Power supply system having noise reduction function

Abstract

To reduce noise generated at the time of power supply in a wireless power supply system.SOLUTION: A power supply system comprises at least a power transmission unit 10, a power transmission side facing section 20, a power reception side facing section 30, and a power reception unit 40. The power transmission unit 10 includes at least a high frequency power source 11 and connects with the ground B. The power transmission side facing section 20 includes at least a power transmission side transmission section 21 and a power transmission side contact section 22. The power reception side facing section 30 includes at least a power reception side transmission section 31 and a power reception side contact section 32. The power reception unit connects with a load C to be a power supply target. When wireless power transmission is performed between the power transmission side transmission section 21 and the power reception side transmission section 31 after arranging the power transmission side facing section 20 and the power reception side facing section 30 so as to face each other, contact between the power transmission side contact section 22 and the power reception side contact section 32 forms a return path A for returning return current of common mode noise caused by the wireless power transmission to the power transmission unit 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply system that enables wireless power supply, and more particularly to a power supply system that has a function for reducing noise generated during power supply. [Background technology]

[0002] Known methods for realizing non-radiative wireless power feeding include a magnetic field coupling method (Patent Document 1) and an electric field coupling method (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-61706 [Patent Document 2] Patent No. 6117314 Summary of the Invention [Problem to be solved by the invention]

[0004] One possible application example of a non-radiative wireless power supply system is to incorporate power transmitting devices into the floors and walls of a facility, roads, and fixtures such as desks and cabinets installed within a structure, and to incorporate power receiving devices into various electrical devices (including batteries, the same applies below) used within the structure to supply power.

[0005] In this case, the high-frequency power supply (RF power supply) installed in the power transmission device is composed of a switching power supply, so ringing generated here in particular becomes noise and is transmitted to the opposing part on the power transmission side (also called the power transmission side opposing part or power transmission coupler) through the electric cable installed in the power transmission device. In particular, common mode noise can be transmitted to the receiving device and have adverse effects due to capacitive coupling between the receiving device (also called the receiving device or receiving coupler) and the transmitting device, even though the receiving device's counterpart is isolated from the transmitting device's counterpart. Furthermore, common mode noise is radiated into the surrounding space, causing moire in images captured by medical electrical equipment such as ultrasonic diagnostic equipment. Countermeasures for this include inserting a ferrite core into the line or inserting a noise-cutting transformer, but a more effective method is to form a common-mode return path.

[0006] Therefore, one of the objects of the present invention is to provide a means capable of reducing noise generated during power feeding in a wireless power feeding system. [Means for solving the problem]

[0007] The present invention, which has been made to solve the above-mentioned problems, is a power supply system that performs wireless power transmission, and includes a power transmission unit, a power transmission side opposing portion, a power receiving side opposing portion, and a power receiving unit, wherein the power transmission unit has at least a high-frequency power source and is connected to earth, the power transmission side opposing portion has at least a power transmission side transmission portion and a power transmission side contact portion, the power receiving side opposing portion has at least a power receiving side transmission portion and a power receiving side contact portion, the power receiving unit is connected to a load to be powered, and the power transmission side opposing portion and the power receiving side opposing portion are arranged opposite each other, so that when wireless power transmission is performed between the power transmission side transmission portion and the power receiving side transmission portion, contact between the power transmission side contact portion and the power receiving side contact portion forms a return path that routes the return current of common mode noise associated with the wireless power transmission from the power receiving side opposing portion to the power transmission unit. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce noise generated during power feeding in a wireless power feeding system. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic functional diagram of a power supply system according to the present invention; [Figure 2] 10 is a schematic diagram of a power transmission side opposing part and a power receiving side opposing part when a magnetic field coupling method is adopted. [Figure 3] FIG. 10 is an equivalent circuit diagram of a power supply system according to the present invention when a magnetic field coupling method is adopted. [Figure 4] FIG. 1 shows a photograph of the test environment for the comparison test. [Figure 5] 10A and 10B are diagrams showing ultrasound images from a comparative test. [Figure 6] FIG. 1 is an equivalent circuit diagram of a power supply system according to the present invention when an electric field coupling method (bipolar type) is adopted. [Figure 7] FIG. 1 is an equivalent circuit diagram of a power supply system according to the present invention when an electric field coupling method (single-pole type) is adopted. [Figure 8] 10 is a schematic diagram of a power transmission side opposing part and a power receiving side opposing part when an electric field coupling method is adopted. [Figure 9] 3A and 3B are schematic diagrams showing the opposing surfaces of the power transmitting side opposing part and the power receiving side opposing part; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, in each drawing, various elements required for wireless power transmission may be omitted to the extent that it does not affect the gist of the present invention. [Example]

