JP6855952B2 - Power receiver, power transmission system, and power receiving method - Google Patents

Description

The present invention relates to a power receiver, a power transmission system, and a power receiving method.

Conventionally, there is a non-contact power feeding system including a power feeding device and a power receiving device that receives power from the power feeding device in a non-contact manner by a resonance method. The power receiving device includes a resonance circuit having a power receiving coil and a resonance capacitor, and a reactance element. When the reactance element is turned on, the resonance circuit and the reactance element form a part of the resonance circuit. Includes a switch element for connecting to and. Further, when the received voltage value of the power received from the power feeding device via the power receiving coil of the resonance circuit is equal to or higher than a predetermined threshold value, the power receiving device sends a signal to turn on the switch element. Further includes a switch control unit that outputs to a switch element (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-01170

By the way, in the conventional non-contact power supply system (power transmission system), when the received voltage value exceeds a predetermined threshold value, the switch element is turned on to shift the resonance frequency to protect the circuit components. The switch element is not provided to adjust the power receiving efficiency when the power receiving device receives power from the transmitter, and the power receiving device does not include a configuration for adjusting the power receiving efficiency.

Therefore, it is an object of the present invention to provide a power receiver, a power transmission system, and a power receiving method capable of protecting an element for adjusting the power receiving efficiency.

The power receiver according to the embodiment of the present invention has a resonance coil portion, a secondary resonance coil that receives power from the primary resonance coil by magnetic field resonance generated with the primary resonance coil, and a secondary resonance coil. A capacitor inserted in series with the resonance coil portion of the side resonance coil, a series circuit of the first switch and the second switch connected in parallel with the capacitor, and a first switch connected in parallel with the first switch. A first rectifying element having a rectifying direction, a second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction, and a secondary resonance coil are supplied. Based on the first detection unit that detects the voltage or current, the second detection unit that detects the voltage between the first switch or the second switch, and the voltage or current detected by the first detection unit. A control unit that adjusts the amount of power received by the secondary resonance coil by controlling the first signal and the second signal for switching the on / off of the first switch and the second switch, respectively. When the voltage between both ends detected by the second detection unit becomes equal to or higher than a predetermined threshold value, the first switch and the second switch are held in the on state.

It is possible to provide a power receiver, a power transmission system, and a power receiving method capable of protecting an element for adjusting the power receiving efficiency.

It is a figure which shows the power transmission system 50. It is a figure which shows the state which electric power is transmitted from a transmitter 10 to electronic devices 40A, 40B by magnetic field resonance. It is a figure which shows the state which electric power is transmitted from a transmitter 10 to electronic devices 40B1 and 40B2 by magnetic field resonance. It is a figure which shows the power receiving device 100 and the power transmission device 80 of embodiment. It is a figure which shows the internal structure of the control part 150. It is a figure which shows the current path in a capacitor 115 and adjustment part 130. It is a figure which shows the AC voltage generated in the secondary side resonance coil 110, and two clocks included in a drive signal. It is a figure which shows the simulation result which shows the characteristic of the power receiving efficiency with respect to a phase difference. It is a figure which shows the power transmission apparatus 80 and the electronic devices 200A and 200B which used the electric power transmission system 500 of embodiment. It is a figure which shows the relationship between the phase difference of a drive signal, and the amount of power received of the power receivers 100A and 100B. It is a task diagram which shows the process which the transmitter 10 and the receivers 100A and 100B execute in order to set a phase difference. It is a figure which shows the equivalent circuit of a power transmission device 80 and electronic devices 200A and 200B. It is a figure which shows the table data which associated the phase difference with respect to the relationship between mutual inductance M _TA and mutual inductance M _TB. It is table data which associates mutual inductance _MTA , _{MTB, and power receiving efficiency.} It is a flowchart which shows the method which the transmitter 10 of embodiment sets the phase difference of the receiver 100A or 100B. It is a figure which shows the relationship between the clock CLK1, the output of D-FF158C, and the output of an OR circuit 158A. It is a figure which shows the simulation result of the time change of the transmission voltage of a primary side resonance coil 12, the voltage between terminals 112X and 112Y of a secondary side resonance coil 110, and the received power of a power receiver 100. It is a task diagram which shows the process which a power receiver 100 and a transmitter 10 perform when an overvoltage occurs. It is a figure which shows the threshold value output circuit 159E. It is a figure which shows the power receiver 100C of the modification of embodiment. It is a figure which shows the control part 150D of the modification of embodiment.

