Power transmission device, wireless power supply system, and method for manufacturing power transmission device

Abstract

A power transmission device (10) that wirelessly supplies power to a power reception device (20) comprises: a power supply unit (2) that supplies a high-frequency power; a first power transmission electrode (11) and a second power transmission electrode (12) that are elongate, form a separated pair, and receive the high-frequency power from the power supply unit; a first voltage detection unit (51) that detects a first voltage between the first power transmission electrode and the second power transmission electrode on the side where the high-frequency power from the power supply unit is received; a second voltage detection unit (52) that detects a second voltage between the first power transmission electrode and the second power transmission electrode; a first capacitor circuit (31) that is connected to the power supply unit side at one end and is connected to the first power transmission electrode at the other end; a second capacitor circuit (32) that is connected to the power supply unit side at one end and is connected to the second power transmission electrode at the other end; and a control unit (4) that controls the capacitance value of at least one of the first capacitor circuit and the second capacitor circuit such that the difference between the first voltage and the second voltage is a value within a prescribed range.

Description

Power transmission device, wireless power supply system, and method for manufacturing power transmission device

[0001] The present disclosure relates to a power transmission device, a wireless power supply system, and a method for manufacturing a power transmission device.

[0002] Wireless power transfer, which wirelessly supplies high-frequency power generated by a high-frequency power supply device to a power receiving device through electric field coupling using the electrostatic capacitance between the power transmitting electrode and the power receiving electrode, has been attracting attention. In this method, by making the power transmitting electrode long, it is possible to continuously supply power to a power receiving device moving on the long electrode. It is expected to be practical because it can use relatively inexpensive electrode materials.

[0003] However, as the power transmitting electrode becomes longer and the distance from the power supply device to the power receiving electrode becomes longer, the capacitance cannot be kept constant, resulting in a problem of reduced efficiency. To address this issue, for example, Patent Document 1 proposes sandwiching a power transmitting electrode member between a power receiving electrode member provided on a mobile object to reduce changes in capacitance between the power receiving electrode member and the power transmitting electrode member. Furthermore, a coil is provided between the high-frequency generator and the power transmitting electrode member, and the electrode reference point is adjusted to reduce the decrease in power transmission efficiency due to changes in the distance between the power transmitting electrode member and the power receiving electrode member.

[0004] JP 2018-68079 A

[0005] However, when the power receiving device is moved, the inductance of the power transmitting electrode fluctuates. Therefore, the conventional technology has a problem in that the influence of the inductance fluctuation cannot be ignored, particularly when a long power transmitting electrode is used.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a power transmission device, a wireless power supply system, and a method for manufacturing a power transmission device that can transmit power to a power receiving device with high transmission efficiency by reducing the effect of inductance fluctuations present in the power transmission electrode.

[0007] The power transmission device according to the present disclosure is a power transmission device that wirelessly supplies power to a power receiving device, and includes a power supply unit that supplies high-frequency power, a pair of spaced-apart, elongated first and second power transmission electrodes that receive high-frequency power from the power supply unit, a first voltage detection unit that detects a first voltage between the first and second power transmission electrodes that receive high-frequency power from the power supply unit, a second voltage detection unit that detects a second voltage between the first and second power transmission electrodes, a first capacitor circuit having one end connected to the power supply unit side and the other end connected to the first power transmission electrode, a second capacitor circuit having one end connected to the power supply unit side and the other end connected to the second power transmission electrode, and a control unit that controls the capacitance value of at least one of the first capacitor circuit and the second capacitor circuit to a value that brings the difference between the first voltage and the second voltage within a set range.

[0008] Another power transmission device according to the present disclosure is a power transmission device that wirelessly supplies power to a power receiving device, and includes a power supply unit that supplies high-frequency power, and a pair of elongated first and second power transmission electrodes that are spaced apart and receive the high-frequency power from the power supply unit, the first and second power transmission electrodes being divided into a plurality of split power transmission electrodes that are connected in series in the longitudinal direction via third and fourth capacitor circuits, respectively, and each of the N1 (N1 is a natural number) split power transmission electrodes that form the first power transmission electrode has a combined inductance value L C1X (x is a natural number from 1 to N1), and the frequency of the high frequency power is f, the capacitance value C d1X is expressed by the following equation (1):

[0009] and the combined inductance values ​​present in the N2 (N2 is a natural number) divided power transmission electrodes forming the second power transmission electrode are expressed as L C2X (x is a natural number from 1 to N2), and the frequency of the high frequency power is f, the capacitance value C d2X is expressed by the following equation (2):

[0010] The control unit controls each of the third capacitor circuits and each of the fourth capacitor circuits so as to satisfy the following condition.

