Non-contact power supply device and power reception device

Abstract

To provide a non-contact power supply device capable of simplifying wiring of a device on a power reception side.SOLUTION: A power reception device 3 of a non-contact power supply device 1, includes: a reception coil 22; and a resonance capacitor 23, and includes: a plurality of resonance circuits (21-1 to 21-n) that receives the power from a power transmission device 2 by resonating the reception coil 22 and the resonance capacitor 23 against an AC power supplied to a transmission coil 12 of the power transmission device 2; and a load coil 24 that is arranged so as to enable an electromagnetic coupling of the reception coil 22 of each resonance circuit, and outputs the power received from the power transmission device 2 by each resonance circuit. The reception coil 22a and the load coil 24 in each resonance circuit are formed as a wiring pattern in a layer having a plurality of layers of which a substrate 5 is different each other, and one end of the reception coil 22 and one end of the load coil 24 in each resonance circuit are connected so as to become a same potential.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a contactless power supply device and a power receiving device used in the contactless power supply device. [Background technology]

[0002] Conventionally, research has been conducted on so-called non-contact power supply (also called wireless power supply) technology, which transmits power through space without going through metal contacts, etc. In a power supply device using non-contact power supply technology (hereinafter simply referred to as a non-contact power supply device), a coil on the primary side (power transmission side) (hereinafter referred to as a transmission coil or primary coil) and a coil of a resonant circuit on the secondary side (power receiving side) (hereinafter referred to as a receiving coil or secondary coil) are electromagnetically coupled, and power is transmitted from the power transmitting side device to the power receiving side device via these two coils.

[0003] In such a non-contact power supply technology, a technology has been proposed that prevents the terminal voltage of a resonant capacitor of a resonant circuit of a power receiving device from becoming excessively high (for example, see Patent Document 1). In this technology, the power receiving device has multiple resonant circuits that receive power from a power transmitting device. Each of the multiple resonant circuits has a receiving coil and a resonant capacitor that resonates with the AC power supplied to the transmitting coil of the power transmitting device together with the receiving coil, and the receiving coils are arranged so as to be electromagnetically coupled to each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-156218 A Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the application of the power receiving device, there may be a demand for miniaturization of the device. However, when a plurality of resonant circuits are provided in the power receiving device as in the above-mentioned technology, a lead wire is provided for each resonant circuit, which complicates the wiring of the power receiving device, and as a result, miniaturization of the power receiving device may be restricted.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a contactless power supply device capable of simplifying the wiring of a power receiving device. [Means for solving the problem]

[0007] As one embodiment of the present invention, there is provided a contactless power supply device having a power transmission device and a power receiving device to which power is transmitted contactlessly from the power transmission device. In this contactless power supply device, the power transmission device has a transmission coil that supplies power to the power receiving device, and a power supply circuit that supplies AC power to the transmission coil. The power receiving device has a reception coil and a resonance capacitor, and has a plurality of resonance circuits that receive power from the power transmission device by resonating the reception coil and the resonance capacitor with AC power supplied to the transmission coil of the power transmission device, and a loading coil that is arranged so as to be electromagnetically coupled to each of the reception coils of the plurality of resonance circuits and outputs the power received by each of the plurality of resonance circuits from the power transmission device. The reception coils and loading coils of each of the plurality of resonance circuits are formed as wiring patterns in different layers of a substrate having multiple layers, and are connected to each other so that one end of the reception coil and one end of the loading coil of each of the plurality of resonance circuits are at the same potential. By having such a configuration, the non-contact power supply device of the present invention can reduce the amount of wiring related to the receiving coil and loading coil of each resonant circuit in the power receiving device, thereby simplifying the wiring of the power receiving device.

[0008] In this contactless power supply device, it is preferable that one end of the receiving coil and one end of the loading coil of each of the plurality of resonant circuits in the power receiving device are grounded. This makes it possible to improve the noise resistance of the power receiving device.

[0009] In the contactless power supply device, the other ends of the receiving coils of the plurality of resonant circuits of the power receiving device are preferably separated from each other. This prevents the power transmission efficiency from decreasing even if the voltage generated by the received power differs for each resonant circuit.

