Wireless power supply system, power transmission device for wireless power supply system

Abstract

A wireless power supply system (10) comprises a power reception device (90) and a power transmission device (20). The wireless power supply system (10) forms an electromagnetic resonance field between the power transmission device (20) and the power reception device (90) to perform wireless power supply and uses the electromagnetic resonance field to perform signal transmission by a resonance modulation. The power transmission device (20) comprises: a power transmission coil (30) that performs wireless power transmission by forming the electromagnetic resonance field; a power transmission circuit (40) having a power transmission resonance circuit (43); a resonance demodulation circuit that achieves a resonance demodulation corresponding to the resonance modulation; a current detection circuit (60) that detects the input current to the power transmission circuit; and a current adjustment circuit (70) that adjusts the input current. The power transmission device (20) detects, by the current detection circuit (60), a state of being unable to detect a signal using the resonance modulation by a power reception circuit (92). The current detection circuit (60) changes the input current using the current adjustment circuit (70) when being in the state of being unable to detect the signal.

Description

[Technical Field]

[0001] The present invention relates to a wireless power supply system that performs wireless power supply and communication. [Background technology]

[0002] An RFID module is described in Patent Document 1. The RFID module in Patent Document 1 estimates the distance to a reader / writer based on the magnitude of the antenna excitation voltage.

[0003] The RFID module of Patent Document 1 adjusts the phase of the carrier wave when the antenna excitation voltage exceeds a predetermined threshold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5290014 specification Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, implantable medical devices have become increasingly multifunctional and multi-channel, resulting in increased power consumption and the burden on patients caused by battery replacement. For this reason, wireless power transfer is expected to be adopted for implantable medical devices. Various technologies for wireless power transfer and communication are being considered.

[0006] However, when an RFID module such as that shown in Patent Document 1 is used for such communication, there are cases where communication is not possible (a state where NULL occurs) even within a range where the power required for communication can be received sufficiently. In particular, when a metal housing is used, such as in an implantable medical device, this state where communication is not possible is likely to occur due to the influence of the metal.

[0007] Therefore, an object of the present invention is to provide a wireless power supply system that can stably transmit signals within a distance range where power can be supplied when transmitting signals together with wireless power supply. [Means for solving the problem]

[0008] A wireless power supply system according to the present invention includes a power receiving device and a power transmitting device. An electromagnetic resonant field is formed between the power transmitting device and the power receiving device to supply power wirelessly, and the electromagnetic resonant field is used to transmit signals by resonance modulation.

[0009] The power receiving device includes a housing having an internal space, a power receiving coil arranged in the internal space and performing wireless power reception by forming an electromagnetic resonance field, a power receiving circuit having a power receiving resonance circuit and a resonance modulation circuit that performs resonance modulation, and a load circuit that performs a predetermined electrical circuit operation using the output power of the power receiving circuit.

[0010] The power transmission device includes a power transmission coil that performs wireless power transmission by forming an electromagnetic resonance field, a power transmission circuit having a power transmission resonance circuit, a power transmission control circuit, a resonance demodulation circuit that performs resonance demodulation corresponding to the resonance modulation, a current detection circuit that detects the input current of the power transmission circuit, and a current adjustment circuit that adjusts the input current.

[0011] The power transmitting device detects a state in which a signal generated by resonance modulation from the power receiving circuit cannot be detected by a current detecting circuit, and when the signal cannot be detected, the current detecting circuit changes the input current by a current adjusting circuit.

[0012] With this configuration, the wireless power supply system avoids a state in which it cannot detect a signal, and stabilizes the execution operation of resonance demodulation. [Effects of the Invention]

[0013] According to the present invention, when signal transmission is performed together with wireless power supply, stable signal transmission can be performed within the distance range in which power can be supplied. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a functional block diagram showing an example of the configuration of a wireless power supply system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a functional block diagram showing an example of the configuration of a power transmitting device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a functional block diagram showing an example of the configuration of the power receiving device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a side cross-sectional view showing an example of the structure of a wireless power supply system according to an embodiment of the present invention. [Figure 5] 5(A), 5(B), 5(C), and 5(D) are diagrams showing waveforms during demodulation. [Figure 6] FIG. 6 is a diagram showing a first example of a current adjustment circuit according to an embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing a second example of a current adjustment circuit according to an embodiment of the present invention. [Figure 8] FIG. 8 is a diagram illustrating an example of a current detection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] A wireless power supply system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram showing an example of the configuration of a wireless power supply system according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing an example of the configuration of a power transmitting device according to an embodiment of the present invention. FIG. 3 is a functional block diagram showing an example of the configuration of a power receiving device according to an embodiment of the present invention. Note that FIG. 1 omits part of the configuration of the power transmitting device 20 and part of the configuration of the power receiving device 90, and the specific configuration of the power transmitting device 20 is shown in FIG. 2, and the specific configuration of the power receiving device 90 is shown in FIG. 3.

[0016] (Schematic configuration of wireless power supply system 10) 1, the wireless power supply system 10 includes a power transmitting device 20 and a power receiving device 90. The wireless power supply system 10 forms an electromagnetic resonant field between the power transmitting device 20 and the power receiving device 90, and performs wireless power supply using this electromagnetic resonant field, as well as signal transmission by resonance modulation using the electromagnetic resonant field.