Hereinafter, embodiments to which the power receiver, power transmission system, and power receiving method of the present invention are applied will be described.

<Embodiment>
Before explaining the embodiment to which the power receiver, the power transmission system, and the power receiving method of the present invention are applied, the premise of the power receiving device, the power transmission system, and the power receiving method of the embodiment is used with reference to FIGS. 1 to 3. Describe the technology.

FIG. 1 is a diagram showing a power transmission system 50.

As shown in FIG. 1, the power transmission system 50 includes an AC power supply 1, a primary side (transmission side) transmitter 10, and a secondary side (power receiving side) receiver 20. The power transmission system 50 may include a plurality of transmitters 10 and receivers 20.

The transmitter 10 has a primary coil 11 and a primary resonant coil 12. The power receiver 20 has a secondary resonance coil 21 and a secondary coil 22. A load device 30 is connected to the secondary coil 22.

As shown in FIG. 1, the transmitter 10 and the power receiver 20 are transmitted by magnetic field resonance (magnetic field resonance) between the primary side resonance coil (LC resonator) 12 and the secondary side resonance coil (LC resonator) 21. Energy (power) is transmitted from the electric device 10 to the power receiving device 20. Here, the power transmission from the primary side resonance coil 12 to the secondary side resonance coil 21 can be not only magnetic field resonance but also electric field resonance (electric field resonance), but in the following description, magnetic field resonance is mainly taken as an example. explain.

Further, in the embodiment, as an example, the frequency of the AC voltage output by the AC power supply 1 is 6.78 MHz, and the resonance frequency of the primary side resonance coil 12 and the secondary side resonance coil 21 is 6.78 MHz. explain.

The power transmission from the primary side coil 11 to the primary side resonance coil 12 is performed by using electromagnetic induction, and the power transmission from the secondary side resonance coil 21 to the secondary side coil 22 also uses electromagnetic induction. Is done.

Further, although FIG. 1 shows a mode in which the power transmission system 50 includes the secondary side coil 22, the power transmission system 50 does not have to include the secondary side coil 22. In this case, the secondary side resonance The load device 30 may be directly connected to the coil 21.

FIG. 2 is a diagram showing a state in which electric power is transmitted from the transmitter 10 to the electronic devices 40A and 40B by magnetic field resonance.

The electronic devices 40A and 40B are a tablet computer and a smartphone, respectively, and have built-in power receivers 20A and 20B, respectively. The power receivers 20A and 20B have a configuration in which the secondary coil 22 is removed from the power receiver 20 (see FIG. 1) shown in FIG. That is, the power receivers 20A and 20B have a secondary resonance coil 21. Although the transmitter 10 is shown in a simplified manner in FIG. 2, the transmitter 10 is connected to the AC power supply 1 (see FIG. 1).

In FIG. 2, the electronic devices 40A and 40B are arranged at equal distances from the transmitter 10, and the receivers 20A and 20B built therein are simultaneously powered by magnetic field resonance in a non-contact state from the transmitter 10. Is receiving power.

Here, as an example, in the state shown in FIG. 2, it is assumed that the power receiving efficiency of the power receiving device 20A built in the electronic device 40A is 40% and the power receiving efficiency of the power receiving device 20B built in the electronic device 40B is 40%. ..

