JP2012075249A - Wireless power transmission apparatus and power reception apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless power transmission system that can prevent a reduction in energy transmission efficiency by avoiding using a frequency unsuitable for energy transmission in power transmission.SOLUTION: A power transmitting side circuit unit 11 includes: an open coil 14 for generating an oscillating magnetic field; a resonant frequency switching circuit 15 for changing the frequency of the oscillating magnetic field; a frequency controller 103 for controlling the resonant frequency switching circuit 15 so as to exclude channels (frequency bands) of decreased efficiency of power transmission to a power receiving side from frequencies of the oscillating magnetic field for power transmission; and a control circuit 101 for controlling the frequency controller 103. The control circuit 101 compares information on received power received from the power receiving side via a communication circuit 105 with information on transmitted power transmitted to the power receiving side to identify channels of decreased efficiency of power transmission to the power receiving side, and controls the frequency controller 103 so as to exclude the channels.

Description

  The present invention relates to a wireless power transmission device that wirelessly transmits energy and a power receiving device that receives transmitted energy.

  In recent years, systems that transmit and receive power wirelessly have been studied. Such a system can be used, for example, when electric power is transmitted to an electric vehicle equipped with a rechargeable battery or an assist bicycle. As such a system, for example, a wireless power transmission system based on a magnetic resonance method using magnetic resonance between a coil on a power transmission side and a coil on a power reception side can be used.

  In such a wireless power transmission system, it can be considered that the frequency of magnetic resonance between the coil on the power transmission side and the coil on the power reception side can be appropriately changed (Patent Document 1). If it carries out like this, the frequency of the magnetic resonance between coils can be changed with time, and electric power can be sent. For this reason, for example, even if a third party tries to illegally steal the transmitted power, the frequency of magnetic resonance changes, so that power cannot be received efficiently. Thereby, theft by a third party can be suppressed.

JP 2009-261104 A

  However, even if the frequency of magnetic resonance is changed in this way, a period in which the frequency of power theft by a third party matches the frequency of power transmission in the wireless power transmission system can occur. For this reason, the above system cannot prevent theft in this period.

  Further, depending on the positional relationship between the power transmission side and the power reception side and the surrounding environment, there may be a frequency at which the efficiency of power transmission is significantly reduced. Therefore, it is preferable to avoid power transmission at such a frequency even if there is no theft. However, in the above system, since the frequency is simply changed, power transmission is performed even at a frequency with low transmission efficiency, and the power transmission efficiency can be reduced accordingly.

  The present invention has been made in view of such problems, and a wireless power transmission system capable of preventing a decrease in energy transmission efficiency by avoiding the use of a frequency not suitable for energy transmission for power transmission. The purpose is to provide.

  A first aspect of the present invention relates to a wireless power transmission apparatus that performs power transmission to a power receiving side using magnetic resonance. The wireless power transmission device according to this aspect includes a power transmission coil that generates an oscillating magnetic field, a frequency changing unit for changing the frequency of the oscillating magnetic field, and a frequency at which the efficiency of power transmission to the power receiving side decreases. And a frequency control unit that controls the frequency changing unit so as to be excluded from the frequency of the oscillating magnetic field.

A second aspect of the present invention relates to a power receiving device that receives power from a power transmission side using magnetic resonance. The power receiving device according to this aspect includes a power receiving coil that generates an oscillating magnetic field by the magnetic resonance, a frequency changing unit for changing a frequency of the oscillating magnetic field by the magnetic resonance, and a frequency control unit that controls the frequency changing unit A degradation frequency identification unit that identifies the frequency of the oscillating magnetic field at which power reception efficiency is reduced, and information for removing the frequency identified by the degradation frequency identification unit from the frequency for power transmission to the power transmission side And a communication unit.

  ADVANTAGE OF THE INVENTION According to this invention, the wireless power transmission system which can prevent the fall of the transmission efficiency of energy can be provided by avoiding using the frequency which is not suitable for energy transmission for power transmission.

It is a figure which shows the structure of the wireless power transmission system which concerns on embodiment. It is a block diagram which shows the circuit structure of the power transmission apparatus which concerns on embodiment. It is a block diagram which shows the circuit structure of the power receiving apparatus which concerns on embodiment. It is a block diagram which shows the circuit structure of the power transmission apparatus which concerns on embodiment. It is a block diagram which shows the circuit structure of the power receiving apparatus which concerns on embodiment. It is a flowchart which shows the process at the time of the power transmission / reception which concerns on embodiment. It is a timing chart which shows the flow of the power transmission and power receiving which concern on embodiment. It is a figure which shows the frequency table and non-use frequency list which concern on embodiment. It is a flowchart which shows the change process of the power transmission frequency which concerns on embodiment. It is a flowchart which shows the invalidation process of the frequency which concerns on embodiment. It is a figure which shows the structure of the log | history table of the power transmission efficiency which concerns on embodiment. It is a figure which shows the example of an update of the frequency table which concerns on embodiment. It is a figure which shows the example of an update of the frequency table which concerns on embodiment. It is a flowchart which shows the reset process of the frequency which concerns on embodiment. It is a figure which shows the example of an update of the frequency table which concerns on embodiment. It is a figure which shows the structure of the frequency switching circuit which concerns on the example 1 of a change. It is a figure which shows the structure of the log | history table of the received electric power which concerns on the example 2 of a change. 10 is a flowchart illustrating frequency invalidation processing according to a second modification.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a wireless power transmission system for an assist bicycle (hereinafter referred to as a bicycle).

  FIG. 1 is a diagram showing a configuration of a wireless power transmission system according to the present embodiment.

  The wireless power transmission system according to the present embodiment charges from the power transmission device 10 side (power transmission side) to the bicycle 20 side (power reception side) using magnetic resonance between the power transmission side coil and the power reception side coil. Is a system for sending power for. The power transmission device 10 is installed in a bicycle parking lot, for example.

  The power transmission device 10 includes a circuit unit 11, a power transmission unit 12, a support 13, an open coil 14, and a resonance frequency switching circuit 15.

  As shown in FIG. 1, the bicycle 20 is parked at the front position of the power transmission device 10 so as to face the power transmission device 10.

  The circuit unit 11 is disposed on the base portion of the power transmission device 10. The circuit unit 11 is provided with a circuit for performing power transmission.

The power transmission unit 12 is supported by the support column 13. The power transmission unit 12 faces the front direction of the power transmission device 10 at a position substantially the same height as the front car 25 of the bicycle 20. When viewed from the front, the power transmission unit 12 has a substantially rectangular outer diameter, and the size of the power transmission unit 12 is substantially the same as that of the front basket 25 of the bicycle 20.

