Wireless power transmission system

Abstract

According to one aspect of the present disclosure, a wireless power transmission system is provided with a power transmission device and a power reception device. The power receiving device is provided with a first power receiving circuit, and the first power receiving circuit is provided with three power receiving coils which are connected in a triangular structure. The three power receiving coils are configured so as to (i) magnetically couple to two or more power transmission coils of the power transmission device, and (ii) output a first multi-phase alternating current in response to two or more single-phase alternating currents being supplied to the two or more power transmission coils, respectively.

Description

Technical Field

[0001] This disclosure relates to a technology for transmitting power wirelessly. Background Technology

[0002] Japanese Patent Application Publication No. 2016-197931 discloses a wireless power transmission device that wirelessly transmits power between a transmitting coil and a receiving coil. The receiving device of this wireless power transmission device includes a filter for removing harmonics. Summary of the Invention

[0003] In the aforementioned wireless power transmission devices, the larger the power transmitted, the larger the filter may be.

[0004] One aspect of this disclosure aims to suppress the scaling up of filter circuits used to remove harmonics from power transmitted wirelessly.

[0005] One aspect of this disclosure provides a wireless power transmission system comprising a power transmitting device and a power receiving device.

[0006] The power transmission device includes a first power transmission circuit and a power supply circuit.

[0007] The first power supply circuit has two or more power supply coils, which are separated from each other.

[0008] The power supply circuit is configured to supply one of two or more single-phase alternating currents to each of the two or more power-generating coils. The two or more single-phase alternating currents have the same frequency but different phases.

[0009] The power receiving device includes a first power receiving circuit and a conversion circuit.

[0010] The first power receiving circuit includes three power receiving coils connected in a delta configuration. The three power receiving coils are configured to (i) be magnetically coupled to the two or more power supply coils, and (ii) output a first multiphase alternating current in response to the two or more single-phase alternating currents being supplied to the two or more power supply coils respectively.

[0011] The conversion circuit is configured to convert the first multiphase AC power into the first DC power.

[0012] In the aforementioned wireless power transmission system, the power transmitted to the first receiving circuit contains a third harmonic component. However, this third harmonic component circulates within the triangular structure and does not flow out of it. Therefore, this wireless power transmission system does not require a filter circuit to remove the third harmonic component. For this wireless power transmission system, a filter circuit capable of removing harmonic components of the fifth harmonic or higher contained in the transmitted power is sufficient. Therefore, the large size of the filter circuit can be suppressed. Attached Figure Description

[0013] Figure 1 This is a perspective view of the wireless power transmission system according to the first embodiment.

[0014] Figure 2 This is a circuit diagram of the wireless power transmission system according to the first embodiment.

[0015] Figure 3 This is a waveform diagram showing the third harmonic component.

[0016] Figure 4 This is a diagram showing the 3rd harmonic component circulating within a triangular structure.

[0017] Figure 5 This is a circuit diagram of a variation of the first embodiment.

[0018] Figure 6 This is a circuit diagram of the wireless power transmission system according to the second embodiment.

[0019] Figure 7 This is a circuit diagram of the wireless power transmission system according to the third embodiment.

[0020] Figure 8 This is a waveform diagram showing the suppression of the 5th harmonic component. Detailed Implementation

[0021] 1. Overview of Implementation Methods

[0022] In this disclosure, terms such as "first" and "second" are used only to distinguish between elements and not to limit the order or number of elements. Therefore, the first element can be called the second element, and similarly, the second element can be called the first element. Furthermore, an element can be present without the second element, and similarly, an element can be present without the first element.

[0023] Some implementations may provide a wireless power transmission system having at least one of the following features.

[0024] Feature 1: Power transmission device;

[0025] Feature 2: The power supply device includes a first power supply circuit, and the first power supply circuit includes two or more power supply coils;

[0026] Feature 3: The two or more power supply coils are separated from each other;

[0027] Feature 4: The power transmission device has a power supply circuit;

[0028] Feature 5: The power supply circuit is configured to supply one of the two or more single-phase AC currents to the two or more power supply coils respectively;

[0029] Feature 6: The two or more single-phase alternating currents have the same frequency, but are in different phases.

[0030] Feature 7: Power receiving device;

[0031] Feature 8: The power receiving device has a first power receiving circuit, which has three power receiving coils connected in a delta configuration;

[0032] Feature 9: The three receiving coils are configured to (i) be magnetically coupled to the two or more transmitting coils, and (ii) output the first multiphase alternating current in response to the two or more single-phase alternating currents being supplied to the two or more transmitting coils respectively; and

[0033] Feature 10: The power transmission device includes a conversion circuit configured to convert the first multiphase alternating current into a first direct current.

[0034] In wireless power transmission systems possessing at least features 1 to 10, the outflow of the third harmonic component from the triangular structure can be suppressed. Therefore, in the aforementioned wireless power transmission systems, a filter for removing harmonic components of the fifth harmonic and above is sufficient. This prevents the need for large-scale filtering circuits.

[0035] Some implementations may include at least one of the following features in addition to at least one of features 1 to 10, or, instead of at least one of features 1 to 11, may include at least one of the following features.

[0036] Feature 11: The conversion circuit includes a first rectifier circuit configured to rectify the first multiphase AC power into the first DC power; and

[0037] Feature 12: The conversion circuit includes a filter circuit configured to remove unwanted harmonic components from the first direct current obtained through the first rectifier circuit.

