JPWO2018221532A1 - Power transmission device, wireless power transmission system, and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control transmission power according to a state of a power receiving device without performing communication from the power receiving device to the power transmitting device. A power transmission device includes an inverter circuit, a power transmission resonator, a measuring instrument, and a control circuit. The measuring instrument measures an input voltage or an output voltage of the inverter circuit and an input current or an output current of the inverter circuit. During the power transmission, the control circuit changes the voltage value of the AC power output from the inverter circuit from the first voltage value to the second voltage value, and before and after the change, the voltage measured by the measuring device and The first measured value and the second measured value of the current are respectively acquired, the third voltage value is determined by the process including the calculation using the first and second measured values, and the third voltage value is determined from the inverter circuit. AC power having the third voltage value is output to continue power transmission. [Selection diagram] FIG.

Description

  The present application relates to a wireless power transmission system, and a power transmission device and a control device used in the wireless power transmission system.

  Development of a wireless power transmission system (also referred to as a non-contact power supply system) for wirelessly transmitting power from a power transmitting device to a power receiving device is under way. Patent Documents 1 and 2 disclose examples of a non-contact power supply system. In the systems of Patent Documents 1 and 2, information such as a received voltage is fed back from a power receiving device to a power transmitting device using wireless communication, and the power transmitting device controls transmission power based on the information.

International Publication No. WO2012 / 073349 International Publication No. WO2014 / 148144

  In the technologies disclosed in Patent Literatures 1 and 2, communication for feeding back information from the power receiving device to the power transmitting device is required. Embodiments of the present disclosure provide a technique for appropriately controlling transmission power according to the state of a power receiving device without performing such communication.

A power transmitting device according to an exemplary embodiment of the present disclosure wirelessly transmits power to a power receiving device including a power receiving resonator. The power transmission device includes an inverter circuit, a power transmission resonator connected to the inverter circuit, one of a voltage input to the inverter circuit and a voltage output from the inverter circuit, and a current input to the inverter circuit. A measuring instrument for measuring one of the currents output from the inverter circuit; and a control circuit for controlling the inverter circuit. The control circuit is configured to output AC power having a first voltage value from the inverter circuit and transmit power from the power transmission resonator to the power reception resonator, while controlling the voltage and current measured by the measurement device. A first measurement value is obtained, and measured by the measuring device in a state where the voltage value of the AC power output from the inverter circuit is changed to a second voltage value different from the first voltage value. A second measurement value of voltage and current is obtained, a third voltage value is determined by a process including an operation using the first and second measurement values, and the third voltage value is determined from the inverter circuit. , And the power transmission is continued.
Further, a wireless power transmission system according to an exemplary embodiment of the present disclosure includes the above-described power transmission device and a power reception device. A control device according to an exemplary embodiment of the present disclosure includes a control circuit in the above-described power transmission device. A program according to an exemplary embodiment of the present disclosure is used in a power transmission device that wirelessly transmits power to a power reception device including a power reception resonator.

  The above-described generic or specific aspects can be realized by an apparatus, a system, a method, an integrated circuit, a computer program, or a recording medium. Alternatively, the present invention may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

  According to the embodiment of the present disclosure, transmission power can be appropriately controlled according to the state of the power receiving device without performing communication from the power receiving device to the power transmitting device.

FIG. 1 is a diagram for describing an overview of a mobile system according to an exemplary embodiment of the present disclosure. FIG. 2 is a perspective view schematically illustrating an example of the moving body 200 according to the exemplary embodiment of the present disclosure. FIG. 3 is a perspective view illustrating an example of an arrangement relationship between the power transmitting coil unit 105 and the power receiving coil unit 205 during charging. FIG. 4 is a block diagram illustrating a configuration of the mobile system according to the exemplary embodiment of the present disclosure. FIG. 5 is a diagram illustrating a configuration example of the inverter circuit 120 and the control circuit 140. FIG. 6 is a diagram illustrating an example of a pulse signal supplied from the control circuit 140 to the switching elements G1 to G4 and a waveform of a voltage output from the inverter circuit 120. FIG. 7 is a diagram showing an equivalent circuit of the power transmitting resonator 110 and the power receiving resonator 210. FIG. 8A is a perspective view illustrating an example of the shape and arrangement of power transmission coil 112 and power reception coil 212. FIG. 8B is a diagram schematically illustrating an example of a shape when the power transmission coil 112 is viewed from the Y direction. FIG. 8C is a diagram schematically illustrating an example of a shape when the power receiving coil 212 is viewed from the Y direction. FIG. 9 is a diagram illustrating a configuration example of the rectifier 220, the capacitor 230, and the power storage element 245. FIG. 10 is a flowchart illustrating an example of an operation when the power transmission device 100 starts power transmission. FIG. 11A is a diagram illustrating an equivalent circuit of a wireless power transmission system according to an exemplary embodiment of the present disclosure. FIG. 11B is a diagram illustrating another equivalent circuit of the wireless power transmission system according to the exemplary embodiment of the present disclosure. FIG. 12 is a flowchart illustrating an operation during power transmission according to the exemplary embodiment of the present disclosure. FIG. 13A is a diagram illustrating an example of a temporal change of the output voltage V1 of the inverter circuit 120. FIG. 13B is a diagram illustrating another example of a temporal change of the output voltage V1 of the inverter circuit 120. FIG. 14A is a diagram illustrating an example of timings of estimation based on two measurements and real-time estimation. 14B is a diagram showing an example of time change of the voltage V1 in the case of controlling the voltage V1 by performing real-time estimated by the period T _2. Figure 15 is a flowchart showing the estimation by two measurements performed every cycle T _1, an example of operation of a combination of a real-time estimation performed in every cycle T _2. FIG. 16A is a schematic diagram illustrating an example in which the voltage measuring device 130a is connected between the DC power supply 50 and the inverter circuit 120. FIG. 16B is a schematic diagram illustrating a configuration example in which the current measuring device 130b is connected between the DC power supply 50 and the inverter circuit 120. FIG. 16C is a schematic diagram illustrating an example in which both the voltage measuring device 130a and the current measuring device 130b are connected between the DC power supply 50 and the inverter circuit 120. FIG. 17A is a schematic diagram illustrating an example in which a DC-DC converter 250 is connected between a capacitor 230 and a storage element 245. FIG. 17B is a schematic diagram showing an example in which a load resistor 240 such as a motor is arranged instead of power storage element 245 in the configuration of FIG. 17A.

  Before describing the embodiments of the present disclosure, the knowledge that became the basis of the present disclosure will be described.

  In the conventional contactless power supply technology, information such as voltage, current, power, or impedance in the power receiving device is fed back to the power transmitting device by wireless communication for power supply control. In order to realize such wireless communication, a device that performs wireless communication such as Wi-Fi (registered trademark) or Bluetooth (registered trademark) is used for both the power transmitting device and the power receiving device.

  However, when the power receiving device is a device such as a mobile body used in a factory or a road, for example, there is a situation where wireless communication between the power transmitting device and the power receiving device cannot be normally performed due to the influence of communication interference or noise. May occur frequently. When the wireless communication is disconnected, the power transmitting device cannot obtain information on the power receiving device, and thus cannot appropriately control transmission power. Furthermore, wireless devices require time for connection and authentication before communication. Until connection and authentication are established, transmission power cannot be controlled. In particular, when power is supplied to a moving power receiving device, even a slight loss of time increases the ratio of the power to the entire power supply time. In addition, mounting a wireless device causes an increase in cost.

  The present inventor has found the above-mentioned problems, and studied a configuration for solving these problems. The present inventor, during power transmission, changes the voltage of the transmitted AC power at short time intervals, from the information on the voltage and current on the power transmission side measured before and after the change, the mutual inductance between the coils and the received voltage, etc. Information can be estimated. This discovery has made it possible to estimate the state of the power receiving device without performing communication from the power receiving device to the power transmitting device, and to appropriately control the transmission power according to the state.