[0010] Furthermore, in this contactless power supply device, the number of turns of the load coil of the power receiving device is preferably smaller than the total number of turns of the receiving coils of each of the multiple resonant circuits of the power receiving device. This makes it easy to operate each resonant circuit under conditions that provide high power transmission efficiency.

[0011] Furthermore, in this contactless power supply device, it is preferable that the power receiving device further has a DC-DC converter that operates to step down or step up the voltage output from the loading coil, and a voltage detection circuit that operates the DC-DC converter when the voltage output from the loading coil exceeds a predetermined threshold value. This makes it easy to operate each resonant circuit under conditions that provide high power transmission efficiency.

[0012] According to another embodiment, there is provided a power receiving device that receives power transmitted in a non-contact manner from a transmission coil of a power transmitting device. The power receiving device includes a receiving coil and a resonant capacitor, and includes a plurality of resonant circuits that receive power from the power transmitting device by resonating the receiving coil and the resonant capacitor with AC power supplied to the transmission coil of the power transmitting device, and a loading coil that is arranged so as to be electromagnetically coupled to each of the receiving coils of the plurality of resonant circuits and outputs the power received by each of the plurality of resonant circuits from the power transmitting device. The receiving coils and loading coils of each of the plurality of resonant circuits are formed as wiring patterns in different layers of a substrate having multiple layers, and are connected to each other so that one end of the receiving coil and one end of the loading coil of each of the plurality of resonant circuits are at the same potential. The power receiving device according to the present invention has such a configuration, and therefore the wiring associated with the receiving coil and loading coil of each resonant circuit can be reduced, thereby simplifying the wiring. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a non-contact power supply device according to an embodiment of the present invention. [Diagram 2] 4 is a schematic cross-sectional side view of a substrate on which the receiving coil and the loading coil of each resonant circuit are arranged. FIG. [Diagram 3] 1(a) to 1(d) are schematic plan views showing the arrangement of the individual receive coils and load coils in each layer of the substrate, as viewed from the normal direction of the substrate surface. [Figure 4] FIG. 2 is a diagram illustrating an example of operating characteristics of a DC-DC converter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A contactless power supply device according to an embodiment of the present invention will be described below with reference to the drawings. In this contactless power supply device, a power receiving device (hereinafter simply referred to as a power receiving device) has a plurality of resonant circuits that resonate with AC power supplied to a transmitting coil of a power transmitting device (hereinafter simply referred to as a power transmitting device). Each resonant circuit of the power receiving device has a receiving coil and a resonant capacitor. The receiving coil of each resonant circuit is disposed so as to be electromagnetically coupled to the loading coil, and the power receiving device outputs the power received by each resonant circuit from the loading coil. Furthermore, the receiving coil and loading coil of each resonant circuit are formed by wiring patterns on different layers of a substrate having a plurality of layers. The receiving coil and loading coil of each resonant circuit are connected to each other through vias in the substrate so that one end of the receiving coil and one end of the loading coil of each resonant circuit are at the same potential. In this manner, one end of the receiving coil and one end of the loading coil of each resonant circuit are connected to each other so as to have the same potential, preferably to ground, thereby simplifying the wiring of the power receiving device.

[0015] FIG. 1 is a schematic diagram of a contactless power supply device according to an embodiment of the present invention. As shown in FIG. 1, the contactless power supply device 1 includes a power transmission device 2 and a power receiving device 3 to which power is transmitted contactlessly from the power transmission device 2 through space. The power transmission device 2 includes a power supply circuit 11, a transmission coil 12, and a capacitor 13. On the other hand, the power receiving device 3 includes n resonant circuits 21-1 to 21-n (where n is an integer of 2 or more, n=3 in the example shown in FIG. 1), a load coil 24, a rectifying and smoothing circuit 25, a voltage detection circuit 26, and a DC-DC converter 27, and outputs the power received from the power transmission device 2 to a load circuit 4. In this embodiment, the contactless power supply device 1 is a contactless power supply device of a type (NP type) in which a receiving coil and a resonant capacitor resonate in parallel on the secondary side without using resonance on the primary side. However, the non-contact power supply device 1 may be a device conforming to another non-contact power supply method, such as a method (SP method) in which a transmission coil 12 and a capacitor 13 resonate in series on the primary side and a reception coil and a resonant capacitor resonate in parallel on the secondary side.