[0017] The power transmitting device 20 and the power receiving device 90 specifically have the following configuration, which performs wireless power feeding using an electromagnetic resonance field and also performs signal transmission by resonance modulation using the electromagnetic resonance field.

[0018] (Power transmission device 20) 1 and 2, the power transmitting device 20 includes a power transmitting coil 30, a power transmitting circuit 40, a power transmitting control circuit 50, a current detection circuit 60, a current adjustment circuit 70, an input voltage conversion circuit 201, an input filter 202, and a regulator 500. The power transmitting circuit 40 includes a driver circuit 41, a power conversion circuit 42, and a power transmitting resonant circuit 43.

[0019] An input terminal of an input voltage conversion circuit 201 is connected to the DC power supply, and an output terminal of the input voltage conversion circuit 201 is connected to an input terminal of an input filter 202. Note that the input voltage conversion circuit 201 and the input filter 202 may be omitted.

[0020] A current detection resistor Rd is connected to the high-side output terminal of the input filter 202, and the current detection resistor Rd is connected to an input terminal of a current adjustment circuit 70. An output terminal of the current adjustment circuit 70 is connected to the high-side input terminal of the power conversion circuit 42. A low-side output terminal of the input filter 202 is connected to the low-side end of the power conversion circuit 42. A specific configuration of the current adjustment circuit 70 will be described later.

[0021] Power conversion circuit 42 includes high-side switching element Q421 (e.g., a power FET) and low-side switching element Q422 (e.g., a power FET). High-side switching element Q421 and low-side switching element Q422 are connected between the high-side input terminal and low-side terminal of power conversion circuit 42. The node between high-side switching element Q421 and low-side switching element Q422 is the output terminal of power conversion circuit 42.

[0022] The output terminal and the low-side terminal of the power conversion circuit 42 are connected to the power transmission resonant circuit 43. The power transmission resonant circuit 43 is connected to the power transmission coil 30.

[0023] The power transmitting resonant circuit 43 is a circuit having a predetermined capacitance. The capacitance of the power transmitting resonant circuit 43 is preferably variable.

[0024] The power transmitting coil 30 is formed of a loop-shaped, wound linear conductor. The length and shape of the power transmitting coil 30 are such that it can be electromagnetically coupled to the power receiving coil 91 of the power receiving device 90, and the inductance of the power transmitting coil 30 is set to a value that can generate an electromagnetic resonance field between the power receiving device 90 and the power transmitting device 20.

[0025] The current detection circuit 60 is connected to both ends of the current detection resistor Rd. The output terminal of the current detection circuit 60 is connected to the power transmission control circuit 50. The specific configuration of the current detection circuit 60 will be described later.

[0026] The power transmission control circuit 50 is a digital control circuit such as an MPU, etc. The power transmission control circuit 50 includes a driving output terminal and a current adjustment output terminal.

[0027] The drive output terminal of power transmission control circuit 50 is connected to driver circuit 41 of power transmission circuit 40. The output terminal of driver circuit 41 is connected to the gate of high-side switching element Q421 and the gate of low-side switching element Q422 of power conversion circuit 42.

[0028] The current adjustment output terminal of the power transmission control circuit 50 is connected to a current adjustment circuit 70 .

[0029] The power transmission control circuit 50 is connected, via a regulator 500, to the Hi-side conductive line between the Hi-side output terminal of the input filter 202 and the current detection resistor Rd.

[0030] (power receiving device 90) 1 and 3, the power receiving device 90 includes a power receiving coil 91, a power receiving circuit 92, an output voltage conversion circuit 93, a power receiving control circuit 94, a storage battery 991, a regulator 940, and a load ZL. The power receiving circuit 92 includes a power receiving resonant circuit 921, a rectifier circuit 922, a smoothing circuit 923, and a resonant modulation circuit 924.

[0031] The power receiving coil 91 is formed of a loop-shaped, wound linear conductor. The length and shape of the power receiving coil 91 are such that it can be electromagnetically coupled to the power transmitting coil 30 of the power transmitting device 20, and the inductance of the power receiving coil 91 is set to a value that can form an electromagnetic resonance field between the power receiving device 90 and the power transmitting device 20.

[0032] The power receiving coil 91 is connected to a power receiving resonant circuit 921. The power receiving resonant circuit 921 is a circuit having a variable capacitance. A power output terminal of the power receiving resonant circuit 921 is connected to an input terminal of a rectifier circuit 922.

[0033] An output terminal of the rectifier circuit 922 is connected to an input terminal of the smoothing circuit 923. An output terminal of the smoothing circuit 923 is connected to the output voltage conversion circuit 93 and the storage battery 991. An output terminal of the output voltage conversion circuit 93 is an output terminal of the power receiving device 90, and is connected to a load ZL.

[0034] The power receiving control circuit 94 is a digital control circuit such as an MPU, etc. The power receiving control circuit 94 includes an output terminal for resonance modulation control.

[0035] The resonance modulation control output terminal of the power receiving control circuit 94 is connected to the resonance modulation circuit 924. The resonance modulation circuit 924 is connected to the power receiving resonance circuit 921.