  Further, a tire stop 13 a is extended on the support column 13. When the front wheel 28 of the bicycle 20 is fixed by the tire stopper 13a as shown in FIG. 1, the power transmission unit 12 and the front surface of the front car 25 are substantially directly opposed to each other.

  The open coil 14 and the resonance frequency switching circuit 15 are accommodated in the power transmission unit 12. The open coil 14 is a resonance coil wound in a square shape and having both ends open. During power transmission, an oscillating magnetic field that vibrates at a predetermined frequency is generated from the open coil 14.

  The resonance frequency switching circuit 15 is a circuit for changing the self-resonance frequency of the open coil 14. The resonance frequency switching circuit 15 receives power for power transmission from the circuit unit 11 and supplies the received power to the open coil 14 by electromagnetic induction.

  The bicycle 20 includes a motor 21, a battery unit 22, a main body frame 23, a headlamp 24, a front car 25, an open coil 26, a resonance frequency switching circuit 27, and a front wheel 28.

  Electric power is supplied to the motor 21 from the battery unit 22. When the motor 21 is driven by this electric power, the driving force of the motor 21 is transmitted to the pedal crankshaft. Thereby, the bicycle 20 can be run with a propulsive force larger than the force with which the user steps on the pedal of the bicycle 20. The electric power of the battery unit 22 is supplied to other electric components such as the headlamp 24 in addition to the motor 21.

  A housing portion is provided on the front surface of the front basket 25 of the bicycle 20, and an open coil 26 and a resonance frequency switching circuit 27 are housed in the housing portion.

  The open coil 26 is a resonant coil wound in a square shape and having both ends open. The central axis of the open coil 26 faces the front direction of the bicycle 20. As described above, when the front wheel 28 of the bicycle 20 is fixed to the tire stopper 13a, the central axis of the open coil 26 substantially coincides with the central axis of the open coil 14 on the power transmission side. At the same time, the distance between these two coils is also kept substantially constant.

  The resonance frequency switching circuit 27 includes a circuit for changing the self-resonance frequency of the open coil 26. The resonance frequency switching circuit 27 includes an excitation coil for taking out the electric power received by the open coil 26 by electromagnetic induction, and a rectifier that rectifies the taken-out electric power. The rectified power is supplied from the resonance frequency switching circuit 27 to the battery unit 22 via the cable.

  By properly maintaining the positional relationship and distance between the power transmission unit 12 and the front car 25, the positional relationship and distance between the open coils 14 and 26 are appropriately maintained. Thereby, the power transmission efficiency at the time of charge is maintained appropriately.

  Each of the open coils 14 and 26 is an LC resonance circuit including the coil's line capacitance as an electrostatic capacitance. The coil portions of the open coils 14 and 26 are each fixed by a predetermined member. As a result, the shapes of these coils are less likely to change, and the change in the self-resonant frequency due to the change in the line capacitance is reduced.

FIG. 2 is a diagram illustrating a circuit configuration of the open coil 14 and the resonance frequency switching circuit 15 on the power transmission side.

  The resonance frequency switching circuit 15 includes a variable capacitance diode 151 and an excitation coil 152.

  As shown in FIG. 2, the variable capacitance diode 151 is connected to the open coil 14 so as to close both ends of the open coil 14. Therefore, the open coil 14 and the variable capacitance diode 151 form an LC resonance circuit.

  The variable capacitance diode 151 is a diode whose capacitance can be changed by changing the bias voltage. Therefore, the self-resonant frequency of the LC resonance circuit formed by the open coil 14 and the variable capacitance diode 151 (hereinafter referred to as “resonance frequency of the open coil 14” for simplicity) is variable.

  During power transmission, an alternating current that vibrates at the resonance frequency of the open coil 14 is applied to the excitation coil 152. As a result, an AC magnetic field is generated in the excitation coil 152, and AC power is supplied from the excitation coil 152 to the open coil 14 by electromagnetic induction. Thereby, the open coil 14 generates an oscillating magnetic field that oscillates at the resonance frequency.

  FIG. 3 is a diagram illustrating a circuit configuration of the open coil 26 and the resonance frequency switching circuit 27 on the power receiving side.

  The resonance frequency switching circuit 27 includes a variable capacitance diode 271, an excitation coil 272, and a rectifier 273.

  As shown in FIG. 3, the variable capacitance diode 271 is connected to the open coil 26 so as to close both ends of the open coil 26. Therefore, the open coil 26 and the variable capacitance diode 271 form an LC resonance circuit 40.

  The self-resonant frequency of the LC resonant circuit 40 (hereinafter referred to as “resonant frequency of the open coil 26” for simplicity) can be changed by changing the bias voltage.

  At the time of charging, the resonance frequency of the open coil 26 is set to be the same as the frequency of the oscillating magnetic field from the power transmission device 10. As a result, the open coil 26 magnetically resonates with the open coil 14 on the power transmission side, and an oscillating magnetic field with the corresponding frequency is generated in the open coil 26.

  By this oscillating magnetic field, an alternating current based on electromagnetic induction is excited in the excitation coil 272, and the power transmitted from the power transmission device 10 is received by the excitation coil 272. The alternating current excited in the excitation coil 272 is rectified by the rectifier 273, and the rectified power is supplied to the battery unit 22 of FIG.

  During charging, the open coil 26 on the power receiving side receives power by magnetic resonance with the open coil 14 on the power transmission side. The electric power received by the open coil 26 is output to the battery unit 22 via the excitation coil 272 and the rectifier 273 of the resonance frequency switching circuit 27, and is supplied to the battery 204 in the battery unit 22. In this way, charging is performed.

  4 and 5 are diagrams illustrating a circuit configuration of the wireless power transmission system. FIG. 4 is a diagram illustrating a circuit configuration of the circuit unit 11. FIG. 5 is a diagram illustrating a circuit configuration of the battery unit 22.

  With reference to FIG. 4, the circuit unit 11 includes a control circuit 101, a power conversion circuit 102, a frequency control device 103, a transmitted power measurement circuit 104, a communication circuit 105, a communication antenna 106, and a storage circuit 107. In the figure, the open coil 14 and the resonance frequency switching circuit 15 are arranged in the power transmission section 12 shown in FIG.

  The control circuit 101 controls each unit for power transmission.

  Based on the control signal from the control circuit 101, the power conversion circuit 102 converts the power supplied from the power supply 108 into the frequency and output power specified by the control circuit 101, and converts the converted power into transmission power. Output to the resonance frequency switching circuit 15 via the measurement circuit 104. The power conversion circuit 102 supplies power to other electrical components of the power transmission apparatus 10 in addition to the resonance frequency switching circuit 15.