[0011] In addition, a wireless power supply system according to the present disclosure includes a power transmission device according to the present disclosure and a power receiving device having a first power receiving electrode and a second power receiving electrode that move on a first power transmitting electrode and a second power transmitting electrode, respectively, of the power transmission device, and wirelessly supplies high-frequency power from the power transmission device to the power receiving device by electric field coupling using electrostatic capacitance between the first power transmitting electrode and the first power receiving electrode, and between the second power transmitting electrode and the second power receiving electrode.

[0012] Further, a method for manufacturing a power transmission device according to the present disclosure is a method for manufacturing a power transmission device that wirelessly supplies power to a power receiving device, the method including the steps of: forming a pair of spaced apart first and second power transmission electrodes that receive high frequency power from a power supply unit that supplies high frequency power; and dividing each of the first and second power transmission electrodes in a longitudinal direction to form a plurality of split power transmission electrodes; and forming N (N is a natural number) split power transmission electrodes that are electrically connected in series in the longitudinal direction via capacitor circuits, each of which has a combined inductance value present in each split power transmission electrode, by L. CX (x is a natural number from 1 to N), and the frequency of the high frequency power is f, the capacitance value C dX is expressed by the following equation (3):

[0013] a step of electrically connecting the split power transmission electrodes adjacent in the longitudinal direction in series via the capacitor circuit; and a step of connecting the start points of the first power transmission electrode and the second power transmission electrode formed by the split power transmission electrodes connected via the capacitor circuit to a power supply unit.

[0014] According to the present disclosure, it is possible to transmit power to a power receiving device with high transmission efficiency by reducing the influence of fluctuations in inductance present in the power transmitting electrode.

[0015] FIG. 1 is a schematic configuration diagram showing a power transmitting device according to embodiment 1. FIG. 2 is a schematic configuration diagram showing a wireless power feeding system according to embodiment 1. FIG. 3 is a circuit diagram showing an example of a capacitor circuit according to embodiment 1. FIG. 4 is a schematic configuration diagram showing a power transmitting device according to embodiment 1. FIG. 5 is a schematic configuration diagram showing a power transmitting device according to embodiment 1. FIG. 6 is a schematic configuration diagram showing a power transmitting device according to embodiment 1. FIG. 7 is a schematic configuration diagram showing an example of a processing circuit that realizes each function of a control unit according to embodiment 1. FIG. 8 is a schematic configuration diagram showing a power transmitting device according to embodiment 2. FIG. 9 is a circuit diagram showing an example of a capacitor circuit according to embodiment 2. FIG. 10 is a schematic configuration diagram showing a power transmitting device according to embodiment 2. FIG. 11 is a schematic configuration diagram showing a power transmitting device according to embodiment 2. FIG. 12 is a schematic flow diagram showing steps in a manufacturing method for a power transmitting device according to embodiment 3. FIG. 13 is a schematic side view showing an example of a capacitor circuit according to embodiment 3.

[0016] Embodiment 1 A power transmission device 10 according to embodiment 1 will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram showing the power transmission device 10 according to embodiment 1, and Fig. 2 is a schematic configuration diagram showing a wireless power feeding system 100 according to embodiment 1.

[0017] The power transmitting device 10 wirelessly supplies power to the power receiving device 20 shown in Fig. 2. The power receiving device 20 has a first power receiving electrode 21 and a second power receiving electrode 22 that move on the first power transmitting electrode 11 and the second power transmitting electrode 12 of the power transmitting device 10, respectively. High-frequency power can be wirelessly supplied from the power transmitting device 10 to the power receiving device 20 by electric field coupling using electrostatic capacitance between the first power transmitting electrode 11 and the first power receiving electrode 21, and between the second power transmitting electrode 12 and the second power receiving electrode 22.

[0018] The power transmission device 10 includes a power supply unit 2 that supplies high-frequency power to the power transmission electrode 1, and a pair of elongated, spaced-apart first and second power transmission electrodes 11 and 12 that receive high-frequency power from the power supply unit 2. The first and second power transmission electrodes 11 and 12 that receive high-frequency power from the power supply unit 2 are each provided with a first voltage detection unit that detects a first voltage between the first and second power transmission electrodes 11 and 12, and the first and second power transmission electrodes 11 and 12 at the end of the power transmission electrode 1 are each provided with a second voltage detection unit that detects a second voltage between the first and second power transmission electrodes 11 and 12. Furthermore, a first capacitor circuit 31 is electrically connected in series between the power supply unit 2 and the first power transmission electrode 11 via wiring 13, and a second capacitor circuit 32 is electrically connected in series between the power supply unit 2 and the second power transmission electrode 12 via wiring 13. The control unit 4 acquires the first voltage detected by the first voltage detection unit 51 and the second voltage detected by the second voltage detection unit 52, and adjusts the capacitance values ​​of the first capacitor circuit 31 and the second capacitor circuit 32 so that the difference between the first voltage and the second voltage is small.

