] The shield members 15a, 15b include a first shield member 15a that covers the power supply coil 11 and the first core 12, and a second shield member 15b that covers the power receiving coil 13 and the second core .

[0026] 3 and 4, each of the shield members 15a and 15b includes a conductor 20 and an insulator 21. The conductor 20 is made of, for example, a metal foil, a metal sheet, etc. Examples of metals used for the conductor 20 include aluminum, copper, etc.

[0027] The insulator 21 is formed integrally with the conductor 20 by applying an insulating adhesive to the conductor 20, or by attaching an insulating resin sheet or film such as polyurethane to the conductor 20.

[0028] 5 shows the shield members 15a, 15b before being attached to the coils 11, 13 and the cores 12, 14. The conductor 20 of each of the shield members 15a, 15b is configured to be rectangular in a plan view, but is not limited to this shape and may have other shapes. The conductor 20 has a first end 20a and a second end 20b. Both the front and back sides and the end faces of each of the ends 20a, 20b are covered with an insulator 21.

[0029] 4, when the shield members 15a, 15b are attached to the cores 12, 14, the first end 20a and the second end 20b of the conductor 20 overlap each other. In this state, the first end 20a and the second end 20b face each other in the thickness direction or in the radial direction of each coil 11, 13. The insulator 21 is located between the opposing first end 20a and second end 20b to insulate them from each other.

[0030] In this state, the entire circumference of the power supply coil 11 is covered by the first shield member 15a. Also, the first surface 12a to the fourth surface 12d of the first core 12 around which the power supply coil 11 is wound are all covered by the first shield member 15a. The power receiving coil 13 is covered by the second shield member 15b all around. Also, the first surface 14a to the fourth surface 14d of the second core 14 around which the power receiving coil 13 is wound are all covered by the second shield member 15b.

[0031] It should be noted that the first shield member 15a is not overlapped on the end face 16a of the straight portion 16 of the first core 12. Moreover, the second shield member 15b is not overlapped on the end face 18a of the straight portion 18 of the second core 14.

[0032] When charging of the battery 10 is required, the power supply coil 11, the first core 12, the power receiving coil 13, and the second core 14 are arranged in positions where power supply is possible (hereinafter referred to as "power supply positions"). Figures 2 and 3 show the coils 11, 13 and the cores 12, 14 arranged in the power supply positions.

[0033] At the power feeding position, the end face 18a of the straight portion 18 of the second core 14 faces the end face 16a of the straight portion 16 of the first core 12. In this embodiment, the end face 18a of the second core 14 contacts the end face 16a of the first core 12, but is not limited to this configuration. As long as power feeding is possible, the end face 18a of the second core 14 may be separated from the end face 16b of the first core 12 at the power feeding position.

[0034] According to the power supply device 1 according to the present embodiment described above, the entire circumference of the power supply coil 11 and the entire circumference of the power receiving coil 13 are covered with the shield members 15a and 15b, thereby preventing the power supply coil 11 and the power receiving coil 13 from being exposed. This makes it possible to reduce leakage magnetic flux of the power supply device 1.

[0035] Moreover, the magnetic fields generated by the coils 11 and 13 can be reflected by the conductor 20 toward the cores 12 and 14. Furthermore, by insulating the first end 20a and the second end 20b of the shield members 15a and 15b with the insulator 21 so as not to be conductive, it is possible to suppress eddy currents generated in the conductor 20 during power supply. This makes it possible to increase the coupling coefficient in the magnetic field coupling section 4, and to efficiently transmit power by the power supply device 1.

[0036] 6 to 12 show other embodiments of the power supply device (magnetic field coupling portion) according to the present invention.

[0037] 6 and 7, the shield members 15a to 15c of the magnetic field coupling portion 4 include, in addition to the above-mentioned first shield member 15a and second shield member 15b, a third shield member 15c that covers a part of the straight portion 16 of the first core 12 and a part of the straight portion 18 of the second core 14. In this example, the straight portions 16, 18 of each core 12, 14 are partially covered on the connecting portion 17, 19 side by the first shield member 15a and the second shield member 15b, and partially covered on the end face 16a, 18a side by the third shield member 15c.