  The frequency control device 103 sets the resonance frequency of the open coil 14 to a target value based on the control signal from the control circuit 101. Specifically, when the frequency control device 103 receives a control signal for setting the resonance frequency to a certain value from the control circuit 101, the resonance frequency of the open coil 14 becomes a value specified by the control circuit 101. Then, an appropriate bias voltage is applied to the variable capacitance diode 151 of the resonance frequency switching circuit 15. In this way, the resonance frequency of the open coil 14 is set.

  The transmitted power measurement circuit 104 measures the power for power transmission input to the resonance frequency switching circuit 15 and supplies the measured value to the control circuit 101. The control circuit 101 writes the received measurement value in the storage circuit 107.

  The communication circuit 105 is a circuit for performing wireless communication with the power receiving side via the communication antenna 106. The communication circuit 105 transmits and receives various information signals to and from the power receiving side based on the control signal from the control circuit 101. For example, at the time of charging, the control circuit 101 transmits information related to the resonance frequency for power transmission to the power receiving side, and the measured value of the power received on the power receiving side or the charging status of the battery 204 Relevant information is received from the power receiving side.

  The storage circuit 107 is a circuit for storing necessary information when the control circuit 101 controls each unit. The storage circuit 107 stores data such as authentication processing before power transmission as well as information used during power transmission.

  The power source 108 that supplies input to the power conversion circuit 102 may be a commercial power source or a DC power source such as a solar power generation system. Other power sources may be used.

  Referring to FIG. 5, the battery unit 22 includes a control circuit 201, a frequency control device 202, a battery management circuit 203, a battery 204, a received power measurement circuit 205, a communication circuit 206, a communication antenna 207, and a storage circuit 208. . As shown in FIG. 1, the open coil 26 and the resonance frequency switching circuit 27 are arranged in a housing portion on the front surface of the front car 25.

  The control circuit 201 controls the operation of the entire device on the power receiving side.

  The frequency control device 202 controls the resonance frequency switching circuit 27 in accordance with a control signal received from the control circuit 201. Specifically, when receiving a control signal for setting the resonance frequency of the open coil 26 to a certain value from the control circuit 201, the frequency control device 202 sets the resonance frequency of the open coil 26 to a value designated by the control circuit 201. Thus, the bias voltage of the variable capacitance diode 271 disposed in the resonance frequency switching circuit 27 is set.

  The battery management circuit 203 manages the charging, output, and the like of the battery 204 based on the control signal from the control circuit 201 and the remaining power of the battery 204. At the time of charging, the battery management circuit 203 relays the power for charging supplied from the resonance frequency switching circuit 27 to the battery 204. Further, the battery management circuit 203 supplies the control circuit 201 with information related to battery management such as the remaining power of the battery 204 and the output voltage. The battery management circuit 203 also performs control related to output of electric power to electric components such as the headlamp 24 disposed on the bicycle 20.

  The received power measuring circuit 205 measures the power for charging output from the resonance frequency switching circuit 27 and transmits the measured value to the control circuit 201. The control circuit 201 writes the received measurement value in the storage circuit 208 and transmits the measurement value to the power transmission side via the communication circuit 206.

  The communication circuit 206 performs wireless communication with the power transmission side via the communication antenna 207. The communication circuit 206 transmits and receives various types of information to and from the power transmission side by wireless communication based on the control signal from the control circuit 201.

  The storage circuit 208 stores information necessary for the control circuit 201 to control each unit. The storage circuit 208 stores data necessary for authentication processing before charging, in addition to information used during charging.

  When the user starts charging the bicycle 20, an operation for starting charging is performed using an operation unit (not shown) or a display screen (not shown) arranged in the power transmission device 10. Is done. As necessary, the user performs authentication procedures, payment of charges for charging (payment with small change or banknotes, payment with a prepaid card, payment with a credit card, etc.) and the like.

  On the power transmission side and the power reception side, after the process before the start of charging is normally completed, the control circuit 101 on the power transmission side starts a process related to power transmission. At the same time, the control circuit 201 on the power reception side starts processing for power reception and charging.

  Power transmission from the power transmission side is performed when the amount of charge of the battery 204 of the bicycle 20 (power receiving side) reaches a target amount, when the amount of transmitted or received power reaches a predetermined amount, or when the power transmission time is a predetermined amount. It ends when the time is reached. The control circuit 101 determines termination based on information obtained from each circuit unit of the circuit unit 11 or information obtained from the power receiving side via wireless communication.

  Information exchange in these processes is performed by wireless communication via the communication antennas 106 and 207. Such wireless communication between the power transmission side and the power reception side is performed by encrypting information.

  In the present embodiment, power transmission is performed by switching a frequency band including a total of eight channels from the first channel (1ch) to the eighth channel (8ch) as needed. Here, the frequency continues from the first channel (1ch) to the eighth channel (8ch) without any gap, and the center frequency of the entire frequency band is several tens of MHz. The frequency width of each channel is fixed to several hundred kHz. However, the number of channels and the frequency width of each channel are not limited to the above.

FIG. 6 is a flowchart showing processing performed by the power transmission side and the power reception side according to the present embodiment. FIG. 6A is a flowchart illustrating processing performed by the power transmission device 10 for power transmission. FIG. 6B is a flowchart illustrating processing performed by the battery unit 22 for power reception.

  Referring to FIG. 6 (a), the control circuit 101 (see FIG. 4) on the power transmission side firstly sets the resonance frequency of the open coil 14 to any frequency of the first channel (1ch) to the eighth channel (8ch). The frequency control device 103 is controlled so as to become (S101). Next, the control circuit 101 controls the power conversion circuit 102 so that the frequency of the transmission power (AC power) matches the resonance frequency of the open coil 14 (S102), and further the magnitude of the transmission power (AC power). The power conversion circuit 102 is controlled so that the length (amplitude) becomes a predetermined magnitude (S103).

  After the setting for power transmission is performed in this way, the power conversion circuit 102 outputs power at a frequency and magnitude set by the control circuit 101 for a predetermined period (S104). As a result, an oscillating magnetic field having the frequency set in S101 is generated in the open coil 14, and power is transmitted to the power receiving side by magnetic resonance.

  At the time of such power output, the power output from the power conversion circuit 102 is measured by the transmission power measurement circuit 104, and the measured value is supplied to the control circuit 101. When one cycle of power transmission processing is thus completed, the process returns to S101, and the next cycle of power transmission processing is similarly performed.

  Referring to FIG. 6B, the power receiving side control circuit 201 (see FIG. 5) has a frequency control device 202 so that the resonance frequency of the open coil 26 is the same as the resonance frequency of the open coil 14 on the power transmission side. Is controlled (S201). Thereby, the resonance frequency of the open coil 14 is adjusted by the resonance frequency switching circuit 27.