[0036] The power receiving control circuit 94 is connected to the output terminal of the smoothing circuit 923 through a regulator 940 .

[0037] (Power transmission and reception control) As will be described in detail later, signal information related to wireless power feeding is sent from the power receiving device 90 to the power transmitting device 20 using resonance modulation and resonance demodulation. The current flowing through the Hi-side transmission line in the power transmitting device 20 changes depending on this signal information.

[0038] The power transmission control circuit 50 analyzes signal information from the power receiving device 90 using the output voltage waveform (current detection voltage waveform) of the current detection circuit 60. The power transmission control circuit 50 determines whether power transmission is permitted or not based on the signal information. If power transmission is permitted, the power transmission control circuit 50 generates a power transmission control setting value so as to transmit power according to the power receiving device 90. The power transmission control circuit 50 provides the power transmission control setting value to the driver circuit 41.

[0039] Driver circuit 41 generates switching control signals that control the switching of high side switching element Q421 and low side switching element Q422 at a predetermined switching frequency based on the power transmission control setting value, and outputs these signals to high side switching element Q421 and low side switching element Q422.

[0040] High side switching element Q421 and low side switching element Q422 are controlled by switching control signals given to them.

[0041] The power transmission control circuit 50 also provides a steady-state setting value to the current adjustment circuit 70. The steady-state setting value is a value that sets the input current to the power conversion circuit 42 during steady state (when no NULL, described below, occurs).

[0042] The current adjustment circuit 70 generates an input voltage and an input current to the power conversion circuit 42 in a steady state from the input voltage Vi based on a steady state set value, and outputs them to the power conversion circuit 42.

[0043] The input voltage and input current to the power conversion circuit 42 in a steady state are preferably set to the minimum power required by the power receiving device 90, which is set in accordance with the specifications of the power receiving device 90. However, it is more preferable that the minimum power at this time has a margin large enough to ensure that the minimum power required by the power receiving device 90 remains even if the positional relationship between the power transmitting coil 30 and the power receiving coil 91 changes slightly.

[0044] The power conversion circuit 42 supplies a transmission current of a predetermined frequency (switching frequency) generated by the switching operation (on / off operation) of the high-side switching element Q421 and the low-side switching element Q422 in response to the steady-state input voltage and input current to the transmission coil 30 through the transmission resonance circuit 43.

[0045] The power transmission coil 30 is excited by a power transmission current of a predetermined frequency, and generates an alternating magnetic field of the predetermined frequency.

[0046] The power receiving coil 91 is coupled to the alternating magnetic field generated by the power transmitting coil 30 and generates a receiving current.

[0047] In this case, the power transmitting coil 30 is set to have a predetermined power transmitting resonance frequency together with the power transmitting resonance circuit 43, and the power receiving coil 91 is set to have a predetermined power receiving resonance frequency together with the power receiving resonance circuit 921. The power transmitting resonance frequency and the power receiving resonance frequency are set to approximately match, and the power transmitting resonance frequency approximately matches the switching frequency of the power conversion circuit 42.

[0048] As a result, an electromagnetic resonance field of a predetermined frequency (power transmission resonance frequency, power reception resonance frequency) is formed between the power transmission coil 30 of the power transmission device 20 and the power reception coil 91 of the power reception device 90. Therefore, the wireless power supply system 10 can supply power from the power transmission device 20 to the power reception device 90 with high efficiency.

[0049] The frequency that forms the electromagnetic resonance field, that is, the frequency of wireless power supply, is preferably a frequency in the ISM band, and is preferably 6.78 MHz or 13.56 MHz.

[0050] The rectifier circuit 922 rectifies the current received from the power receiving coil 91 to DC, and the smoothing circuit 923 smoothes the DC current. The DC current output from the smoothing circuit 923 is converted to a predetermined voltage in the output voltage conversion circuit 93 and supplied to the load ZL. The DC current output from the smoothing circuit 923 is also used to charge the storage battery 991.

[0051] The load ZL includes a load circuit that performs a predetermined electrical circuit operation using the power output from the power receiving circuit 92 through the output voltage conversion circuit 93. The load circuit includes, for example, at least one of a sensing circuit, a signal processing circuit, and a wireless communication circuit. As a specific example, if the power receiving device 90 is an implantable medical device, the load ZL performs processing that is performed by an implantable medical device (sensing of signals obtained from within the body, filtering and amplification of the sensing signals, wireless communication processing of the sensing signals using Wi-Fi, Bluetooth (registered trademark), etc.), etc.

[0052] In this way, the wireless power supply system 10 forms an electromagnetic resonance field and can supply power with high efficiency from the power transmitting device 20 to the power receiving device 90. As a result, the wireless power supply system 10 can achieve high-efficiency power supply to the load ZL connected to the power receiving device 90 and high-efficiency charging of the storage battery 991 of the power receiving device 90.

[0053] (communication) The power receiving control circuit 94 generates signal information related to wireless power feeding to the power transmitting device 20 and outputs it to the resonance modulation circuit 924. The resonance modulation circuit 924 changes the resonance condition of the power receiving resonance circuit 921 based on the bits ("0", "1") of the signal information. In this way, the power receiving circuit 92 achieves resonance modulation based on the signal information.