[0019] Here, the first voltage detection unit 51 acquires a first voltage via a detection path 511 from wiring 13 connected to the first power transmission electrode 11 and the second power transmission electrode 12 that receive high-frequency power. The second voltage detection unit 52 acquires a second voltage via a detection path 521 from wiring 13 connected to the first power transmission electrode 11 and the second power transmission electrode 12 at the end of the power transmission electrode 1. The control unit 4 acquires the first voltage and the second voltage via a communication line 41 and controls the capacitor circuits 31 and 32 using control paths 311 and 321. These pieces of data may be acquired via a wired connection or wirelessly.

[0020] The capacitance values ​​are adjusted, for example, as follows. When power supply starts, the capacitance values ​​of the first capacitor circuit 31 and the second capacitor circuit 32 are temporarily set to their smallest values. Then, a first voltage, which is the output voltage from the power supply unit 2, and a second voltage, which is, for example, the voltage between the first power transmission electrode 11 and the second power transmission electrode 12 at the end of the power transmission electrode 1 that is located farthest from the power supply unit 2, are acquired. The capacitance values ​​of the first capacitor circuit 31 and the second capacitor circuit 32 are increased until the voltage difference between the first voltage and the second voltage falls within a predetermined set range. After the voltage difference falls within the set range, the capacitance values ​​are changed if the voltage difference exceeds the set range. For example, if the voltage difference becomes smaller when the capacitance value is increased, the capacitance value is increased further. If the voltage difference becomes larger, the capacitance value is adjusted to a smaller value. Conversely, if the voltage difference becomes smaller when the capacitance value is decreased, the capacitance value may be decreased further.

[0021] 3, the capacitor circuit 31 can be composed of a capacitor 311 and a switch 312. For example, in the figure, capacitors 311 represented by C1 to Cn (n is a natural number of 2 or more) and switches 312 represented by S1 to Sn (n is a natural number of 2 or more) are connected in series, and a circuit is formed in which a plurality of these capacitors 311 and switches are connected in parallel. Using such a capacitor circuit 31, the capacitance value of the capacitor circuit 31 can be changed by controlling the ON / OFF of the switches S1 to Sn with the control unit 4. The capacitor circuit 32 does not necessarily have to be the same as the capacitor circuit 31, but a similar circuit can be used.

[0022] The first voltage is the output voltage from the power supply unit 2 and is not affected by the path inductance. Furthermore, because the termination of the power transmitting electrode 1 is open, the current output from the power supply unit 2 effectively flows in a loop from the power supply unit 2 to the power receiving device 20. In other words, because no current flows through the power transmitting electrode 1 that is farther away from the power receiving device 20, the second voltage is equal to the voltage applied between the power receiving electrodes of the power receiving device 20. Therefore, by switching the capacitor to a capacitor with a smaller capacity or a larger capacity in response to fluctuations in the voltage difference between the first voltage and the second voltage, the difference between the first voltage and the second voltage can be kept within a set range, and as a result, the effect of the path inductance can be compensated for.

[0023] Furthermore, in a long power transmission electrode 1, the first voltage may be the voltage between the first power transmission electrode 11 and the second power transmission electrode 12 located close to the power supply unit 2, and the second voltage may be the voltage between the first power transmission electrode 11 and the second power transmission electrode 12 located far from the power supply unit 2. Therefore, for example, as shown in Fig. 4, the power transmission electrode 1 may be divided into divided power transmission electrodes 6, and the power supply unit 2 and a capacitor circuit 31 may be connected in series via the divided power transmission electrodes 6, and further connected to the divided power transmission electrodes 6 continuing in the longitudinal direction. The capacitor circuit 32 may be configured in a similar manner.

[0024] The first voltage is the output voltage of the power supply unit 2, but may be disposed between the capacitor circuits 31 and 32 close to the power supply unit 2 and each divided power transmitting electrode 6, as shown in Fig. 5. In other words, the first voltage is detected on the side that receives high-frequency power from the power supply unit 2. Similarly, the second voltage is not limited to being detected at the end of the power transmitting electrode 1, but is detected at a position farther from the power supply unit 2 than the first voltage detection unit 51.