  Thereafter, the resonance frequency switching circuit 27 receives power in response to the transmission of power from the power transmission side (S202). That is, the open coil 26 on the power receiving side is magnetically coupled to the oscillating magnetic field generated in the open coil 14 on the power transmission side, and an oscillating magnetic field is generated in the open coil 26. By this oscillating magnetic field, an alternating current based on electromagnetic induction is excited in the excitation coil 272 (see FIG. 3), and the excited alternating current is rectified by the rectifier 273. The rectified current is output to the battery management circuit 203 via the received power measuring circuit 205. In this way, power is received.

  At the time of such power reception, the power output from the resonance frequency switching circuit 27 (rectifier 273) is measured by the received power measuring circuit 205, and the measured value is supplied to the control circuit 201. When one cycle of power transmission processing is thus completed, the process returns to S201, and the next cycle of power transmission processing is similarly performed.

  FIG. 7 is a timing chart schematically showing the passage of time of power transmission processing on the power transmission side and the power reception side. The first, second, and third stages from the top of FIG. 7 schematically show the transmission power on the power transmission side, the transmission frequency, and the timer time. Further, the fourth, fifth, and sixth stages from the top of FIG. 7 schematically show the received power on the power receiving side, the power receiving frequency, and the timer time. One cycle in the processing flow in FIGS. 6A and 6B corresponds to T1 in FIG.

In the present embodiment, the frequency on the power transmission side (the resonance frequency of the open coil 14 and the frequency of the AC power of the power conversion circuit 102) and the frequency on the power reception side (the resonance frequency of the open coil 26) are changed every three cycles. The The power transmission side control circuit 101 and the power reception side control circuit 201 each include a timer, and the timers are synchronized with each other. Such synchronization adjustment is performed by performing wireless communication for synchronization between the communication circuit 105 on the power transmission side and the communication circuit 206 on the power reception side. The control circuit 101 on the power transmission side and the control circuit 201 on the power reception side switch the frequency band (channel) used for power transmission and reception each time each timer measures T (3 × T1).

  Here, frequency switching is performed based on a common frequency table held by each of the power transmission side and the power reception side.

  FIG. 8A is a diagram showing the configuration of the frequency table. As shown in the figure, in the frequency table, frequency bands (channels) used for power transmission and reception and effective periods of the respective frequency bands are ranked and held. Power transmission and power reception are used in order from the highest frequency band. When the frequency band used for power transmission and reception reaches the lowest frequency band, the frequency band returns to the highest frequency band. In the example of FIG. 8A, the frequency band used for power transmission and reception is switched in the order of 8 ch → 6 ch → 1 ch → 2 ch → 5 ch → 3 ch → 8 ch. In the present embodiment, the usage period of each channel is fixed at T (T = 3 × T1). However, the usage period of each channel may be set to be different from each other.

  The frequency table is generated by the control circuit 101 on the power transmission side. The generated frequency table is stored in the storage circuit 107 on the power transmission side, and is simultaneously transferred to the power reception side via the communication circuit 105. The power receiving control circuit 201 stores the frequency table received via the communication circuit 206 in the storage circuit 208. Thus, a common frequency table is held on the power transmission side and the power reception side.

  The frequency table thus shared is used on the power transmission side and the power reception side until the power transmission side control circuit 101 updates the frequency table. The control circuit 101 on the power transmission side updates the frequency table when the power transmission efficiency of the power is significantly reduced in any one of the frequency bands (channels) included in the frequency table. The updated frequency table does not include a frequency band (channel) in which the power transmission efficiency is significantly reduced. The control circuit 101 adds a frequency band (channel) in which power transmission efficiency is significantly reduced to the unused frequency list. The unused frequency list is stored in the storage circuit 107 on the power transmission side.

  FIG. 8B is a diagram showing the configuration of the unused frequency list. As shown in the figure, the unused frequency list holds frequency bands (channels) that are not used and times when the frequency bands (channels) are not used.

  When updating the frequency table, a new frequency table is generated from a frequency band (channel) excluding the frequency band (channel) listed in the unused frequency list. The generated new frequency table is stored in the storage circuit 107 on the power transmission side, and is simultaneously transferred to the power reception side via the communication circuit 105. The power receiving side control circuit 201 stores the new frequency table received via the communication circuit 206 in the storage circuit 208. In this way, new frequency tables are held on the power transmission side and the power reception side. In the power transmission side storage circuit 107 and the power reception side storage circuit 208, the new frequency table is stored in a storage area different from the frequency table currently in use.

  Thus, when the new frequency table is stored in the storage circuit 107 on the power transmission side and the storage circuit 208 on the power reception side, the update flags (see FIG. 8C) held in the storage circuits 107 and 208 are respectively 0. Is changed to 1. The control circuits 101 and 201 can identify whether a new frequency table has been generated by referring to the update flag. The update flag is set to a value of 0 by default.

At the start of charging, an unused frequency band (channel) is not registered in the unused frequency list. Therefore, the control circuit 101 generates a frequency table by arranging all channels (ch1 to ch8) randomly or pseudo-randomly. Thereafter, when an unused channel is registered in the unused frequency list, the control circuit 101 generates a new frequency table from the remaining channels excluding this channel.

  Note that the length of the generated frequency table (the number of frequency bands included in the frequency table) may be constant or may be different every time it is generated. The frequency table may include a plurality of the same channel numbers.

<Frequency change processing>
FIG. 9 is a flowchart showing frequency change processing during power transmission. Note that the frequency changing process is performed in the control circuit 101 on the power transmission side and the control circuit 201 on the power reception side, respectively. Hereinafter, for the sake of convenience, the description will be given as processing performed in the control circuit 101 on the power transmission side.

  First, the control circuit 101 assigns 1 to a variable i as an initial process (S301). At the same time, the control circuit 101 resets and starts the timer (S302). Then, the control circuit 101 refers to the i-th rank in the frequency table (see FIG. 8A) held in the storage circuit 107, and sets the frequency band of the channel of this rank to the frequency band used for power transmission. (S303).

  For example, in the frequency table shown in FIG. 8A, the channel when the rank is 1 is 8ch. In this case, the control circuit 101 sets the channel used for power transmission to ch8.

The channel thus set is maintained until the time measured by the timer reaches T (T = 3 × T1: see FIG. 7) (S304: NO). When the time measured by the timer reaches T (S304: YES), the process proceeds to step S305, and the channel (frequency band) used for power transmission.
A process for switching is performed.