[0038] In a wireless power transmission system having at least features 1 to 12, not only can the third harmonic component be removed from the first direct current, but also the unwanted harmonic components can be removed.

[0039] Some implementations may include at least one of the following features in addition to at least one of features 1 to 12, or may replace at least one of features 1 to 12 with at least one of the following features.

[0040] Feature 13: The two or more power supply coils include three power supply coils;

[0041] Feature 14: The two or more single-phase alternating currents include three single-phase alternating currents that are 120° out of phase with each other;

[0042] Feature 15: The feeding circuit is configured to supply one unidirectional alternating current from the three single-phase alternating currents to the three transmitting coils respectively; and

[0043] Feature 16: The three power transmission coils are configured to receive the three single-phase alternating currents and simulate a triangular structure.

[0044] In a wireless power transmission system possessing at least features 1-10 and 13-16, power transmission can continue even if any one of the three transmitting coils fails. If the three transmitting coils are actually connected in a delta configuration, power transmission can be stopped if any one of the three transmitting coils fails.

[0045] Some implementations may include at least one of the following features in addition to at least one of features 1 to 16, or may replace at least one of features 1 to 16 with at least one of the following features.

[0046] Feature 17: The first power transmission circuit includes two or more capacitors, which together with the two or more power transmission coils form two or more series resonant circuits.

[0047] Feature 18: The first power receiving circuit includes three additional capacitors, which, together with the three power receiving coils, form three additional series resonant circuits; and

[0048] Feature 19: Each of the two or more series resonant circuits and each of the three additional series resonant circuits is configured to resonate at the same frequency.

[0049] In a wireless power transmission system possessing at least features 1-10 and 17-19, the three receiving coils resonate with the magnetic fields generated by the two or more transmitting coils to produce a new magnetic field. This new magnetic field then excites the resonance of the two or more transmitting coils. This process is repeated between the three receiving coils and the two or more transmitting coils, thereby causing magnetic resonance between them. Therefore, the power transmission efficiency is improved compared to power transmission via electromagnetic coupling. Furthermore, this configuration also increases the degree of freedom in the relative positions between the transmitting and receiving devices.

[0050] Some implementations may include at least one of the following features in addition to at least one of features 1 to 19, or may replace at least one of features 1 to 19 with at least one of the following features.

[0051] Feature 20: A second power receiving circuit, different from the first power receiving circuit;

[0052] Feature 21: The second power receiving circuit (i) comprises three additional power receiving coils connected in a delta or star configuration; and (ii) is configured to output a second multiphase alternating current; and

[0053] Feature 22: The conversion circuit includes a second rectifier circuit, which is configured to (i) rectify the second multiphase AC power into a second DC power, and (ii) combine the second DC power with the first DC power in parallel.

[0054] In wireless power transmission systems possessing at least features 1 to 10 and 20 to 22, the capability of the receiving device can be improved. Specifically, when the second receiving circuit has three additional receiving coils connected in a star configuration, in addition to the third harmonic component, the output of the fifth and seventh harmonic components can also be suppressed from the second receiving circuit. Therefore, what is needed for the wireless power transmission system is a filter circuit that removes harmonic components above the 11th harmonic. This allows for further miniaturization of the filter circuit.

[0055] Some embodiments may include at least one of the following features in addition to at least one of features 1 to 22, or may replace at least one of features 1 to 22 with at least one of the following features.

[0056] Feature 23: The power receiving device is (i) field electrical equipment or (ii) a battery pack for the field electrical equipment.

[0057] In a wireless power transmission system having at least features 1 to 10, 23, power can be supplied wirelessly to the field electrical equipment or its battery pack.

[0058] Examples of the electrical equipment used on site include power equipment used on construction, manufacturing, gardening, and other work sites. Specifically, this includes power tools (or electric tools) for stone processing, metal processing, wood processing, and gardening, but is not limited to the above-mentioned equipment.

[0059] More specifically, examples of electrical equipment used on-site include electric screwdrivers, electric wrenches, electric drills, electric impact drills, electric chainsaws, electric circular saws, electric reciprocating saws, electric jigsaws, electric cutting machines, electric hammers, electric planers, electric grinders, electric blowers, electric nail machines (including rivet guns), electric hedge trimmers, electric lawn mowers, electric lawn trimmers, electric harvesters, electric trowels, electric vibrators, electric rammers, electric compactors, electric pumps, electric pile drivers, electric concrete saws, electric leveling machines, electric cutting saws, electric sprayers, and electric spreaders. Seeders, electric cleaners, electric dust collectors, robotic vacuum cleaners, robotic lawnmowers, electric drills, electric soil conditioners, electric air pumps, electric lubricators (e.g., electric grease guns), fan vests, heated jackets, electric fans, laser rangefinders (or laser rangefinder devices), laser levels, receivers for laser levels, wall-mounted scanners, radios, televisions, loudspeakers, lamps (i.e., lighting fixtures), electric hot and cold boxes, electric kettles, coffee makers (or coffee pots, or coffee liqueurs), microwave ovens, portable power supplies, and power distribution units, but not limited to the above-mentioned equipment.

[0060] Some embodiments may include the following features in addition to at least one of features 1 to 23, or may include the following features instead of at least one of features 1 to 23.

[0061] Feature 24: The conversion circuit is configured to supply at least the first DC power to the battery pack used for the field electrical equipment.

[0062] In a wireless power transmission system having at least features 1 to 10, 23, and 24, the battery pack can be charged at least by the first direct current.