[0025] The detection paths 511, 521 of the first voltage detection unit 51 and the second voltage detection unit 52 may be directly connected to the power transmission electrode 1. Alternatively, as shown in FIG. 6 , voltages may be detected using voltage detection electrodes 53 provided on the first power transmission electrode 11 and the second power transmission electrode 12, respectively. By providing the voltage detection electrodes 53, it is possible to detect the voltage at a desired position on the long power transmission electrode 1 and the divided power transmission electrode 6. For example, the voltage at the center of the power transmission electrode 1 can be detected. Furthermore, by using the voltage detection electrodes 53 to detect the first voltage and the second voltage through inter-electrode capacitive coupling, highly accurate detection values ​​can be obtained. Because a high voltage is applied to the power transmission electrode 1, the effects of common-mode noise can be a problem. While it is possible to prevent common-mode noise by connecting a voltage divider circuit using resistors and capacitors, errors due to differences in the characteristics of the resistors and capacitors can be a problem. By using the voltage detection electrodes 53 to detect the first voltage and the second voltage through inter-electrode capacitive coupling, errors due to the above-mentioned components, such as resistors and capacitors, can be eliminated and the effects of common-mode noise can be suppressed.

[0026] The setting range of the voltage difference between the first voltage and the second voltage is preferably set so that the voltages are equal, that is, the voltage difference is zero. However, since the value changes depending on the length of the power transmitting electrode 1 and the position of the moving power receiving device 20, a certain tolerance is set to determine the setting range. The tolerance or setting range may be stored in the memory unit 402 of the control unit 4 and used, or may be input from the input / output interface 403. When the value is to be changed depending on the conditions, a data table may be prepared in the memory unit 402 so that the control unit 4 can automatically select from the data table.

[0027] Here, the power supply unit 2 is a power supply that outputs a high-frequency voltage or a high-frequency current and supplies high-frequency power to the power transmitting electrode 1. The power supply unit 2 may be a high-frequency power supply device or an AC power supply. It may also be one that supplies high-frequency power from a DC power supply via a power converter. The DC power supply includes a switching circuit, such as a DC-DC converter, that converts the voltage of DC power input from an external source and outputs the converted DC power. The voltage output from the DC power supply is determined by the ON / OFF operation of the switch elements of the switching circuit. The power converter includes, for example, a bridge-configured inverter or a class E inverter that converts the DC power output from the DC power supply into AC power and outputs the converted AC power. A resonant circuit using an inductor and a capacitor may be added to the output section. The output waveform may be a sine wave or a rectangular wave, and may include multiple frequency components.

[0028] Each function of the control unit 4 is realized by a processing circuit. FIG. 7 is a configuration diagram showing an example of a processing circuit that realizes each function of the control unit 4. As shown in FIG. 7, the control unit 4 includes an arithmetic processing unit 401 such as a central processing unit (CPU), a storage unit 402 that exchanges data with the arithmetic processing unit 401, an input / output interface 403 that inputs and outputs signals between the arithmetic processing unit 401 and the outside, and the like. The arithmetic processing unit 401 may include an application specific integrated circuit (ASIC), an integrated circuit (IC), a digital signal processor (DSP), a field programmable gate array (FPGA), various signal processing circuits, and the like. Furthermore, multiple arithmetic processing units 401 of the same type or different types may be provided, and each process may be shared and executed. The storage unit 402 may include a random access memory (RAM) configured to be able to read and write data from the arithmetic processing unit 401, a read-only memory (ROM) configured to be able to read data from the arithmetic processing unit 401, and the like. The input / output interface 403 is composed of, for example, an A / D converter that inputs sensor signals output from an object detection sensor, a current sensor, etc. to the arithmetic processing unit 401, and an A / D converter that outputs control signals to the capacitor circuits 31 and 32.

[0029] In this way, the power transmission device 10 that wirelessly supplies power to the power receiving device 20 includes a power supply unit 2 that supplies high-frequency power, a pair of elongated first and second power transmission electrodes 11 and 12 that are spaced apart and receive high-frequency power from the power supply unit 2, a first voltage detection unit 51 that detects a first voltage between the first and second power transmission electrodes 11 and 12 that receive high-frequency power from the power supply unit 2, a second voltage detection unit 52 that detects a second voltage between the first and second power transmission electrodes 11 and 12, a first capacitor circuit 31 having one end connected to the power supply unit 2 and the other end connected to the first power transmission electrode 11, a second capacitor circuit 32 having one end connected to the power supply unit 2 and the other end connected to the second power transmission electrode 12, and a control unit that controls the capacitance value of at least one of the first capacitor circuit 31 and the second capacitor circuit 32 to a value that brings the difference between the first voltage and the second voltage into a set range, thereby making it possible to control the capacitance values ​​of the capacitor circuits 31 and 32 in a circuit formed at the position of the power receiving device 20. Therefore, even if the position of the power receiving device 20 changes, the influence of fluctuations in inductance in the section from the power supply unit 2 to the power receiving electrode can be reduced, and power can be transmitted to the power receiving device with high transmission efficiency.

[0030] At least one of the first power transmission electrode 11 and the second power transmission electrode 12 is formed from a divided power transmission electrode 6, and at least one of the first capacitor circuit 31 and the second capacitor circuit 32 is arranged between the divided power transmission electrodes 6, so that the capacitor circuits 31, 32 can be arranged at the desired position.

