JP2014236536A - Radio power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio power transmission system that selectively supplies power from a power transmission apparatus to a power reception apparatus and enables signal retention when the power reception apparatus is not supplied power from the power transmission apparatus.SOLUTION: In a radio power transmission system 100, each power reception apparatus 120 comprises: a power reception unit 121 for performing radio power transmission with a power transmission unit 111; a power reception side control unit 122 for controlling a load 10 connected with the power reception apparatus 120; a radio communication transmission/reception circuit 123 used in radio communication; and a power storage unit 124. The power storage unit 124 receives and stores power when the power reception unit 121 receives power from the power transmission unit 111, and supplies the stored power to the power reception side control unit 122 when the power reception unit 121 does not receive power from the power transmission unit 111.

Description

The present invention relates to a wireless power transmission system that selectively performs power transmission wirelessly from one power transmission device to a plurality of power receiving devices.

  In recent years, a wireless power transmission system that supplies power to devices wirelessly without using a power cord or the like has been developed. As an example, as a technique for charging a battery mounted on a vehicle using an external power source, a technology for wirelessly transmitting power from a power transmitting device connected to the external power source to a power receiving device on the vehicle side is known. In a wireless power transmission system that charges a battery using an external power source, power is transmitted from one power transmitting device to one power receiving device, and thus control thereof is relatively easy.

  On the other hand, development of a wireless power transmission system that selectively transmits power from one power transmitting device to a plurality of power receiving devices is also underway. For example, in Patent Document 1, the power transmission device is configured to be able to change the resonance frequency discretely or continuously, and each of the plurality of power receiving devices has a unique resonance frequency. Then, by changing the resonance frequency of the power transmission device, it is possible to selectively transmit power to the power receiving device having the same resonance frequency.

  In Patent Document 2, a switching circuit that switches supply / non-supply of AC power from an excitation element to a rectifier circuit and a reception unit that receives priority of power reception for each power reception circuit are provided for each power receiving device, and short-range wireless A technique for controlling a switching circuit so that each power receiving device does not receive power simultaneously by determining the priority of each power receiving device using a communication means is disclosed.

JP 2010-63245 A JP 2011-19291 A

  However, in a wireless power transmission system that selectively supplies power to a plurality of power receiving devices from a power transmitting device, a period in which the power receiving device does not receive power from the power transmitting device occurs. Therefore, if the power receiving device has a built-in control device that holds signals input from the outside, the signal held in the control device is erased as soon as the power receiving device stops receiving power from the power transmission device. Problem arises.

  For example, in an automobile equipped with a plurality of electrical devices, switch signals for operating each electrical device and signals from various sensors are input to each control device, but power supply from the power transmission device is cut off after the signal is input. Then, the control device cannot hold the input signal and is erased. As a result, there arises a problem that the electric device cannot be operated normally.

  The present invention has been made to solve these problems. A wireless power transmission system capable of selectively feeding power from a power transmitting device to a power receiving device and holding a signal when the power receiving device is not fed from the power transmitting device. The purpose is to provide.

  According to a first aspect of the wireless power transmission system of the present invention, a power transmission device having a variable resonance frequency, and one or more power receiving devices that have different inherent resonance frequencies and supply power to loads connected thereto, A power transmission unit including a primary resonance unit having a variable resonance frequency, and a power transmission side control unit that controls a resonance frequency of the primary resonance unit. The power receiving device includes a secondary side resonance unit that resonates when the resonance frequency of the primary side resonance unit is substantially equal to the inherent resonance frequency, and receives power from the power transmission unit, And a power receiving side control unit that receives power from the power receiving unit and controls the load at the connection destination.

  In another aspect of the wireless power transmission system of the present invention, the power receiving device includes a power storage unit that receives and stores power from the power receiving unit, and the one or more power receiving devices are discrete from the power transmitting device at predetermined time intervals. The power storage units of each of the one or more power receiving devices supply power to the power receiving side control units when the power receiving units finish receiving power from the power transmission units. And

  According to another aspect of the wireless power transmission system of the present invention, the power receiving unit includes two or more power receiving devices. When the voltage of the power storage unit drops to a predetermined voltage threshold, the power receiving unit sets the resonance frequency of the power receiving unit to a priority level. It is characterized by being spontaneously switched to a higher resonance frequency of the power receiving device.