[0011] <1> Overall configuration (Fig. 1, Fig. 2) The power supply system according to the present invention (hereinafter also referred to as the present system) is a system for wireless power transmission, In the schematic functional diagram shown in Figure 1, the system is configured to include at least a power transmission unit 10 connected to earth B, a power transmission side opposing part 20, a power receiving side opposing part 30, and a power receiving unit 40 connected to a load C, with the power transmission unit 10 and the power transmission side opposing part 20 connected by a power transmission side shielded cable 50, and the power receiving side opposing part 30 and the power receiving unit connected by a power receiving side shielded cable 60. Furthermore, between the power transmitting unit 10 and the power receiving unit 40, a return path A for common mode noise is formed. In this system, the noise generated during wireless power transmission is reduced by the return path A by arranging the power transmission side opposing part 20 connected to the power transmission unit 10 and the power receiving side opposing part 30 connected to the power receiving unit 40 opposite each other. Each part will be described in detail below.

[0012] <2> Power transmission unit (Figure 1) The power transmission unit 10 is a device provided on the power transmission side for transmitting high-frequency power to a power transmission side opposing part 20 opposing a power receiving side opposing part 30. The power transmission unit 10 has at least a high frequency power supply 11, and the housing of the power transmission unit 10 is connected to earth B to form a frame ground (FG).

[0013] <3> Power transmission side facing part (Fig. 1, Fig. 2) The power transmission side facing part 20 is a member that is disposed opposite the power reception side facing part 30 to perform wireless power transmission. The power-transmitting-side opposing portion 20 is also called a power-transmitting head or a power-transmitting coupler. In the present invention, the form of the power-transmission-side opposing part 20 is not particularly limited, and it is possible to select one that also serves as a component of the floors and walls of the facility, passageways, and fixtures such as desks and cabinets. The power-transmitting-side opposing part 20 has at least a power-transmitting-side transmitting part 21 and a power-transmitting-side contact part 22 . Each part will be described in detail below.

[0014] <3.1> Transmission section on the power transmission side (Fig. 1) The power-transmitting-side transmission unit 21 is a member that transmits a magnetic field, an electric field, or the like to the power-receiving-side transmission unit 31 when wireless power transmission is performed. The power transmission side transmitting section 21 corresponds to a coil in the magnetic field coupling method, and corresponds to an electrode plate in the electric field coupling method.

[0015] <3.2> Power transmission side contact (Fig. 1) The power transmitting side contact portion 22 is a portion that is brought into contact with the power receiving side contact portion 32 when wireless power transmission is performed.

[0016] <3.2.1> Example of the power transmission side contactor configuration In the present invention, the power transmitting side contact portion 22 may have any shape, structure, etc., as long as it can come into contact with the power receiving side contact portion 32 (described later) and conduct electricity. The power-transmitting-side contact portion 22 may have the following configuration. (1) Configuration Example 1: A configuration using a housing that configures the power-transmission-side opposing unit 20. (2) Configuration Example 2: A configuration in which a separate conductive member is provided on the surface of the power transmission side facing part 20 facing the power reception side facing part 30. In this configuration, possible configurations include attaching a ring-shaped conductive member to the bottom of the housing that constitutes the power transmission side facing part 20, arranging linear or strip-shaped conductive members at intervals in one direction, arranging them in a mesh-like or spiral pattern in multiple directions to provide openings partitioned by the conductive member, punching a flat plate-shaped conductive member to provide holes or slits, and combining the above-mentioned configurations as appropriate. In this embodiment (FIG. 2), configuration example 1 is adopted.

[0017] <3.2.2> GND connection wire (Fig. 1, Fig. 2) The power-transmission-side contact portion 22 is connected to the power-transmission-side shielded cable 50 via a GND connection line 52. This is to ensure a return path A, which will be described later.