The power receiving efficiency of the power receivers 20A and 20B is represented by the ratio of the power received by the secondary coil 22 of the power receivers 20A and 20B to the power transmitted from the primary coil 11 connected to the AC power supply 1. When the transmitter 10 does not include the primary coil 11 and the primary resonance coil 12 is directly connected to the AC power supply 1, the primary resonance is replaced with the power transmitted from the primary coil 11. The received power may be obtained using the power transmitted from the coil 12. When the power receivers 20A and 20B do not include the secondary coil 22, the received power may be obtained by using the power received by the secondary resonance coil 21 instead of the power received by the secondary coil 22. ..

The power receiving efficiency of the power receiving devices 20A and 20B is determined by the coil specifications of the power transmitting device 10 and the power receiving devices 20A and 20B, and the distance and attitude between them. In FIG. 2, since the configurations of the power receivers 20A and 20B are the same and they are arranged at the same distance and posture from the transmitter 10, the power receiving efficiencies of the power receivers 20A and 20B are equal to each other. %.

Further, it is assumed that the rated output of the electronic device 40A is 10 W and the rated output of the electronic device 40B is 5 W.

In such a case, the power transmitted from the primary resonance coil 12 (see FIG. 1) of the transmitter 10 is 18.75 W. 18.75W can be obtained by (10W + 5W) / (40% + 40%).

By the way, when the electric power of the transmitters 10 to 18.75 W is transmitted to the electronic devices 40A and 40B, the electric power receivers 20A and 20B receive a total of 15 W of electric power, and the electric power receivers 20A and 20B are equal. In order to receive electric power to the electric power, each of them receives 7.5 W of electric power.

As a result, the electronic device 40A has a power shortage of 2.5 W, and the electronic device 40B has a power surplus of 2.5 W.

That is, even if the electric power of 18.75 W from the transmitter 10 is transmitted to the electronic devices 40A and 40B, the electronic devices 40A and 40B cannot receive the power in a well-balanced manner. In other words, the power supply balance is not good when the electronic devices 40A and 40B receive power at the same time.

FIG. 3 is a diagram showing a state in which electric power is transmitted from the transmitter 10 to the electronic devices 40B1 and 40B2 by magnetic field resonance.

The electronic devices 40B1 and 40B2 are smartphones of the same type, and have built-in power receivers 20B1 and 20B2, respectively. The power receivers 20B1 and 20B2 are equivalent to the power receiver 20B shown in FIG. That is, the power receivers 20B1 and 20B2 have a secondary resonance coil 21. Although the transmitter 10 is shown in a simplified manner in FIG. 3, the transmitter 10 is connected to the AC power supply 1 (see FIG. 1).

In FIG. 3, the angles (postures) of the electronic devices 40B1 and 40B2 with respect to the transmitter 10 are the same, but the electronic device 40B1 is arranged at a position farther from the transmitter 10 than the electronic device 40B2. The power receivers 20B1 and 20B2, which are built in the electronic devices 40B1 and 40B2, respectively, simultaneously receive electric power from the transmitter 10 in a non-contact state by magnetic field resonance.

Here, as an example, in the state shown in FIG. 3, the power receiving efficiency of the power receiving device 20B1 built in the electronic device 40B1 is 35%, and the power receiving efficiency of the power receiving device 20B2 built in the electronic device 40B2 is 45%. ..

Here, since the angles (attitudes) of the electronic devices 40B1 and 40B2 with respect to the transmitter 10 are equal, the power receiving efficiency of the receivers 20B1 and 20B2 is determined by the distance between each of the receivers 20B1 and 20B2 and the transmitter 10. Therefore, in FIG. 3, the power receiving efficiency of the power receiving device 20B1 is lower than the power receiving efficiency of the power receiving device 20B2. The rated output of the electronic devices 40B1 and 40B2 is 5W.

In such a case, the power transmitted from the primary resonance coil 12 (see FIG. 1) of the transmitter 10 is 12.5 W. 12.5W can be obtained by (5W + 5W) / (35% + 45%).