  According to another aspect of the wireless power transmission system of the present invention, the primary-side resonance unit and the secondary-side resonance unit are configured by coils, and are transmitted from the power transmission unit to the power reception unit by a magnetic field resonance method. Two or more capacitors connected in series or in parallel with the secondary resonance unit, and the resonance frequency is given priority by spontaneously switching the connection of one or more of the two or more capacitors. It is characterized by switching to the resonance frequency of another power receiving device having a high degree.

  Another aspect of the wireless power transmission system of the present invention is characterized in that the connection of the one or more capacitors is switched when the voltage of the power storage unit drops to the predetermined voltage threshold.

  According to another aspect of the wireless power transmission system of the present invention, the primary-side resonance unit and the secondary-side resonance unit are configured by a capacitor, and power is transmitted from the power transmission unit to the power reception unit by an electric field resonance method. , Including two or more coils connected in series or in parallel with the secondary side resonance unit, and the resonance frequency is given priority by spontaneously switching the connection of one or more of the two or more coils. It is characterized by switching to the resonance frequency of another power receiving device having a high degree.

  Another aspect of the wireless power transmission system of the present invention is characterized in that the connection of the one or more coils is switched when the voltage of the power storage unit drops to the predetermined voltage threshold.

  In another aspect of the wireless power transmission system of the present invention, the power receiving device includes a wireless communication transmitting / receiving circuit that enables wireless communication when each of the power receiving units receives power from the power transmitting unit, and the power receiving side control unit Comprises power monitoring means for monitoring the power received by the power receiving section from the power transmitting section, and the power monitoring means is lower than the power when the received power is received from the power transmitting section at the specific resonance frequency. When it is determined that the power is less than or equal to a predetermined power threshold value, the operation of the wireless communication transmitting / receiving circuit of the power receiving device is stopped.

  According to the present invention, it is possible to provide a wireless power transmission system that selectively feeds power from a power transmitting device to a power receiving device and that can retain a signal when the power receiving device is not powered from the power transmitting device.

It is a block diagram which shows the structure of the wireless power transmission system of 1st Embodiment of this invention. In the wireless power transmission system of 1st Embodiment, it is a block diagram which shows an example which selectively supplies electric power with a wireless power transmission system from a power transmission apparatus to several power receiving apparatus. It is a graph which shows an example of the voltage change of the electrical storage part when electric power is supplied to the receiving side control part from the electrical storage part of the wireless power transmission system of 1st Embodiment. In the wireless power transmission system of 2nd Embodiment of this invention, it is a block diagram which shows an example which selectively supplies electric power with a wireless power transmission system from a power transmission apparatus to several power receiving apparatus. It is a block diagram which shows the structure of the wireless power transmission system of 2nd Embodiment of this invention, and the structure of a receiving device. It is a block diagram which shows another structure of the power receiving apparatus of the wireless power transmission system of 2nd Embodiment. It is a block diagram which shows the structure of the power receiving apparatus of the wireless power transmission system of 3rd Embodiment of this invention.

  A wireless power transmission system according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  As an example of a system that selectively supplies power to a plurality of power receiving devices from a single power transmitting device connected to a power source, a plurality of power receiving devices are mounted, each configured to receive power from a battery and operate as necessary. There is a car. In a conventional automobile, a large amount of wire harnesses including a power cable for supplying power to each power receiving device from a battery, a signal line for transmitting signals used for various controls, and the like are mounted. On the other hand, reduction of wire harnesses has been strongly desired due to the demand for weight reduction of automobiles.

  The wireless power transmission system of the present invention can selectively transmit wireless power from a power transmission device to a plurality of power receiving devices, and can be applied to power supply from a vehicle battery to a plurality of power receiving devices. The power cable can be greatly reduced. In addition, by installing a wireless LAN in an automobile, signals and the like used for various controls can be transmitted and received by wireless communication, and signal lines can be greatly reduced. In the following, an embodiment of the wireless power transmission system of the present invention will be described by taking as an example the case where the wireless power transmission system of the present invention is applied to power transmission of an automobile. Here, it is assumed that the vehicle is equipped with a wireless LAN.