[0054] When such resonance modulation occurs, a change occurs in the electromagnetic field coupling state between the power receiving coil 91 and the power transmitting coil 30. This changes the amplitude of the power transmitting current flowing through the power transmitting coil 30. In other words, the circuit formed by the power transmitting coil 30 and the power transmitting resonant circuit 43 achieves resonance demodulation.

[0055] The amplitude of the power transmission current changes due to resonance demodulation, and the current flowing through the Hi-side transmission line in the power transmitting device 20 changes.

[0056] The output voltage of the current detection circuit 60 is affected by the current flowing through the Hi-side transmission line. Therefore, the output voltage of the current detection circuit 60 changes when the current flowing through the Hi-side transmission line changes.

[0057] The power transmission control circuit 50 detects this change and demodulates the signal information, thereby realizing signal transmission from the power receiving device 90 to the power transmitting device 20. That is, the wireless power transfer system 10 can realize signal transmission by resonance modulation and resonance demodulation using an electromagnetic resonance field.

[0058] (Example of the physical structure of the wireless power supply system 10) The wireless power supply system 10 capable of wirelessly supplying power and transmitting signals as described above can be applied to, for example, a system as shown in Fig. 4. Fig. 4 is a side cross-sectional view showing an example of the structure of a wireless power supply system according to an embodiment of the present invention.

[0059] As shown in FIG. 4, the power receiving device 90 of the wireless power feeding system 10 is embedded inside a living body, and the power transmitting device 20 is placed outside the living body.

[0060] (Structure of power receiving device 90) The power receiving device 90 includes a housing 98. The housing 98 is a sealed container having an internal space 980. The housing 98 is made of a biocompatible material. More specifically, the housing 98 includes a box-shaped first member 981 having an opening, and a plate-shaped second member 982 that closes the opening of the first member 981. The first member 981 is made of a biocompatible metal, such as titanium or a titanium alloy. The second member 982 is made of a biocompatible non-metal, such as sapphire glass.

[0061] A circuit board 99, a power receiving coil 91, an insulating film 911, a ferrite sheet 912, a storage battery 991, and a plurality of electronic components 992 are arranged inside the housing 98. The plurality of electronic components 992 are, for example, mountable electronic components that realize the circuit configuration of the power receiving device 90 described above.

[0062] A storage battery 991 and a plurality of electronic components 992 are mounted on a first surface of the circuit board 99. A cable 9930 is connected to the first surface of the circuit board 99. The cable 9930 is connected to an electrode pad 993 outside the housing 98 through a feedthrough formed in a first member 981 of the housing 98.

[0063] A power receiving coil 91, an insulating film 911, and a ferrite sheet 912 are arranged on the second surface side of the circuit board 99. More specifically, the ferrite sheet 912 is arranged on the second surface of the circuit board 99, and a flat film-like power receiving coil 91 supported by the insulating film 911 is arranged on the surface of the ferrite sheet 912 (the surface opposite the second surface of the circuit board 99). The power receiving coil 91 is connected to electronic components 992 that constitute the power receiving circuit 92 through the circuit board 99.

[0064] The power receiving coil 91 is positioned so that its flat membrane surface is close to the power receiving surface of the housing 98 (the surface of the housing 98 having the second member 982), so that the flat membrane surface is approximately parallel to the power receiving surface, and so that it overlaps the second member 982.

[0065] (Structure of power transmission device 20) The power transmitting device 20 includes a housing 29. The housing 29 has an internal space 290.

[0066] The housing 29 contains a circuit board 21, a power transmission coil 30, an insulating film 301, a ferrite sheet 302, and a plurality of electronic components 22. The plurality of electronic components 22 are, for example, mountable electronic components that realize the circuit configuration of the power transmission device 20 described above.

[0067] A plurality of electronic components 22 are mounted on the circuit board 21. A flat-film-shaped power transmission coil 30 supported by an insulating film 301 is connected to the circuit board 21. A ferrite sheet 302 is disposed on the opposite side of the insulating film 301 from the power transmission coil 30.

[0068] The power transmitting coil 30 is disposed so that its flat membrane surface is close to the power transmitting surface of the housing 29 and is substantially parallel to the power transmitting surface.

[0069] (Positional Relationship Between Power Transmitting Device 20 and Power Receiving Device 90 During Wireless Power Supply) 4, during wireless power feeding, the power receiving device 90 is placed on the power transmitting device 20 so that the power receiving surface is substantially parallel to the power transmitting surface and the power receiving surface and the power transmitting surface are closely opposed to each other. In this case, the power transmitting coil 30 of the power transmitting device 20 and the power receiving coil 91 of the power receiving device 90 are placed so as to substantially oppose each other.

[0070] By being arranged in this state, the power transmitting device 20 and the power receiving device 90 generate the above-mentioned electromagnetic resonance field and realize wireless power feeding. Furthermore, the power receiving device 90 and the power transmitting device 20 realize signal transmission using resonance modulation and resonance demodulation.

[0071] (How to avoid NULL during communication) In communication while wireless power supply is being performed as described above, there are cases where communication is not possible (a state where NULL occurs) even within a range where the power required for communication can be received sufficiently, as described above.