  In step S305, the control circuit 101 determines whether a new frequency table is registered in the storage circuit 107 (S305). Specifically, if the value of the update flag (see FIG. 8C) held in the storage circuit 107 is 0, the control circuit 101 determines that a new frequency table is not registered (S305: NO). ), And proceeds to the next step (S306). If the value of the update flag is 1, the control circuit 101 determines that a new frequency table is registered (S305: YES), and proceeds to the frequency table update process (S308).

  When a new frequency table is not registered (S305: NO), the control circuit 101 determines whether or not the variable i has reached k (S306). Here, k is the lowest rank in the frequency table currently in use. That is, k = 6 in the frequency table of FIG.

  If the variable i has not reached k (S306: NO), 1 is added to the variable i (S307), and the process proceeds to step S302. As a result, the channel (frequency band) used for power transmission is switched to the channel of the next rank in the currently used frequency table (S302 to S304).

On the other hand, when the variable i reaches k (S306: YES), the variable i is set to 1 (S301), and the process proceeds to step S302. As a result, the channel (frequency band) used for power transmission is switched to the highest-order channel in the currently used frequency table (
S302 to S304).

  In this way, the control circuit 101 sequentially switches the channel (frequency band) used for power transmission to the channel (frequency band) listed in the frequency table every time T. When the lowest channel of the frequency table is used for power transmission, the frequency band for power transmission is set again in order from the highest channel.

  If it is determined in step S305 that a new frequency table is registered (S213: NO), the control circuit 101 performs processing for updating the frequency table used for power transmission (S308). That is, in step S308, the control circuit 101 overwrites the new frequency table in the storage area of the currently used frequency table set in the storage circuit 107, and sets the update flag to 0.

  Thus, when the update process of the frequency table is completed, the variable i is set to 1 (S301), and the process proceeds to step S302. Thereby, the channel (frequency band) used for power transmission is switched to the highest-order channel in the new frequency table (S302 to S304). Thereafter, the channel (frequency band) is switched using the new frequency table until the update flag is set to 1 again.

<Abnormality detection>
By the way, in the present embodiment, as described above, when the power transmission efficiency is significantly reduced in any frequency band (channel) included in the frequency table in use, a new frequency table is created. Then, power transmission is performed using the generated new frequency table. Hereinafter, processing when generating a new frequency table will be described.

  FIG. 10A is a flowchart showing a process for detecting an abnormality during power transmission. In addition, the process by the flowchart of the figure is performed about the power transmission in period T1 of FIG. That is, the process according to the flowchart of FIG. 10A is performed for one cycle of power transmission (see FIG. 6A) performed by a predetermined channel (frequency band).

  With reference to Fig.10 (a), the control circuit 101 acquires the measured value P1 of the electric power in the period T1 measured by the transmitted power measurement circuit 104 at the time of power transmission (S401). In addition, the control circuit 101 acquires the measured power value P2 in the period T1 measured by the received power measurement circuit 205 on the power receiving side according to the power transmission via the communication circuit 105 (S402). Further, the control circuit 101 calculates the transmission efficiency η (η = P2 / P1) in the period T1 from the ratio between the acquired transmission power value P1 and the received power value P2 (S403). Then, the control circuit 101 stores the power transmission efficiency η thus obtained as history information in the history table of the storage circuit 107 (S404).

  FIG. 11 is a diagram showing the configuration of the history table. As shown in the drawing, the history of power transmission efficiency η in the period T1 is stored for each channel in the history table. For example, when the power transmission channel is switched according to the frequency table of FIG. 8A, the transmission efficiency η of each channel is obtained in the order of 8ch → 6ch → 1ch → 2ch → 5ch → 3ch → 8ch. The determined power transmission efficiency η is stored as the history of the corresponding channel in the history table. Here, since the frequency band of each channel is used for power transmission for three cycles (3 × T1), the power transmission efficiency η is obtained three times for each channel, and the three times of power transmission efficiency η are stored in the history table. The

Returning to FIG. 10, when the control circuit 101 stores the transmission efficiency η for one cycle (T1) in the history table in this way, the channel ((1) used in the cycle depends on whether the transmission efficiency η is below the threshold value η0). It is determined whether or not there is an abnormality in the power transmission status by (frequency band) (S405).

  When η ≧ η0, the control circuit 101 determines that there is no abnormality in the power transmission status (S445: NO), and ends the abnormality detection process in the cycle (T1). On the other hand, if η <η0, the control circuit 101 determines that there is an abnormality in the power transmission status (S405: YES), and determines whether to invalidate the channel (frequency band) used in the cycle (S406). ).

  The threshold η0 is, for example, a value obtained by subtracting a predetermined value from the average value of the transmission efficiency η of each channel stored in the history table, or a value obtained by multiplying the average value by a predetermined ratio less than a predetermined value 1. Set as Alternatively, for example, a predetermined constant may be set as the threshold η0. However, in this case, there is a possibility that the threshold value η0 is not appropriate due to aging deterioration of the power receiving side or power transmission side device, a temporary change in the surrounding environment, and the like. On the other hand, as described above, when the threshold value η0 is set based on the statistical analysis data of the average value, the power transmission efficiency changes over all channels due to aging, temporary changes in the surrounding environment, and the like. Even if it does, abnormality determination (S221) can be appropriately performed using threshold value (eta) 0.

  The update of the threshold value η0 performed by the control circuit 101 may be performed every time the power transmission efficiency η is calculated, or may be performed every time the power transmission efficiency η is calculated twice or more. Note that the number of power transmission efficiencies stored in the history table is relatively small at the start or immediately after charging. Therefore, statistical data such as an average value of power transmission efficiency may be unstable. For this reason, the default threshold value η0 may be used at the start of charging or for a certain period immediately after that, or the abnormality detection process of FIG. 10A may not be performed. By not performing abnormality detection processing for a certain period after the start of charging, erroneous detection of abnormality by the control circuit 101 can be avoided.

<Invalidation determination process>
FIG. 10B is a flowchart for explaining the invalidation determination process in step S406 of FIG.

  First, the control circuit 101 acquires, from the history table, the power transmission efficiency η from the most recent to N times for the determination target channel (S501). Next, the control circuit 101 determines whether the channel to be determined should be invalidated depending on whether the power transmission efficiency η up to N times before is less than the threshold value η0 (S502).

  When any of the transmission efficiency η up to N times before is not less than the threshold η0 (S502: NO), the control circuit 101 suspends invalidation of the channel to be determined, and performs the process for the cycle (T1). finish. On the other hand, if all of the transmission efficiencies η up to N times before are less than the threshold η0 (S502: YES), the control circuit 101 proceeds to step S503 and performs a process of invalidating the determination target channel.