[0031] By configuring at least one of the first capacitor circuit 31 and the second capacitor circuit 32 as a circuit in which multiple series-connected capacitors 311 and switches 312 are connected in parallel, the desired capacitance value can be easily achieved by controlling the ON / OFF of the switch 312.

[0032] Embodiment 2. A power transmission device 10 according to embodiment 2 will be described with reference to the drawings. Fig. 8 is a schematic configuration diagram showing the power transmission device 10 according to embodiment 2. The power transmission device 10 of embodiment 2 differs from embodiment 1 in that the first power transmission electrode 11 and the second power transmission electrode 12 are formed from a plurality of divided power transmission electrodes 6, and each divided power transmission electrode 6 is connected in series in the longitudinal direction to a third capacitor circuit 33 and a fourth capacitor circuit 34, respectively. Otherwise, the power transmission device 10 is similar to embodiment 1.

[0033] 8 , the first power transmission electrode 11 and the second power transmission electrode 12 of the power transmission device 10 are configured such that a third capacitor circuit 33 and a fourth capacitor circuit 34 are provided between, for example, a plurality of divided power transmission electrodes 6 of the same length and the same thickness, and the third capacitor circuit 33 and the fourth capacitor circuit 34 are connected in series. The power transmission device 10 configured in this manner controls the capacitance values ​​of the first capacitor circuit 31 and the second capacitor circuit 32 regardless of where the power receiving device 20 is located, thereby reducing the effect of inductance fluctuations and enabling power to be transmitted to the power receiving device with high transmission efficiency.

[0034] 9, the capacitor circuit 33 can be configured with a capacitor 331 and a switch 332, similar to the capacitor circuit 31. For example, in the figure, capacitors 331 represented by C1 to Cn (n is a natural number of 2 or more) and switches 332 represented by S1 to Sn (n is a natural number of 2 or more) are connected in series, and a circuit is formed in which a plurality of these capacitors 331 and switches 332 are connected in parallel. Using such a capacitor circuit 33, the capacitance value of the capacitor circuit 33 can be changed by controlling the ON / OFF of the switches S1 to Sn with the control unit 4. The capacitor circuit 34 does not necessarily have to be the same as the capacitor circuit 33, but a similar circuit may be used.

[0035] 10 , a second voltage detection unit 52 that detects the second voltage between the first power transmission electrode 11 and the second power transmission electrode 12 that are distant from the power supply unit 2 may be provided between the divided power transmission electrodes 6, and the capacitance value of at least one of the first capacitor circuit 31, the second capacitor circuit 32, the third capacitor circuit 33, and the fourth capacitor circuit 34 may be adjusted so that the difference between the first voltage and the second voltage is zero or within a set range. Here, by sequentially assigning the second voltage detection unit 52 the role of detecting the first voltage between the first power transmission electrode 11 and the second power transmission electrode 12 that receive high-frequency power from the power supply unit 2, it is possible to detect the first voltage and the second voltage between adjacent divided power transmission electrodes 6.

[0036] The control unit 4 can sequentially set the voltages obtained from the second voltage detection unit 52 as the first voltage and the second voltage, and control the capacitance value of at least one of the third capacitor circuit 33 and the fourth capacitor circuit 34 to a value that causes the difference between the first voltage and the second voltage between adjacent divided power transmission electrodes 6 to be within a set range. The second voltage detection unit 52 may be provided between adjacent divided power transmission electrodes 6, or may be provided across multiple divided power transmission electrodes 6. The power transmission device 10 configured in this manner can finely adjust the voltage from the side that receives high-frequency power from the power supply unit 2 to the end of the power transmission electrode 1.

[0037] 11 , the capacitance values ​​of the third capacitor circuit 33 and the fourth capacitor circuit 34 can also be adjusted by the control unit 4. To improve power supply efficiency, it is desirable for high-frequency power to be transmitted through the divided power transmitting electrodes 6 by series resonance, but the inductance present in each divided power transmitting electrode 6 cannot be expressed by self-inductance alone, but is a combination of the self-inductance and the mutual inductance of the paired divided power transmitting electrodes 6.

[0038] Therefore, in the power transmission device 10 of this embodiment, the control unit 4 controls the capacitance values ​​Cd of the capacitor circuits 33 and 34 that couple the divided power transmission electrodes 6 so that the combined inductance Lc present in each divided power transmission electrode 6 becomes a value that satisfies the series resonance. For example,C1X (x is a natural number from 1 to N1), and the frequency of the high frequency power is f, the capacitance value C d1X is expressed by the following equation (1):

[0039] The combined inductance values ​​of the N2 (N2 is a natural number) divided power transmission electrodes 6 that form the second power transmission electrode 12 are expressed as L C2X (x is a natural number from 1 to N2), and the frequency of the high frequency power is f, the capacitance value C d2X is expressed by the following equation (2):

[0040] Therefore, the capacitor circuits 33 and 34 are controlled so as to satisfy these.