[0016] First, the power transmitting device 2 will be described. The power supply circuit 11 supplies AC power to the transmission coil 12. For this purpose, the power supply circuit 11 includes, for example, a DC power source that supplies DC power, an inverter circuit that converts the DC power supplied from the DC power source into AC power and supplies the AC power to the transmission coil 12, and a control circuit that controls the inverter circuit. The inverter circuit may be a full-bridge inverter in which four switching elements (for example, MOSFETs) are connected in a full-bridge configuration, or a half-bridge inverter in which two switching elements are connected in a half-bridge configuration. Alternatively, the inverter circuit may have the same configuration as an E-class amplifier. The control circuit controls the on / off switching of each switching element included in the inverter circuit so that the frequency of the AC power supplied to the transmission coil 12 becomes a predetermined frequency (for example, a frequency at which each resonant circuit can resonate when the degree of coupling between the reception coil of each resonant circuit of the power receiving device 3 and the transmission coil 12 is a predetermined value). The power supply circuit 11 may further include a DC-DC converter between the DC power source and the inverter circuit.

[0017] The transmission coil 12 is electromagnetically coupled to the reception coil of each resonant circuit of the power receiving device 3, thereby transmitting the AC power supplied from the power supply circuit 11 to the resonant circuits 21-1 to 21-n of the power receiving device 3 through space.

[0018] The capacitor 13 is connected in series with the transmitting coil 12 between the transmitting coil 12 and the inverter circuit of the power supply circuit 11. In this embodiment, the capacitor 13 is provided to block DC power. Therefore, the capacitance of the capacitor 13 is set so that a resonant circuit formed by the transmitting coil 12 and the capacitor 13 does not resonate with the AC power supplied to the transmitting coil 12, that is, so that the frequency of the AC power supplied to the transmitting coil 12 is different from the resonant frequency of the resonant circuit. Note that when the power supply circuit 11 has a full-bridge inverter, the capacitor 13 may be omitted.

[0019] Next, the power receiving device 3 will be described. Each of the n resonant circuits 21-1 to 21-n includes a receiving coil 22 and a resonant capacitor .

[0020] In this embodiment, in each of the resonant circuits 21-1 to 21-n, the receiving coil 22 and the resonant capacitor 23 are connected in parallel. In each of the resonant circuits 21-1 to 21-n, the receiving coil 22 and the resonant capacitor 23 form a closed loop. Furthermore, the inductance of the receiving coil 22 and the capacitance of the resonant capacitor 23 of each of the resonant circuits 21-1 to 21-n are set so that the products of the inductance and capacitance of each resonant circuit can be equal to each other, and each resonant circuit can resonate with the AC power supplied to the transmission coil 12. For example, the inductance of each of the receiving coils 22 of the resonant circuits 21-1 to 21-n is set to be the same as each other, and the capacitance of each of the resonant capacitors 23 of the resonant circuits 21-1 to 21-n is set to be the same as each other.

[0021] Furthermore, the receiving coil 22 of each of the resonant circuits 21-1 to 21-n is disposed so as to be electromagnetically coupled to the loading coil 24. Therefore, when the power transmitting device 2 and the power receiving device 3 are in a positional relationship in which power can be transmitted from the power transmitting device 2 to the power receiving device 3, the receiving coil 22 of each of the resonant circuits 21-1 to 21-n resonates together with the resonant capacitor 23 and is electromagnetically coupled to the transmitting coil 12, whereby each of the resonant circuits receives power from the transmitting coil 12. Furthermore, the power received by each of the resonant circuits 21-1 to 21-n is output via the loading coil 24.

[0022] The loading coil 24 is disposed so as to be electromagnetically coupled to the receiving coils 22 of the resonant circuits 21-1 to 21-n. Both ends of the loading coil 24 are connected to the rectifying and smoothing circuit 25. Therefore, the power received by each of the resonant circuits 21-1 to 21-n from the power transmitting device 2 is output from the loading coil 24 to the load circuit 4 via the rectifying and smoothing circuit 25 and the DC-DC converter 27.