[0018] <4> Opposite side of the power receiving side (Fig. 1) The power receiving side facing part 30 is a member that is disposed opposite the power transmitting side facing part 20 to perform wireless power transmission. The power-receiving-side facing portion 30 is also called a power-receiving head or a power-receiving coupler. In the present invention, the form of the power-receiving-side facing part 30 is not particularly limited. The power-receiving-side facing portion 30 has at least a power-receiving-side transmitting portion 31 and a power-receiving-side contact portion 32 . Each part will be described in detail below.

[0019] <4.1> Receiving side transmission section (Fig. 1) The power receiving side transmission unit 31 is a member that receives a magnetic field, an electric field, and the like from the power transmitting side transmission unit 21 when wireless power transmission is performed. Like the transmitting / receiving-side transmission section 21, the receiving-side transmission section 31 corresponds to a coil in the magnetic field coupling system and corresponds to an electrode plate in the electric field coupling system.

[0020] <4.2> Receiving side contact part (Fig. 1) The power receiving side contact portion 32 is a member for coming into contact with the power transmitting side contact portion 22 when wireless power transmission is performed.

[0021] <4.2.1> Example of the power transmission side contactor configuration In the present invention, the power receiving side contact portion 32 may have any shape, structure, etc., as long as it can come into contact with the power transmitting side contact portion 22 and conduct electricity. The power receiving side contact portion 32 may have the following configuration. (1) Configuration Example 1: A configuration using a housing that configures the power receiving side facing part 30. (2) Configuration Example 2: A configuration in which a separate conductive member is provided on the surface of the power receiving side facing part 30 facing the power transmitting side facing part 20. In this configuration, possible configurations include attaching a ring-shaped conductive member to the bottom of the housing that constitutes the power receiving side opposing part 30, arranging linear or strip-shaped conductive members at intervals in one direction, arranging them in a mesh-like manner in multiple directions, or arranging them in a spiral, thereby providing a mesh section divided by the conductive members, punching a flat conductive member to provide holes or slits, and combining the above-mentioned configurations as appropriate. In this embodiment (FIG. 2), configuration example 1 is adopted.

[0022] <4.2.2> GND connection wire (Fig. 1, Fig. 2) The power-receiving-side contact portion 32 is connected to the power-receiving-side shielded cable 60 via a GND connection line 62. This is to ensure a return path A, which will be described later.

[0023] <5> Power receiving unit (Figure 1) The power receiving unit 40 is a device provided on the power receiving side for supplying (including "charging") the power generated by the power transmitting side counterpart 20 and the power receiving side counterpart 30 to a power supply target. The power transmission unit 10 is electrically connected to a load 41 provided in an electrical device to be supplied with power.

[0024] <6> Shielded cable on the power transmission side and shielded cable on the power receiving side (Fig. 1) The power transmission side shielded cable 50 and the power receiving side shielded cable 60 are made of low impedance power cables with excellent electromagnetic shielding properties, such as Noilex Cable (registered trademark) manufactured by SWCC Corporation.

[0025] <7> Return path (Figure 1) The return path A is a path that connects the power receiving unit 40 and the power transmitting unit 10.

[0026] <7.1> Connection configuration (Fig. 1) As shown in FIG. 1, the return path A is made up of the following combination of connections: (1) A GND connection line 61 that connects the power receiving unit 40 and one end of the power receiving side shielded cable 60. (2) A GND connection wire 62 that connects the other end of the power-receiving-side shielded cable 60 to the power-receiving-side contact portion 32 of the power-receiving-side opposing portion 30. (3) Connection by contact between the power receiving side contact portion 32 of the power receiving side opposing portion 30 and the power transmitting side contact portion 22 of the power transmitting side opposing portion 20 (contact point A1). (4) A GND connection line 52 that connects the power-transmission-side contact portion 22 of the power-transmission-side opposing portion 20 and one end of the power-transmission-side shielded cable 50. (5) A GND connection line 51 that connects the other end of the power-transmitting-side shielded cable 50 to the power-transmitting unit 10.