  In the process of step S503, the control circuit 101 registers the channel to be determined together with the current time in the unused frequency list of FIG. 8B (S503). Further, the control circuit 101 generates a new frequency table from channels not registered in the unused frequency list (S504), and simultaneously sets the update flag to 1 (S505). As described above, the frequency table generated in this way is used as a frequency table for power transmission in the frequency table changing process (S308) in the flowchart of FIG.

Note that the invalidation determination in step S502 may be performed based on other conditions. For example, the determination condition in step S502 may be that not all of the transmission power efficiency η of the past N times of the determination target channel but a certain number or more of the power transmission efficiency η is less than the threshold value η0. Alternatively, the determination condition in step S502 may be that the average value of power transmission efficiency η in the past N times of the channel to be determined is less than the threshold value η0. Further, the threshold used in step S502 may be another threshold instead of the threshold η0 used in step S405 of FIG. For example, a value obtained by adding or subtracting a numerical value from the threshold value η0 used in step S405 in FIG. 10A may be used as the threshold value in step S502.

  Note that the transmission power value P1 or the received power value P2 acquired by the control circuit 101 in order to calculate the transmission efficiency P1 / P2 may be an abnormal value, that is, a value that is extremely outside the normally assumed range. In this case, the transmission efficiency η (η = P1 / P2) calculated based on these measured values P1 and P2 is not added to the history table, and is excluded from the determination target in step S405. Also good. By doing so, the threshold value η0 can be made more appropriate. Further, unnecessary abnormality detection processing can be avoided, and the reliability of invalidation determination processing can be improved.

<Update example of frequency table>
FIG. 12 is a diagram illustrating an example of updating the frequency table. FIG. 4A shows an example of a frequency table before update, and FIG. 4B shows an example of a new frequency table after update. Here, the frequency table is circulated with 6T as one cycle. Before the update, three channels of 2ch, 4ch, and 7ch are registered in the unused frequency list, and a frequency table is generated from the 5 channels of 1ch, 3ch, 5ch, 6ch, and 8ch. In FIG. 2A, the channel (frequency band) used for power transmission is hatched.

  In this example, the 6ch frequency band is invalidated by the processing of the flowchart of FIG. The frequency table shown in FIG. 12A includes two invalid channels (301 and 302 in FIG. 12). The new frequency table is generated, for example, by replacing the two channels 301 and 302 with other channels that are not invalidated, either randomly or pseudo-randomly. In the example of FIG. 12B, the two channels (301, 302) are replaced with 1ch (311) and 3ch (312), respectively, and a new frequency table is generated.

  Note that the new frequency table can also be generated by methods other than those described above. For example, as shown in FIG. 13B, a new frequency table may be created by simply deleting the invalidated channel. In this case, the cycle of the new frequency table is shortened by 2T compared to the frequency table before the update because the two channels (301, 302) in FIG.

  Also, the new frequency table need not be generated based on the frequency table before update. That is, a completely new frequency table may be generated from channels other than those registered in the unused frequency list. For example, a frequency table having a desired length can be created by arranging all channels not listed in the unused frequency list in a random or pseudo-random manner.

<Return processing>
FIG. 14A is a flowchart showing a process for returning a channel registered in the unused frequency list as described above to a usable state.

In this process, the control circuit 101 acquires the current time from time to time (S601), and acquires the elapsed time ΔD from the unused time of each channel registered in the unused frequency list to the current time (S601). Further, the control circuit 101 determines whether or not the elapsed time ΔD acquired for each channel is equal to or greater than a predetermined time D0 (S603). In this determination, if there is a channel satisfying ΔD ≧ D0 (S603: YES), the control circuit 101 deletes the channel from the unused frequency list (S604). As a result, the channel for which the time D0 or more has elapsed from the non-use time returns to the usable state.

  When the unused channel returns to the usable state, a new frequency table including the recovered channel is generated at the next update timing.

  FIG. 15 is a diagram illustrating a generation example of a new frequency table when a channel is returned to a use state. FIGS. 12A and 12B are examples of generating new tables when the sixth channel is invalidated and the second channel is restored in the examples of FIGS. 12A and 13A, respectively. Is shown.

  In FIG. 12A, the channels (301, 302) in FIG. 12A are replaced with the restored second channels, and a new frequency table is generated. Also, in FIG. 13B, the channel (301, 302) in FIG. 13A is deleted, and the restored second channel is added, thereby generating a new frequency table.

  Even when the channel is restored in this way, a new frequency table need not be generated based on the frequency table before the update. That is, a completely new frequency table may be generated from channels other than those registered in the unused frequency list. For example, a frequency table having a desired length can be created by arranging all channels not listed in the unused frequency list in a random or pseudo-random manner.

  In the restoration process of FIG. 14 (a), since the unused channel is restored to the usable state based on the elapsed time from the unused time, the transmission on the channel is still performed after the restoration. It can happen that the efficiency is low. However, in such a case, the restored channel is registered again in the unused frequency list by the processing of FIG. 10, and is set to the unused state. For this reason, no problem occurs even if the unused channel is returned to the usable state based on the elapsed time from the unused time.

  Note that the return process may be changed as shown in FIG. In this process, steps S611 to S613 are added as compared to FIG. That is, the control circuit 101 tries to transmit power through a channel whose elapsed time from the non-use time is equal to or longer than the time D0 (S611). At this time, power transmission using the frequency table is temporarily interrupted. In this trial, if the transmission efficiency η of power transmission by the channel is improved, that is, if η <η0 is not satisfied (S612: YES), the control circuit 101 selects the channel from the unused frequency list. It is deleted (S604). On the other hand, if the transmission efficiency η of power transmission through the channel is not improved, that is, if η <η0 (S612: NO), the control circuit 101 sets the unused time of the channel in the unused frequency list to the current time. (S613).

  According to the return process of FIG. 14B, it is further confirmed whether or not the power transmission efficiency has improved for the channel to be returned to the usable state, so that a more appropriate return process can be realized.

In FIG. 14B, when the elapsed time from the non-use time becomes equal to or greater than the predetermined time D0, power transmission is attempted using the non-use channel. Instead, a predetermined time is used. It may be performed at intervals, for example, every few minutes to several hours, or when the number of channels registered in the unused frequency list increases too much. Alternatively, after charging of one bicycle is completed, when charging to another bicycle is started, an attempt to transmit power through an unused channel may be performed.

  As described above, according to the present embodiment, since the frequency band in which the efficiency of power transmission to the power receiving side is reduced is excluded from the frequency band for power transmission, power transmission can be performed efficiently. For example, when power theft occurs, the efficiency of power transmission to the power receiving side decreases, and the frequency at this time is excluded from the frequency for power transmission. For this reason, it is possible to more reliably avoid theft.