[0041] For example, the combined inductance L of each divided power transmission electrode 6 C1 , L C2 Since the capacitance C varies depending on the length, thickness, and width of the divided power transmission electrode 6, the distance between the divided power transmission electrode 6 and the paired divided power transmission electrode 6, the capacitance C that satisfies the above formulas (1) and (2) is d1X , C d2X By controlling the frequency to the value shown in FIG.

[0042] 12 , a third capacitor circuit 33 and a fourth capacitor circuit 34 may be provided between divided power transmission electrodes 6 of different lengths. If the divided power transmission electrodes 6 constituting the first power transmission electrode 11 and the second power transmission electrode 12 have different lengths, the combined inductance Lc of the divided power transmission electrodes 6 will be different. However, by controlling at least one of the capacitor circuit 33 and the capacitor circuit 34 with the control unit 4 so as to satisfy the above-described formula (1) or formula (2), it is possible to achieve series resonance.

[0043] The split power transmission electrodes 6 may have different lengths in the first power transmission electrode 11 or the second power transmission electrode 12. Although the example in which the split power transmission electrodes 6 have different lengths has been described, if the split power transmission electrodes 6 have different thicknesses, widths, or distances between the pair of split power transmission electrodes 6 (the distance between the first power transmission electrode 11 and the second power transmission electrode 12), the combined inductance Lc present in the split power transmission electrodes 6 will also be different. However, by controlling at least one of the capacitor circuits 33 and 34 by the control unit 4 so as to satisfy the above-described formula (1) or formula (2), it is possible to cause series resonance.

[0044] The combined inductance Lc present in each divided power transmitting electrode 6 when the length, thickness, etc. are different is calculated, for example, by storing design values ​​of the self-inductance of each divided power transmitting electrode 6 as a data table in the storage unit 402, adding up the mutual inductances of the paired power transmitting electrodes 1, and performing electromagnetic field analysis or the like. Each function of the control unit 4 is realized by the calculation processing unit 401 executing software or a program stored in the storage unit 402 and working in cooperation with hardware. Setting data set in the control unit 4 may be stored in the storage unit 402 as part of the software or program, or may be input via the input / output interface 403. Using the combined inductance Lc thus derived, the control unit 4 controls at least one of the capacitor circuit 33 and the capacitor circuit 34 so as to satisfy the above-described formula (1) or (2), thereby enabling series resonance.

[0045] In this way, the combined inductance L C1 , L C2 The capacitance values ​​C of the capacitor circuits 33 and 34 that couple the divided power transmitting electrodes 6 are set to satisfy the series resonance even if the capacitances are different. d1 , C d2By controlling the power supply unit 2 using the control unit 4, the circuit formed by each divided power transmitting electrode 6 becomes a low impedance circuit due to series resonance, thereby reducing the voltage difference between each divided power transmitting electrode 6. Therefore, regardless of the location of the power receiving device 20, the effect of inductance fluctuations can be reduced, making it possible to transmit power to the power receiving device with high transmission efficiency. Furthermore, when a device such as an inverter is used in the power supply unit 2, unstable operation can be reduced.

[0046] The power transmission device 10 of this embodiment can set or control the capacitance value more precisely using the capacitor circuits 33 and 34 provided between the divided power transmission electrodes 6, thereby reducing the effect of inductance fluctuations and enabling power to be transmitted to the power receiving device with high transmission efficiency.

[0047] Third Embodiment A method for manufacturing the power transmission device 10 according to the third embodiment will be described. In the second embodiment, in order to improve the power supply efficiency, the capacitance values ​​C d1 , C d2 In the third embodiment, the capacitance values ​​C of the third capacitor circuit 33 and the fourth capacitor circuit 34 are controlled by the control unit 4. d1 , C d2 13 is a schematic flow diagram showing steps in a method for manufacturing a power transmission device according to the third embodiment. First, a pair of spaced apart first and second power transmission electrodes 11 and 12 that receive high-frequency power from a power supply unit 2 that supplies high-frequency power are divided in the longitudinal direction to form a plurality of split power transmission electrodes 6 (step ST01). N (N is a natural number) split power transmission electrodes 6 are then electrically connected in series in the longitudinal direction via respective capacitor circuits, and the combined inductance values ​​present in each split power transmission electrode 6 are calculated as L CX (x is a natural number from 1 to N), and the frequency of the high frequency power is f, the capacitance value C dX is expressed by the following equation (3):

[0048] The capacitance value C dThe capacitor circuit is fabricated with the determined capacitance (step ST02). The split power transmission electrodes 6 adjacent to each other in the longitudinal direction are then electrically connected in series via the capacitor circuit (step ST03). The start points of the first power transmission electrode 11 and the second power transmission electrode 12 formed by the split power transmission electrodes 6 connected via the capacitor circuit are then connected to the power supply unit 2 (step ST04).