[0063] Some embodiments may include at least one of the following features in addition to at least one of features 1 to 24, or may include at least one of the following features instead of at least one of features 1 to 24.

[0064] Feature 25: The power transmission device further comprises a second power transmission circuit, which is different from the first power transmission circuit;

[0065] Feature 26: The second power supply circuit has two or more additional power supply coils; and

[0066] Feature 27: The two or more additional power supply coils include three additional power supply coils.

[0067] In a wireless power transmission system having at least features 1 to 10, 25, and 26, when the phases of the two or more additional single-phase alternating currents supplied to the two or more additional power supply coils in the second power supply circuit are different from the phases of the two or more single-phase alternating currents supplied to the two or more power supply coils in the first power supply circuit, the harmonic components contained in the first direct current output from the first power receiving circuit can be further suppressed.

[0068] In some implementations, features 1 to 27 can be combined in any way.

[0069] In some implementations, any one of features 1 to 27 may be eliminated.

[0070] 2. Specific Exemplary Implementations

[0071] Specific exemplary embodiments of this disclosure will now be described with reference to the accompanying drawings.

[0072] 2-1. First Implementation Method

[0073] This first embodiment provides Figure 1 The wireless power transmission system 1 shown.

[0074] 2-1-1. Overall Composition of Wireless Power Transmission System

[0075] like Figure 1 As shown, the wireless power transmission system 1 includes a power supply device 2 and a first power receiving device 6-1 to an nth power receiving device 6-n (n is a natural number of 2 or more). Figure 1 Only the first power receiving device 6-1 and the second power receiving device 6-2 are shown for illustrative purposes only. In other embodiments, the nth power receiving device 6-n may be excluded from the wireless power transmission system 1.

[0076] The power transmission device 2 has a housing 21. In this first embodiment, the housing 21 has a flat, generally rectangular shape. In other embodiments, the housing 21 may have any other shape.

[0077] The housing 21 has an upper surface 21a, which is configured to house at least one of the first power receiving device 6-1 to the nth power receiving device 6-n. In this first embodiment, the upper surface 21a has a generally square planar shape. In other embodiments, the upper surface 21a may have any other planar shape.

[0078] The first power receiving device 6-1 to the nth power receiving device 6-n can each be a field electrical device or a battery pack used for field electrical devices.

[0079] In this first embodiment, the field electrical equipment may be an electric work machine, a light, an electric fan, a hot / cold box, a radio, an electric air compressor, a laser level, a portable power supply, or a power distributor. The field electrical equipment may have a built-in battery pack or may be configured to have a removable battery pack.

[0080] Examples of electric work machines include, but are not limited to, power tools, electric vacuum cleaners, electric lawnmowers, and gardening tools.

[0081] A power distributor may have more than one port for outputting power. Examples of more than one port include terminals for connecting to a battery pack, USB terminals, and DC plugs, but are not limited to the examples mentioned above.

[0082] In the following text, the first power receiving device 6-1 to the nth power receiving device 6-n are collectively referred to as power receiving device 6, and no distinction is made between them.

[0083] 2-1-2. Electrical Configuration of Wireless Power Transmission Systems

[0084] 2-1-2-1. Electrical Configuration of Power Transmission Equipment

[0085] like Figure 2 As shown, the power supply device 2 is configured to operate by receiving three-phase AC power from the three-phase AC power supply 100. In this first embodiment, the three-phase AC power supply 100 is a three-phase three-wire 200-volt power supply, but is not limited to this type of power supply.

[0086] The power supply device 2 has a converter group 3, a transmission circuit 4, and a control circuit 5 in the housing 21.

[0087] The converter group 3 includes a first power supply converter 31A to a third power supply converter 31C.

[0088] The first power converter 31A is connected to phase L1 (or phase A, or phase R) and phase L2 (or phase B, or phase S) of the three-phase AC power supply 100. The second power converter 31B is connected to phase L2 and phase L3 (or phase C, or phase T) of the three-phase AC power supply 100. The third power converter 31C is connected to phase L3 and phase L1 of the three-phase AC power supply 100.

[0089] Each of the first power converters 31A to the third power converter 31C is configured to output single-phase alternating current having a preset supply voltage and a preset transmission frequency. In this first embodiment, the preset supply voltage is 90 volts, but is not limited to 90 volts. The preset transmission frequency is 6.78 MHz, but is not limited to 6.78 MHz.

[0090] The power transmission circuit 4 includes a first power transmission module 30A to a third power transmission module 30C configured to perform similar operations to each other.

[0091] The first power supply module 30A has a first power supply coil 41A, a first capacitor 42A, and a second capacitor 43A. The two ends of the first power supply coil 41A are connected to the output of the first power supply converter 31A via the first capacitor 42A and the second capacitor 43A.

[0092] The second power supply module 30B has a second power supply coil 41B, a third capacitor 42B, and a fourth capacitor 43B. The two ends of the second power supply coil 41B are connected to the output of the second power supply converter 31B via the third capacitor 42B and the fourth capacitor 43B.

[0093] The third power supply module 30C has a third power supply coil 41C, a fifth capacitor 42C, and a sixth capacitor 43C. The two ends of the third power supply coil 41C are connected to the output of the third power supply converter 31C via the fifth capacitor 42C and the sixth capacitor 43C.

[0094] The first power supply coil 41A to the third power supply coil 41C have essentially the same characteristics. The first, third, and fifth capacitors 42A to 42C and the second, fourth, and sixth capacitors 43A to 43C have essentially the same characteristics.