[0027] <7.2> Function of the return path (Fig. 3) FIG. 3 is an equivalent circuit of the power supply system shown in FIG. In the power supply system of this embodiment, the power transmission side opposing part 20 and the power receiving side opposing part 30 are arranged opposite each other, and wireless power transmission is performed using a magnetic field coupling method via the power transmission side transmission part 21 and the power receiving side transmission part 31, which are made of coils. At this time, a contact point A1 is formed where the power transmitting side contact portion 22 and the power receiving side contact portion 32 come into contact, and the return current of the common mode noise that has been transmitted to the power receiving unit 40 side due to capacitive coupling from L1 to L2, together with the return current generated in the power transmitting side opposing portion 20, is returned to the power transmitting unit 10 via the power transmitting side opposing portion 20, thereby reducing the common mode noise.

[0028] <8> Comparative test (Figures 4 and 5) A comparative test was carried out on noise generation between a conventional power supply system using an electric field coupling method and a power supply system according to the present invention.

[0029] <8.1> Test environment (Fig. 4) Figure 3 shows a photograph of the test environment. In this test, load C was an ultrasound diagnostic device (manufacturer: Hitachi Medical Corporation, model number: HUB7500), and wireless power was supplied using a power supply system based on the conventional magnetic field coupling method and the power supply system according to the present invention. Changes in the ultrasound image when a human hand touched the ultrasound diagnostic device during wireless power supply were verified.

[0030] <8.2> Test results (Figure 5) FIG. 5(a) is a photograph of an ultrasound image when a power supply system according to the present invention is used without a return path, and FIG. 5(b) is a photograph of an ultrasound image when a power supply system according to the present invention is used. In Figure 5(a), noise is transmitted to the ultrasound diagnostic device when the human body touches it, causing moire (interference fringes) to appear in the ultrasound image, whereas in Figure 5(b), no moire occurs when the human body touches it, and there is no change in the ultrasound image.

[0031] <9> summary As described above, according to the power feeding system of the present invention, by providing a return path, it is possible to suppress radiation noise caused by common mode noise that occurs in conventional wireless power feeding circuits. [Example]

[0032] <1> Example of using the electric field coupling method (bipolar type) (Figure 6) A second embodiment of the power supply system according to the present invention will be described with reference to FIG. In this embodiment, as shown in the equivalent circuit in Figure 6, an electric field coupling method is adopted in which, when the power transmitting side transmission unit 20 and the power receiving side transmission unit 30, each composed of electrodes, are brought close to each other, power is supplied using a capacitor formed between the electrodes.

[0033] The power feeding system according to this embodiment may have a configuration in which the capacitor C1 provided in the power-transmitting-side opposing part 20 is moved to the power transmitting unit 10 side, for example. Similarly, the capacitor C2 provided in the power receiving side facing portion 30 may be moved to the power receiving unit 40 side.

[0034] <2> summary In this embodiment, as in the first embodiment, the power transmitting side contact portion 22 and the power receiving side contact portion 32 come into contact with each other to form a contact point A1. Therefore, a return current generated in the power transmitting side opposing portion 20 due to wireless power transmission and a return current flowing from the power receiving unit 40 to the power receiving side opposing portion 30 are returned to the power transmitting unit 10 via the power transmitting side opposing portion 20, thereby reducing the noise generated by the high frequency power source 11. C By forming a return path for the common mode noise transmitted to the power receiving side via the power receiving terminal, the radiation of this noise can be reduced. [Example]

[0035] <1> Examples of using the capacitive coupling method (single-pole type) (Figs. 7 to 9) A third embodiment of the power supply system according to the present invention will be described with reference to FIGS. In the wireless power supply circuit of the electric field coupling type shown in the previous Example 2 (Fig. 6), electrode pairs (power transmitting side transmission section 21 and power receiving side transmission section 31) were provided in two locations on the circuit, whereas in the wireless power supply circuit of this Example shown in Fig. 7, the above-mentioned electrode pair is provided in only one location, and direct wiring is used between the power transmitting side contact section 22 and the power receiving side contact section 32, so that wireless power supply is apparently performed with one electrode pair.

[0036] <2> Configuration example (Fig. 8, Fig. 9) An example of the configuration of the equivalent circuit shown in FIG. 7 will be described with reference to FIGS. In the power supply system according to this embodiment, the power transmission side opposing part 20 has a power transmission side transmitting part 21 made of an electrode, a power transmission side insulating part 23 made of an electrically insulating member, and power transmission side contact parts 22a and 22b that are in contact with each other, and the surface of the power transmission side contact part 22b is exposed on the surface facing the power receiving side opposing part 30 (power transmission side opposing surface 24). The power receiving side opposing part 30 has a power receiving side transmitting part 31 made of an electrode, a power receiving side insulating part 33 made of an electrically insulating material, and power receiving side contact parts 32a and 32b that are in contact with each other, which are arranged in this order toward the side opposing the power transmitting side opposing part 20, and the surface of the power receiving side contact part 32b is exposed on the surface facing the power transmitting side opposing part 20 (power receiving side opposing surface 34).