(First embodiment)
A wireless power transmission system according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a wireless power transmission system 100 according to the present embodiment. FIG. 2 is a configuration diagram showing an example of selectively supplying power from the power transmitting device 110 to the plurality of power receiving devices 120 by the wireless power transmission method in the wireless power transmission system 100 of the present embodiment. Here, as an example, four power receiving devices 120 (120-1 to 4) are arranged, but the number of power receiving devices 120 is not limited to this and may be one or more.

  It is assumed that the power transmitting device 110 and the power receiving devices 120-1 to 120-4 communicate with each other via a wireless LAN. In FIG. 2, power feeding from the power transmitting device 110 to each power receiving device 120 is indicated by a solid arrow, and wireless communication is indicated by a broken line. In wireless communication between the power transmission device 110 and each power reception device 120, a control signal or the like for performing power transmission / reception control is transmitted and received.

  In the example illustrated in FIG. 2, between the power transmission device 110 and the power reception devices 120-1 to 4, in order to appropriately perform communication between the power transmission device 110 and the power reception devices 120-1 to 120-4. These communications are normally performed in order at predetermined time intervals, and this is repeated sequentially. That is, the power transmission device 110 communicates with the power receiving devices 120-1 to 120-4 in the order of numbers (1) to (4) illustrated in FIG. 2, and when the communication with the power receiving device 120-4 ends, the receiving device again. Return to communication with 120-1 (number (5)). Similarly, the communication is repeated in the order of the power receiving devices 120-1 to 120-4.

  As described above, in order to sequentially perform communication between the power transmitting device 110 and the power receiving devices 120-1 to 120-4, the power required for the power receiving device 120 that is a communication target to perform wireless communication is secured. There is a need. Therefore, the power transmission device 110 wirelessly transmits power to the power receiving device 120 that is a communication target, and at the same time starts wireless communication. It is also assumed that necessary power is supplied to a load connected to the power receiving device 120 to be communicated.

  Here, when the wireless power transmission is configured to be selectively transmitted from the power transmission device 110 to the plurality of power reception devices 120, a period in which each power reception device 120 is not supplied with power from the power transmission device 110 occurs. Occurs. Each of the power receiving devices 120-1 to 120-4 is connected to a load, and includes a control unit (power receiving side control unit) for controlling each load. The control unit holds a switch signal for operating a load input from the outside, signals from various sensors, and the like. However, when power is not supplied from the power transmission device 110, the control unit cannot hold these signals. Therefore, the wireless power transmission system 100 according to the present embodiment is configured such that power can be supplied to the control unit even during a period in which the power receiving devices 120-1 to 120-4 are not supplied with power from the power transmission device 110.

  In the wireless power transmission system 100 of the present embodiment illustrated in FIG. 1, the power transmission device 110 includes a power transmission unit 111 that performs wireless power transmission, a power transmission side control unit 112 that controls the power transmission unit 111, and wireless communication transmission / reception used for wireless communication. Circuit 113. In addition, each of the power receiving devices 120 includes a power receiving unit 121 that performs wireless power transmission with the power transmitting unit 111, a power receiving side control unit 122 that controls the load 10 connected to the power receiving device 120, and wireless communication used for wireless communication. And a transmission / reception circuit 123.

  The power receiving side control unit 122 controls the load 10 and supplies the power received by the power receiving unit 121 to the load 10. In addition, the power receiving side control unit 122 can be connected to a signal input unit 11 for inputting a switch signal, a sensor signal, and the like from the outside. The signal input from the signal input unit 11 is stored in the power receiving side control unit 122 and can be used for controlling the load 10.

  The power transmission unit 111 includes a primary side resonance unit (not shown) whose resonance frequency is variable, while the power reception unit 121 is a secondary side resonance unit (not shown) having a unique resonance frequency that is different for each power receiving device 120. ). The power transmission unit 111 sequentially adjusts the resonance frequency of the primary side resonance unit to the resonance frequency of the secondary side resonance unit of each power reception unit 121 by the control from the power transmission side control unit 112, thereby Power can be transmitted to each power receiving unit 121 by resonance with the secondary resonance unit. Accordingly, each power receiving device 120 can receive power discretely from the power transmitting device 110 only while the resonance frequency of the primary side resonance unit matches the unique resonance frequency of the secondary side resonance unit.