[0072] Figures 5(A), 5(B), 5(C), and 5(D) are diagrams showing waveforms during demodulation. In Figures 5(A), 5(B), 5(C), and 5(D), the horizontal axis represents the number of counts, which corresponds to time, and the vertical axis represents the code value, which corresponds to the amplitude of the current flowing through the Hi-side transmission line.

[0073] Figures 5(A), 5(B), and 5(C) show examples of the above-mentioned steady-state power supply, each with a different distance between the power transmitting coil and the power receiving coil. Figure 5(D) shows an example of the control of the present invention when a NULL occurs during steady-state power supply.

[0074] As shown in Figures 5(A), 5(B), and 5(C), when the above-mentioned steady-state power supply is performed, as shown in Figures 5(A) and 5(C), unless the distance is a certain distance, the peak modulated by the signal information is sufficiently higher than the noise, making it possible to detect the peak and demodulate it.

[0075] However, as shown in Fig. 5(B), at a certain distance, the difference between the height of the peak modulated by the signal information and the height of the noise is small (null occurs), making it difficult to detect the peak and demodulate. This phenomenon is likely to occur when metal is present near the power transmitting coil 30 and the power receiving coil 91, and is likely to occur when power is supplied to an implantable medical device with a metal housing in the case shown in Fig. 4 above.

[0076] To solve this problem, if the power transmission control circuit 50 of the power transmitting device 20 cannot detect a peak, it generates instruction data for the current adjustment circuit 70 to change the input current to the power conversion circuit 42 and provides the instruction data to the current adjustment circuit 70. The current adjustment circuit 70 controls the input current to the power conversion circuit 42 within a range in which wireless power transmission can be performed stably.

[0077] For example, specifically, if the power transmission control circuit 50 cannot detect a peak, it generates instruction data to make the current higher than the steady-state input current to the power conversion circuit 42 and provides it to the current adjustment circuit 70.

[0078] The current adjusting circuit 70 increases the input current to the power conversion circuit 42 based on the instruction data.

[0079] 4(D), the peak modulated by the signal information becomes sufficiently higher than the noise without changing the distance between the power transmitting coil 30 and the power receiving coil 91. This allows the power transmission control circuit 50 to detect and demodulate the peak.

[0080] In this way, by using the wireless power supply system 10 of this embodiment, it is possible to avoid the occurrence of NULL, and when performing communication together with wireless power supply, it is possible to transmit signals stably within the distance range where power can be supplied.

[0081] Furthermore, if the power receiving device 90 is an implantable medical device, the position of the power receiving device 90 cannot be easily changed. Even in such a case, the wireless power feeding system 10 can prevent the occurrence of NULL by performing the above-described control. As a result, the wireless power feeding system 10 can stably transmit signals to the implantable medical device within the distance range where power can be fed.

[0082] In the above description, the wireless power supply system 10 avoids NULL by minimizing the input current during steady state and increasing the input current when NULL occurs. However, the wireless power supply system 10 can also avoid NULL by setting the input current during steady state to a certain degree high and decreasing the input current within a range where power can be supplied when NULL occurs.

[0083] However, by setting the input current in steady state to the minimum necessary and increasing the input current when avoiding NULL, the wireless power transfer system 10 can minimize the amount of power supply while stably achieving wireless power transfer and signal transmission. Furthermore, by reducing the amount of power supply, heat generation due to the received current in the power receiving device 90 can be suppressed. As a result, for example, if the power receiving device 90 is an implantable medical device, adverse effects on the living body due to this heat can be suppressed.

[0084] Furthermore, noise during rectification of the received current can be reduced, and adverse effects of this noise on electronic components in the power receiving device 90, particularly on sensing of biological signals in the case of an implantable medical device, can be suppressed.

[0085] (Specific configuration 1 of the current adjustment circuit) 6 is a diagram illustrating a first example of a current adjustment circuit according to an embodiment of the present invention. As shown in FIG. 6, a current adjustment circuit 70 includes a DC-DC converter 71, a DA converter 72, an inductor L731, a capacitor C732, a resistor R733, a resistor R734, a resistor R735, and a capacitor C736.

[0086] The DC-DC converter 71 includes an input terminal VIN, an output terminal SW, a ground terminal GND, and a feedback terminal FB. The input terminal VIN is connected to the Hi-side transmission line, and the ground terminal GND is connected to the reference potential (ground potential) of the power transmitting device 20.

[0087] The DC-DC converter 71 converts the DC input voltage Vi at the input terminal VIN into a predetermined DC voltage based on the voltage at the feedback terminal FB, and outputs the converted voltage.

[0088] The inductor L731 is connected between the output terminal SW of the DC-DC converter 71 and the output terminal Pout70 of the current adjustment circuit 70. The capacitor C732 is connected between the node between the inductor L731 and the output terminal Pout70 and the feedback terminal FB.

[0089] Resistors R733, R734, and R735 are connected in series in this order from the node side between the node between inductor L731 and output terminal Pout70 and the reference potential. The node between resistors R733 and R734 is connected to feedback terminal FB.

[0090] The capacitor C736 is connected between the node between the inductor L731 and the output terminal Pout70 and the reference potential.