[0023] The rectifying and smoothing circuit 25 is connected between the loading coil 24 and the DC-DC converter 27, and rectifies and smoothes the power output from the loading coil 24 to convert it into DC power. The rectifying and smoothing circuit 25 outputs the converted DC power to the DC-DC converter 27. In this embodiment, the rectifying and smoothing circuit 25 has a half-end rectifier circuit formed of one diode connected to one end of the loading coil 24 opposite to the grounded end, and a smoothing capacitor that smoothes the power rectified by the half-end rectifier circuit on the output side of the half-end rectifier circuit. By configuring the rectifying and smoothing circuit 25 as a half-end rectifier circuit in this way, the potential at the negative output terminal of the rectifying and smoothing circuit 25 can be made the same potential as the potential at one end of the receiving coil 22 and one end of the loading coil 24 of each of the resonance circuits 21-1 to 21-n. Therefore, it is possible to ground one end of the receiving coil 22 and one end of the loading coil 24 of each of the resonance circuits 21-1 to 21-n. As a result, it is possible to improve the resistance of the power receiving device 3 to noise.

[0024] The voltage detection circuit 26 is connected between the rectifying and smoothing circuit 25 and the DC-DC converter 27, and turns on the DC-DC converter 27 when the voltage output from the rectifying and smoothing circuit 25 exceeds a predetermined threshold. In this embodiment, the voltage detection circuit 26 is composed of a Zener diode. The anode terminal of the Zener diode is connected to the on / off control terminal of the DC-DC converter 27, and the cathode terminal is connected to the positive output terminal of the rectifying and smoothing circuit 25. Therefore, when the voltage output from the rectifying and smoothing circuit 25 is equal to or lower than the breakdown voltage of the Zener diode (corresponding to the above-mentioned predetermined threshold), a relatively low voltage is applied to the on / off control terminal of the DC-DC converter 27, and the DC-DC converter 27 is turned off. On the other hand, when the voltage output from rectifying and smoothing circuit 25 exceeds the breakdown voltage of the Zener diode, a relatively high voltage equivalent to the voltage output from rectifying and smoothing circuit 25 is applied to the on / off control terminal of DC-DC converter 27, so that DC-DC converter 27 turns on and operates so as to maintain the output power constant. Note that voltage detection circuit 26 is not limited to the above example, and may have another circuit configuration that can turn on DC-DC converter 27 when the output voltage from rectifying and smoothing circuit 25 exceeds a predetermined threshold value.

[0025] The DC-DC converter 27 is connected between the rectifying and smoothing circuit 25 and the load circuit 4. When a voltage that turns on is applied to the on / off control terminal, the DC-DC converter 27 converts the voltage input via the rectifying and smoothing circuit 25 to step up or step down so that the power output from the DC-DC converter 27 is constant, and outputs the DC power having the converted voltage to the load circuit 4 via a smoothing capacitor connected between the DC-DC converter 27 and the load circuit 4. When a voltage that turns off is applied to the on / off control terminal, the DC-DC converter 27 stops outputting power to the load circuit 4. In order to improve the power transmission efficiency, it is preferable that the DC-DC converter 27 is a step-down DC-DC converter. However, the DC-DC converter 27 may be a step-up or step-up / step-down DC-DC converter as long as it can output a voltage at which the load circuit 4 operates.

[0026] The arrangement of the receiving coil 22 and the loading coil 24 of each of the resonant circuits 21-1 to 21-n will be described below.

[0027] FIG. 2 is a schematic side cross-sectional view of the substrate 5 on which the receiving coils 22 and the loading coils 24 of the resonant circuits 21-1 to 21-n are arranged. Also, FIGS. 3(a) to 3(d) are schematic plan views showing the arrangement of the individual receiving coils 22 and the loading coils 24 in the layers 5a to 5d of the substrate 5 as viewed from the normal direction of the surface of the substrate 5. Note that in FIGS. 3(a) to 3(d), wiring patterns other than the individual resonant circuits 21-1 to 21-n and the loading coils 24 are omitted. In this example, the power receiving device 3 has three resonant circuits (i.e., n=3). Furthermore, in FIGS. 2 and 3(a) to 3(d), the receiving coils of the resonant circuits 21-k (k=1, 2, 3) are denoted as receiving coils 22-k, respectively.