  As a resonance method between the primary side resonance unit and the secondary side resonance unit, either a magnetic field resonance method or an electric field resonance method may be used. When the magnetic field resonance method is used, each of the primary side resonance unit and the secondary side resonance unit is constituted by a coil. When the electric field resonance method is used, each of the primary side resonance unit and the secondary side resonance unit is constituted by a capacitor. Below, the case where a magnetic field resonance system is used as an example is demonstrated.

  The power receiving apparatus 120 further includes a power storage unit 124 in addition to the above configuration. The power storage unit 124 can receive power from the power receiving unit 121 and store the power when the power receiving unit 121 receives power from the power transmitting unit 111. While the power receiving unit 121 is receiving power from the power transmitting unit 111, the power receiving side control unit 122 and the wireless communication transmitting / receiving circuit 123 also receive power from the power receiving unit 121 and perform predetermined operations.

  When the resonance frequency of the primary-side resonance unit is switched to the resonance frequency of another power reception device 120 by the control from the power transmission side control unit 112, the power reception unit 121 of the power reception device 120 that has received power until then is received from the power transmission unit 111. The power receiving side control unit 122 and the wireless communication transmitting / receiving circuit 123 of the power receiving device 120 stop operating. However, since it is necessary to hold the signal stored in the power receiving side control unit 122, electric power is required to hold the power receiving unit 120 after the power receiving unit 121 of the power receiving device 120 stops receiving power from the power transmission unit 111. It is.

  Therefore, the power storage unit 124 supplies power to the power receiving side control unit 122 during a period from when the power receiving device 120 finishes receiving power from the power transmitting device 110 to when it next receives power again. The power receiving side control unit 122 can receive power from the power storage unit 124 during a period in which power cannot be received from the power receiving unit 121 and can hold an input signal. Then, when the power receiving device 120 receives power from the power transmitting device 110 again, the power receiving device 120 can be appropriately operated.

  The capacity of the power storage unit 124 is based on a voltage lower limit value (referred to as an operating voltage threshold value V1) necessary for the power receiving side control unit 122 to hold a signal and an operation time (T1) during which the signal is held. It is determined. Here, the operation time T1 corresponds to a time interval from when the power receiving device 120 is supplied with power from the power transmission device 110 to when power is supplied next. FIG. 3 shows an example of a voltage change in the power storage unit 124 when power is supplied from the power storage unit 124 to the power receiving side control unit 122. In FIG. 3, the elapsed time from the start of power supply from the power storage unit 124 to the power receiving side control unit 122 is shown on the horizontal axis, and the voltage of the power storage unit 124 is shown on the vertical axis.

  FIG. 3 shows that when power supply from the power storage unit 124 to the power receiving side control unit 122 is started, the voltage of the power storage unit 124 decreases with time. When the operation time T1 has elapsed, it is required that the voltage of the power storage unit 124 is ensured to be equal to or higher than the operation voltage threshold V1. By determining the capacity of the power storage unit 124 so that the voltage when the operating time T1 has elapsed is equal to or higher than the operating voltage threshold V1, the power receiving side control unit 122 receives the power necessary for holding the signal from the power storage unit 124. Can do.

  According to the wireless power transmission system 100 of the present embodiment, it is possible to selectively transmit wireless power from the power transmitting device 110 to the power receiving device 120 at predetermined time intervals, and the power receiving side control unit 122 provided in each power receiving device 120. Can receive power from the power storage unit 124 and hold necessary signals even during a period during which power cannot be received from the power receiving unit 121.

(Second Embodiment)
A wireless power transmission system according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a configuration diagram showing an example of selectively supplying power from the power transmitting device 110 to the plurality of power receiving devices 220 by the wireless power transmission method in the wireless power transmission system 200 of the present embodiment, as in FIG. 2. Again, the number of power receiving devices is four for simplicity of explanation. 5A shows the configuration of the wireless power transmission system 200 according to the present embodiment, and FIG. 5B shows the configuration of the power receiving device 220.