[0037] As shown in FIG. 8, the power transmitting side contact portion 22a also serves as a housing for the power transmitting side opposing portion 20, and similarly, the power receiving side contact portion 32a also serves as a housing for the power receiving side opposing portion 30. As shown in FIG. 9, the power-transmitting-side contact portion 22b and the power-receiving-side contact portion 32b are configured in a mesh shape by arranging linear conductive members in the vertical and horizontal directions. With this configuration, when the power transmission side opposing portion 20 and the power receiving side opposing portion 30 are arranged opposite each other, the power transmission side contact portion 22b and the power receiving side contact portion 32b come into contact, thereby forming a return path A and ensuring protective grounding of the power receiving side electrical equipment (load C) on the power transmission side, and wireless power transmission is performed between the power transmission side electrode portion 10 and the power receiving side electrode portion 60. Furthermore, in the circuit according to this embodiment, the transmitting electrode is one pole and the GND side also serves as a noise return path, which essentially becomes a normal mode noise path, reducing radiation noise.

[0038] <3> summary According to the power supply system of this embodiment, when wireless power transmission is performed, in addition to the effect of reducing noise described in the previous embodiments 1 and 2, there is an additional effect that, by ensuring protective earthing on the load C side, it is no longer necessary to provide a separate earth cable for the electrical device to be powered, and therefore the passage of people or the movement of objects is no longer hindered due to the earth cable. Therefore, this is particularly useful when medical electrical equipment (electrical equipment belonging to Class I, which requires protective earthing as specified in JIS T 0601-1) is used as the electrical equipment to be powered. [Explanation of symbols]

[0039] 10: Power transmission unit 11:High frequency power supply 20: Power transmission side opposing part 21: Power transmission side transmission unit 22: Power transmission side contact part 23: Transmission side insulation part 24: Facing the power transmission side 30: Power receiving side facing part 31: Receiving side transmission unit 32: Receiving side contact part 33: Receiving side insulation part 34: Facing the power receiving side 40: Power receiving unit 50: Transmission side shielded cable 51, 52: GND connection wire 60: Receiving side shielded cable 61,62: GND connection wire A: Return path A1: Contact point B: Earth C: Load

Claims

1. A power supply system that performs wireless power transmission, The power transmission device includes a power transmission unit, a power transmission side opposing part, a power receiving side opposing part, and a power receiving unit, the power transmitting unit has at least a high frequency power source and is connected to a ground; the power-transmitting-side opposing portion has at least a power-transmitting-side transmitting portion and a power-transmitting-side contact portion, the power-receiving-side opposing portion has at least a power-receiving-side transmitting portion and a power-receiving-side contact portion, The power receiving unit is connected to a load to be supplied with power, The power transmitting side opposing portion and the power receiving side opposing portion are disposed opposite each other, and when wireless power transmission is performed between the power transmitting side transmission portion and the power receiving side transmission portion, a return path is formed by contact between the power transmitting side contact portion and the power receiving side contact portion, which returns a return current of common mode noise accompanying the wireless power transmission to the power transmitting unit. Power supply system.

2. The return path is The power receiving unit is characterized in that it is formed by a housing of the power receiving unit, a power receiving side shielded cable connecting the housing of the power receiving unit and the power receiving side contact part, the power receiving side contact part, the power transmitting side contact part, a power transmitting side shielded cable connecting the power transmitting side contact part and the housing of the power transmitting unit, and the housing of the power transmitting unit. The power supply system according to claim 1 .

3. the power transmission side contact portion is configured by a housing of the power transmission side opposing portion, The power receiving side contact portion is formed by a housing of the power receiving side facing portion. The power supply system according to claim 1 .

4. the power transmission side contact portion is provided in a mesh shape on the surface facing the power receiving side facing portion, The power receiving side contact portion is provided in a mesh shape on the surface facing the power transmitting side opposing portion. The power supply system according to claim 1 .

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