  Moreover, according to this Embodiment, since the return process of the frequency which is not used is performed, it can prevent that the frequency band which is not used for electric power transmission increases too much. Therefore, it is possible to prevent a decrease in frequency bands that can be used for power transmission, and it is possible to use many frequency bands for power transmission. As a result, it is possible to prevent a decrease in power transmission efficiency as a whole.

  Further, according to the present embodiment, encrypted communication is used when performing wireless communication. This makes it difficult for a third party to know information regarding the frequency used for power transmission, and makes it more difficult for the third party to steal power. As a result, it is possible to prevent a decrease in power transmission efficiency as a whole.

<Modification 1>
In the above embodiment, the open coils 14, 26 are adjusted by adjusting the bias voltages applied to the variable capacitors 151, by adjusting the capacitances of the variable capacitors 151, 271 connected to both ends of the open coils 14, 26. The resonance frequency of was changed. On the other hand, in this modified example, the resonance frequency of the open coils 14 and 26 is changed by switching the connection state of the plurality of capacitance elements by switching.

  FIGS. 16A, 16B, and 16C are circuit diagrams illustrating this modification. Although the circuit configuration for the open coil 14 on the power transmission side is shown in the figure, the open coil 26 on the power receiving side is configured similarly.

  In FIG. 16A, three variable capacitance diodes 161a, 161b, 161c and three switches 162a, 162b, 162c are connected in parallel to the open coil. The frequency control device 103 performs opening / closing (ON / OFF) of the switches 162 a, 162 b, and 162 c based on a control signal transmitted from the control circuit 101.

  In this modification, no bias voltage is applied to the variable capacitance diodes 161a, 161b, and 161c, and each variable capacitance diode plays the same role as a capacitor. The capacitances of the variable capacitance diodes 161a, 161b, and 161c are different from each other. The open coil 14 and the variable capacitance diodes 161a, 161b, and 161c form an LC resonance circuit.

  By changing the on / off combination of the switches 162a, 162b, and 162c, eight different resonance frequencies are realized. Here, the number of variable capacitance diodes is three, but may be two or four or more.

In FIG. 14B, three capacitors 163a, 163b, 163c and three switches 164a, 164b, 164c are connected in parallel. Also in this configuration, the capacitances of the capacitors 163a, 163b, and 163c are different from each other. Therefore, also in this configuration, as in the case of FIG. 8A, eight different resonance frequencies are realized by changing the on / off combinations of the switches 164a, 164b, and 164c. The number of capacitors 163a, 163b, and 163c arranged in parallel is not limited to three, and may be two or four or more.

  In FIG. 14C, three inductors 165a, 165b, 165c and switches 166a, 166b, 166c are connected in series. In this configuration, the inductances of the inductors 165a, 165b, and 165c are different from each other. Therefore, in this configuration as well, in the same way as in the cases (a) and (b) of the figure, eight different resonance frequencies can be realized by changing the on / off combinations of the switches 166a, 166b, and 166c. . The number of inductors 165a, 165b, and 165c arranged in series is not limited to three, and may be two or four or more.

<Modification 2>
In the above-described embodiment, whether or not to use the frequency used for power transmission in the unused frequency list is determined by the control circuit 101 on the power transmission side based on the power transmission efficiency. In this modification, the control circuit 201 on the power receiving side determines whether or not to place the frequency used for power transmission on the unused frequency list based on the measurement value measured by the received power measuring circuit 205. In this modification, the information on the transmitted power on the power transmission side is not taken into account in the determination.

  During charging, the control circuit 201 stores the measured power value measured by the received power measurement circuit 205 for each channel in the storage circuit 208 as a received power history table. FIG. 17 is a diagram illustrating a configuration of a received power history table. As shown in the figure, the history of the measured value P of the received power in the period T1 of FIG. 7 is stored for each channel in the received power history table. For example, when the channel at the time of receiving power is switched according to the frequency table of FIG. 8A, the measured value P of the received power of each channel is acquired in the order of 8ch → 6ch → 1ch → 2ch → 5ch → 3ch → 8ch. The acquired measurement value P is stored as the history of the corresponding channel in the history table. Here, since the frequency band of each channel is used for receiving power for 3 cycles (3 × T1), the measured value P of received power is obtained three times for each channel, and the measured value P of three times is stored in the history table. Stored in

  FIG. 18A is a flowchart showing the abnormality detection process in this modification.

  First, the control circuit 201 acquires the received power measurement value P from the received power measurement circuit 205 (S411), and stores the acquired measurement value P in the history table (S412). Further, the control circuit 201 determines whether the acquired measurement value P is smaller than the threshold value P0 (S413). If P <P0, invalidation determination processing is performed (S414).

  FIG. 18B is a flowchart showing invalidation determination processing in the present modification example.

  First, the control circuit 201 acquires the received power P from the latest to N times before the determination target channel from the received power history table (S511). Next, the control circuit 201 determines whether the channel to be determined should be invalidated depending on whether the received power P up to N times before is all less than the threshold value P0 (S512).

  If any of the received power P up to N times before is not less than the threshold value P0 (S512: NO), the control circuit 201 suspends invalidation of the channel to be determined and performs processing for the cycle (T1). Exit. On the other hand, if all of the received power P up to N times before is less than the threshold value P0 (S512: YES), the control circuit 201 proceeds to step S513, and transmits information for invalidating the determination target channel to the communication circuit. It transmits to the power transmission side via 206.

  Receiving this information, the power transmission side control circuit 101 registers the channel in the unused frequency list and generates a new frequency table excluding the channel. The generated new frequency table is transmitted from the power transmission side control circuit 101 to the power reception side control circuit 201 via the communication circuit 105. As a result, a new frequency table is shared between the power transmission side and the power receiving side, and thereafter, power transmission / reception is performed using the new frequency table.

  In this modification, the threshold value P0 used in steps S413 and S512 is set, for example, as a value obtained by subtracting a certain constant from the average value of received power of each channel or a value obtained by multiplying the average value by a ratio of less than 1. Can be done. The constant may be a predetermined constant, or may be determined in consideration of dispersion of received power measurement values measured in the past.

  Here, a new frequency table is generated on the power transmission side. However, a new frequency table may be generated on the power transmission side. In this case, the unused frequency list and the update flag shown in FIGS. 8B and 8C are held in the storage circuit 208 on the power receiving side. Then, in step S512 in FIG. 18B, the power receiving side control circuit 201 determines that the received power P up to N times before is less than the threshold value P0 (S512: YES), the channel is set to an unused frequency. Register to the list and generate a new frequency table excluding the channel. The generated new frequency table is transmitted from the power receiving side control circuit 201 to the power receiving side control circuit 101 via the communication circuit 206. As a result, a new frequency table is shared between the transmission side and the reception side, and thereafter, power transmission and reception using the new frequency table is performed.