  In the wireless power transmission system 200 of the present embodiment, normally, wireless power transmission is normally performed between the power transmitting device 110 and the power receiving devices 220-1 to 220-4 in the same manner as in the first embodiment. An interrupt operation to the power receiving device 220 with high frequency is possible. In FIG. 4, as an example, the power receiving device 220-3 is a power receiving device with a high priority.

  In FIG. 4, the power receiving device 220-1 to the power receiving device 220-4 are selectively supplied in order of (1) to (4), and then the power receiving device 220-1 is again supplied with high priority. A case where an interruption operation is performed on the power receiving device 220-3 is illustrated. When there is an interrupt operation to the power receiving device 220-3 having a high priority, the power transmission side control unit 112 of the power transmission device 110 sets the resonance frequency of the power transmission unit 111 to the power receiving device 220- instead of the resonance frequency of the power receiving device 220-1. 3 resonance frequency. As a result, the power transmitting device 110 supplies power to the power receiving device 220-3 without supplying power to the power receiving device 220-1 (number (5) shown in FIG. 4). The interruption operation to the power receiving device 220-3 is performed by, for example, transmitting the activation request signal of the power receiving device 220-3 to the wireless communication transmission / reception circuit 113 of the power transmission device 110 and outputting the signal to the power transmission side control unit 112. Frequency switching is performed.

  As described above, when there is an interrupt operation to the power receiving device 220-3 having a high priority, the power feeding to the power receiving device 220-1 that is scheduled to be powered again after the power receiving device 220-4 is performed. This is performed after power supply to 220-3 is completed (number (6) shown in FIG. 4). As a result, in power receiving device 220-1, the time interval from the previous power supply to the next power supply becomes longer than the normal time interval, and power storage unit 224 may be discharged during that time. If the power storage unit 224 is discharged, the signal of the power receiving side control unit 222 cannot be held, and the load 10 connected to the power receiving device 220-1 may not be properly controlled.

  Thus, in the wireless power transmission system 200 of the present embodiment, when the power stored in the power storage unit 224 of the power receiving device 220-1 is consumed, the power receiving unit 221 receives power spontaneously from the power transmission unit 111 of the power transmission device 110. Configured to start. When power is being transmitted from the power transmitting device 110 to the power receiving device 220-3 having a high priority, the power receiving unit 221 of the power receiving device 220-1 is also configured so that the power receiving device 220-1 can also receive power from the power transmitting device 110 at the same time. Is made to coincide with the resonance frequency of the power receiving device 220-3 having a high priority.

  FIG. 5B illustrates the power receiving device 220 configured to match the resonance frequency with the resonance frequency of the power receiving device 220-3 having a high priority when the stored power of the power storage unit 124 is consumed. The power receiving device 220 according to the present embodiment is different from the power receiving unit 121 according to the first embodiment in the configuration of the power receiving unit 221. FIG. 5B shows a configuration in the case where the power receiving unit 221 receives power from the power transmitting unit 111 by the magnetic field resonance method. Similarly to the power reception unit 121 of the first embodiment, the power reception unit 221 includes a secondary side resonance coil 231 that is a secondary side resonance unit, a capacitor (referred to as a first capacitor) 232, a secondary side induction coil 233, and rectification. Circuit 234. When the secondary resonance coil 231 receives power by magnetic resonance with the primary resonance coil (not shown) of the power transmission unit 111, an alternating current flows through the secondary induction coil 233, and this is rectified to direct current by the rectifier circuit 234. To the power receiving side control unit 222 and the wireless communication transmitting / receiving circuit 223. The electric power supplied to the power receiving side control unit 222 is further supplied to the load 10.

  In the power receiving unit 221 of this embodiment, another capacitor (referred to as a second capacitor) 235 is connected in parallel with the first capacitor 232, and a relay 236 for turning on / off the connection of the second capacitor 235 is provided. It has been. In FIG. 5B, the secondary resonance coil 231 and the two capacitors 232 and 235 are connected in parallel. However, the present invention is not limited to this, and the secondary resonance coil 231 and the two capacitors 232 and 235 are connected. May be connected in series.