[0028] 2, the substrate 5 made of an insulator is, for example, a substrate having a thickness of about 1 mm to several mm and has a plurality of layers 5a to 5d. The receiving coil 22-k and the loading coil 24 of each resonant circuit 21-k are arranged on different layers of the substrate 5. In this example, the loading coil 24 is arranged on the second layer 5c in order from the side closest to the transmitting coil 12 during power transmission. However, the layer on which the loading coil 24 is arranged is not limited to this example, and the loading coil 24 may be arranged on any of the layer 5a farthest from the transmitting coil 12, the layer 5d closest to the transmitting coil 12, or another intermediate layer 5b.

[0029] As shown in FIG. 3(a) to FIG. 3(d), the receiving coils 22-k and the loading coils 24 are formed as wiring patterns having a line width of less than 1 mm to several mm on different layers of the substrate 5 so that they are coaxial and preferably have the same outer diameter. By arranging the receiving coils 22-k and the loading coils 24 in this manner, the receiving coils 22-k and the loading coils 24 can be electromagnetically coupled to each other. One end of each receiving coil 22-k and one end of the loading coil 24 are connected to each other through a via 51 provided in the substrate 5. Therefore, one end of each receiving coil 22-k and one end of the loading coil 24 are at the same potential. By forming the receiving coils 22-k and the loading coil 24 in this manner, it is not necessary to provide a lead wire for each of these coils, and therefore the wiring is simplified. Note that a higher voltage is applied to the loading coil 24 than to each resonant circuit 21-k, so in order to reduce loss, it is preferable that the width of the wiring pattern of the loading coil 24 is wider than the width of the wiring pattern of each receiving coil 22-k.

[0030] Furthermore, in the layer 5c where the loading coil 24 is provided, one end of the loading coil 24 is connected to the grounded via 52. Therefore, one end of each receiving coil 22-k and one end of the loading coil 24 are grounded. Therefore, the influence of noise is suppressed. Meanwhile, the other ends of each receiving coil 22-k are provided so as to be separated from each other. In the example shown in FIG. 3(a) to FIG. 3(d), the other end of each receiving coil 22-k is connected to one end of the corresponding resonant capacitor provided in the layer 5a through a via. This is for the following reason. That is, since the receiving coils 22-k of each resonant circuit 21-k are provided in different layers of the substrate 5, the degree of coupling to the transmitting coil 12 is slightly different for each resonant circuit 21-k. As a result, the voltage of the power received by each resonant circuit 21-k is also slightly different. Here, if the other ends of the receiving coils 22-k are also connected to each other, a current corresponding to the difference in voltage generated from the resonant circuit that generates the highest voltage to the other resonant circuits among the resonant circuits 21-k flows, resulting in a decrease in power transmission efficiency. However, as in this embodiment, the other ends of the receiving coils 22-k are separated from each other, preventing such a current from flowing between the resonant circuits, thereby suppressing a decrease in power transmission efficiency.

[0031] Furthermore, the number of turns of the loading coil 24 is preferably smaller than the total number of turns of each of the receiving coils 22. In particular, the number of turns of the loading coil 24 is preferably 1 turn or less than 1 turn (for example, 0.5, 0.6, or 0.8 turns).

[0032] In this embodiment, each resonant circuit 21-k is configured so that the receiving coil 22 and the resonant capacitor are in parallel resonance. When such parallel resonance is used for power transmission, it is known that the resistance of the load connected to the resonant circuit, which optimizes the power transmission efficiency, is relatively large. In this embodiment, the receiving coil 22 and the loading coil 24 of each resonant circuit 21-k are arranged so as to be electromagnetically coupled to each other, so that the power receiving device 3 can be represented by an equivalent circuit that receives power through one resonant circuit and outputs the received power to the load. The equivalent resistance R" of the load (hereinafter, for convenience of explanation, referred to as the equivalent load) in this equivalent circuit is calculated by multiplying the equivalent resistance R' of the load connected to the loading coil 24 by the square of the ratio m of the total number of turns of the receiving coil 22 of each resonant circuit 21-k to the number of turns of the loading coil 24. In the example shown in FIG. 2 and FIG. 3(a) to FIG. 3(d), the number n of resonant circuits is 3. Moreover, the number of turns of each receiving coil 22-k is 2, and the number of turns of the loading coil 24 is 1. Therefore, m=(3*2) 2 = 36. Therefore, the equivalent resistance R” of the equivalent load is m 2 *R'=36*R'. Thus, the larger the value of the ratio m, the larger the equivalent resistance R" of the equivalent load, making it easier to optimize the power transmission efficiency. Therefore, by setting the relationship between the number of turns of each receiving coil 22 and the number of turns of the loading coil 24 as described above, it becomes easy to optimize the power transmission efficiency. Furthermore, by setting the number of turns of the loading coil 24 to one turn or less than one turn, it becomes easy to connect one end of the loading coil 24 to the via 52 that is grounded. Furthermore, even if the number of turns of the receiving coil 22-k of each resonant circuit is two or more, it becomes easy to ground one end of the receiving coil 22-k through the via 51 connected to the loading coil 24.