[0095] The first power supply coil 41A to the third power supply coil 41C, together with the first, third, and fifth capacitors 42A to 42C and the second, fourth, and sixth capacitors 43A to 43C, form three series resonant circuits that resonate at the aforementioned predetermined transmission frequency. Furthermore, the first power supply coil 41A to the third power supply coil 41C are positioned on the back side of the upper surface 21a so that the magnetic flux radiates toward the upper surface 21a.

[0096] The control circuit 5 takes the form of a microcomputer (or microprocessor, or microcontroller), which includes at least a central processing unit (CPU) 51 and a memory 52. ​​The memory 52 is a semiconductor memory that includes volatile memory and non-volatile memory, but is not limited to semiconductor memory.

[0097] In other embodiments, the control circuit 5 may also include an additional microcomputer. In still other embodiments, in addition to or instead of a microcomputer, the control circuit 5 may also include a graphics processing unit (GPU), an embedded neural network processor (NPU), an artificial intelligence (AI) processor, and / or an AI chip. In still other embodiments, in addition to or instead of a microcomputer, the control circuit 5 may also include logic circuits (or logic gates, or wired logic connections) comprising two or more circuit elements. In still other embodiments, in addition to or instead of a microcomputer, the control circuit 5 may also include application-specific integrated circuits (ASICs) and / or application-specific standard products (ASSPs). In still other embodiments, in addition to or instead of a microcomputer, the control circuit may also include a programmable logic device (PLD) capable of implementing reconfigurable logic circuits. Examples of programmable logic devices (PLDs) include, but are not limited to, field-programmable gate arrays (FPGAs).

[0098] Control circuit 5 controls the first power converter 31A to the third power converter 31C so that the single-phase alternating current supplied from the first power converter 31A to the third power converter 31C to the corresponding first power coil 41A to third power coil 41C are 120° (i.e., 2π / 3 radians) out of phase with each other. Thus, the first power coil 41A to the third power coil 41C simulate a delta structure (or form an equivalent circuit of a delta structure).

[0099] 2-1-2-2. Electrical Configuration of the Power Receiving Device

[0100] like Figure 2 As shown, the power receiving device 6 includes a power receiving circuit 7, a rectifier circuit 8, a filter circuit 9, a power receiving converter 10, and a load 11.

[0101] The power receiving circuit 7 has a first power receiving coil 71A to a third power receiving coil 71C and a first capacitor 72A to a third capacitor 72C.

[0102] The first receiving coil 71A to the third receiving coil 71C are connected in a delta configuration. The first receiving coil 71A to the third receiving coil 71C have essentially the same characteristics.

[0103] Capacitors 72A through 72C are connected to connection points U, V, and W of the first receiving coil 71A through 71C, respectively. The three-phase AC power output from connection points U, V, and W by capacitors 72A through 72C is supplied to the rectifier circuit 8. Capacitors 72A through 72C essentially have the same characteristics. Capacitors 72A through 72C, together with the first receiving coil 71A through 71C, form three series resonant circuits. These three series resonant circuits are configured to resonate at the aforementioned predetermined transmission frequency. In other words, the power transmission circuit 4 and the power receiving circuit 7 are configured to transmit power between the power transmission device 2 and the power receiving device 6 via magnetic resonance.

[0104] The rectifier circuit 8 is configured to convert the three-phase alternating current output from the power receiving circuit 7 into a first direct current through full-wave rectification. In this first embodiment, the rectifier circuit 8 is a three-phase bridge rectifier circuit (or a three-phase full-wave rectifier) ​​having six diodes (not shown) or six thyristors (not shown); however, the rectifier circuit 8 is not limited to a three-phase bridge rectifier circuit.

[0105] The filter circuit 9 is configured to remove harmonic components of the fifth harmonic or higher contained in the output of the rectifier circuit 8. In this first embodiment, the filter circuit 9 is a low-pass filter formed by the coil 91 and the capacitor 92, but it is not limited to the low-pass filter described above.

[0106] The power converter 10 is configured to (i) receive a first DC power via a filter circuit 9; (ii) convert the first DC power into output power corresponding to the load 11; and (iii) supply the output power to the load 11.

[0107] The load 11 may be (i) a battery cell, (ii) a light source (e.g., a light-emitting diode (LED)), (iii) an actuator (e.g., an electric motor), (iv) a drive circuit configured to drive the actuator, or (v) a connector configured to connect to an external load not shown.

[0108] 2-1-3. Technical Effects of the First Embodiment

[0109] The first embodiment described in detail above can achieve the following first to third technical effects.

[0110] 2-1-3-1. First technical effect

[0111] In the wireless power transmission system 1, the power transmitting device 2 wirelessly transmits three-phase alternating current from the first power transmitting coil 41A to the third power transmitting coil 41C to the power receiving device 6. The power receiving device 6 wirelessly receives the three-phase alternating current through the first power receiving coil 71A to the third power receiving coil 71C connected in a delta configuration.

[0112] like Figure 3 As shown, when the first receiving coil 71A to the third receiving coil 71C receive three-phase alternating current, three third harmonic components are generated. These third harmonic components circulate within the delta structure, thus being suppressed from flowing out of the receiving circuit 7.

[0113] Therefore, the filter circuit 9 does not need to remove the third harmonic component with the highest electrical power among the unwanted harmonic components; it only needs to remove the fifth harmonic and higher harmonic components with higher frequencies and lower electrical power. Thus, the size of the filter circuit 9 can be reduced, and the size of the power receiving device 6 can be suppressed.