  Relay 236 is energized and closed when power is stored in power storage unit 224, and is not excited and opened when the power stored in power storage unit 224 decreases. When the inductance of the secondary resonance coil 231 is L, the capacities of the first capacitor 232 and the second capacitor 235 are C1 and C2, and the combined capacity of both is C, the power receiving unit 221 when the relay 236 is closed This resonance frequency is a specific resonance frequency determined from the combined capacitance C of the first capacitor 232 and the second capacitor 235 and the inductance L of the secondary resonance coil 231.

  In contrast, when the stored power of the power storage unit 224 decreases and the relay 236 is opened, the resonance frequency of the power reception unit 221 is determined from the capacitance C1 of the first capacitor 232 and the inductance L of the secondary resonance coil 231. Frequency. When the power stored in the power storage unit 224 is reduced and the relay 234 is opened, the resonance frequency of the power reception unit 221 is matched with the resonance frequency of the power reception device 220-3 having a high priority so that power can be received from the power transmission device 110. There is a need. Therefore, the first capacitor 232 has a resonance frequency determined from the capacitance C1 of the first capacitor 232 and the inductance L of the secondary resonance coil 231 so that it matches the resonance frequency of the power receiving device 220-3 having a high priority. The capacity C1 is determined in advance.

  The power receiving unit 221 of the power receiving device 220-1 has impedance matching so that power can be efficiently received from the power transmitting device 110 during normal wireless power transmission in which the second capacitor 235 is connected and magnetic resonance is performed at a specific resonance frequency. Has been done. For this reason, when the connection of the second capacitor 235 is turned off and only the first capacitor 232 is connected, the power supplied by the impedance mismatch is reduced.

  When the first capacitor 232 and the second capacitor 235 are connected to the secondary resonance coil 231, and the power is received efficiently at a specific resonance frequency, the impedance of the power receiving unit 221 is Z0, and the connection of the second capacitor 235 is off. Let Z be the impedance of the power receiving unit 221 when the power is set. Further, the power required by the power receiving side control unit 222 for normal operation is P0, and the power required for the power receiving side control unit 222 to hold a signal is P1. Here, for simplicity of explanation, it is assumed that the power received by the power receiving unit 221 from the power transmitting unit 111 when the matching impedance is Z0 is equal to the power P0 required by the power receiving side control unit 122 for normal operation.

After the stored power of the power storage unit 224 is reduced and the connection of the second capacitor 235 is turned off, the power supplied due to impedance mismatch is reduced, but at least the power receiving side control unit 222 holds the signal. It is necessary to receive the power P <b> 1 necessary for the power transmission from the power transmission unit 111 of the power transmission device 110. The reflection coefficient ρ when the impedance of the power receiving unit 221 is Z is given by the following equation.

Accordingly, when the impedance of the power receiving unit 221 is Z, the power received by the power receiving unit 221 from the power transmitting unit 111 is (1−ρ) P0. This received power is required to be higher than the power P1 necessary for the power receiving side control unit 222 to hold a signal, as shown by the following equation.
P1 <(1-ρ) P0 (2)

  Therefore, it is necessary to determine the impedances Z0 and Z of the power receiving unit 221 so as to satisfy Expression (2). The capacitance C1 of the first capacitor 232 is determined so that the resonance frequency determined by the inductance L of the secondary resonance coil 231 matches the resonance frequency of the power receiving device 220-3 having a high priority. It is necessary to determine the capacitance C2 of the second capacitor 235 so as to satisfy (2). In addition, the inherent resonance frequency of the power reception unit 221 is determined from the combined capacitance C of the capacitance C1 of the first capacitor 235 and the capacitance C2 of the second capacitor 235 determined in this way.

ここで、式（３）はコイルＬとコンデンサＣが直列に接続されたときのインピーダンス、式（４）はコイルＬとコンデンサＣが並列に接続されたときのインピーダンス、をそれぞれ算出する式である。 The circuit impedance Z of the power receiving unit 221 is given by the following equation.

Here, Expression (3) is an expression for calculating the impedance when the coil L and the capacitor C are connected in series, and Expression (4) is an expression for calculating the impedance when the coil L and the capacitor C are connected in parallel. .