[0038] The third shield member 15c is configured in a cylindrical or tubular shape, and has an internal space capable of accommodating a part of the straight portion 16 of the first core 12 and a part of the straight portion 18 of the second core 14. The third shield member 15c has a first opening 22 into which the straight portion 16 of the first core 12 can be inserted, and a second opening 23 into which the straight portion 18 of the second core 14 can be inserted. The third shield member 15c is fixed to the first core 12 with a part of the straight portion 16 of the first core 12 inserted into the first opening 22.

[0039] In addition, the coils 11, 13 are not wound around the straight portions 16, 18 of the cores 12, 14 that are accommodated in the third shield member 15c.

[0040] 6 shows a state immediately before the second core 14 is arranged at the power supply position. From this state, the end (end face 18a) of the straight portion 18 of the second core 14 is inserted into the second opening 23 of the third shield member 15c, whereby the third shield member 15c can guide the second core 14 to the power supply position. That is, the third shield member 15c also functions as a guide portion that guides the second core 14 to the power supply position. Furthermore, the third shield member 15c can position each of the cores 12 and 14 such that the end face 16a of the first core 12 and the end face 18a of the second core 14 are in contact with each other without being misaligned after the second core 14 is arranged at the power supply position.

[0041] As shown in FIG. 7, the third shielding member 15c includes a conductor 20 and an insulator 21, similar to the first shielding member 15a and the second shielding member 15b. In this example, the first end 20a and the second end 20b of the conductor 20 do not overlap each other. The first end 20a and the second end 20b face each other in the circumferential direction of each coil 11, 13 via the insulator 21. The insulator 21 is located between the first end 20a and the second end 20b and connects them together. The third shielding member 15c is not limited to this example, and may have a structure in which the first end 20a and the second end 20b overlap each other via the insulator 21, similar to the first shielding member 15a and the second shielding member 15b.

[0042] 8, a third shield member 15c is fixed to an end of a straight portion 18 of the second core 14 of the magnetic field coupling unit 4. A part of the straight portion 18 of the second core 14 is inserted in advance from the second opening 23 of the third shield member 15c. In this state, the third shield member 15c is fixed to the straight portion 18 of the second core 14.

[0043] When the power receiving coil 13 and the second core 14 are moved to the power supply position, the second core 14 approaches the first core 12, and the end of the straight portion 16 of the first core 12 is inserted into the second opening 23 of the third shield member 15c. Thereafter, the second core 14 moves while being guided by the third shield member 15c to the power supply position where the end face 18a of the straight portion 18 contacts the end face 16a of the straight portion 16 of the first core 12.

[0044] In the example shown in Figure 9, the conductor 20 of the third shield member 15c in the magnetic field coupling portion 4 has a first portion 24 into which a part of the straight portion 16 of the first core 12 and a part of the straight portion 18 of the second core 14 are inserted, and a second portion 25 formed integrally with the first portion 24.

[0045] 6 and 7, the first portion 24 has a first opening 22 and a second opening 23. The third shield member 15c is fixed to the straight portion 16 of the first core 12 in a state in which a part of the straight portion 16 is inserted in advance from the first opening 22 of the first portion 24.

[0046] The second portion 25 functions as a guide portion that guides the straight portion 18 of the second core 14 to the second opening 23 of the first portion 24. An inner surface 25a of the second portion 25 is inclined at a predetermined angle with respect to the first portion 24.

[0047] When the receiving coil 13 and the second core 14 are moved to the power supply position, if the position of the second core 14 is deviated from the intended position, a part of the straight portion 18 of the second core 14 will first contact the inner surface 25a of the second portion 25 before being inserted into the first portion 24 of the third shielding member 15c.