  Hereinafter, an outline of an embodiment of the present disclosure will be described.

  A power transmission device according to an aspect of the present disclosure wirelessly transmits power to a power reception device including a power reception resonator. The power transmission device includes an inverter circuit, a power transmission resonator connected to the inverter circuit, a measuring instrument, and a control circuit that controls the inverter circuit. The measuring device measures one of a voltage input to the inverter circuit and a voltage output from the inverter circuit, and one of a current input to the inverter circuit and a current output from the inverter circuit. The control circuit performs the following operation. (1) In the state where the AC power having the first voltage value is output from the inverter circuit and the power is transmitted from the power transmitting resonator to the power receiving resonator, the first of the voltage and the current measured by the measuring device is measured. Get the measured value of. (2) In a state where the voltage value of the AC power output from the inverter circuit is changed to a second voltage value different from the first voltage value, a second voltage and current measured by the measuring device are changed. Get the measured value of. (3) A third voltage value is determined by a process including an operation using the first and second measurement values, and the inverter circuit outputs AC power having the third voltage value to perform power transmission. continue.

  According to the above configuration, transmission power can be appropriately controlled according to a change in the state of the power receiving device without performing communication from the power receiving device to the power transmitting device.

  The power transmitting resonator includes a power transmitting coil, and the power receiving resonator includes a power receiving coil. The control circuit estimates one or more parameter values indicating the state of the power receiving device by, for example, an operation using the first and second measurement values. The third voltage value can be determined from the estimated parameter value with reference to data defining the correspondence between the value of the one or more parameters and the value of the voltage to be output from the inverter circuit. . Data defining such correspondence is stored in a recording medium such as a memory in the power transmission device, for example, in the form of a table or a mathematical expression or a function. The data may be, for example, a table that defines the correspondence between the mutual inductance between the coils or the voltage output from the power receiving resonator and the output voltage of the inverter circuit.

The control circuit performs the determination of the acquisition and the third voltage values of the first and second measurement values, for example, every period T _1. When the value of one or more parameters indicating the state of the power receiving device estimated from the first and second measured values changes from the value of the parameter estimated at the previous time, the control circuit sets a third voltage value Is set to a value different from the first voltage value. On the other hand, when the value of the parameter is the same as the value of the parameter at the time of the previous estimation, the control circuit sets the third voltage value to the same value as the first voltage value. Whether or not the value of each parameter has changed from the value at the time of the previous estimation can be determined by determining whether the difference or the change rate of the parameter from the previous value exceeds a threshold.

  The one or more parameters include a mutual inductance between the power transmission coil included in the power transmission resonator and the power reception coil included in the power reception resonator, a voltage output from the power reception resonator, a current output from the power reception resonator, And at least one of the power output from the power receiving resonator. Specific processing for estimating these parameters will be described later.

  The power receiving device is, for example, a moving object. “Moving object” means a movable object driven or charged by electric power. The moving object can be, for example, an automated guided vehicle (AGV), an electric vehicle (EV), a mobile robot, an unmanned aerial vehicle (Unmanned Aerial Vehicle: UAV, so-called drone). The power receiving device may be a device that does not move by itself, such as a mobile device.

  The power transmitting device may include a sensor that detects whether the power receiving device is moving with respect to the power transmitting device. Such a sensor may be a sensor using, for example, visible light or infrared light, or may be a sensor that detects movement of the power receiving device based on a change in voltage or current in a circuit of the power transmitting device.

  The measuring instrument continuously performs two measurements within a relatively short time. For example, two measurements are performed at time intervals such that the mutual inductance between the power transmitting coil and the power receiving coil can be considered to be constant. This time interval is set shorter as the speed at which the power receiving device moves during power transmission is higher. The measuring device may be configured to measure in response to an instruction from the control circuit, or may be configured to constantly monitor voltage and current at fixed short time intervals.

  The control circuit can adjust the output voltage of the inverter circuit (hereinafter, may be referred to as “transmission voltage”) in various ways. For example, the transmission voltage can be adjusted by changing the duty ratio, phase, or frequency of a control signal supplied to each of the plurality of switching elements included in the inverter circuit, or changing the DC voltage input to the inverter circuit. it can. The control of the DC voltage input to the inverter circuit is possible in a mode in which the power transmission device includes a DC-DC converter connected between the inverter circuit and the DC power supply. In such an embodiment, the control circuit can change the DC voltage input to the inverter circuit by controlling on / off of a switching element included in the DC-DC converter.

  The present disclosure also includes a control device including the control circuit described above, and a computer program (hereinafter, simply referred to as a program) that defines an operation performed by the control circuit. Such a program is stored in a recording medium such as a memory in the power transmission device, and causes the control circuit to execute the above-described operation.

  Hereinafter, exemplary embodiments of the present disclosure will be described. However, an unnecessary detailed description may be omitted. For example, a detailed description of well-known matters or a redundant description of substantially the same configuration may be omitted. This is to prevent the following description from being unnecessarily redundant and to facilitate understanding of those skilled in the art. The inventor provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and it is not intended that the present invention limit the subject matter described in the claims. Absent. In the following description, the same or similar components are denoted by the same reference numerals.

(Embodiment)
<Structure>
FIG. 1 is a diagram for describing an overview of a mobile system according to the present embodiment. A mobile system is an example of a wireless power transmission system according to the present disclosure. The mobile system can be used, for example, as a system for transporting articles in a factory. The mobile system includes at least one wireless power transmission device (hereinafter, simply referred to as “power transmission device”) 100 and at least one mobile device 200. The moving body 200 is an example of a power receiving device. The moving body 200 may be, for example, an automatic guided vehicle (AGV) that autonomously moves in a factory and conveys articles to a required location. FIG. 1 illustrates four power transmission devices 100 and four moving objects 200. The number of each of the power transmission device 100 and the moving body 200 is not limited to four, and is arbitrary.

  The power transmission device 100 wirelessly transmits power to the mobile unit 200. The power transmission device 100 includes a power transmission coil unit 105 including a power transmission coil that transmits AC power to a space. The moving body 200 has a power receiving coil unit 205 including a power receiving coil. Power is wirelessly transmitted from the power transmission coil to the power reception coil by coupling the power transmission coil and the power reception coil by magnetic field resonance. As described above, in the present embodiment, wireless power transmission using magnetic resonance coupling (sometimes called “magnetic resonance coupling” or “resonant magnetic coupling”) is used. According to the wireless power transmission using the magnetic resonance coupling method, power transmission over a longer distance is possible as compared with the method using electromagnetic induction. Note that the technology of the present disclosure is not limited to the magnetic field resonance coupling method, but is also applicable to wireless power transmission by an electromagnetic induction method. Therefore, the present disclosure also includes a configuration based on the electromagnetic induction method.

  The moving body 200 includes a capacitor and a motor. The power received by the power receiving coil in the power receiving coil unit 205 is rectified and stored in a capacitor. As the capacitor, for example, a large-capacity and low-resistance capacitor such as an electric double layer capacitor or a lithium ion capacitor can be used. The moving body 200 can move by driving a motor with the electric power stored in the capacitor.

  When the moving body 200 moves, the charged amount (that is, charged amount) of the capacitor decreases. For this reason, recharging is required to continue moving. Therefore, when the amount of charge falls below a predetermined threshold during the movement, mobile unit 200 moves to the vicinity of power transmission device 100 and performs charging. As shown in FIG. 1, if the power transmitting devices 100 are installed at a plurality of locations, the moving body 200 only needs to move to the vicinity of the nearest power transmitting device 100, so that the moving distance can be reduced.

  Such a system can be used, for example, as a system for transporting articles in a factory, as described above. The moving body 200 typically has a carrier on which articles are loaded, and functions as a cart that moves autonomously in the factory and transports the articles to a required location. The mobile system can be used not only in factories but also in, for example, stores, hospitals, homes, and any other places. The moving body 200 is not limited to the AGV, and may be another industrial machine or a service robot. The moving body 200 may be any device having a movable mechanism, such as a manned vehicle, an unmanned aerial vehicle (UNV), or a cleaning robot. The power receiving device according to the present disclosure is not limited to a mobile object. The technology of the present disclosure can be applied to any wireless power transmission system in which the relative position between the power transmission coil and the power reception coil can change during power transmission.