[0114] Here, we will explain the circulation of the aforementioned third harmonic components within the triangular structure.

[0115] The third harmonic component i generated in the first receiving coil 71A to the third receiving coil 71C a ~i c It is represented by the following mathematical expressions (1) to (3).

[0116] i a =sin(ωt) (1)

[0117]

[0118] 3rd harmonic component i a3 ~i c3 They are represented by the following mathematical expressions (4) to (6), respectively.

[0119] i a3 =i·sin(3ωt) (4)

[0120]

[0121] Simplifying mathematical expressions (5) and (6), we can obtain the following mathematical expressions (7) and (8).

[0122] i b3 =i·sin(3ωt-2π) (7)

[0123] i c3 =i·sin(3ωt-4π) (8)

[0124] From mathematical formulas (4), (7) and (8), it can be clearly seen that the third harmonic component i a3 ~i c3 They are in phase with each other and have the same magnitude (or amplitude).

[0125] like Figure 4 As shown, the third harmonic components flowing out from connection points U, V, and W are respectively taken as I. a Ib I c As shown in the following mathematical formula (9), the third harmonic component i flowing through the second receiving coil 71B b3 The third harmonic component I flows out from the connection point V. b The third harmonic component i flowing through the first receiving coil 71A a3 sum.

[0126] i b3 =i a3 +I b (9)

[0127] From mathematical formulas (4) and (7), we can see that, since i a3 =i b3 Therefore, the third harmonic component I flowing out from the connection point V b The third harmonic component I flowing out from connection points U and W is zero. a I c This is also true. Therefore, the third harmonic component i a3 i b3 i c3 It will not flow out of the triangular structure, but will circulate within the triangular structure.

[0128] The size of filter circuit 9 will be explained next.

[0129] If the preset transmission frequency for power transmission between the power transmitting device 2 and the power receiving device 6 is 6.78MHz, then the frequency of the third harmonic component is 20.34MHz, and the frequency of the fifth harmonic component is 33.9MHz. The inventors assume that the impedance of the filter circuit 9 (i.e., the low-pass filter) is 100Ω and the capacitance is 800pF.

[0130] Under the above conditions, the inventors obtained the inductance of the low-pass filter, which can achieve a gain of -20dB at the frequency of the third harmonic component, and estimated the volume of each coil when the obtained inductance is achieved by two coils.

[0131] The inventors calculated that the volume of each coil was 0.792 ml (=12mm×11mm×6mm).

[0132] At the frequency of the 5th harmonic component, the inventors calculated under similar conditions that the volume of each coil was 0.147 ml (=7mm×6mm×3.5mm).

[0133] Therefore, if the filter circuit 9 does not need to remove the third harmonic component, the space occupied by the coil 91 can be reduced to less than 1 / 5.

[0134] 2-1-3-2. Second technical effect

[0135] In power transmission device 2, the first power transmission module 30A to the third power transmission module 30C are driven individually. Therefore, if any one of the first power transmission module 30A to the third power transmission module 30C fails, power can continue to be supplied through the remaining two power transmission modules. Thus, the reliability of power transmission device 2 is improved. In this case, the control circuit 5 can control the remaining two power transmission modules to ensure that the power transmitted to the power receiving device 6 does not decrease.

[0136] 2-1-3-3. Third technical effect

[0137] In the power receiving device 6, the first power receiving coil 71A to the third power receiving coil 71C are connected in a delta configuration. Therefore, if any one of the first power receiving coil 71A to the third power receiving coil 71C fails (e.g., is disconnected), power can continue to be received through the remaining two power receiving coils. As a result, the reliability of the power receiving device 6 is improved.

[0138] 2-1-4. Word Matching

[0139] In this first embodiment, the power transmission circuit 4 corresponds to an example of the first power transmission circuit in the embodiment overview. The first power transmission coil 41A to the third power transmission coil 41C correspond to an example of two or more power transmission coils and three power transmission coils in the embodiment overview. The combination of the converter group 3 and the control circuit 5 corresponds to an example of the feed circuit in the embodiment overview. The preset transmission frequency corresponds to an example of the same frequency in the embodiment overview. The power receiving circuit 7 corresponds to an example of the first power receiving circuit in the embodiment overview. The first power receiving coil 71A to the third power receiving coil 71C correspond to an example of three power receiving coils in the embodiment overview. The combination of the rectifier circuit 8 and the filter circuit 9 corresponds to an example of the conversion circuit in the embodiment overview. The rectifier circuit 8 corresponds to an example of the first rectifier circuit in the embodiment overview.

[0140] 2-1-5. Variations of the first embodiment

[0141] Any one of the first power supply module 30A to the third power supply module 30C can be excluded from the power supply device 2.

[0142] In addition / or, such as Figure 5 As shown, instead of the three-phase AC power supply 100, the power supply device 2 can be configured to receive three-phase AC power from the three-phase AC power supply 110. The three-phase AC power supply 110 is a three-phase four-wire 200-volt power supply.

[0143] In this case, in addition to the wires corresponding to phases L1, L2 and L3, an additional wire (i.e., a neutral wire) is also needed to supply the reference potential to the power transmission device 2.

[0144] The first power converter 31A is connected to the three-phase AC power supply 110 to receive the voltage between phase L1 and the neutral line. The second power converter 31B is connected to the three-phase AC power supply 110 to receive the voltage between phase L2 and the neutral line. The third power converter 31C is connected to the three-phase AC power supply 110 to receive the voltage between phase L3 and the neutral line.