By the way, when the electric power of 12.5 W from the transmitter 10 is transmitted to the electronic devices 40B1 and 40B2, the electric power receivers 20B1 and 20B2 receive a total of 10 W of electric power. Further, in FIG. 3, since the power receiving efficiency of the power receiving device 20B1 is 35% and the power receiving efficiency of the power receiving device 20B2 is 45%, the power receiving device 20B1 receives about 4.4 W of power, and the power receiving device 20B2 receives about 4.4 W of power. , Approximately 5.6% of the power will be received.

As a result, the electronic device 40B1 has a power shortage of about 0.6 W, and the electronic device 40B2 has a power surplus of 0.6 W.

That is, even if the electric power of 12.5 W from the transmitter 10 is transmitted to the electronic devices 40B1 and 40B2, the electronic devices 40B1 and 40B2 cannot receive the electric power in a well-balanced manner. In other words, the power supply balance when the electronic devices 40B1 and 40B2 receive power at the same time is not good (there is room for improvement).

Here, the power supply balance when the angles (postures) of the electronic devices 40B1 and 40B2 with respect to the transmitter 10 are the same and the distances of the electronic devices 40B1 and 40B2 from the transmitter 10 are different has been described.

However, since the power receiving efficiency is determined by the distance and the angle (posture) between the transmitter 10 and the power receivers 20B1 and 20B2, if the angles (postures) of the electronic devices 40B1 and 40B2 are different in the positional relationship shown in FIG. The power receiving efficiencies of the power receivers 20B1 and 20B2 are different from the above-mentioned 35% and 45%.

Further, even if the distances of the electronic devices 40B1 and 40B2 from the transmitter 10 are the same, if the angles (postures) of the electronic devices 40B1 and 40B2 with respect to the transmitter 10 are different, the power receiving efficiencies of the receivers 20B1 and 20B2 will be different values. ..

As described above, as shown in FIG. 2, when power is simultaneously transmitted from the transmitter 10 to electronic devices 40A and 40B having different rated outputs by magnetic field resonance, it is difficult for the electronic devices 40A and 40B to receive power in a well-balanced manner. Is.

Further, as shown in FIG. 3, even if the rated outputs of the electronic devices 40B1 and 40B2 are equal to each other, if the angles (postures) of the electronic devices 40B1 and 40B2 with respect to the transmitter 10 are different, the power receiving efficiency of the power receivers 20B1 and 20B2 is high. Since they are different from each other, it is difficult for the electronic devices 40B1 and 40B2 to receive power in a well-balanced manner.

Further, in FIGS. 2 and 3, a case where the electronic devices 40A and 40B and the electronic devices 40B1 and 40B2 receive power at the same time has been described, but there are a plurality of electronic devices 40A and 40B or electronic devices 40B1 and 40B2. It is also conceivable that the electronic devices of the above will receive power separately in a time-division manner.

However, when a plurality of electronic devices receive power separately in a time-division manner, the other electronic devices cannot receive power while each electronic device is receiving power, so that the power reception of all the electronic devices is completed. The problem arises that it takes time.

Next, the power receiver, the power transmission system, and the power receiving method of the embodiment will be described with reference to FIGS. 4 to 9.

FIG. 4 is a diagram showing a power receiver 100 and a power transmission device 80 of the embodiment. The power transmission device 80 includes an AC power source 1 and a power transmission device 10. The AC power supply 1 and the transmitter 10 are the same as those shown in FIG. 1, but FIG. 4 shows a more specific configuration.

The power transmission device 80 includes an AC power source 1 and a power transmission device 10.

The transmitter 10 includes a primary coil 11, a primary resonant coil 12, a matching circuit 13, a capacitor 14, a control unit 15, and an antenna 16.

The power receiver 100 includes a secondary resonance coil 110, a capacitor 115, a voltmeter 116, a rectifier circuit 120, an adjustment unit 130, a smoothing capacitor 140, a control unit 150, a voltmeter 155B, output terminals 160X, 160Y, an antenna 170, and a detection unit. Includes 180 and voltmeters 181X, 181Y. A DC-DC converter 210 is connected to the output terminals 160X and 160Y, and a battery 220 is connected to the output side of the DC-DC converter 210.