[0091] A digital input terminal of the DA converter 72 is connected to the power transmission control circuit 50. An analog output terminal of the DA converter 72 is connected to a node between the resistor R734 and the resistor R735.

[0092] In this configuration, the power transmission control circuit 50 inputs set value data for current adjustment to the DA converter 72. The DA converter 72 supplies an output voltage corresponding to the set value data for current adjustment to the node between resistors R734 and R735. As a result, the voltage at the feedback terminal FB of the DC-DC converter 71 becomes a value corresponding to the output voltage corresponding to the set value data.

[0093] Therefore, the power transmission control circuit 50 can adjust the voltage of the feedback terminal FB to avoid NULL by changing the value of the set value data to avoid NULL from a steady state.

[0094] As a result, the output voltage of the DC-DC converter 71 is adjusted from a steady-state voltage to a voltage for avoiding NULL, and the input current of the power conversion circuit 42 is adjusted from a steady-state current to a current for avoiding NULL.

[0095] Therefore, when the wireless power supply system 10 performs communication in addition to wireless power supply, the wireless power supply system 10 can perform communication more stably within the distance range in which power can be supplied.

[0096] Furthermore, the current adjustment circuit 70 adjusts the input voltage of the power conversion circuit 42 according to a set value from the power transmission control circuit 50, thereby adjusting the input current of the power conversion circuit 42. By using such a configuration, the wireless power transfer system 10 can increase the input current to the power conversion circuit 42 without adding an additional current supply circuit to the power conversion circuit 42.

[0097] (Specific configuration of current adjustment circuit 2) Fig. 7 is a diagram showing a second example of a current adjustment circuit according to an embodiment of the present invention. As shown in Fig. 7, a current adjustment circuit 70A includes a DA converter 72 and a current mirror circuit 74. The current mirror circuit 74 includes resistors R7411, R7412, R742, npn transistors Q741, and Q742, and forms a constant current circuit.

[0098] The base terminals of transistor Q741 and transistor Q742 are connected together, and the node between these base terminals is connected to the collector terminal of transistor Q741. The emitter terminals of transistor Q741 and transistor Q742 are connected to the reference potential.

[0099] The collector terminal of transistor Q741 is connected to the Hi-side transmission line via resistors R7412 and R7411. The collector terminal of transistor Q742 is connected to the Hi-side transmission line via resistor R742.

[0100] The emitter terminal of transistor Q742 is connected to the high input terminal of power conversion circuit 42 of current adjustment circuit 70A.

[0101] A digital input terminal of the DA converter 72 is connected to the power transmission control circuit 50. An analog output terminal of the DA converter 72 is connected to the node between the resistor R7411 and the resistor R7412.

[0102] With this configuration, the current adjustment circuit 70A can reduce the input current of the power conversion circuit 42 using the voltage from the DA converter 72.

[0103] Furthermore, with this configuration, the circuit configuration of the current adjustment circuit 70A is simplified, and the circuit of the power transmission device 20 can be simplified.

[0104] (Specific configuration of current detection circuit) Fig. 8 is a diagram showing an example of a current detection circuit according to an embodiment of the present invention. As shown in Fig. 8, the current detection circuit 60 is configured by a differential amplifier circuit. Specifically, the current detection circuit 60 includes an operational amplifier OP60, resistors R601, R602, R603, and R604.

[0105] The inverting input terminal of the operational amplifier OP60 is connected to the output side (current adjustment circuit 70 side) of the current detection resistor Rd through a resistor R601.

[0106] The non-inverting input terminal of the operational amplifier OP60 is connected to the input side (input filter 202 side) of the current detection resistor Rd through a resistor R603. The non-inverting input terminal of the operational amplifier OP60 is connected to the reference potential through a resistor R604.

[0107] The output terminal of the operational amplifier OP60 is connected to the inverting input terminal through a resistor R602.

[0108] With this configuration, the current detection circuit 60 outputs to the power transmission control circuit 50 a current detection voltage that corresponds to the voltage across the current detection resistor Rd that is generated by the current flowing through the current detection resistor Rd.

[0109] With this configuration, the power transmitting device 20 converts the current obtained by the resonance modulation and the resonance demodulation into a voltage and amplifies it, enabling more reliable and stable detection. This allows the power transmitting device 20 to improve the accuracy of detecting NULL and more reliably avoid NULL. Therefore, the wireless power supply system 10 can transmit signals more stably within the distance range where power can be supplied.

[0110] <1> A wireless power feeding system including a power receiving device and a power transmitting device, wherein an electromagnetic resonance field is formed between the power transmitting device and the power receiving device to feed power wirelessly, and the electromagnetic resonance field is used to transmit a signal by resonance modulation, The power receiving device is a housing having an internal space; a power receiving coil disposed in the internal space and configured to receive power wirelessly by forming the electromagnetic resonance field; a power receiving circuit including a power receiving resonant circuit and a resonant modulation circuit that performs the resonant modulation; a load circuit that performs a predetermined electrical circuit operation using the output power of the power receiving circuit; Equipped with The power transmission device is a power transmission coil that performs wireless power transmission by forming the electromagnetic resonance field; a power transmission circuit having a power transmission resonant circuit; and a power transmission control circuit; a resonant demodulation circuit that performs resonant demodulation corresponding to the resonant modulation; a current detection circuit that detects an input current of the power transmission circuit; a current adjustment circuit that adjusts the input current; Equipped with The power transmission device is The current detection circuit detects a state in which the signal due to the resonance modulation from the power receiving circuit cannot be detected, When the signal cannot be detected, the current adjustment circuit changes the input current, A wireless power supply system that avoids a state in which the signal cannot be detected and stabilizes the execution operation of the resonance demodulation.