[0145] Alternatively, the first power supply coil 41A to the third power supply coil 41C can be connected in a star configuration.

[0146] 2-2. Second Implementation Method

[0147] This second embodiment provides, as follows: Figure 6 The wireless power transmission system 1a shown is the same as the wireless power transmission system 1 in the first embodiment, but with some modifications. Therefore, in the following description, only the parts that differ from the first embodiment will be highlighted, and the same reference numerals will be used for the parts that are the same as those in the first embodiment, and their descriptions will be omitted.

[0148] 2-2-1. Differences from the first embodiment

[0149] like Figure 6 As shown, instead of the power receiving device 6, the wireless power transmission system 1a includes a power receiving device 6a.

[0150] exist Figure 6 The configuration of the power transmission device 2 is shown in a simplified manner in the diagram. Specifically, the three-phase AC power supply 100, the first power transmission converter 31A to the third power transmission converter 31A-31C, and the control circuit 5 are shown as the first AC power supply AC1 to the third AC power supply AC3. Therefore, each of the first AC power supply AC1 to the third AC power supply AC3 is configured to output the single-phase AC power described in the first embodiment.

[0151] 2-2-2. Electrical Configuration of the Power Receiving Device

[0152] The power receiving device 6a differs from the power receiving device 6 in the first embodiment in that, instead of the power receiving circuit 7, the rectifier circuit 8, and the filter circuit 9, the power receiving device 6a has a first power receiving circuit 7A and a second power receiving circuit 7B, a first rectifier circuit 8A and a second rectifier circuit 8B, and a filter circuit 9a.

[0153] The first power receiving circuit 7A has the same configuration as the power receiving circuit 7 in the first embodiment.

[0154] The second power receiving circuit 7B includes a fourth power receiving coil 71D to a sixth power receiving coil 71F, and a fourth capacitor 72D to a sixth capacitor 72F.

[0155] The fourth receiving coil 71D to the sixth receiving coil 71F (i) have essentially the same characteristics; (ii) are connected in a star configuration. Therefore, each of the fourth receiving coil 71D to the sixth receiving coil 71F has a first terminal that is connected to each other.

[0156] The fourth capacitor 72D to the sixth capacitor 72F (i) have substantially the same characteristics; (ii) they are respectively connected to the second terminal of the corresponding fourth receiving coil 71D to the sixth receiving coil 71F. The fourth capacitor 72D to the sixth capacitor 72F supply the three-phase AC power output from the fourth receiving coil 71D to the sixth receiving coil 71F to the second rectifier circuit 8B. The fourth capacitor 72D to the sixth capacitor 72F, together with the fourth receiving coil 71D to the sixth receiving coil 71F, form three additional series resonant circuits. These additional series resonant circuits are configured to resonate at the aforementioned preset transmission frequency.

[0157] The first rectifier circuit 8A has the same configuration as the rectifier circuit 8 in the first embodiment.

[0158] The second rectifier circuit 8B has the same configuration as the first rectifier circuit 8A, but is configured to convert the three-phase AC power output from the second power receiving circuit 7B into a second DC power.

[0159] The second DC power is combined with the first DC power output from the first rectifier circuit 8A and supplied to the filter circuit 9A.

[0160] Similar to filter circuit 9, filter circuit 9a is a low-pass filter composed of coil 91a and capacitor 92a. However, filter circuit 9a differs from filter circuit 9 in that it is configured to remove harmonic components of the 11th harmonic or higher contained in the synthesized first and second DC currents.

[0161] 2-2-3. Technical Effects of the Second Embodiment

[0162] In addition to the first to third technical effects, the second embodiment described above can also achieve the following fourth technical effect.

[0163] 2-2-3-1. Fourth technical effect

[0164] like Figure 8 As shown, in the wireless power transmission system 1a, the phase of the output current from the fourth receiving coil 71D to the sixth receiving coil 71F connected in a star configuration is offset by 30° relative to the phase of the output current from the first receiving coil 71A to the third receiving coil 71C connected in a delta configuration. Figure 8The output current waveforms from the fourth receiving coil 71D and the first receiving coil 71A are shown. Additionally, the output current waveforms from the fifth receiving coil 71E and the second receiving coil 71B, as well as the output current waveforms from the sixth receiving coil 71F and the third receiving coil 71C, are shown, except that they are phase-shifted by 120° or 240° respectively. Figure 8 The waveforms shown are identical. The 5th harmonic component generated by the 4th receiving coil 71D is typically out of phase with respect to the 5th harmonic component generated by the 1st receiving coil 71A. The 5th harmonic component generated by the 5th receiving coil 71E is typically out of phase with respect to the 5th harmonic component generated by the 2nd receiving coil 71B. The 5th harmonic component generated by the 6th receiving coil 71F is typically out of phase with respect to the 5th harmonic component generated by the 3rd receiving coil 71C. Therefore, when the outputs of the 1st receiving circuit 7A and the 2nd receiving circuit 7B are full-wave rectified and combined, the 5th harmonic component is suppressed. The 7th harmonic component is also suppressed in the same way.

[0165] Generally, in existing technologies, as a harmonic reduction measure in semiconductor applications, a combination of three-phase transformers is used to increase the number of output phases. In the first embodiment, because a set of three-phase AC currents is fully rectified, the number of output phases is six. In the second embodiment, because two sets of three-phase AC currents with phase offsets are fully rectified, the number of output phases is twelve.