First, the transmitter 10 will be described. As shown in FIG. 4, the primary side coil 11 is a loop-shaped coil, and is connected to the AC power supply 1 via a matching circuit 13 between both ends. The primary side coil 11 is arranged in close proximity to the primary side resonance coil 12 in a non-contact manner, and is electromagnetically coupled to the primary side resonance coil 12. The primary side coil 11 is arranged so that its own central axis coincides with the central axis of the primary side resonance coil 12. Matching the central axes improves the coupling strength between the primary coil 11 and the primary resonance coil 12, suppresses magnetic flux leakage, and eliminates unnecessary electromagnetic fields from the primary coil 11 and the primary resonance coil. This is to suppress the occurrence around 12.

The primary coil 11 generates a magnetic field by AC power supplied from the AC power supply 1 via the matching circuit 13, and transmits the power to the primary resonance coil 12 by electromagnetic induction (mutual induction).

As shown in FIG. 4, the primary side resonance coil 12 is arranged in close contact with the primary side coil 11 in a non-contact manner and is electromagnetically coupled to the primary side coil 11. Further, the primary resonance coil 12 has a predetermined resonance frequency and is designed to have a high Q value. The resonance frequency of the primary side resonance coil 12 is set to be equal to the resonance frequency of the secondary side resonance coil 110. A capacitor 14 for adjusting the resonance frequency is connected in series between both ends of the primary resonance coil 12.

The resonance frequency of the primary resonance coil 12 is set to be the same frequency as the frequency of the AC power output by the AC power supply 1. The resonance frequency of the primary resonance coil 12 is determined by the inductance of the primary resonance coil 12 and the capacitance of the capacitor 14. Therefore, the inductance of the primary resonance coil 12 and the capacitance of the capacitor 14 are set so that the resonance frequency of the primary resonance coil 12 is the same as the frequency of the AC power output from the AC power supply 1. Has been done.

The matching circuit 13 is inserted to match the impedance between the primary coil 11 and the AC power supply 1, and includes an inductor L and a capacitor C.

The AC power supply 1 is a power supply that outputs AC power having a frequency required for magnetic field resonance, and incorporates an amplifier that amplifies the output power. The AC power supply 1 outputs, for example, high-frequency AC power of about several hundred kHz to several tens of MHz.

The capacitor 14 is a variable capacitance type capacitor inserted in series between both ends of the primary resonance coil 12. The capacitor 14 is provided to adjust the resonance frequency of the primary resonance coil 12, and the capacitance is set by the control unit 15.

The control unit 15 controls the output voltage and output frequency of the AC power supply 1, controls the capacitance of the capacitor 14, and the like. Further, the control unit 15 performs data communication with the power receiver 100 through the antenna 16.

The power transmission device 80 as described above transmits the AC power supplied from the AC power supply 1 to the primary coil 11 to the primary resonance coil 12 by magnetic induction, and receives power from the primary resonance coil 12 by magnetic field resonance. The power is transmitted to the secondary resonance coil 110 of the above.

Next, the secondary resonance coil 110 included in the power receiver 100 will be described. Here, as an example, a mode in which the resonance frequency is 6.78 MHz will be described.

The secondary resonance coil 110 has the same resonance frequency as the primary resonance coil 12 and is designed to have a high Q value. The secondary resonance coil 110 has a resonance coil portion 111 and terminals 112X and 112Y. Here, the resonance coil portion 111 is actually the secondary side resonance coil 110 itself, but here, the one in which terminals 112X and 112Y are provided at both ends of the resonance coil portion 111 is referred to as the secondary side resonance coil 110. handle.

A capacitor 115 for adjusting the resonance frequency is inserted in series in the resonance coil unit 111. Further, the adjusting unit 130 is connected in parallel to the capacitor 115. Further, terminals 112X and 112Y are provided at both ends of the resonance coil portion 111. The terminals 112X and 112Y are connected to the rectifier circuit 120. The terminals 112X and 112Y are examples of the first terminal and the second terminal, respectively.