  Although the case where the magnetic field resonance method is used as the wireless power transmission method has been described above, the electric field resonance method can also be used in the wireless power transmission system of the present embodiment. FIG. 6 shows a configuration of a power receiving device (referred to as 220 ′) of this embodiment when the electric field resonance method is used. The power receiving device 220 ′ includes a secondary resonance capacitor 231 ′ instead of the secondary resonance coil 231 as a secondary resonance unit, and a coil (referred to as a first coil) 232 ′ instead of the first capacitor 232. I have. In the electric field resonance method, the secondary induction coil 233 is unnecessary, and when an alternating current is generated in the secondary resonance capacitor 231 ′ due to electric field resonance with the primary resonance capacitor (not shown) of the power transmission unit 111, this is converted into a rectifier circuit. The power is rectified to direct current at 234 and supplied to the power receiving side control unit 222 and the wireless communication transmitting / receiving circuit 223. Furthermore, instead of the second capacitor 235, another coil (referred to as a second coil) 235 'is connected in parallel with the first coil 232'. Here, the two coils 232 ′ and 235 ′ are connected in parallel, but the present invention is not limited to this, and the two coils 232 ′ and 235 ′ may be connected in series.

  According to the wireless power transmission system 200 of the present embodiment, when the power of the power storage unit of another power receiving device is insufficient due to an interruption of a power receiving device with a high priority, the resonance frequency of the power receiving device is set to be a power receiving device with a high priority. It is possible to receive power in accordance with the resonance frequency of the device, and thereby it is possible to hold a signal stored in the power receiving side control unit of the power receiving device. In the present embodiment, the number of capacitors or coils connected to the secondary side resonance coil or the secondary side resonance capacitor is two, but is not limited to this and may be three or more. In addition, when switching the resonance frequency to the resonance frequency of the power receiving device having a high priority, it can be performed by turning on / off connection of one or more capacitors or coils.

  When the interruption to the power receiving device with a high priority is completed, the power receiving device that has switched the resonance frequency to the resonance frequency of the power receiving device with a high priority returns this to the original unique resonance frequency. In addition, the order of power transmission to each power receiving device after completion of the interruption is controlled on the power transmission device 110 side so that the power of the power storage unit of each power receiving device is not insufficient. The power transmission device 110 determines the order of power transmission to each power receiving device so that the period during which each power receiving device does not receive power after the end of the interruption is the same as the initial period during which power is not received before the occurrence of the interrupt.

(Third embodiment)
In the wireless power transmission system 200 according to the second embodiment, when the power receiving unit 221 of the power receiving device 220-1 is switched from the inherent resonance frequency to the resonance frequency of the power receiving device 220-3 having a higher priority, the power receiving device 220-1. The wireless communication transmitting / receiving circuit 223 also receives power from the power receiving unit 221. As a result, the wireless communication transmitting / receiving circuit 223 of the power receiving device 220-1 is in a state in which wireless communication can be performed. When the wireless communication transmitting / receiving circuit 223 of the power receiving device 220-1 performs wireless communication and may interfere with wireless communication performed by the power receiving device 220-3 having a high priority, the wireless communication by the power receiving device 220-1 is performed. It needs to be stopped.

  When the power receiving unit 221 of the power receiving device 220-1 receives power from the transmitting unit 111 at a unique resonance frequency, high power can be received because the impedance is matched. On the other hand, when the power receiving unit 221 of the power receiving device 220-1 receives power by matching the resonance frequency of the power receiving device 220-3 having a high priority, the power received by the impedance mismatch is reduced. Therefore, the power received by the power receiving unit 221 from the power transmitting unit 111 can be monitored, and when the received power is low, the operation of the wireless communication transmitting / receiving circuit 223 of the power receiving device 220-1 can be stopped.

  As a wireless power transmission system according to the third embodiment of the present invention, a configuration of a power receiving device 320 including a power monitoring unit 340 for monitoring the power received by the power receiving unit 221 is illustrated in FIG. FIG. 7 is a block diagram illustrating a configuration of the power receiving device 320 included in the wireless power transmission system of the present embodiment. In the present embodiment, the power monitoring unit 340 is provided in the power receiving side control unit 322.