[0048] Thereafter, the straight portion 18 of the second core 14 slides in contact with the inner surface 25a of the second portion 25 as the second core 14 moves, and is guided to the second opening 23 of the first portion 24. This makes it possible to accurately move the second core 14 to the power feeding position while correcting any positional deviation of the second core 14.

[0049] 10, the conductor 20 of the third shield member 15c in the magnetic field coupling portion 4 has a first portion 24, a second portion 25, and a third portion 26. The configuration of the first portion 24 is the same as that of the third shield member 15c shown in FIGS.

[0050] The second portion 25 is formed on the first opening 22 side of the first portion 24. The second portion 25 is overlapped on the outside of the first shield member 15a that covers a part of the straight portion 16 of the first core 12. In other words, the second portion 25 functions as a covering portion that covers a part of the first shield member 15a. The second portion 25 is fixed to a part of the first shield member 15a.

[0051] The third portion 26 is formed on the second opening 23 side of the first portion 24. When the second core 14 is disposed at the power feeding position, the third portion 26 is overlapped on the outside of the second shield member 15b that covers a part of the straight portion 18 of the second core 14. In other words, the third portion 26 functions as a covering portion that covers a part of the second shield member 15b.

[0052] When the power receiving coil 13 and the second core 14 are moved to the power feeding position, the end of the straight portion 18 of the second core 14 is inserted into the third shield member 15c from the third portion 26. The end of the straight portion 18 passes through the inside of the third portion 26 without contacting the inner surface of the third portion 26. Thereafter, the end of the straight portion 18 is inserted into the second opening 23 of the first portion 24. Furthermore, a part of the second shield member 15b covering the straight portion 18 of the second core 14 is inserted into the inside of the third portion 26 related to the third shield member 15c.

[0053] When end face 18a of straight portion 18 of second core 14 moves to a power supply position where it contacts end face 16a of straight portion 16 of first core 12, a portion of second shielding member 15b becomes covered by third portion 26 of third shielding member 15c.

[0054] In the example shown in Figure 11, of the two third shield members 15c in the magnetic field coupling portion 4, one third shield member 15c is pre-fixed to one of a pair of straight portions 16 associated with the first core 12, and the other third shield member 15c is pre-fixed to one of a pair of straight portions 18 associated with the second core 14.

[0055] When the power receiving coil 13 and the second core 14 are moved to the power feeding position, the second core 14 is brought close to the first core 12, so that an end of the straight portion 16 of the opposing first core 12 is inserted into a first opening 22 of the third shield member 15c provided on the second core 14. Also, an end of the straight portion 18 of the opposing second core 14 is inserted into a second opening 23 of the third shield member 15c provided on the first core 12. The second core 14 moves to the power feeding position while being guided by each of the third shield members 15c.

[0056] 12, the shield members 15a to 15d include the first shield member 15a to the third shield member 15c described above, as well as a fourth shield member 15d that engages with the third shield member 15c. The third shield member 15c is fixed to the straight portion 16 of the first core 12 in advance, and the fourth shield member 15d is fixed to the straight portion 18 of the second core 14 in advance.

[0057] The fourth shield member 15d has a first opening 27 into which the straight portion 18 of the second core 14 is inserted, and a second opening 28 into which the third shield member 15c is inserted. The fourth shield member 15d is fixed to the straight portion 18 of the second core 14 in a state in which the straight portion 18 is inserted into the first opening 27. A part of the straight portion 18 of the second core 14 is accommodated inside the fourth shield member 15d. In this state, the inner surface of the fourth shield member 15d does not contact the first surface 14a to the fourth surface 14d of the second core 14, and is separated from these surfaces 14a to 14d. That is, a gap into which a part of the third shield member 15c is inserted is formed between the inner surface of the fourth shield member 15d and each of the surfaces 14a to 14d of the second core 14.

[0058] When the receiving coil 13 and the second core 14 are moved to the power supply position, the second core 14 is brought close to the first core 12, and the third shield member 15c fixed to the straight portion 16 of the first core 12 is inserted into the second opening 28 of the fourth shield member 15d.