[0166] The order n of the generated harmonic components is known to be represented by the following mathematical formula (10).

[0167] n=mp±1 (10)

[0168] Where m is a natural number greater than or equal to 1, and p is the number of output phases.

[0169] Therefore, the filter circuit 9a of the twelve-phase power receiving device 6a does not need to remove harmonic components below the 7th harmonic; it only needs to remove harmonic components above the 11th harmonic, which have higher frequencies and lower power. Therefore, the size of the filter circuit 9a can be smaller than that of the filter circuit 9.

[0170] 2-2-4. Word Matching

[0171] In this second embodiment, the second power receiving circuit 7B corresponds to an example of the second power receiving circuit in the embodiment overview. The fourth power receiving coil 71D to the sixth power receiving coil 71F correspond to an example of the three additional power receiving coils in the embodiment overview. The second rectifier circuit 8B corresponds to an example of the second rectifier circuit in the embodiment overview.

[0172] 2-2-5. Variations of the second embodiment

[0173] The fourth receiving coil 71D to the sixth receiving coil 71F can be connected in a delta configuration. In this case, instead of the filter circuit 9a, the receiving device 6a can include the filter circuit 9 in the first embodiment to remove harmonic components of the fifth harmonic and above.

[0174] Alternatively, the first power supply coil 41A to the third power supply coil 41C can be connected in a star configuration.

[0175] 2-3. Third Implementation Method

[0176] This third embodiment provides Figure 7 The wireless power transmission system 1b shown is different from the wireless power transmission system 1A in the second embodiment, but with some modifications. Therefore, in the following description, only the parts that differ from the second embodiment will be highlighted, while the parts that are the same as those in the second embodiment will be labeled with the same reference numerals and their descriptions will be omitted.

[0177] 2-3-1. Differences from the second embodiment

[0178] like Figure 7 As shown, instead of the power supply device 2 and the power receiving device 6a, the wireless power transmission system 1b includes a power supply device 2b and a power receiving device 6b.

[0179] 2-3-2. Electrical Configuration of Power Transmission Equipment

[0180] The power transmission device 2b includes a first power transmission circuit 4A and a second power transmission circuit 4B. The first power transmission circuit 4A and the second power transmission circuit 4B are connected in parallel. The first power transmission circuit 4A and the second power transmission circuit 4B are configured such that (i) they each receive single-phase AC power from a first AC power source AC1 to a third AC power source AC3; and (ii) they operate in the same phase. Specifically, the first power transmission circuit 4A and the second power transmission circuit 4B each have the same configuration as the power transmission circuit 4 in the second embodiment.

[0181] 2-3-3. Electrical Configuration of the Power Receiving Device

[0182] The difference between the power receiving device 6b and the power receiving device 6a is that (i) in addition to having the first power receiving circuit 7A, the second power receiving circuit 7B, the first rectifier circuit 8A, and the second rectifier circuit 8B, it also has the third power receiving circuit 7C, the fourth power receiving circuit 7D, the third rectifier circuit 8C, and the fourth rectifier circuit 8D; (ii) instead of the filter circuit 9a, it has the filter circuit 9b.

[0183] The third power receiving circuit 7C has the same configuration as the first power receiving circuit 7A. The fourth power receiving circuit 7D has the same configuration as the second power receiving circuit 7B.

[0184] The third rectifier circuit 8C has the same configuration as the first rectifier circuit 8A, but is configured to convert the three-phase AC power output from the third power receiving circuit 7C into a third DC power.

[0185] The fourth rectifier circuit 8D has the same configuration as the first rectifier circuit 8A, but is configured to convert the three-phase AC power output from the fourth power receiving circuit 7D into a fourth DC power.

[0186] The first through fourth DC currents are combined in parallel and supplied to the filter circuit 9b.

[0187] Similar to filter circuit 9a, filter circuit 9b is also a low-pass filter composed of coil 91b and capacitor 92b. However, the difference between filter circuit 9b and filter circuit 9a is that filter circuit 9b is configured to remove harmonic components above the 11th harmonic contained in the synthesized DC current from the 1st to the 4th harmonic.

[0188] 2-3-4. Technical Effects of the Third Embodiment

[0189] In addition to the first to fourth technical effects, the third embodiment described above can also achieve the following fifth technical effect.

[0190] 2-3-4-1. Fifth technical effect

[0191] Since the wireless power transmission system 1b includes a first power transmission circuit 4A, a second power transmission circuit 4B, and a first power receiving circuit 7A to a fourth power receiving circuit 7D, it can achieve a stronger power transmission capability than the wireless power transmission system 1a in the second embodiment.

[0192] Alternatively, if the power transmission capability of wireless power transmission system 1b is set to be equal to that of wireless power transmission system 1a, the maximum ratings (e.g., rated temperature, rated current, etc.) required for the circuit elements of the first power transmission circuit 4A, the second power transmission circuit 4B, and the first to fourth power receiving circuits 7A to 7D in wireless power transmission system 1b can be reduced. Therefore, cheaper circuit elements can be used for the first power transmission circuit 4A, the second power transmission circuit 4B, and the first to fourth power receiving circuits 7A to 7D.

