JP7628246B2 - Power supply device - Google Patents

Description

The present invention relates to a power supply device that supplies power wirelessly.

In recent years, wireless power supply (non-contact power supply) that does not require 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).

For example, Patent Document 1 discloses a power supply device that uses electromagnetic resonance. The power supply device includes a power supply unit provided in the power supply equipment and a power receiving unit mounted on the vehicle.

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.

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 up 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).

The power receiving section includes a power receiving coil unit. The power receiving coil unit includes a power receiving coil that electromagnetically resonates with the power supply 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.

The power-receiving shield case, like the power-feeding shield case, is made of a metal shield. The power-receiving shield case has a bottom wall that covers part of the power-receiving 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).

JP 2014-179438 A

In conventional power supply devices, the power supply shield case and the power receiving shield case are partially open, so that part of the power supply coil and part of the power receiving coil are exposed from each shield case. This causes leakage flux from the exposed parts of each coil, resulting in a decrease in power transmission efficiency.

The present invention was made in consideration of the above circumstances, and its technical objective is to reduce leakage magnetic flux in power supply devices.

The present invention is intended to solve the above problems, and provides a power supply device including 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 that covers the entire circumference of the power supply coil and the entire circumference of the power receiving coil, the shielding member including a conductor and an insulator, the conductor having a first end and a second end that are arranged to face each other, and the insulator being disposed between the first end and the second end.

According to this configuration, by covering 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 with a shielding material, it is possible to eliminate exposure of each coil and each core and reduce leakage flux of the power supply device. In addition, by insulating the first end and second end of the shielding material with an insulator so that they are not conductive, it is possible to suppress eddy currents that occur in the conductor when power is supplied. As a result, it is possible to improve the power transmission efficiency of the power supply device.

The power supply device may include a guide portion for guiding the first core or the second core to a position where power can be supplied. This guide portion makes it possible to precisely position each coil and each core at a position where power can be supplied.

The present invention makes it possible to reduce leakage magnetic flux from the power supply device.

FIG. 2 is a circuit diagram of a power supply device. FIG. 2 is a plan view showing a magnetic field coupling portion of the power supply device. 3 is a cross-sectional view taken along the line III-III of FIG. 2. 4 is a cross-sectional view taken along the line IV-IV of FIG. 2. FIG. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. FIG. 13 is a plan view showing a magnetic field coupling portion of a power supply device according to another embodiment. 13 is a graph showing measurement results of leakage inductance. 13 is a graph showing measurement results of excitation inductance.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figs. 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 illustrated.

The power supply device can be used in charging systems for electric vehicles (EVs), automated guided vehicles (AGVs), and the like. However, 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 automated guided vehicle will be described.

As shown in FIG. 1, the power supply device 1 includes a power supply unit 2 as a primary circuit provided in the charging station, a power receiving unit 3 as a secondary circuit provided in the 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.

The power supply unit 2 includes, for example, a power source 5 and a switching circuit 6. The switching circuit 6 is configured with, 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 the DC voltage applied by the power source 5 into a square wave AC voltage by the switching circuit 6.

The power receiving unit 3 includes, for example, a rectifier circuit 8 and a battery 10 as a secondary battery. The rectifier circuit 8 is composed of four diodes 9b each connected in parallel with a resonant capacitor 9a, 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.

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 and 15b for suppressing leakage magnetic flux.

The power supply coil 11 and the power receiving coil 13 are made of insulated wire and are wound around each core 12, 14 with a predetermined number of turns.

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

As shown in FIG. 4, the cross section of each core 12, 14 is rectangular, but is not limited to this shape. Each core 12, 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.

The shielding members 15a and 15b include a first shielding member 15a that covers the power supply coil 11 and the first core 12, and a second shielding member 15b that covers the power receiving coil 13 and the second core 14.

As shown in Figs. 3 and 4, each shield member 15a, 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.

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.

Figure 5 shows the shield members 15a, 15b before being attached to each coil 11, 13 and each core 12, 14. The conductor 20 of each shield member 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 end 20a, 20b are covered with an insulator 21.

As shown in FIG. 4, when each shield member 15a, 15b is attached to each core 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 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.

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

The first shield member 15a is not overlapped on the end face 16a of the straight portion 16 of the first core 12. The second shield member 15b is not overlapped on the end face 18a of the straight portion 18 of the second core 14.

When it becomes necessary to charge the battery 10, 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 can be supplied (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.

In the power supply position, the end face 18a of the straight portion 18 in the second core 14 faces the end face 16a of the straight portion 16 in 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 this configuration is not limited. As long as power supply is possible, the end face 18a of the second core 14 may be separated from the end face 16b of the first core 12 in the power supply position.

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 shielding members 15a and 15b, so that the power supply coil 11 and the power receiving coil 13 are not exposed. This makes it possible to reduce the leakage magnetic flux of the power supply device 1.

The magnetic field generated by each coil 11, 13 can be reflected toward each core 12, 14 by the conductor 20. Furthermore, the first end 20a and the second end 20b of the shield members 15a, 15b are insulated by the insulator 21 so that they are not conductive, thereby suppressing eddy currents generated in the conductor 20 during power supply. This increases the coupling coefficient in the magnetic field coupling section 4, enabling the power supply device 1 to transmit power efficiently.

Figures 6 to 12 show other embodiments of the power supply device (magnetic field coupling unit) according to the present invention.

6 and 7, the shield members 15a to 15c of the magnetic field coupling portion 4 include the first shield member 15a and the second shield member 15b described above, as well as 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.

The third shield member 15c is configured in a cylindrical or tubular shape and has a space inside that can accommodate 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.