[0033] Furthermore, in this embodiment, since the load coil 24 is connected to the load circuit 4 via the DC-DC converter 27, the equivalent resistance R' of the load connected to the load coil 24 is a value obtained by multiplying the resistance R of the load circuit 4 by the square of the ratio (Vo / Vin) of the output voltage Vo from the DC-DC converter 27 to the input voltage Vin to the DC-DC converter 27 (i.e., R'=R*(Vo / Vin) 2 Therefore, by performing a step-down operation of DC-DC converter 27, it is possible to make equivalent resistance R″ larger than resistance R of load circuit 4, making it easier to optimize power transmission efficiency.

[0034] In addition, in order to keep the output power constant, the DC-DC converter 27 operates so that the duty ratio of the switching element of the DC-DC converter 27 becomes higher as the input voltage Vin becomes lower. As the duty ratio becomes higher, the average value of the current flowing to the input side of the DC-DC converter 27 increases, and the equivalent resistance R' becomes smaller. Therefore, when the input voltage Vin is low, the output power from the DC-DC converter 27 may not be the target power value, and the operation of the DC-DC converter 27 may become unstable. Alternatively, when there are multiple operating conditions under which the output voltage from the DC-DC converter 27 is constant, the lower the input voltage Vin, the easier it is to converge to the operating condition with the smaller equivalent resistance R' among the multiple operating conditions. Conversely, as the input voltage Vin becomes higher, the DC-DC converter 27 operates so that the duty ratio of the switching element becomes lower, and the equivalent resistance R' becomes larger. Therefore, as described above, by turning on DC-DC converter 27 when the voltage output from rectifying and smoothing circuit 25 exceeds a predetermined threshold, it becomes possible to stabilize the operation of DC-DC converter 27 and operate DC-DC converter 27 under the operating condition where equivalent resistance R' becomes larger. As a result, it becomes possible to improve the power transmission efficiency.

[0035] FIG. 4 is a diagram showing an example of the operating characteristics of the DC-DC converter 27. In FIG. 4, the horizontal axis represents the equivalent resistance R', and the vertical axis represents the output power Wo from the DC-DC converter 27. A graph 400 represents the relationship between the equivalent resistance R' and the output power Wo due to the operation of the DC-DC converter 27. As shown in the graph 400, there are two equivalent resistances R' (operating points A and B) that provide the target output power Wt. As described above, when the input voltage Vin is low, the DC-DC converter 27 operates so that the equivalent resistance R' is low, and therefore the DC-DC converter 27 operates so that the value of the equivalent resistance R' approaches the operating point A where the value is lower. On the other hand, if the input voltage Vin is sufficiently high (i.e., higher than a predetermined threshold), it is possible to operate the DC-DC converter 27 so that the value of the equivalent resistance R' approaches the operating point B where the value is higher. As a result, it is possible to increase the equivalent resistance R'' of the equivalent load, and it is possible to improve the power transmission efficiency.

[0036] As described above, the power receiving device of this contactless power supply device has a plurality of resonant circuits capable of resonating with AC power supplied to the transmitting coil of the power transmitting device, and a loading coil for extracting the power received in each resonant circuit. The receiving coil and loading coil of each resonant circuit are formed by wiring patterns on different layers of a substrate having a plurality of layers, and the receiving coil and loading coil of each resonant circuit are connected so that one end of the receiving coil and one end of the loading coil of each resonant circuit are at the same potential. Therefore, this contactless power supply device can simplify the wiring of the power receiving device. Furthermore, by the power receiving device receiving power through the plurality of resonant circuits, an excessive rise in the voltage between the resonant capacitor terminals of each resonant circuit is suppressed.