The secondary resonance coil 110 is connected to the rectifier circuit 120 without the intervention of the secondary coil. When the secondary resonance coil 110 is in a state where resonance can occur by the adjusting unit 130, the secondary resonance coil 110 outputs the AC power transmitted by the magnetic field resonance from the primary resonance coil 12 of the transmitter 10 to the rectifying circuit 120.

The capacitor 115 is inserted in series with the resonance coil portion 111 in order to adjust the resonance frequency of the secondary resonance coil 110. The capacitor 115 has terminals 115X and 115Y. The adjusting unit 130 is connected to the capacitor 115 in parallel.

The voltmeter 116 is connected in parallel to the capacitor 115 and measures the voltage between both terminals of the capacitor 115. The voltmeter 116 detects the voltage of the AC power received by the secondary resonance coil 110, and transmits a signal representing the voltage to the control unit 150. The AC voltage measured by the voltmeter 116 is used to synchronize the drive signals that drive the switches 131X and 131Y. The voltmeter 116 is an example of the first detection unit. An ammeter may be used instead of the voltmeter 116 to measure the voltage from the current waveform.

The rectifier circuit 120 has four diodes 121-124. The diodes 121 to 124 are connected in a bridge shape, and the electric power input from the secondary resonance coil 110 is full-wave rectified and output.

The adjusting unit 130 is connected in parallel to the capacitor 115 in the resonance coil unit 111 of the secondary resonance coil 110.

The adjusting unit 130 includes switches 131X and 131Y, diodes 132X and 132Y, capacitors 133X and 133Y, and terminals 134X and 134Y.

The switches 131X and 131Y are connected in series with each other between the terminals 134X and 134Y. The switches 131X and 131Y are examples of the first switch and the second switch, respectively. The terminals 134X and 134Y are connected to the terminals 115X and 115Y of the capacitor 115, respectively. Therefore, the series circuit of the switches 131X and 131Y is connected in parallel to the capacitor 115.

The diode 132X and the capacitor 133X are connected in parallel to the switch 131X. The diode 13Y and the capacitor 133Y are connected in parallel to the switch 131Y. In the diodes 132X and 132Y, the anodes of each other are connected to each other, and the cathodes of each other are connected to the capacitor 115. That is, the diodes 132X and 132Y are connected so that their rectifying directions are opposite to each other.

A voltmeter 181X is connected in parallel to the switch 131X, the diode 132X, and the capacitor 133X, and a voltmeter 181Y is connected in parallel to the switch 131Y, the diode 132Y, and the capacitor 133Y.

The diodes 132X and 132Y are examples of the first rectifying element and the second rectifying element, respectively. Further, the adjusting unit 130 may not include the capacitors 133X and 133Y.

As the switch 131X, the diode 132X, and the capacitor 133X, for example, a FET (Field Effect Transistor) can be used. The body diode between the drain and the source of the P-channel type or N-channel type FET may be connected so as to have a rectifying direction such as the diode 132X. When using an N-channel FET, the source is the anode of the diode 132X and the drain is the cathode of the diode 132X.

Further, the switch 131X is realized by switching the connection state between the drain and the source by inputting the drive signal output from the control unit 150 to the gate. Further, the capacitor 133X can be realized by the parasitic capacitance between the drain and the source.

Similarly, as the switch 131Y, the diode 132Y, and the capacitor 133Y, for example, an FET can be used. The body diode between the drain and the source of the P-channel type or N-channel type FET may be connected so as to have a rectifying direction like the diode 132B. When using an N-channel FET, the source is the anode of the diode 132Y and the drain is the cathode of the diode 132Y.

Further, the switch 131Y is realized by switching the connection state between the drain and the source by inputting the drive signal output from the control unit 150 to the gate. Further, the capacitor 133Y can be realized by the parasitic capacitance between the drain and the source.