In addition, the coils 11 and 13 are not wound around the straight sections 16 and 18 of the cores 12 and 14 that are housed in the third shield member 15c.

Figure 6 shows the state immediately before the second core 14 is placed in 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, so that the third shield member 15c can guide the second core 14 to the power supply position. In other words, 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 core 12, 14 so that the end face 16a of the first core 12 and the end face 18a of the second core 14 are in contact without misalignment after the second core 14 is placed in the power supply position.

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. 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. 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.

In the example shown in FIG. 8, the third shield member 15c is fixed to the end of the straight portion 18 of the second core 14 of the magnetic field coupling portion 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.

When the 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. The second core 14 then 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.

In the example shown in FIG. 9, the conductor 20 of the third shield member 15c in the magnetic field coupling portion 4 includes a first portion 24 into which a portion of the straight portion 16 of the first core 12 and a portion of the straight portion 18 of the second core 14 are inserted, and a second portion 25 that is integral with the first portion 24.

The first portion 24 has a first opening 22 and a second opening 23, similar to the third shielding member 15c illustrated in Figures 6 and 7. The third shielding member 15c is fixed to the straight portion 16 of the first core 12 with a portion of the straight portion 16 already inserted through the first opening 22 of the first portion 24.

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. The inner surface 25a of the second portion 25 is inclined at a predetermined angle with respect to the first portion 24.

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 first comes into contact with the inner surface 25a of the second portion 25 before being inserted into the first portion 24 of the third shield member 15c.

Then, as the second core 14 moves, the straight portion 18 of the second core 14 slides in contact with the inner surface 25a of the second portion 25 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 supply position while correcting any misalignment of the second core 14.

In the example shown in FIG. 10, the conductor 20 of the third shielding 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 shielding member 15c shown in FIGS. 6 and 7.

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 portion 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 portion of the first shield member 15a. The second portion 25 is fixed to a portion of the first shield member 15a.

The third portion 26 is formed on the second opening 23 side of the first portion 24. When the second core 14 is placed in the power supply position, the third portion 26 is overlapped on the outside of the second shield member 15b that covers a portion 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 portion of the second shield member 15b.

When the receiving coil 13 and the second core 14 are moved to the power supply 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. The end of the straight portion 18 is then 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.

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

In the example shown in FIG. 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.

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 end of the straight portion 16 of the opposing first core 12 is inserted into the first opening 22 of the third shield member 15c provided on the second core 14. Also, the end of the straight portion 18 of the opposing second core 14 is inserted into the second opening 23 of the third shield member 15c provided on the first core 12. The second core 14 moves to the power supply position while being guided by each third shield member 15c.

In the example shown in FIG. 12, the shield members 15a to 15d include the first shield member 15a to the third shield member 15c already described, as well as a fourth shield member 15d that engages with the third shield member 15c. The third shield member 15c is pre-fixed to the straight portion 16 of the first core 12, and the fourth shield member 15d is pre-fixed to the straight portion 18 of the second core 14.

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 with the straight portion 18 inserted into the first opening 27. A portion of the straight portion 18 of the second core 14 is housed 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. In other words, a gap is formed between the inner surface of the fourth shield member 15d and each surface 14a to 14d of the second core 14, into which a portion of the third shield member 15c is inserted.

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.

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. The second core 14 then 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.

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

In the above embodiment, the first shielding member 15a to the fourth shielding member 15d are configured as separate members, but the present invention is not limited to this configuration. For example, the third shielding member 15c or the fourth shielding member 15d may be configured integrally with the first shielding member 15a or the second shielding member 15b.

In the above embodiment, the insulator 21 covers only the ends 20a, 20b of the conductor 20, but this is not limited thereto, and the insulator 21 may cover the entire surface of the conductor 20 (the ends 20a, 20b and both the front and back surfaces).

In the above embodiment, the power supply device 1 is configured so 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 so that the first core 12 moves toward the second core 14, or so that both the first core 12 and the second core 14 are movable.

The following describes an example of the present invention, but the present invention is not limited to this example.

To confirm the effects of the present invention, the inventors measured the excitation inductance and leakage inductance at the electromagnetic coupling part of the power supply device. To achieve optimal power transmission, it is desirable to reduce the leakage inductance at the electromagnetic coupling part while preventing the excitation inductance from decreasing.

In the example, the power supply coil, first core, receiving coil, and second core in the power supply device illustrated in FIG. 2 were covered with aluminum foil as a shielding material. In the example, the ends of the aluminum foil were overlapped, and insulating resin was placed between the ends. In addition, a power supply device in which the coils and 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 each coil and each core were overlapped, and these ends were in contact (conducted) without an insulator between them was prepared as Comparative Example 2. The turns ratio of the power supply coil and the receiving coil in each example was 50:9.

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.

As shown in Figure 13, for example, when comparing leakage inductance in the frequency range of 10,000 to 100,000 Hz, it can be seen that the leakage inductance of the embodiment is smaller than that of comparative example 1. On the other hand, the leakage inductance of the embodiment is larger than that of comparative example 2.

As shown in Figure 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 was found that it is not suitable for highly efficient power transmission.

As a result of the above, the embodiment is able to reduce leakage inductance while maintaining high excitation inductance.

REFERENCE SIGNS LIST 1: power supply device 11: power supply coil 12: first core 13: power receiving coil 14: second core 15a: first shield member 15b: second shield member 15c: third shield member (guide portion)
15d Fourth shield member (guide portion)
20 Conductor 20a First end of conductor 20b Second end of conductor 21 Insulator

Claims (2)

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. 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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