[0193] 2-3-5. Word Matching

[0194] In this third embodiment, the second power supply circuit 4B corresponds to an example of the second power supply circuit in the embodiment overview. The first power supply coil 41A to the third power supply coil 41C in the second power supply circuit 4B correspond to an example of two or more additional power supply coils and three additional power supply coils in the embodiment overview. The second power receiving circuit 7B, the third power receiving circuit 7C, or the fourth power receiving circuit 7D correspond to an example of the second power receiving circuit in the embodiment overview.

[0195] 2-3-6. Variations of the third embodiment

[0196] The first power supply circuit 4A and the second power supply circuit 4B can be configured to operate with a specific phase offset (e.g., 15°) from each other.

[0197] Alternatively, the wireless power transmission system 1b can be configured such that (i) the first power supply circuit 4A transmits three-phase AC power to the first power receiving circuit 7A and the second power receiving circuit 7B; and (ii) the second power supply circuit 4B transmits three-phase AC power to the third power receiving circuit 7C and the fourth power receiving circuit 7D. In this case, the number of output phases of the power receiving device 6b is twenty-four phases. Therefore, it can be seen from mathematical formula (10) that the filter circuit 9b is sufficient to remove harmonic components above the 23rd harmonic.

[0198] Alternatively, the first power supply coil 41A to the third power supply coil 41C in the first power supply circuit 4A and / or the first power supply coil 41A to the third power supply coil 41C in the second power supply circuit 4B can be connected in a star configuration.

[0199] Alternatively, the three receiving coils in the third receiving circuit 7C can be connected in a star configuration.

[0200] Alternatively, the three receiving coils in the second receiving circuit 7B and / or the three receiving coils in the fourth receiving circuit 7D can be connected in a delta configuration.

[0201] 2-4. Further Implementation Methods

[0202] The embodiments of this disclosure have been described above. However, this disclosure is not limited to the first to third embodiments and can be implemented by modification.

[0203] In a further embodiment, one or more additional power supply circuits and / or one or more additional power receiving circuits may be provided in any one of the wireless power transmission systems 1, 1a, and 1b.

[0204] 2-5. Supplementary Explanation

[0205] Multiple functions of one constituent element in the above embodiments can be implemented by multiple constituent elements, or one function of one constituent element can be implemented by multiple constituent elements. Furthermore, multiple functions of multiple constituent elements can be implemented by one constituent element, or one function implemented by multiple constituent elements can be implemented by one constituent element. Additionally, a portion of the configuration of the above embodiments can be omitted. At least a portion of the configuration of the above embodiments can be added to the configurations of the other embodiments described above, or at least a portion of the configuration of the above embodiments can be replaced by the configurations of the other embodiments described above.

Claims

1. A wireless power transmission system comprising a power transmitting device and a power receiving device, characterized in that, The power transmission device includes: The first power supply circuit has two or more power supply coils, which are separated from each other. as well as The power supply circuit is configured to supply one unidirectional alternating current from two or more single-phase alternating currents to the two or more power-generating coils, wherein the two or more single-phase alternating currents have the same frequency but different phases. The power receiving device includes: The first power receiving circuit has three power receiving coils connected in a delta structure. The three power receiving coils are configured to (i) be magnetically coupled to the two or more power supply coils, and (ii) output a first multiphase alternating current in response to the two or more single-phase alternating currents being supplied to the two or more power supply coils respectively. as well as A conversion circuit configured to convert the first multiphase alternating current into a first direct current.

2. The wireless power transmission system according to claim 1, characterized in that, The conversion circuit includes: A first rectifier circuit, configured to rectify the first multiphase alternating current into the first direct current; and A filter circuit configured to remove unwanted harmonic components from the first direct current obtained through the first rectifier circuit.

3. The wireless power transmission system according to claim 1 or 2, characterized in that, The two or more power supply coils include three power supply coils. The two or more single-phase alternating currents include three single-phase alternating currents that are 120° out of phase with each other. The power supply circuit is configured to supply one unidirectional alternating current from the three single-phase alternating currents to the three power transmission coils, respectively. The three power-transmitting coils are configured to receive the three single-phase alternating currents and simulate a triangular structure.

4. The wireless power transmission system according to any one of claims 1 to 3, characterized in that, The first power transmission circuit includes two or more capacitors, which, together with the two or more power transmission coils, form two or more series resonant circuits. The first power receiving circuit includes three additional capacitors, which, together with the three power receiving coils, form three additional series resonant circuits. Each of the two or more series resonant circuits and each of the three additional series resonant circuits is configured to resonate at the same frequency.

5. The wireless power transmission system according to any one of claims 1 to 4, characterized in that, It also has a second power receiving circuit, which is different from the first power receiving circuit. The second power receiving circuit (i) includes three additional power receiving coils connected in a delta or star configuration; and (ii) is configured to output a second multiphase alternating current. The conversion circuit includes a second rectifier circuit, which is configured to (i) rectify the second multiphase AC power into a second DC power, and (ii) combine the second DC power with the first DC power in parallel.

6. The wireless power transmission system according to any one of claims 1 to 5, characterized in that, The power receiving device is (i) field electrical equipment or (ii) a battery pack for the field electrical equipment.

7. The wireless power transmission system according to claim 6, characterized in that, The conversion circuit is configured to supply at least the first DC power to the battery pack used for the field electrical equipment.

8. The wireless power transmission system according to any one of claims 1 to 7, characterized in that, The power transmission device also includes a second power transmission circuit, which is different from the first power transmission circuit. The second power supply circuit has two or more additional power supply coils.

9. The wireless power transmission system according to claim 8, characterized in that, The two or more additional power supply coils include three additional power supply coils.

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