  The power monitoring unit 340 monitors the power received by the power receiving unit 320 and wirelessly determines that the received power is equal to or lower than a predetermined power threshold lower than the received power when receiving power at a specific resonance frequency. Control is performed so that the communication transceiver circuit 323 does not operate. Accordingly, it is possible to prevent the wireless communication performed by the power receiving device 220-3 having a high priority from being disturbed.

  In addition, the description in this Embodiment shows an example of the wireless power transmission system which concerns on this invention, and is not limited to this. The detailed configuration and detailed operation of the wireless power transmission system in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Load 100, 200 Wireless power transmission system 110 Power transmission apparatus 111 Power transmission part 112 Power transmission side control part 113 Wireless communication transmission / reception circuit 120,220,320 Power reception apparatus 121,221 Power reception part 122,222,322 Power reception side control part 123,223 323 Wireless communication transmission / reception circuit 124, 224 Power storage unit 231 Secondary resonance coil 232 First capacitor 233 Secondary induction coil 234 Rectifier circuit 235 Second capacitor 236 Relay 340 Power monitoring means

Claims (8)

A wireless power transmission system comprising: a power transmitting device having a variable resonance frequency; and one or more power receiving devices each having a unique resonance frequency and supplying power to a load connected thereto,
The power transmission equipment is
A power transmission unit including a primary resonance unit having a variable resonance frequency and transmitting power;
A power transmission side control unit for controlling a resonance frequency of the primary side resonance unit,
The power receiving device is:
A power receiving unit that includes a secondary side resonance unit that resonates when a resonance frequency of the primary side resonance unit is substantially equal to the inherent resonance frequency, and receives power from the power transmission unit;
A wireless power transmission system comprising: a power receiving side control unit that receives power from the power receiving unit and controls the load at a connection destination. The power receiving device includes a power storage unit that receives and stores power from the power receiving unit,
The one or more power receiving devices receive power sequentially and discretely from the power transmission device at a predetermined time interval, and each of the power storage units of the one or more power receiving devices receives power from the power transmission unit. 2. The wireless power transmission system according to claim 1, wherein power is supplied to each of the power receiving side control units when the operation is terminated. Comprising two or more power receiving devices,
The power reception unit, when the voltage of the power storage unit drops to a predetermined voltage threshold, the resonance frequency of the power reception unit is spontaneously switched to the resonance frequency of another power reception device having a higher priority. Item 3. The wireless power transmission system according to Item 1 or 2. The primary side resonance unit and the secondary side resonance unit are configured by coils and are transmitted from the power transmission unit to the power reception unit by a magnetic field resonance method,
The power receiving unit includes two or more capacitors connected in series or in parallel with the secondary resonance unit, and the resonance is achieved by spontaneously switching connection of one or more capacitors of the two or more capacitors. The wireless power transmission system according to claim 3, wherein the frequency is switched to a resonance frequency of another power receiving device having a higher priority. The wireless power transmission system according to claim 4, wherein the connection of the one or more capacitors is switched when the voltage of the power storage unit drops to the predetermined voltage threshold value. The primary-side resonance unit and the secondary-side resonance unit are configured by capacitors and are transmitted from the power transmission unit to the power reception unit by an electric field resonance method,
The power receiving unit includes two or more coils connected in series or in parallel with the secondary resonance unit, and the resonance is achieved by spontaneously switching connection of one or more of the two or more coils. The wireless power transmission system according to claim 3, wherein the frequency is switched to a resonance frequency of another power receiving device having a higher priority. The wireless power transmission system according to claim 6, wherein the connection of the one or more coils is switched when the voltage of the power storage unit decreases to the predetermined voltage threshold value. The power receiving device includes a wireless communication transmission / reception circuit that enables wireless communication when each of the power receiving units receives power from the power transmission unit,
The power receiving side control unit includes power monitoring means for monitoring the power received by the power receiving unit from the power transmitting unit,
When the power monitoring unit determines that the received power is equal to or lower than a predetermined power threshold lower than the power when the power is received from the power transmission unit at the inherent resonance frequency, the power monitoring unit of the power receiving device The wireless power transmission system according to any one of claims 1 to 7, wherein the operation is stopped.

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