[0049] The capacitor circuit 33 and the capacitor circuit 34 may use a single capacitor 3 or may be a combination of a plurality of capacitors 3. Electrostatic coupling may be achieved by providing a gas space such as air between adjacent split power transmitting electrodes 6, or by providing a dielectric 7 such as resin between adjacent split power transmitting electrodes 6. The distance between adjacent split power transmitting electrodes 6 is set to a length that does not prevent the power receiving electrodes of the power receiving device 20 from supplying power by electric field coupling.

[0050] 14 is a schematic side view showing an example of a capacitor circuit connected to the split power transmission electrodes 6, showing the connection between the split power transmission electrodes 6 arranged in the longitudinal direction and the capacitor circuit as viewed from the side. As shown in Fig. 14, the capacitor circuits 33 and 34 may be configured by combining auxiliary electrodes 8 and capacitors 3, which partially face each other and are arranged with a spacer or dielectric 7 between them. The auxiliary electrodes 8 are insulated from the split power transmission electrodes 6 by the spacer or dielectric 7, and adjacent split power transmission electrodes 6 are electrostatically coupled to each other.

[0051] The capacitor circuits 33 and 34 are fabricated by arranging an auxiliary electrode 8 with a spacer or dielectric 7 between them so that a portion of the auxiliary electrode 8 faces each of the adjacent divided power transmission electrodes 6, and connecting each of the adjacent divided power transmission electrodes 6 to a capacitor 3.

[0052] The length of the auxiliary electrode 8 and the area facing the power transmitting electrode 1 may be arbitrary. In this case, the capacitance value C3 of the capacitor 3 is calculated by the above-mentioned equation (3). dx The capacitance C7 of the dielectric 7 between the auxiliary electrode 8 and the divided power transmitting electrode 6 may be calculated by subtracting half of the capacitance C7 from the capacitance C7.

[0053] In this way, by coupling the split power transmitting electrodes 6 with the capacitor circuits 33 and 34 whose capacitance values ​​Cd are adjusted so that the combined inductance Lc present in each split power transmitting electrode 6 satisfies series resonance, the circuit formed by each split power transmitting electrode 6 becomes a low impedance circuit due to series resonance, thereby reducing the voltage difference between each split power transmitting electrode 6. Therefore, no matter where the power receiving device 20 is located, the effect of fluctuations in inductance present in the power transmitting electrode 1 can be reduced, and power can be transmitted to the power receiving device 20 with high transmission efficiency. Furthermore, when a device such as an inverter is used in the power supply unit 2, unstable operation can be reduced.

[0054] In the above-described first to third embodiments, the length of the split power transmission electrode 6 in the longitudinal direction may be determined arbitrarily, and the number of divisions may also be determined arbitrarily. The lengths of the split power transmission electrodes 6 may be the same or may differ for each split power transmission electrode 6. Furthermore, although the example in which the split power transmission electrode 1 is formed linearly by the split power transmission electrodes 6 has been shown, the split power transmission electrodes 6 may be formed in a wavy shape, or may be partially curved to form a curved shape.

[0055] Furthermore, although various exemplary embodiments are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0056] REFERENCE SIGNS LIST 1 power transmitting electrode, 2 power supply unit, 4 control unit, 6 divided power transmitting electrode, 7 dielectric, 8 auxiliary electrode, 10 power transmitting device, 11 first power transmitting electrode, 12 second power transmitting electrode, 13 wiring, 20 power receiving device, 21 first power receiving electrode, 22 second power receiving electrode, 31, 32, 33, 34 capacitor circuit, 41 communication line, 51 first voltage detection unit, 52 second voltage detection unit, 53 voltage detection electrode, 100 wireless power feeding system, 3, 311 capacitor, 312 switch, 511, 521 detection path

Claims

1. A power transmission device that wirelessly supplies power to a power receiving device, comprising: a power supply unit that supplies high frequency power; a pair of long, spaced-apart first and second power transmission electrodes that receive the high frequency power from the power supply unit; a first voltage detection unit that detects a first voltage between the first and second power transmission electrodes that receive the high frequency power from the power supply unit; a second voltage detection unit that detects a second voltage between the first and second power transmission electrodes; a first capacitor circuit having one end connected to the power supply unit side and the other end connected to the first power transmission electrode; a second capacitor circuit having one end connected to the power supply unit side and the other end connected to the second power transmission electrode; and a control unit that controls the capacitance value of at least one of the first capacitor circuit and the second capacitor circuit to a value that brings the difference between the first voltage and the second voltage within a set range.