  FIG. 2 is a perspective view schematically illustrating an example of the moving body 200 according to the present embodiment. The moving body 200 includes a power receiving coil unit 205 installed on a side surface, a plurality of wheels including driving wheels 207 driven by a motor, and a loading platform 206 on which articles are placed. The power receiving coil unit 205 houses a power receiving resonator including a power receiving coil.

  FIG. 3 is a perspective view illustrating an example of an arrangement relationship between the power transmitting coil unit 105 and the power receiving coil unit 205 during charging. FIG. 3 shows XYZ coordinates indicating X, Y, and Z directions orthogonal to each other. In the following description, the coordinate system shown in the figure is used. The XY plane is parallel to the horizontal plane or floor, and the direction in which the moving body 200 moves forward is defined as the positive direction of the X axis, and the direction vertically above is defined as the positive direction of the Z axis.

  The orientation of the structure shown in the drawings of the present application is set in consideration of the clarity of the description, and does not limit the orientation when the embodiment of the present disclosure is actually implemented. Further, the shape and size of the whole or a part of the structure shown in the drawings do not limit the actual shape and size.

  As shown in FIG. 3, the power transmission coil 112 in the power transmission coil unit 105 has a conductor wire (winding) wound so as to be relatively long in the X direction and relatively short in the Z direction. Similarly, the power receiving coil 212 in the power receiving coil unit 205 has a conductor wire (winding) wound long in the X direction and short in the Z direction. As illustrated, the shapes and sizes of the power transmission coil 112 and the power reception coil 212 in the present embodiment are asymmetric. In the present embodiment, the size of the region defined by the winding of the power receiving coil 212 is smaller than the size of the region defined by the winding of the power transmitting coil 112.

  Power transmission is performed in a state where the power transmission coil 112 and the power reception coil 212 face each other. More specifically, a state where the surface defined by the winding of power transmission coil 112 and the surface defined by the winding of power reception coil 212 (in the illustrated example, both are parallel to the XZ plane) face each other. Is charged. The charging is possible not only when these surfaces are completely parallel but also when they are inclined with respect to each other.

  In the present embodiment, since the power transmission coil 112 has a shape that is long in the X direction, even if the moving body 200 is slightly displaced in the X direction, the facing state between the coils is maintained, and power transmission with high efficiency is achieved. Can be maintained.

  The moving body 200 can grasp the position and the direction of the mobile unit 200 and the position and the direction of the power transmission coil 112 using various sensors. Thereby, the power transmission device 100 closest to the own device is identified, and the power transmission device 100 moves to the vicinity of the power transmission device 100 to enable high-efficiency power transmission, that is, the power reception coil 212 is opposed to the power transmission coil 112 in close proximity. You can take a posture. The moving body 200 may move to the next closest power transmitting apparatus 100 when the closest power transmitting apparatus 100 is supplying power to another moving body 200.

  Hereinafter, the configuration of the mobile system of the present embodiment will be described in more detail.

  FIG. 4 is a block diagram showing the configuration of the mobile system of the present embodiment.

  The power transmission device 100 includes an inverter circuit 120 connected to an external direct current (DC) power supply 50, a power transmission resonator 110 connected to the inverter circuit 120, and a voltage measuring device 130a that measures a voltage output from the inverter circuit 120. And a current measuring device 130b for measuring a current output from the inverter circuit 120, a control circuit 140 for controlling the inverter circuit 120, and a sensor 150 for detecting the position and / or movement of the moving body 200. The power transmission resonator 110 includes the power transmission coil 112 described above. In the following description, the voltage measuring device 130a and the current measuring device 130b may be collectively referred to as "measuring device 130". The measuring device 130 in the present embodiment measures the voltage and the current output from the inverter circuit 120. As described later, the voltage measuring device 130a may measure a voltage input to the inverter circuit 120. Similarly, the current measuring device 130b may measure the current input to the inverter circuit 120.

  The moving body (power receiving device) 200 includes a power receiving resonator 210, a rectifier (rectifying circuit) 220 connected to the power receiving resonator 210, a capacitor 230 connected to the rectifier 220, and a power storage element 245 connected to the capacitor 230. And The power receiving resonator 210 includes the power receiving coil 212 described above. Power storage element 245 includes an electric double layer capacitor or a battery. The power transmission device 100 and the moving body 200 may include other components not shown. In addition, the mobile system does not necessarily need to include all of the components illustrated in FIG. 4 and can be omitted as appropriate.

  Hereinafter, each component will be described in more detail.

<DC power supply>
The DC power supply 50 is a power supply that outputs a DC voltage of a predetermined magnitude. The DC power supply 50 may include, for example, a converter that converts commercial AC power into DC power having an operating voltage of the power transmission device 100 and outputs the DC power.

<Inverter circuit and control circuit>
Inverter circuit 120 converts DC power supplied from DC power supply 50 to AC power. The inverter circuit 120 can be, for example, a full-bridge inverter circuit. The full-bridge inverter circuit can output AC power having a desired frequency and voltage value by adjusting the switching timing of the four switching elements. Each switching element switches between a conductive state and a non-conductive state according to a pulse signal supplied from the control circuit 140.

  FIG. 5 is a diagram illustrating a configuration example of the inverter circuit 120 and the control circuit 140. The inverter circuit 120 shown in FIG. 5 has a configuration of a full-bridge inverter circuit having four switching elements G1 to G4. Each switching element may be a transistor such as an IGBT (Insulated-Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor).

  The control circuit 140 includes a control IC 142, a gate driver 144, and a memory 143. The control IC 142 executes a control program stored in the memory 143 to determine a voltage (meaning an effective value; the same applies hereinafter) and a frequency of AC power to be output to the inverter circuit 120. In the present embodiment, in particular, the voltage or the frequency at which the efficiency is maximized is determined based on the values of the voltage V1 and the current I1 measured by the measuring device 130. Details of this operation will be described later. The gate driver 144 supplies a pulse signal having the frequency and the duty ratio determined by the control IC 142 to the gates of the switching elements G1 to G4. Thereby, the conduction (on) / non-conduction (off) state of each of the switching elements G1 to G4 is controlled. Note that a part or the whole of the control circuit 140 can be realized by an integrated circuit such as a microcomputer.

  When the switching elements G1 and G4 among the four switching elements G1 to G4 are turned on (conducting state), a voltage having the same polarity as the DC voltage supplied from the DC power supply 50 is output from the inverter circuit 120. On the other hand, at the timing when the switching elements G2 and G3 are turned on (conduction state), a voltage having a polarity opposite to the DC voltage supplied from the DC power supply 50 is output from the inverter circuit 120. The control circuit 140 causes the inverter circuit 120 to output AC power of a desired frequency and voltage by adjusting the timing of the pulse signal supplied to each of the switching elements G1 to G4.

FIG. 6 is a diagram illustrating an example of a pulse signal supplied from the control circuit 140 to the switching elements G1 to G4 and a waveform of a voltage output from the inverter circuit 120. In FIG. 6, symbol E represents the magnitude of the voltage output from DC power supply 50, and symbol T represents the period. A period during which the output voltage V1 of the inverter circuit 120 is equal to the magnitude E of the output voltage of the DC power supply 50 is controlled by the duty ratio d _inv . That is, the control circuit 140 by adjusting the duty ratio d _inv, the output voltages V ₁ can be adjusted amplitude and the effective value of the AC voltage approximating a sine wave.

  Note that the inverter circuit 120 is not limited to the configuration illustrated in FIG. For example, a half-bridge type configuration may be used. Even in such a case, a desired AC voltage can be output by adjusting the timing of the gate drive pulse given to the two switching elements. The inverter circuit 120 can be realized by, for example, a commercially available high-frequency power supply device.