[0059] As the second core 14 moves further toward the first core 12, the fourth shield member 15d approaches the first core 12 while being guided by the outer surface of the third shield member 15c. As a result, the straight portion 18 of the second core 14 located inside the fourth shield member 15d is inserted into the second opening 23 of the third shield member 15c. Thereafter, the second core 14 moves to a power supply position where the end face 18a of the straight portion 18 contacts the end face 16a of the straight portion 16 of the first core 12.

[0060] The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

[0061] In the above embodiment, the first shield member 15a to the fourth shield member 15d are formed of separate members, but the present invention is not limited to this configuration. For example, the third shield member 15c or the fourth shield member 15d may be integral with the first shield member 15a or the second shield member 15b.

[0062] In the above embodiment, an example was given of an insulator 21 that covers only each end 20a, 20b of the conductor 20, but this is not limited to the above, and the insulator 21 may cover the entire surface of the conductor 20 (each end 20a, 20b and both the front and back surfaces).

[0063] In the above embodiment, the power supply device 1 is configured such that the second core 14 moves toward the first core 12, but the present invention is not limited to this configuration. The power supply device 1 may be configured such that the first core 12 moves toward the second core 14, or such that both the first core 12 and the second core 14 are movable. EXAMPLES

[0064] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0065] In order to confirm the effects of the present invention, the inventors measured the excitation inductance and leakage inductance in the electromagnetic coupling part of the power supply device. In order to realize a suitable power transmission, it is desirable to reduce the leakage inductance in the electromagnetic coupling part and not reduce the excitation inductance.

[0066] In the embodiment, the power supply coil, the first core, the power receiving coil, and the second core in the power supply device illustrated in FIG. 2 were covered with aluminum foil as a shielding material. In the embodiment, the ends of the aluminum foil were overlapped, and an insulating resin was placed between the ends. In addition, a power supply device in which the coils and the cores were not covered with a shielding material was prepared as Comparative Example 1. Furthermore, a power supply device in which the ends of the aluminum foil covering the coils and the cores were overlapped, and the ends were in contact (conducted) without an insulator was prepared as Comparative Example 2. The turn ratio of the power supply coil and the power receiving coil in each example was 50:9.

[0067] The measurement results are shown in Figures 13 and 14. Figure 13 shows the relationship between leakage inductance and frequency, and Figure 14 shows the relationship between excitation inductance and frequency.

[0068] 13, for example, when comparing the leakage inductance in the frequency range of 10,000 to 100,000 Hz, it is found that the leakage inductance of the example is smaller than that of the comparative example 1. On the other hand, the leakage inductance of the example is larger than that of the comparative example 2.

[0069] 14, when comparing the excitation inductance, the excitation inductance of the embodiment is similar to that of Comparative Example 1, and is larger than that of Comparative Example 2. Although Comparative Example 2 has a larger leakage inductance than the embodiment, the excitation inductance is significantly reduced, and it has been found that it is not suitable for highly efficient power transmission.

[0070] As described above, the embodiment makes it possible to reduce the leakage inductance while maintaining the excitation inductance high. [Explanation of symbols]

[0071] 1 Power supply device 11 Power coil 12 First Core 13 Receiving coil 14 Second Core 15a First shield member 15b Second shield member 15c Third shield member (guide part) 15d Fourth shield member (guide part) 20 Conductors 20a First end of conductor 20b second end of conductor 21 Insulators

Claims

1. A feeding coil; A receiving coil; a first core around which the power supply coil is wound; A second core around which the power receiving coil is wound; a shield member that covers an entire periphery of the power supply coil and an entire periphery of the power receiving coil, The shield member includes a conductor and an insulator. The electrical conductor has a first end and a second end disposed opposite each other; The power supply device, wherein the insulator is disposed between the first end and the second end.

2. The power supply device according to claim 1 , further comprising a guide portion for guiding the first core or the second core to a position where power can be supplied.

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