The switch 131X, the diode 132X, and the capacitor 133X are not limited to those realized by the FET, and may be realized by connecting the switch, the diode, and the capacitor in parallel. This also applies to the switch 131Y, the diode 132Y, and the capacitor 133Y.

The switches 131X and 131Y are switched on / off in opposite phases. When the switch 131X is off and the switch 131Y is on, a resonance current flows in the adjusting unit 130 in the direction from the terminal 134X to the capacitor 133X and the switch 131Y toward the terminal 134Y, and the capacitor 115 resonates from the terminal 115X to the terminal 115Y. The current is ready to flow. That is, in FIG. 4, a resonance current can flow in the secondary resonance coil 110 in the clockwise direction.

Further, when the switch 131X is on and the switch 131Y is off, a current path is generated in the adjusting unit 130 from the terminal 134X to the terminal 134Y via the switch 131X and the diode 132Y. Since this current path is parallel to the capacitor 115, no current flows through the capacitor 115.

Therefore, from the state where the switch 131X is off and the switch 131Y is turned on and the resonance current is flowing in the secondary resonance coil 110 in the clockwise direction, the switch 131X is turned on and the switch 131Y is turned off. If this is done, the resonance current will not be generated. This is because the current path does not include the capacitor.

Further, when the switch 131X is on and the switch 131Y is off, a resonance current flows in the adjusting unit 130 in the direction from the terminal 134Y to the capacitor 133Y and the switch 131X toward the terminal 134X, and the capacitor 115 has the terminal 115Y to the terminal 115X. The resonance current can flow through the switch. That is, in FIG. 4, a resonance current can flow in the secondary resonance coil 110 in the counterclockwise direction.

Further, when the switch 131X is off and the switch 131Y is on, a current path is generated in the adjusting unit 130 from the terminal 134Y to the terminal 134X via the switch 131Y and the diode 132X. Since this current path is parallel to the capacitor 115, no current flows through the capacitor 115.

Therefore, from the state where the switch 131X is on and the switch 131Y is off and the resonance current is flowing in the secondary resonance coil 110 in the counterclockwise direction, the switch 131X is off and the switch 131Y is on. When switched, no resonant current is generated. This is because the current path does not include the capacitor.

By switching the switches 131X and 131Y as described above, the adjusting unit 130 switches between a state in which a resonance current can be generated and a state in which a resonance current is not generated. Switching between the switches 131X and 131Y is performed by a drive signal output from the control unit 150.

The frequency of the drive signal is set to the AC frequency that the secondary resonance coil 110 receives.

The switches 131X and 131Y cut off the alternating current at the high frequency as described above. For example, the adjusting unit 130, which is a combination of two FETs, can cut off the alternating current at high speed.

The operation of the drive signal and the adjusting unit 130 will be described later with reference to FIG.

The smoothing capacitor 140 is connected to the output side of the rectifier circuit 120, smoothes the power rectified by the rectifier circuit 120 in full wave, and outputs it as DC power. Output terminals 160X and 160Y are connected to the output side of the smoothing capacitor 140. The power that has been full-wave rectified by the rectifier circuit 120 can be treated as substantially AC power because the negative component of the AC power is inverted to the positive component, but it was full-wave rectified by using the smoothing capacitor 140. Stable DC power can be obtained even when the power includes ripples.

The line connecting the upper terminal of the smoothing capacitor 140 and the output terminal 160X is the line on the high voltage side, and the line connecting the lower terminal of the smoothing capacitor 140 and the output terminal 160Y is the line on the low voltage side. Is.

The control unit 150 holds data representing the rated output of the battery 220 in the internal memory. Further, in response to a request from the control unit 15 of the transmitter 10, the power received by the receiver 100 from the transmitter 10 (received power) is measured, and data representing the received power is transmitted to the transmitter 10 via the antenna 170. Send.