[0111] <2> the current adjustment circuit changes the input current by changing the input voltage supplied to the power transmission circuit; <1> Wireless power supply system.

[0112] <3> the housing of the power receiving device is made of a biocompatible material; the power receiving device is embedded inside a living body, The power transmitting device is placed outside the living body. <1> or <2> Wireless power supply system.

[0113] <4> The biocompatible material is titanium or a titanium alloy. <3> Wireless power supply system.

[0114] <5> the current adjustment circuit controls the input current within a range in which the wireless power transmission is performed. <1> ~ <4> Any of the wireless power supply systems.

[0115] <6> The range in which the wireless power transmission is performed is a range in which the wireless power transmission has a predetermined power value or more. <1> ~ <5> Any of the wireless power supply systems.

[0116] <7> The frequency of the wireless power supply is in the 6.78 MHz band or the 13.56 MHz band. <1> ~ <6> Any of the wireless power supply systems.

[0117] <8> The load circuit includes a sensing circuit, a signal processing circuit, and a wireless communication circuit. <1> ~ <7> Any of the wireless power supply systems.

[0118] <9> the current adjustment circuit includes a DC-DC converter and a DA converter; the power transmission control circuit provides a set value to the DA converter, varies the feedback voltage of the DC-DC converter, and adjusts the input voltage; <1> ~ <8> Any of the wireless power supply systems.

[0119] <10> the current adjustment circuit includes a constant current circuit using a current mirror; setting the input current using a power transmission control circuit; <1> ~ <9> Any of the wireless power supply systems.

[0120] <11> The current detection circuit a shunt resistor connected to a line through which the input current flows; a voltage amplifier that amplifies a voltage obtained from a voltage generated across the shunt resistor; It consists of <1> ~ <10> Any of the wireless power supply systems.

[0121] <12> A power transmitting device of a wireless power feeding system that forms an electromagnetic resonant field to a power receiving device to feed power wirelessly and transmits a signal by resonance modulation using the electromagnetic resonant field, a power transmission coil that performs wireless power transmission by forming the electromagnetic resonance field; a power transmission circuit having a power transmission resonant circuit; and a power transmission control circuit; a resonant demodulation circuit that performs resonant demodulation corresponding to the resonant modulation; a current detection circuit that detects an input current of the power transmission circuit; a current adjustment circuit that adjusts the input current; Equipped with The current detection circuit detects a state in which the signal generated by the resonance modulation from the power receiving device cannot be detected, When the signal cannot be detected, the current adjustment circuit changes the input current, Preventing a state in which the signal cannot be detected and stabilizing the execution operation of the resonance demodulation. A power transmission device for a wireless power supply system.

[0122] <13> the current adjustment circuit controls the input current within a range in which the wireless power transmission is performed. <12> A power transmission device for a wireless power supply system.

[0123] <14> The range in which the wireless power transmission is performed is a range in which the wireless power transmission has a predetermined power value or more. <12> or <13> A power transmission device for a wireless power supply system.

[0124] <15> The frequency of the wireless power supply is in the 6.78 MHz band or the 13.56 MHz band. <12> ~ <14> A power transmitting device of any one of the wireless power supply systems.

[0125] <16> the current adjustment circuit includes a DC-DC converter, a DA converter, and a digital control circuit, and the digital control circuit provides a set value to the DA converter, varies a feedback voltage of the DC-DC converter, and sets an input voltage; <12> ~ <15> A power transmitting device of any one of the wireless power supply systems.

[0126] <17> the current adjustment circuit includes a constant current circuit using a current mirror; setting the input current using a power transmission control circuit; <12> ~ <16> A power transmitting device of any one of the wireless power supply systems.

[0127] <18> The current detection circuit a shunt resistor connected to a line through which the input current flows; a voltage amplifier that amplifies a voltage obtained from a voltage generated across the shunt resistor; It consists of <12> ~ <17> A power transmitting device of any one of the wireless power supply systems. [Explanation of symbols]

[0128] 10: Wireless power supply system 20: Power transmission equipment 21: Circuit board 22: Electronic parts 29: Cabinet 30: Transmission coil 40: Power transmission circuit 41: Driver circuit 42: Power conversion circuit 43: Power transmission resonance circuit 50: Power transmission control circuit 60: Current detection circuit 70, 70A: Current adjustment circuit 71: DC-DC converter 72: DA converter 74: Current mirror circuit 90: Power receiving device 91: Receiving coil 92: Power receiving circuit 93: Output voltage conversion circuit 94: Power receiving control circuit 98: Cabinet 99: Circuit board 991: Storage battery 201: Input voltage conversion circuit 202: Input filter 290: Interior space 301: Insulating film 302: Ferrite sheet 500: Regulator 911: Insulating film 912: Ferrite sheet 921: Receiving resonance circuit 922: Rectifier circuit 923: Smoothing circuit 924: Resonant modulation circuit 940: Regulator 980:Interior space 981: First member 982: Second member 991: Storage battery 992: Electronic Components 993: Electrode pads 9930: Cable