<Transmitting and receiving resonators>
FIG. 7 is a diagram showing an equivalent circuit of the power transmitting resonator 110 and the power receiving resonator 210. The power transmission resonator 110 is a series resonance circuit having an inductance component (L ₁ ), a capacitance component (C ₁ ), and a resistance component (R ₁ ) by the power transmission coil 112. The power receiving resonator 210 is a series resonance circuit having an inductance component (L ₂ ), a capacitance component (C ₂ ), and a resistance component (R ₂ ) by the power receiving coil 212. The capacitance components (C1 and C2) may be parasitic capacitance components of the power transmitting coil 112 and the power receiving coil 212, respectively, or may be a capacitor provided separately.

  The resonance frequency of power transmission resonator 110 and the resonance frequency of power reception resonator 210 are set to substantially the same value. The resonance frequency is not particularly limited, but can be set, for example, to 5 kHz or more and 50 MHz or less. The resonance frequency is more preferably 10 kHz or more and 1 MHz. Each resonator is not limited to a series resonance circuit and may be a parallel resonance circuit. Not limited to the illustrated configuration, for example, as disclosed in Patent Document 1, a primary coil coupled to the power transmitting resonator 110 by electromagnetic induction, and a secondary coil coupled to the power receiving resonator 210 by electromagnetic induction. It may be provided.

  FIG. 8A is a perspective view for describing the shapes and arrangement of the power transmission coil 112 and the power reception coil 212 in more detail. FIG. 8A shows an example in which the width of the power transmission coil 112 in the Y direction is smaller than that of the example of FIG. The two-dot chain line shown in FIG. 8A indicates the normal line of the plane defined by the coils 112 and 212. FIG. 8B schematically illustrates a shape when the power transmission coil 112 is viewed from the Y direction. FIG. 8C schematically illustrates a shape when the power receiving coil 212 is viewed from the Y direction.

  The power transmission coil 112 is a winding wound by a first conductor wire, and includes a first upper portion 112a and a first lower portion 112b extending in the lateral direction, and two arc-shaped portions connecting these. Including. The power receiving coil 212 is a winding wound around a second conductor wire, and includes a second upper portion 212a and a second lower portion 212b extending in the lateral direction, and two arc-shaped portions connecting these. Including.

  A first rectangular surface 112c (FIG. 8B) defined by an upper portion 112a and a lower portion 112b of the power transmitting coil 112, and a second upper portion 212a and a second lower portion 212b of the power receiving coil 212. The defined second rectangular surface 212c (FIG. 8C) is perpendicular or inclined with respect to the horizontal plane. The power receiving coil 112 is arranged on a side surface of the moving body 200, and the second rectangular surface 212 c faces the first rectangular surface 112 c of the power transmitting coil 112 during power transmission.

  The power transmission coil 112 and the power reception coil 212 are not limited to the illustrated shapes. For example, the shape of each coil may be rectangular (including a square) or elliptical (including a circle). The structure of each coil 112, 212 may be appropriately modified depending on the configuration of the system to which the coil is applied. For example, in the present embodiment, each of the coils 112 and 212 has a structure extending in the X direction, but need not necessarily have such a structure. Further, the power transmission coil 112 does not necessarily need to have a size larger than the power reception coil 212. The power transmitting coil 112 and the power receiving coil may have the same structure. The structure of each coil 112 is arbitrary as long as power transmission is possible.

<Rectifier, capacitor, storage element>
FIG. 9 is a diagram illustrating a configuration example of the rectifier 220, the capacitor 230, and the power storage element 245.

  Rectifier 220 may be a full-wave rectifier circuit including a diode bridge and a smoothing capacitor, as shown. Rectifier 220 may be another type of full-wave rectifier circuit or a half-wave rectifier circuit. Rectifier 220 converts AC power from power receiving resonator 210 into DC power and outputs the DC power.

  Capacitor 230 is connected in parallel with rectifier 220. Capacitor 230 is provided to reduce and stabilize the fluctuation of the DC voltage supplied from rectifier 220 to power storage element 245. The capacitor 230 may be omitted if unnecessary.

  Power storage element 245 is connected in parallel with capacitor 230. The storage element 245 is, for example, a capacitor or a battery. Power storage element 245 may include both a capacitor and a battery. As the capacitor, for example, an electric double layer capacitor or a lithium ion capacitor can be used. Since the electric double layer capacitor or the lithium ion capacitor has a small internal resistance (for example, several tens of mΩ), charging and discharging with a large current can be performed with low loss. For this reason, rapid charging is possible. In addition, since the capacitance is larger than other types of capacitors, continuous discharge for a relatively long time is possible. As the battery, a secondary battery with high energy density and high charge / discharge efficiency, such as a lithium ion battery, can be used.

<Sensor>
The sensor 150 detects the position or the movement of the moving body 200. The sensor 150 may be, for example, a sensor using light (visible light or near infrared light). The sensor 150 may be configured to detect the movement of the moving body 200 based on the output of the measuring device 130. Whether or not the moving body 200 is moving can be determined based on a time change of at least one of the voltage and the current measured by the measuring device 130.

<Operation>
Next, the operation of the power transmission device 100 will be described.

  FIG. 10 is a flowchart illustrating an example of an operation when the power transmission device 100 starts power transmission. When the power is turned on, the control circuit 140 of the power transmission device 100 in this example performs weak power transmission and performs an operation of detecting the moving body 200 that is the power reception device. When the moving body 200 is detected in the vicinity, the control circuit 140 starts power supply to the moving body 200.

In the example of FIG. 10, the control circuit 140 sets the voltages _{V 1} to minute value starts weak power transmission (step S11). In this state, the instrument 130 measures the voltage _{V 1} and current _{I 1} output from the inverter circuit 120 (step S12). Control circuit 140, based on the values of _{V 1} and _{I 1,} the mobile 200 determines whether there a possible power receiving position (step S13). When the moving body 200 is not located at a position where power can be received (No in step S14), the control circuit 140 stops weak power transmission (step S15). Control circuit 140, (Yes in step S16) after the time _{T 0,} executes the operation of step S11 again. If the mobile 200 is present capable receiving position (Yes in step S14), and the control circuit 140 starts the power supply to the mobile 200 to increase the output voltage _{V 1.}

  The detection of the power receiving device in step S13 can be determined based on, for example, whether or not a difference between a predetermined reference value depending on the value of V1 and the value of I1 exceeds a threshold value. As the moving body 200 approaches, the mutual inductance between the power transmitting coil and the power receiving coil increases. Due to the influence, the current flowing in the circuit of the power transmission device 100 changes. The approach of the moving body 200 can be detected based on the change in the current.

  In the example of FIG. 10, the approach of the moving body 200 (power receiving device) is detected based on the current and the voltage in the circuit of the power transmitting device 100. Instead of such a detection method, for example, the approach of the moving body 200 may be detected using the sensor 150 (see FIG. 4).

<Estimation of power receiving device state>
The power transmission device 100 according to the present embodiment estimates the state of the mobile unit 200 without using information transmitted from the mobile unit 200 during power supply to the mobile unit 200, and appropriately adjusts the transmission power according to the state. Can be controlled. Hereinafter, the method will be described specifically.

  In the following description, information or a parameter indicating the state of the mobile unit 200 may be referred to as a “power receiving parameter”. The power receiving parameter may include, for example, at least one of mutual inductance between coils, current, voltage, power, and impedance in a circuit of the power receiving device.

FIG. 11A is a diagram illustrating an equivalent circuit of the wireless power transmission system according to the present embodiment. The equivalent circuit shown in FIG. 11A can also be represented as shown in FIG. 11B. 11A and 11B, components (see FIG. 4) such as the inverter circuit 120 connected to the power transmission resonator 110 are collectively represented as one AC power supply. Components such as the rectifier 220 connected to the power receiving resonator 210 are collectively represented as one load. Let _{RL be} the resistance value of the load. A component such as a rectifier circuit connected to the power receiving resonator 210 actually has a reactance component in addition to a resistance component. However, in FIGS. 11A and 11B, for simplicity, the reactance component is ignored, and the load is represented as a resistance. The angular frequency of the AC power transmitted to the omega, the mutual inductance between L _m. The angular frequency ω is the same as the driving angular frequency of the inverter circuit 120.