[0037] According to a modified example, the rectifying and smoothing circuit 25 of the power receiving device 3 may have a full-wave rectifying circuit in which four diodes are connected in a full bridge configuration, instead of a half-end rectifying circuit consisting of one diode. In this case, the potential of each terminal on the output side of the rectifying and smoothing circuit 25 connected to the load circuit 4 is different from the potential of one end of the receiving coil 22 and one end of the loading coil 24 of each resonant circuit connected to each other, so that one end of the receiving coil 22 and one end of the loading coil 24 of each resonant circuit are not grounded by grounding one end of the load circuit 4. In addition, when it is assumed that the voltage output from the rectifying and smoothing circuit 25 of the power receiving device 3 during power transmission is a voltage at which the load circuit 4 can operate, the voltage detection circuit 26 and the DC-DC converter 27 may be omitted.

[0038] In this way, those skilled in the art can make various modifications to the embodiments within the scope of the present invention. [Explanation of symbols]

[0039] 1. Non-contact power supply device 2. Power transmission equipment 11 Power supply circuit 12 Transmitting coil 13 Capacitor 3 Power receiving device 4 Load circuit 5 Substrate 51, 52 Via 21-1~21-n resonant circuit 22, 22-1 to 22-3 Receiving coil 23 Resonant Capacitor 24 Load coil 25 Rectifier smoothing circuit 26 Voltage detection circuit 27 DC-DC converter

Claims

1. A contactless power supply device having a power transmission device and a power receiving device to which power is transmitted contactlessly from the power transmission device, The power transmitting device is A transmission coil for supplying power to the power receiving device; a power supply circuit for supplying AC power to the transmitting coil; The power receiving device is a plurality of resonant circuits each including a receiving coil and a resonant capacitor, the receiving coil and the resonant capacitor resonating with AC power supplied to the transmitting coil of the power transmitting device, thereby receiving power from the power transmitting device; a loading coil that is arranged so as to be electromagnetically coupled to the receiving coil of each of the plurality of resonant circuits and that outputs electric power received from the power transmitting device by each of the plurality of resonant circuits; the receiving coil and the loading coil of each of the plurality of resonant circuits are formed as wiring patterns in different layers of a substrate having a plurality of layers, and one end of the receiving coil and one end of the loading coil of each of the plurality of resonant circuits are connected to each other so that they have the same potential; Non-contact power supply device.

2. The contactless power supply device according to claim 1 , wherein one end of the receiving coil and one end of the loading coil of each of the plurality of resonant circuits are grounded.

3. The contactless power supply device according to claim 1 , wherein the other ends of the receiving coils of the respective resonant circuits are separated from each other.

4. The contactless power supply device according to claim 1 , wherein the number of turns of the loading coil is smaller than a total number of turns of the receiving coils of the plurality of resonant circuits.

5. The power receiving device is a DC-DC converter that operates to step down or step up the voltage output from the loading coil; a voltage detection circuit that operates the DC-DC converter when the voltage output from the loading coil exceeds a predetermined threshold; The contactless power supply device according to claim 1 or 2, further comprising:

6. A power receiving device that receives power transmitted in a non-contact manner from a transmission coil of a power transmitting device, a plurality of resonant circuits each including a receiving coil and a resonant capacitor, the receiving coil and the resonant capacitor resonating with AC power supplied to the transmitting coil of the power transmitting device, thereby receiving power from the power transmitting device; a loading coil that is arranged so as to be electromagnetically coupled to the receiving coil of each of the plurality of resonant circuits and that outputs electric power received from the power transmitting device by each of the plurality of resonant circuits; the receiving coil and the loading coil of each of the plurality of resonant circuits are formed as wiring patterns in different layers of a substrate having a plurality of layers, and one end of the receiving coil and one end of the loading coil of each of the plurality of resonant circuits are connected to each other so that they have the same potential; Powered device.

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