Claims

1. A wireless power feeding system including a power receiving device and a power transmitting device, wherein an electromagnetic resonance field is formed between the power transmitting device and the power receiving device to feed power wirelessly, and the electromagnetic resonance field is used to transmit a signal by resonance modulation, The power receiving device is a housing having an internal space; a power receiving coil disposed in the internal space and configured to receive power wirelessly by forming the electromagnetic resonance field; a power receiving circuit including a power receiving resonant circuit and a resonant modulation circuit that performs the resonant modulation; a load circuit that performs a predetermined electrical circuit operation using the output power of the power receiving circuit; Equipped with The power transmission device is a power transmission coil that performs wireless power transmission by forming the electromagnetic resonance field; a power transmission circuit having a power transmission resonant circuit; and a power transmission control circuit; a resonant demodulation circuit that performs resonant demodulation corresponding to the resonant modulation; a current detection circuit that detects an input current of the power transmission circuit; a current adjustment circuit that adjusts the input current; Equipped with The power transmission device is The current detection circuit detects a state in which the signal due to the resonance modulation from the power receiving circuit cannot be detected, When the signal cannot be detected, the current adjustment circuit changes the input current, Preventing a state in which the signal cannot be detected and stabilizing the execution operation of the resonance demodulation. Wireless power supply system.

2. the current adjustment circuit changes the input current by changing the input voltage supplied to the power transmission circuit; The wireless power supply system according to claim 1 .

3. the housing of the power receiving device is made of a biocompatible material; the power receiving device is embedded inside a living body, The power transmitting device is placed outside the living body. The wireless power supply system according to claim 1 or 2.

4. The biocompatible material is titanium or a titanium alloy. The wireless power supply system according to claim 3 .

5. the current adjustment circuit controls the input current within a range in which the wireless power transmission is performed. The wireless power supply system according to claim 1 or 2.

6. The range in which the wireless power transmission is performed is a range in which the wireless power transmission has a predetermined power value or more. The wireless power supply system according to claim 1 or 2.

7. The frequency of the wireless power supply is in the 6.78 MHz band or the 13.56 MHz band. The wireless power supply system according to claim 1 or 2.

8. The load circuit includes a sensing circuit, a signal processing circuit, and a wireless communication circuit. The wireless power supply system according to claim 1 or 2.

9. the current adjustment circuit includes a DC-DC converter and a DA converter; the power transmission control circuit provides a set value to the DA converter, varies the feedback voltage of the DC-DC converter, and adjusts the input voltage; The wireless power supply system according to claim 1 or 2.

10. the current adjustment circuit includes a constant current circuit using a current mirror; setting the input current using a power transmission control circuit; The wireless power supply system according to claim 1 or 2.

11. The current detection circuit a shunt resistor connected to a line through which the input current flows; a voltage amplifier that amplifies a voltage obtained from a voltage generated across the shunt resistor; It consists of The wireless power supply system according to claim 1 or 2.

12. A power transmitting device of a wireless power feeding system that forms an electromagnetic resonant field to a power receiving device to feed power wirelessly and transmits a signal by resonance modulation using the electromagnetic resonant field, a power transmission coil that performs wireless power transmission by forming the electromagnetic resonance field; a power transmission circuit having a power transmission resonant circuit; and a power transmission control circuit; a resonant demodulation circuit that performs resonant demodulation corresponding to the resonant modulation; a current detection circuit that detects an input current of the power transmission circuit; a current adjustment circuit that adjusts the input current; Equipped with The current detection circuit detects a state in which the signal generated by the resonance modulation from the power receiving device cannot be detected, When the signal cannot be detected, the current adjustment circuit changes the input current, Preventing a state in which the signal cannot be detected and stabilizing the execution operation of the resonance demodulation. A power transmission device for a wireless power supply system.

13. the current adjustment circuit controls the input current within a range in which the wireless power transmission is performed. The power transmitting device of the wireless power supply system according to claim 12.

14. The range in which the wireless power transmission is performed is a range in which the wireless power transmission has a predetermined power value or more. The power transmitting device of the wireless power supply system according to claim 12 or 13.

15. The frequency of the wireless power supply is in the 6.78 MHz band or the 13.56 MHz band. The power transmitting device of the wireless power supply system according to claim 12 or 13.

16. the current adjustment circuit comprises a DC-DC converter, a DA converter, and a digital control circuit, the digital control circuit giving a set value to the DA converter, varying a feedback voltage of the DC-DC converter, and setting an input voltage; The power transmitting device of the wireless power supply system according to claim 12 or 13.

17. the current adjustment circuit includes a constant current circuit using a current mirror; setting the input current using a power transmission control circuit; The power transmitting device of the wireless power supply system according to claim 12 or 13.

18. The current detection circuit a shunt resistor connected to a line through which the input current flows; a voltage amplifier that amplifies a voltage obtained from a voltage generated across the shunt resistor; It consists of The power transmitting device of the wireless power supply system according to claim 12 or 13.

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