  In the following description, the AC voltage and the AC current are represented by phasor. That is, the voltage and the current are treated as complex numbers. In the phasor display, the absolute values of the voltage and the current represent their effective values.

The phasor of the voltage and current of the AC power supply, and v ₁ and i _1, respectively. The effective value of the voltage and current of the AC power supply, when _{V 1} and _{I 1 respectively,} V ₁ = | _v 1 | and _I 1 = | _{i 1} | is. Similarly, the phasor of the load voltage and current, when _{v 2} and _{i 2, respectively,} V 2 = | _{v 2} | and _I 2 = | _{i 2} | is.

Voltage _{v 1} and the current _{i 1} is shown in FIGS. 11A and 11B, represents the voltage _{v 1} and the current _{i 1} of the AC power output from the inverter circuit 120, respectively. Voltage v ₂ and the current i ₂ is input to the load represents the voltage and current output from the power reception resonator 210, respectively.

ここで、ｊは虚数単位である。From the circuit equations of the equivalent circuits shown in FIGS. 11A and 11B, v ₁ , i _1, v ₂ , and i ₂ satisfy the following equations (1) and (2).

Here, j is an imaginary unit.

In the following description, it is assumed that ω is equal to the resonance angular frequency ω ₀ = 1 / (L ₁ C ₁ ) ^1/2 = 1 / (L ₂ C ₂ ) ^1/2 . However, even if the resonance condition ω = ω ₀ is not satisfied, the following discussion is valid if the deviation between ω and ω ₀ is small. For example, if the value of | ω−ω ₀ | / ω ₀ is 0.05 or less, the following discussion is sufficiently effective.

Substituting v ₂ = R _L i ₂ into equation (2) yields i ₂ = j ｛ωL _m / (R ₂ + R _L )｝ i ₁ from the resonance condition ωL ₂ = 1 / ωC ₂ . This equation shows that advances 90 ° the phase of the i ₂ is i ₁ phase. Clearing the _{i 2} from equation (1) using this _{equation, v 1 = {R 1 /} ω 2 Lm 2 / (R 2 + R L)} i 1 is obtained. This equation shows that v ₁ and i ₁ have the same phase. Also, from v ₂ = R _L i ₂ , v ₂ and i ₂ have the same phase. From these phase relations, the resonance ^{_{conditions, v 1 = V 1 e jθ}} , i 1 = I 1 e jθ, v 2 = jV 2 e jθ, and _i 2 = _jI can be expressed as 2 ^{e j.theta..} Here, θ represents the phase. By substituting these v ₁ , i ₁ , v ₂ , and i ₂ into equations (1) and (2), V ₁ , I ₁ , V ₂ , and I ₂ are represented by the following equation (3) containing only real numbers. ) And (4) are satisfied.

By solving equations (3) and (4), the following equations (5) and (6) are obtained.

The effective value V ₁ of the voltage is obtained, for example, by integrating real-time waveform of the voltage measured by the voltage measuring instrument 130a in the power transmission device 100. Similarly, the effective value I ₁ of the current is obtained by integrating real-time waveform of the current measured by the current measuring device 130b in the power transmitting apparatus 100.

In the formula (5) and _(6), three unknown parameters of V 2, _{I 2} and _{L m} are present. Since the number of equations is smaller than the number of unknown parameters, V ₂ , I ₂ and L _m cannot be calculated as they are.

Therefore, the power transmission device 100 in the present embodiment changes the value of the transmission voltage during power transmission, and measures the voltage and the current before and after the change. From the voltage and current values obtained by the two measurements, at least one of L _m , V ₂ , and I ₂ can be estimated. Hereinafter, this estimation method will be described more specifically.

  The control circuit 140 drives the inverter circuit 120 to transmit power from the power transmission coil 112 to the power reception coil 122 during power transmission. This state is called a first state. The control circuit 140 acquires the measured values of the voltage and the current measured by the measuring devices 130a and 130b in the first state. This measured value is referred to as a first measured value. Next, the control circuit 140 changes the value of the voltage output from the inverter circuit 120 to a second value different from the voltage value in the first state. This state is called a second state. The control circuit 140 acquires the measured values of the voltage and current measured by the measuring devices 130a and 130b in the second state. This measured value is called a second measured value.

If the time from acquisition of the first measurement to the acquisition of the second measured value is sufficiently short, the change of the voltage V ₂ of the storage element 245 is small. For example, if the time from the acquisition of the first measurement to the acquisition of the second measured value is less than 0.1 seconds, it is possible to suppress the variation in the voltage V ₂ to 0.1V or less. In this case, the two measurements of the above, V ₂ can be assumed to be constant.

Obtained from the first measurement value, the effective value of the alternating-current power voltage and current output from the inverter circuit 120, and V ₁₀ and I _10, respectively. Obtained from the second measurement value, the effective value of the effective value and the current of the AC power voltage output from the inverter circuit 120, and V ₁₁ and I _11, respectively. When V ₂ is assumed to be constant, from equation (5), the following equation is obtained (7) and (8).

The following equation (9) is obtained from the equation (6).

By using equations (7) to (9), three unknown parameters of V ₂ , I ₂ and L _m can be calculated.

Clearing the _{V 2} from equation (7) and (8), the estimated equation of _{L m} (10) is obtained.

On the other hand, the estimated equation _{V 2} of the following from equation (7) (11) is obtained.

Further, the following equation (12) for estimating I ₂ is obtained from equations (9) and (11).
Is obtained.

The control circuit 140 can estimate the mutual inductance L _m , the receiving voltage V ₂ , and the receiving current I ₂ by the calculations of Expressions (10) to (12). Accordingly, the parameters of the power receiving device can be estimated from the information on the voltage and current in power transmitting device 100 without communication between power transmitting device 100 and mobile unit 200.

Control circuit 140, based on the parameters of the estimated power receiving device, for example, as one or both of V ₂ and I ₂ is the desired value, the voltage value of the AC power output from the inverter circuit 120 (the third Voltage value) and power transmission is continued at the determined voltage value. Thereby, even when the mobile unit 200 moves during power transmission, power supply can be optimized. For example, it is possible to suppress a decrease in transmission efficiency and to stabilize power supply.

In a memory 143 shown in FIG. 5, data such as a table or a formula defining a correspondence relationship between at least one parameter of L _m , V ₂ , and I ₂ and a voltage V ₁ to be output from the inverter circuit 120 is stored in advance. Is stored. Control circuit 140, by referring to the data, from the estimated parameters, it is possible to determine the value after the change voltage V _1. The data, corresponding to the voltage V ₁₀ and the current I ₁₀ obtained from the first measurement value, and the combination of the voltage V ₁₁ and the current I ₁₁ obtained from the second measurement value, the voltages V ₁ to be transmission The relationship may be prescribed. In that case, the control circuit 140 should transmit the power from the combination of V ₁₀ , I ₁₀ , V ₁₁ , and I ₁₁ by referring to the data without performing the calculations of Expressions (10) to (12). it can be determined voltage V _1.

The control circuit 140 refers to the data, the effective value I ₁₀ RMS V ₁₀ and the current of the voltage obtained from the first measurement value, voltage effective value V ₁₁ and obtained from the second measurement value a combination of the effective value I ₁₁ of the current, estimating the power receiving parameters, such as the mutual inductance L _m.

The memory 143 includes a voltage V ₂ in the moving object 200, data defining the relationship between the amount of charge of the power storage device 245 may be stored. The control circuit 140 refers to the data, it is possible to estimate the charge amount of the power storage device 245 from the voltage V _2. The control circuit 140 can perform control such as stopping power supply from the power transmission device 100 to the moving body 200 if the charge amount is equal to or more than the reference value.