  As described above, when a new frequency table is generated on the power receiving side, the restoration process of the unused channel is also performed by the control circuit 201 on the power receiving side. Such return processing is performed in the same manner as in FIGS. 14 (a) and 14 (b).

  The embodiment of the present invention and the two modified examples have been described above, but the present invention is not limited to the above-described embodiment and modified example, and the embodiment of the present invention is not limited to the above-described embodiment. Various other changes are possible.

  For example, the frequency of the return process and the determination criterion (threshold value) may be appropriately changed according to the length of the unused frequency list. For example, when the ratio of the number of channels described in the unused frequency list to the total number of channels is high, the frequency of the return process may be increased, or the determination condition related to the return process may be changed to a direction in which the return process is easy to return. By doing so, the proportion of channels described in the unused frequency list can be easily reduced, and the number of channels used for power transmission can be increased. As a result, a frequency at which the efficiency of power transmission is not bad can be used effectively for power transmission, and the efficiency of power transmission can be improved.

  Moreover, in the said embodiment and the modification, the time which transmits electric power in each frequency band was fixed to the time T as FIG. 7 or FIG. 8 (a) shows. However, the time for transmitting power may be different for each frequency band. In this case, the effective period of the frequency table shown in FIG. 8 is individually set to a predetermined period for each channel. Further, the time T in step S304 in FIG. 9 is set to the valid period corresponding to the channel in the frequency table. By doing so, it becomes more difficult to improperly receive the transmitted power, and the power transmission efficiency can be prevented from decreasing.

  Moreover, in the said embodiment and modification, the frequency table produced in the power transmission side or the power receiving side was shared by the power transmission side and the power receiving side via radio | wireless communication. Alternatively, the unused frequency list may be shared between the power transmission side and the power reception side, and the frequency table may be generated with the same rule on both the power transmission side and the power reception side.

  In this case, for example, all channels that can be used for power transmission, except for the channels listed in the unused frequency list, are arranged in a pseudo-random manner based on a pseudo-random number generation algorithm that is common to the power transmission side and the power reception side. A frequency table may be created. In order to create exactly the same frequency table on the power transmission side and the power reception side, for example, when sharing the unused frequency list, the seed value for generating the pseudo-random number is simultaneously set between the power transmission side and the power reception side. Share it on

  By doing so, it is not necessary to share the data of the frequency table itself by wireless communication. In addition, this makes it possible to share the frequency table between the power transmission side and the power reception side without accompanying a large amount of data transmission / reception. Therefore, it becomes more difficult to receive the transmitted power inappropriately, and it is possible to suppress a reduction in power transmission efficiency.

  Further, in the above-described embodiment and modified examples, the frequency value is not directly described in the frequency table and the unused frequency list, and the channel is described. Instead, frequency values may be directly described in the frequency table and the unused frequency list. When a frequency value is described in the unused frequency list, there is a possibility that transmission efficiency or power efficiency is lowered even in a certain frequency band centered on each described frequency. Therefore, when creating a frequency table on the power transmission side or the power reception side, it is preferable not to use a predetermined frequency band centered on each frequency value described in the unused frequency list for power transmission.

  In addition, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

10 ... Power transmission device (wireless power transmission device)
15 ... Resonant frequency switching circuit (frequency changing unit)
20 ... Bicycle (power-receiving side, power-receiving device)
22 ... Battery unit (power receiving side, power receiving device)
27 ... Resonant frequency switching circuit (frequency changing unit)
14 ... Open coil (power transmission coil)
26 ... Open coil (receiving coil)
101 ... Control circuit (frequency control unit)
103 ... Frequency control device (frequency control unit, frequency change unit)
104 ... Transmission power measurement circuit (frequency control unit)
106 ... Communication antenna (communication unit)
107: Memory circuit (frequency control unit)
105 ... Communication circuit (communication unit)
201 ... Control circuit (frequency control unit, deterioration frequency specifying unit)
202 ... Frequency control device (frequency control unit, frequency change unit)
205 ... Received power measuring circuit (frequency control unit, deterioration frequency specifying unit)
206 ... Communication circuit (communication unit)
207 ... Communication antenna (communication unit)
208 ... Memory circuit (frequency control unit, deterioration frequency specifying unit)

Claims (6)

In a wireless power transmission device that transmits power to the power receiving side using magnetic resonance,
A power transmission coil that generates an oscillating magnetic field;
A frequency changing unit for changing the frequency of the oscillating magnetic field;
A frequency control unit that controls the frequency changing unit so as to exclude the frequency at which the efficiency of power transmission to the power receiving side is reduced from the frequency of the oscillating magnetic field for power transmission;
A wireless power transmission device comprising: The wireless power transmission device according to claim 1,
A communication unit for communicating with the power receiving side;
The frequency control unit compares the information regarding the received power received from the power receiving side via the communication unit with the information regarding the transmitted power transmitted to the power receiving side, and the efficiency of power transmission to the power receiving side is reduced. Specify the frequency to
A wireless power transmission device. The wireless power transmission device according to claim 1 or 2,
The frequency control unit, after excluding the frequency at which the efficiency of power transmission to the power receiving side is reduced from the frequency of the oscillating magnetic field, tries power transmission using the excluded frequency at a predetermined timing. Thus, if the efficiency of power transmission to the power receiving side does not decrease, the excluded frequency is restored to be effective as the frequency of the oscillating magnetic field for power transmission.
A wireless power transmission device. In the wireless power transmission device according to any one of claims 1 to 3,
The frequency control unit generates a table that holds a lineup of frequencies for power transmission, and sets the frequency of the oscillating magnetic field for power transmission based on the table.
A wireless power transmission device. The wireless power transmission device according to claim 4,
The frequency control unit updates the table so as to exclude frequencies at which the efficiency of power transmission to the power receiving side decreases.
A wireless power transmission device. In a power receiving device that receives power from the power transmission side using magnetic resonance,
A power receiving coil for generating an oscillating magnetic field by the magnetic resonance;
A frequency changing unit for changing the frequency of the oscillating magnetic field by the magnetic resonance;
A frequency control unit for controlling the frequency changing unit;
A deterioration frequency specifying unit that specifies the frequency of the oscillating magnetic field at which power reception efficiency is reduced;
A communication unit for transmitting information for removing the frequency specified by the deteriorated frequency specifying unit from the frequency for power transmission to the power transmission side;
A power receiving device comprising:

Images