2. A power transmission device as described in claim 1, wherein at least one of the first power transmission electrode and the second power transmission electrode is formed as a divided power transmission electrode, and at least one of the first capacitor circuit and the second capacitor circuit is disposed between the divided power transmission electrodes.

3. The power transmission device according to claim 1, wherein the first power transmission electrode and the second power transmission electrode are formed by a plurality of split power transmission electrodes, and the split power transmission electrodes are connected in series in the longitudinal direction with a third capacitor circuit and a fourth capacitor circuit, respectively.

4. The power transmission device described in claim 3, wherein the second voltage detection units are provided in multiple locations between multiple divided power transmission electrodes, and the control unit controls the capacitance values ​​of at least one of the third capacitor circuit and the fourth capacitor circuit to values ​​such that the difference between the first voltage and the second voltage between adjacent divided power transmission electrodes or between multiple divided power transmission electrodes is within a set range, by sequentially setting the voltages acquired from the second voltage detection units as the first voltage and the second voltage.

5. A power transmission device as described in claim 1, wherein at least one of the first capacitor circuit and the second capacitor circuit is a circuit in which a plurality of series-connected capacitors and switches are connected in parallel, and the control unit adjusts the capacitance value by controlling the opening and closing of the switches.

6. The power transmitting device according to claim 1, wherein at least one of the first power transmitting electrode and the second power transmitting electrode has a voltage detection electrode for detecting an output voltage by electrostatic coupling between electrodes.

7. A power transmission device that wirelessly supplies power to a power receiving device, comprising: a power supply unit that supplies high frequency power; and a pair of long, spaced apart first and second power transmission electrodes that receive the high frequency power from the power supply unit, wherein the first and second power transmission electrodes are divided into a plurality of split power transmission electrodes that are connected in series in the longitudinal direction via a third capacitor circuit and a fourth capacitor circuit, respectively; and a combined inductance value present in each of N1 split power transmission electrodes (N1 is a natural number) that form the first power transmission electrode is expressed as L C1X (x is a natural number from 1 to N1), and the frequency of the high frequency power is f, the capacitance value C d1X is expressed by the following formula (1): and L each of the composite inductance values ​​present in each of the N2 divided power transmission electrodes (N2 is a natural number) forming the second power transmission electrode. C2X (x is a natural number from 1 to N2), and the frequency of the high frequency power is f, the capacitance value C d2X is expressed by the following formula (2): a control unit that controls each of the third capacitor circuits and each of the fourth capacitor circuits so as to satisfy the above.

8. A power transmission device as described in claim 7, wherein at least one of the third capacitor circuit and the fourth capacitor circuit is a circuit in which a plurality of series-connected capacitors and switches are connected in parallel, and the control unit adjusts the capacitance value by controlling the opening and closing of the switches.

9. A power transmitting device according to any one of claims 1 to 8, wherein the power supply unit transmits AC power from an AC power source or from a DC power source via a power converter.

10. A wireless power supply system comprising: a power transmission device as described in any one of claims 1 to 9; and a power receiving device having a first power receiving electrode and a second power receiving electrode which move on the first power transmission electrode and the second power transmission electrode of the power transmission device, respectively, and which wirelessly supplies the high-frequency power from the power transmission device to the power receiving device by electric field coupling using electrostatic capacitance between the first power transmission electrode and the first power receiving electrode, and between the second power transmission electrode and the second power receiving electrode.

11. A method for manufacturing a power transmission device for wirelessly supplying power to a power receiving device, comprising the steps of: forming a pair of first and second power transmission electrodes spaced apart from each other to receive high-frequency power from a power supply unit that supplies high-frequency power; and dividing each of the first and second power transmission electrodes in a longitudinal direction to produce a plurality of split power transmission electrodes; and forming N (N is a natural number) split power transmission electrodes electrically connected in series in the longitudinal direction via a capacitor circuit, and calculating a composite inductance value present in each of the split power transmission electrodes by L. CX (x is a natural number from 1 to N), and the frequency of the high frequency power is f, the capacitance value C dX is expressed by the following formula (3): a step of electrically connecting the split power transmission electrodes adjacent in the longitudinal direction in series via the capacitor circuit; and a step of connecting start points of the first power transmission electrode and the second power transmission electrode formed by the split power transmission electrodes connected via the capacitor circuit to the power supply unit.

12. A method for manufacturing a power transmission device as described in claim 11, in which the capacitor circuit is fabricated by arranging an auxiliary electrode with a spacer or dielectric between it and each of the adjacent split power transmission electrodes, with a portion of the auxiliary electrode facing each of the adjacent split power transmission electrodes, and connecting a capacitor to each of the adjacent split power transmission electrodes.

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