The control circuit 140 estimates the power receiving parameters, for example, every period _{T 1.} Period T ₁ may be set to a value in the range of several seconds, for example, from a few milliseconds (ms). In one example, the period _{T 1} may be set to about 100ms time. Control circuit 140, estimates of parameters, if changed from the value when the previously estimated, changing the voltage V ₁ output from the inverter circuit 120, otherwise, maintains the voltages V ₁ I do. Whether or not the estimated value of the parameter has changed can be determined based on whether or not the difference or the rate of change between the current estimated value and the previous estimated value exceeds a predetermined threshold. For example, the control circuit 140, the value of parameters such as the mutual inductance Lm estimated, only when the difference or the rate of change of the value of the same parameter when the previously estimated exceeds a threshold, changing the voltage V _1.

Hereinafter, the parameter estimation processing at the time of power transmission in the present embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating an operation at the time of power transmission in the present embodiment. When estimating the state of the power receiving device, the control circuit 140 first causes the inverter circuit 120 to output AC power having the first voltage value (step S101). In the present embodiment, the first voltage value is the effective value of the AC voltage already being transmitted. The control circuit 140 acquires the first measurement value measured by the measuring device 130 in that state (step S102). First measurement value corresponds to _{V 10} and _{I 10} described above. Since V ₁₀ and I ₁₀ are effective values, when the measurement value output from the measuring device 130 is an instantaneous value, the control circuit 140 performs necessary calculations to perform the effective value V _{10 of the} voltage and the effective value of the current. get the I _10.

Next, the control circuit 140 causes the inverter circuit 120 to output AC power having a second voltage value different from the first voltage value (Step S103). That is, the transmission voltages V ₁ to change to a different second voltage value to the first voltage value so far. The second voltage value is set to a value such that the difference from the first voltage value is larger than the magnitude of the noise component. For example, the second voltage value can be set to a value that is about half of the first voltage value. The second voltage value may be set to a value larger than the first voltage value.

The control circuit 140 acquires the second measured values of the voltage and the current in that state (step S104). Second measurement value corresponds to _{V 11} and _{I 11} described above. Since V ₁₁ and I ₁₁ are effective values, when the measurement value output from the measuring instrument 130 is an instantaneous value, the control circuit 140 performs necessary calculations to perform the effective value V _{11 of the} voltage and the effective value of the current. get the I _11.

Next, the control circuit 140 calculates the parameters L _m , V indicating the state of the power receiving device by calculation using the first measurement value (V ₁₀ , I ₁₀ ) and the second measurement value (V ₁₁ , I ₁₁ ). _2, to calculate the _{I 2} (step S105). This calculation is performed using the above equations (10) to (12). Subsequently, the control circuit 140 refers to data in a table or the like stored in the memory 143 and determines the third voltage of the AC power to be output to the inverter circuit 120 from the estimated values of the parameters L _m , V ₂ , and I _2. The value is determined (Step S106). The control circuit 140 causes the inverter circuit 120 to output AC power having the third voltage value, and continues power transmission (step S107). Thereafter, the control circuit 140 determines whether the time _{T 1} from the previous measurement has elapsed (step S108). If the time _{T 1} is passed, is performed the operation of steps S102 S107 again. At this time, the third voltage value is treated as a new first voltage value. The first to third voltage values in each process may be different from the previous value.

The third voltage value is set to the same value as the first voltage value when the estimated values of the parameters L _m , V ₂ , and I ₂ have not changed from the previous values. On the other hand, when the values of the estimated parameters L _m , V ₂ , and I ₂ have changed from the previous values, the third voltage value is set to a value different from the first voltage value.

Figure 13A is a diagram showing an example of a time variation of the output voltage V ₁ of the inverter circuit 120. In the example of FIG. 13A, the voltage V ₁ was after the first estimate has not changed, i.e., the third voltage value is set to the same value as the first voltage value. On the other hand, after the second and third estimates are voltages V ₁ is changed, i.e., the third voltage value is set to a value different from the first voltage value.

As shown in FIG. 13A, the time required for the acquisition of the first measurement value in step S102 _{(V 10, I} 10) and _{t a.} Second measurement value in step S104 the time required for acquisition of the _{(V 11, I} 11) and _{t b.} Step S105 and S106 the time required for the determination of the parameter estimation and the third voltage value at the _{t c.} In the example of FIG. 13A, after acquiring the first measurement value, the control circuit 140 sets the voltage V ₁ to the second voltage value at time t _b + t _c until the determination of the third voltage value. ing. The present invention is not limited to this example, and after acquiring the second measurement value, the control circuit 140 may return the voltage V1 to the first measurement value and then perform the operations of steps S105 and S106. FIG. 13B shows an example of such an operation. In the example illustrated in FIG. 13B, the time when the voltage V1 is set to the second measurement value is tb, and at the subsequent time tc, the parameters of the power receiving device are estimated and the third voltage value is determined.

  The above estimation method can be applied both at the start of power supply to the mobile unit 200 and during power supply.

<Real-time estimation of power reception parameters>
In the above example, as shown in FIG. 13A, for example, the voltage value of the AC power output from the inverter circuit 120 is kept constant from the estimation of the power reception parameter based on the two measurements until the start of the two measurements again. It is. By estimating the power reception parameter in a shorter cycle T ₁ and changing the voltage value of the AC power output from the inverter circuit 120, the operation of the mobile unit 200 can be more finely controlled. However, it takes time t _a + t _b + t _c to perform two measurements and to estimate the power reception parameter. Further, if the second state is frequently set, the operation of the moving body 200 may be affected.

Therefore, estimation of the power reception parameters by two measurements is carried out at a relatively long period T _1, further short period T _2, may be performed to estimate the power reception parameters by one measurement. Period _{T 2} are shorter than the period _{T 1,} for example, _T 2 / _{T 1} may be set to 1/10 or less 1/1000 or more. T ₁ can be, for example, an integer multiple of T ₂ . In one example, the period _{T 1} is about 100 ms, the period _{T 2} are set to about 1 ms. In the following description, the estimation of the power receiving parameters performed in a sufficiently short time interval such as the period T _2, referred to as real-time estimation.

  FIG. 14A is a diagram illustrating an example of timings of estimation based on two measurements and real-time estimation. In FIG. 14A, estimation based on two measurements is referred to as estimation 1, and estimation based on one measurement (real-time estimation) is referred to as estimation 2. As shown, Estimation 2 is performed more frequently than Estimation 1.

In the real-time estimation, different methods are applied depending on whether the moving body 200 is moving or stationary while transmitting power. When the moving body 200 is moving, the relative position between the power transmitting coil and the power receiving coil changes, so that the mutual inductance _Lm may change. On the other hand, the receiving voltage V ₂ for the time T ₂ are largely unchanged. Therefore, using equation (5) Equation (13) below obtained by modifying, as V ₂ is constant, it is possible to estimate only the mutual inductance L _m in real time.

In equation (13), V ₁ and I ₁ are obtained from real-time measurements by measuring instruments 130a, 130b. V _2, before performing the real-time estimation is a value obtained by calculation of equation (11). Control circuit 140 in every cycle _{T 2,} can be using equation (13), for estimating the _{L m} in real time. In this case, a small V ₂ of the change is estimated for each period T _1, a large L _m changes are estimated for each shorter period T _2.

In this example, the control circuit 140 when the power receiving device is moved with respect to the power transmission device 100, for each period T _1, the operation using the first and second measurement values, mutual inductance L _m, and performing a first process of estimating the voltage V ₂ output from the receiving coil. Then, in every cycle T ₂ shorter than the period T _1, by using the value of the voltage V ₂ which is estimated in the first process of the previous estimates of the mutual inductance L _m by the calculation formula (13). The fact that the power receiving device is moving with respect to the power transmitting device 100 can be detected by the sensor 150.

If the moving object 200 is stopped in the power transmission, the mutual inductance L _m does not change, receiving voltage V ₂ may vary. In particular, when the charge amount of the power storage device 245 at the transmission start is substantially zero, V ₂ may vary significantly. Therefore, when the moving body 200 is stopped, as L _m is constant, it is possible by using the equation (11) the same following equations (14) to estimate only V ₂ in real time .

In equation (14), V ₁ and I ₁ are obtained from real-time measurements by measuring instruments 130a, 130b. L _m, before performing the real-time estimation is a value obtained by calculation of equation (10). Control circuit 140 in every cycle _{T 2,} can be using equation (14), estimates the _{V 2} in real time. In this case, small L _m of the change is estimated for each period T _1, a large V ₂ changes are estimated for each shorter period T _2.

In this example, the control circuit 140 when the power receiving device is stationary relative to the power transmission device 100, for each period T _1, the operation using the first and second measurement values, mutual inductance L _m, and performing a first process of estimating the voltage V ₂ output from the receiving coil. Then, the control circuit 140 in every cycle T ₂ shorter than the period T _1, by using the value of the mutual inductance L _m estimated in the first processing of the previous, wherein the calculation of the equation (14) voltage V ₂ Is estimated. The fact that the power receiving device is stationary with respect to the power transmitting device 100 can be detected by the sensor 150.

As described above, in the real-time estimation, among the receiving parameters such as L _m , V _2, and I ₂ , it is assumed that a parameter having a small change is constant, and other parameters having a large change are estimated in real time. As the parameter having a small change, an estimation parameter obtained by two measurements performed before the start of the real-time estimation is used.

14B is a diagram showing an example of a time variation of the voltage V ₁ of the case of controlling the voltages V ₁ performs real-time estimated by the period T _2. As shown, the control circuit 140 in this example, based on the power receiving parameters estimated by real-time estimation for each period T _2, to determine the voltage value of the AC power output from the inverter circuit 120. Control circuit 140, when the parameters previously estimated, the difference or the rate of change of the newly estimated parameter exceeds a predetermined value, changes the voltage V _1. Thereby, the operation of the moving body 200 can be more finely controlled.

Figure 15 is a flowchart showing the estimation by two measurements performed every cycle T _1, an example of operation of a combination of a real-time estimation performed in every cycle T _2. Steps S202 to S205 in FIG. 15 show an estimation process based on two measurements. Steps S211 to S214 show a real-time estimation process.

The control circuit in this example 140, in every cycle _{T 2} shorter than the period _{T 1,} to perform a real-time estimation process in S214 from step S211. Control circuit 140, in step S211, it is determined whether elapsed time T ₂ from the start of the previous real-time estimation process. If this determination is Yes, the control circuit 140 acquires the measured values V ₁ and I ₁ of the voltage and current measured by the measuring device in step S212. In step S213, the control circuit 140 estimates a power receiving parameter. As described above, if the mobile 200 is moving is assumed to be constant receiving voltage V _2, to estimate the mutual inductance L _m by the calculation formula (13). Conversely, if the mobile 200 is stationary, it is assumed that the mutual inductance L _m is constant, estimates the receiving voltage V ₂ by the operation of Equation (14). Control circuit 140, in step S214, the based on the power receiving parameters estimated by referring to a table to determine the next value of the transmission voltages V ₁ to be set.

Control circuit 140, from the previous step S202 until the time _{T 1} is elapsed, repeats S214 from step S211. When the time _{T 1} is elapsed, it performs the S205 from step S202, to determine the updated value of the transmission voltage V1. The processing in steps S202 to S205 is the same as the processing described with reference to FIG.

  According to the above operation, power reception parameters can be estimated with high frequency without performing communication with the power receiving device during power transmission.

<Current and voltage conversion>
The effective value I ₁ of the effective value V ₁ and current of the voltage used in the above estimation method is the effective value of the sine wave signal having an angular frequency omega. However, the voltage output from the inverter circuit 120 is not limited to a sine wave and may be a rectangular wave. In such a case, the control circuit 140 performs the above-described calculation after appropriately converting the value measured by the measuring device 130.

The waveform of the voltage output from the inverter circuit 120 may be a rectangular wave. On the other hand, the waveform of the current output from the inverter circuit 120 can be considered to be substantially a sine wave. It is assumed that the voltage is a rectangular wave having a period 2π / ω having a maximum value V _1m and a minimum value −V _1m . The effective value of the voltage obtained from the measuring instrument 130a and _{V 1 m,} the effective value of the current obtained from the instrument 130b and _{I 1 m.}

The effective value V _{1 m} of the voltage of the rectangular wave, can not be used as it is as an effective value V ₁ of the voltage sine wave. It is necessary to expand the square wave to a Fourier series to derive a coefficient V ₁ of a term 2 ^1/2 V ₁ × sin (ωt + θ) having a sine wave component of the angular frequency ω. This indicates that V ₁ = ((2 × 2 ^1/2 ) / π) V _1m should be satisfied. On the other hand, since the current output from the inverter circuit 120 can be handled as a sine wave, it is possible to set I ₁ = I _1m .

_Conversion of DC voltage value V _2dc and DC current value I _{2dc of} power storage element 145 and effective value V ₂ of output voltage from power receiving resonator and effective value I _{2 of} output current in power receiving device will be described.

As shown in FIGS. 4 and 9, AC power output from power receiving resonator 210 is stored in power storage element 245 as DC power via rectifier 220 and capacitor 230. In storage element 245, the DC voltage value is estimated as V _2dc = (π / (2 × 2 ^1/2 )) V _2, and the DC current value is I _2dc = ((2 × 2 ^1/2 ) / π ) it is estimated to _{I 2.} Therefore, when performing power transmission control by estimating V _2dc and I _2dc instead of V ₂ and I ₂ , the control circuit 140 _converts V ₂ and I ₂ to V _2dc and I _2dc based on the above equation. Just convert it.

  The arrangement of measuring devices 130a and 130b or the partial configuration of power storage element 245 may be different from the configuration in the present embodiment. Even in such a case, the processing in the present embodiment can be applied by converting the measured effective value of the voltage and the effective value of the current using an appropriate formula.

  16A to 16C show another example of the arrangement of the voltage measuring device 130a and the current measuring device 130b. FIG. 16A is a schematic diagram illustrating an example in which the voltage measuring device 130a is connected between the DC power supply 50 and the inverter circuit 120. FIG. 16B is a schematic diagram illustrating an example in which the current measuring device 130b is connected between the DC power supply 50 and the inverter circuit 120. FIG. 16C is a schematic diagram illustrating an example in which both the voltage measuring device 130a and the current measuring device 130b are connected between the DC power supply 50 and the inverter circuit 120.

In the example of FIG. 16A, the voltage measuring device 130a measures the voltage input to the inverter circuit 120. Using the effective value V _{1m of the} voltage obtained from the voltage measuring device 130a, the effective value of the AC voltage output from the inverter circuit 120 is calculated as V ₁ = ((2 × 2 ^1/2 ) / π) V _1m Can be obtained by

In the example of FIG. 16B, the current measuring device 130b measures the current input to the inverter circuit 120. Using the effective value I _{1m of the} current obtained from the current measuring device 130b, the effective value of the alternating current output from the inverter circuit 120 is calculated as I ₁ = (π / (2 × 2 ^1/2 )) I _1m Can be obtained by

In the example of FIG. 16C, the voltage measuring device 130a and the current measuring device 130b measure the voltage and the current input to the inverter circuit 120, respectively. In this example, the effective value of the AC voltage output from the inverter circuit 120 is obtained by the calculation of V ₁ = ((2 × 2 ^1/2 ) / π) V _1m , and the effective value of the AC current is I ₁ = ( π / (2 × 2 ^1/2 )) I _1m can be obtained.

FIG. 17A is a schematic diagram illustrating an example in which a DC-DC converter 250 is connected between a capacitor 230 and a storage element 245. FIG. 17B is a schematic diagram showing an example in which a load resistor 240 such as a motor is arranged instead of power storage element 245 in the configuration of FIG. 17A. In these examples, power transmission control may be performed based on the voltage and current of the DC power output from DC-DC converter 250. In that case, the control circuit 140 calculates the voltage and the current output from the DC-DC converter 250 from the values of V2 and I2 calculated by the above-described processing. When the duty ratio D of DC-DC converter 250 is constant, DC voltage value is estimated as V _2dc = (π / (2 × 2 ^1/2 )) V ₂ D in power storage element 245 or load resistor 240. You. The DC current value is estimated as I _2dc = ((2 × ^1/2 ) / π) I ₂ / D.

<Effect>
According to the present embodiment, the transmission power can be appropriately controlled according to the position of the power receiving device, the state of the impedance, and the like without performing communication from the power receiving device to the power transmitting device 100. For this reason, it is possible to eliminate the influence of communication interference or the like that occurs in a use environment such as a factory or a road. Also, there is no time loss due to connection and approval before communication. Furthermore, since there is no need to mount a wireless device in both the electric device 100 and the moving body 200, it is possible to improve the maintainability of the system and to reduce the size and cost.

  The power transmitting device and the power receiving device may include a communication device for a purpose different from feedback control during power transmission. For example, a form in which communication is performed to perform alignment between the power transmitting device and the power receiving device before starting power transmission is also included in the present disclosure.

  The processing based on the expressions (10) to (12), (13), and (14) in the above description is an example, and can be appropriately modified and used. For example, the formula may be corrected and used as necessary so that the error is reduced.

  The technology of the present disclosure can be applied to a wireless power transmission system to a mobile body such as an automatic guided vehicle (AGV). The technology of the present disclosure can be applied to other industrial machines, multicopters, service robots, and the like.

  50: Direct current (DC) power supply 100: Wireless power transmitting device 105: Power transmitting coil unit 110: Power transmitting resonator 112: Power transmitting coil 112a: First upper part 112b: First 1 Lower side portion 112c: First rectangular surface 120: Inverter circuit 130: Current measuring device 140: Control circuit 142: Control IC 143: Memory 144: Gate driver 150 sensor 200 moving body 205 receiving coil unit 207 driving wheel 210 receiving resonator 212 receiving coil 212a second upper part 212b Second lower portion 212c: second rectangular surface 220: rectifier 230: capacitor 240: load resistance of motor or the like 245: storage Electric element 250 ・ ・ ・ DC-DC converter

Claims (14)

A power transmitting device that wirelessly transmits power to a power receiving device including a power receiving resonator,
An inverter circuit,
A power transmission resonator connected to the inverter circuit,
A measuring instrument for measuring one of a voltage input to the inverter circuit and a voltage output from the inverter circuit, and one of a current input to the inverter circuit and a current output from the inverter circuit;
A control circuit for controlling the inverter circuit,
The control circuit includes:
A first measurement value of a voltage and a current measured by the measuring device in a state where the inverter circuit outputs AC power having a first voltage value and transmits power from the power transmitting resonator to the power receiving resonator. And get
In a state where the voltage value of the AC power output from the inverter circuit is changed to a second voltage value different from the first voltage value, a second measurement value of a voltage and a current measured by the measuring device And get
A third voltage value is determined by a process including an operation using the first and second measurement values,
A power transmission device that outputs AC power having the third voltage value from the inverter circuit to continue power transmission. The control circuit includes:
By the calculation using the first and second measurement values, the value of one or more parameters indicating the state of the power receiving device is estimated,
The third voltage value is determined from the estimated parameter value with reference to data defining the correspondence between the value of the one or more parameters and the value of the voltage to be output from the inverter circuit. The power transmission device according to claim 1. The control circuit includes:
Determination of the acquisition and the third voltage value of the first and second measurement values, run in every cycle T _1,
When the value of the one or more parameters indicating the state of the power receiving device estimated from the first and second measured values changes from the value of the parameter estimated last time, the third voltage value Is set to a value different from the first voltage value,
The power transmission device according to claim 2, wherein the third voltage value is set to the same value as the first voltage value when the value of the parameter is the same as the value of the parameter estimated last time. .   The one or more parameters are a mutual inductance between a power transmission coil included in the power transmission resonator and a power reception coil included in the power reception resonator, a voltage output from the power reception resonator, and an output from the power reception resonator. The power transmission device according to claim 2, wherein the power transmission device includes at least one of a current to be supplied and power output from the power receiving resonator. The one or more parameters include the mutual inductance;
Obtained from the first measurement value, the effective value of the voltage and current output from the inverter circuit, and V ₁₀ and I _10, respectively,
The effective values of the voltage and current output from the inverter circuit obtained from the second measurement value are V ₁₁ and I ₁₁ , respectively.
The mutual inductance and _{L m,}
The resistance value of the power transmission resonator and R _1,
The resistance value of the power receiving resonator is R ₂ ,
When the driving angular frequency of the inverter circuit is ω,
The control circuit includes:

Estimating the mutual inductance L _m by the calculation of the power transmission device according to claim 4. The one or more parameters include at least one of a voltage output from the power receiving resonator and a current output from the power receiving resonator,
The voltage output from the power receiving resonator is V ₂ ,
When the current output from the power reception resonator and I _2,
The control circuit includes:

Or

The operation by the voltage V ₂ and the current I ₁ of at least one of estimating the power transmission device according to claim 5. The control circuit, when the power receiving device is moving with respect to the power transmitting device,
In every cycle T _1, by the operation using the first and second measurement values, executes a first process of estimating the mutual inductance L _m, and the voltage V ₂ output from the power reception resonator ,
Wherein in every cycle T ₂ shorter than the period T _1, by using the estimated value of the voltage V ₂ in the first process of the previous,

Estimating the mutual inductance L _m by the calculation of the power transmission device according to claim 6. The control circuit, when the power receiving device is stationary with respect to the power transmitting device,
In every cycle T _1, by the operation using the first and second measurement values, executes a first process of estimating the mutual inductance L _m, and the voltage V ₂ output from the power reception resonator ,
Wherein in every cycle T ₂ shorter than the period T _1, by using the value of the mutual inductance L _m estimated in the first process of the previous,

Estimating the voltage V ₂ by the operation of the power transmission device according to claim 6 or 7.   The power transmission device according to any one of claims 1 to 8, further comprising a sensor that detects whether the power reception device is moving with respect to the power transmission device.   The power transmitting device according to any one of claims 1 to 9, wherein the power receiving device is a moving body. The inverter circuit has a plurality of switching elements,
The control circuit supplies a pulse signal for determining a conduction / non-conduction state to each of the plurality of switching elements, and adjusts a duty ratio of the pulse signal to thereby control the AC output from the inverter circuit. The power transmission device according to claim 1, wherein the power transmission device controls a voltage value of electric power. A power transmission device according to any one of claims 1 to 11,
And a power receiving device.   A control device comprising the control circuit in the power transmission device according to any one of claims 1 to 11. A program used in a power transmitting device that wirelessly transmits power to a power receiving device including a power receiving resonator,
The power transmission device,
An inverter circuit,
A power transmission resonator connected to the inverter circuit,
A measuring instrument for measuring one of a voltage input to the inverter circuit and a voltage output from the inverter circuit, and one of a current input to the inverter circuit and a current output from the inverter circuit;
A control circuit for controlling the inverter circuit,
The program includes:
A first measurement value of a voltage and a current measured by the measuring device in a state where the inverter circuit outputs AC power having a first voltage value and transmits power from the power transmitting resonator to the power receiving resonator. And get
In a state where the voltage value of the AC power output from the inverter circuit is changed to a second voltage value different from the first voltage value, a second measurement value of a voltage and a current measured by the measuring device And get
A third voltage value is determined by a process including an operation using the first and second measurement values,
A program for causing the inverter circuit to output AC power having the third voltage value and to continue power transmission.

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