When the control unit 150 receives data representing the phase difference from the transmitter 10, it generates a drive signal using the received phase difference to drive the switches 131X and 131Y. The received power may be obtained by the control unit 150 based on the voltage V measured by the voltmeter 155B and the internal resistance value R of the battery 220. The received power P is obtained by ^{P = V 2 / R.}

Further, the control unit 150 controls to turn on both the switches 131X and 131Y when the overvoltage of the voltage between both ends of the switch 131X or 131Y is detected. In this case, the switches 131X and 131Y are held in the ON state rather than being driven by the drive signal.

When the voltage between both ends of the switch 131X or 131Y detected by the detection unit 180 drops and the overvoltage is eliminated, the control unit 150 releases the holding of the switches 131X and 131Y in the on state and drives them again by the drive signal. To do.

The detection unit 180 is connected to the voltmeters 181X and 181Y, and detects the voltage between both ends of the switch 131X or 131Y. The detection unit 180 outputs a voltage value representing an absolute value of the voltage between both ends of the switch 131X or 131Y.

The detection unit 180 is provided in order to detect the overvoltage of the switch 131X or 131Y. The overvoltage of the switch 131X or 131Y means that the absolute value of the voltage between both ends of the switch 131X or 131Y exceeds the allowable voltage (predetermined threshold value) of the switch 131X or 131Y.

The voltmeters 181X and 181Y are connected in parallel to the switches 131X and 131Y, respectively. One of the terminals of the voltmeters 181X and 181Y is grounded as shown in FIG. The voltmeter 181X detects the voltage value of the left terminal with respect to the right terminal of the switch 131X, and the voltmeter 181Y detects the voltage value of the right terminal with respect to the left terminal of the switch 131Y. The overvoltage is determined by whether the absolute value of the positive or negative voltage with respect to the grounded terminal exceeds a predetermined value.

Here, the control unit 150 will be described with reference to FIG. FIG. 5 is a diagram showing an internal configuration of the control unit 150.

The control unit 150 includes a comparator 151, a PLL (Phase Locked Loop) 152, a phase shift circuit 153, a phase control unit 154, an inverter 155A, a voltmeter 155B, a reference phase detection unit 156, a processing unit 157, and an OR circuit 158A. It has a 158B, a D-FF (D-Flip Flop) 158C, and a comparator 158D.

The comparator 151 compares the AC voltage detected by the voltmeter 116 with a predetermined reference voltage Vref, and outputs a clock to the PLL 152.

The PLL 152 has a phase comparator 152A, a compensator 152B, and a VCO (Voltage Controlled Oscillator) 152C. The phase comparator 152A, the compensator 152B, and the VCO 152C are connected in series, and the output of the VCO 152C is connected so as to be fed back to the phase comparator 152A. With such a configuration, the PLL 152 outputs a clock synchronized with the signal input from the comparator 151.

The phase shift circuit 153 is connected to the output side of the PLL 152, and shifts the phase of the clock output from the PLL 152 with respect to the reference phase based on the signal representing the phase difference input from the phase control unit 154. And output. As the phase shift circuit 153, for example, a Phase Shifter may be used.

When the signal representing the phase difference transmitted from the transmitter 10 is input, the phase control unit 154 converts the signal representing the phase difference into a signal for the phase shift circuit 153 and outputs the signal.

Based on the signal input from the phase control unit 154, the clock whose phase is shifted by the phase difference with respect to the reference phase is branched into two on the output side of the phase shift circuit 153, and one of them is ORed as clock CLK1 as it is. It is output to the circuit 158A, and the other is inverted by the inverter 155A and output to the OR circuit 158B as the clock CLK2. The clocks CLK1 and CLK2 are control signals output by the control unit 150.

The reference phase detection unit 156 adjusts the phase of the clock output by the phase shift circuit 153 with respect to the clock output by the PLL 152 by controlling the shift amount in which the phase shift circuit 153 shifts the phase of the clock, and receives the maximum power. Detect the phase at which efficiency is obtained.

Then, the reference phase detection unit 156 holds the detected phase as the reference phase in the internal memory. Since the operating point at which the power receiving efficiency is maximized is the point at which the voltage value detected by the voltmeter 116 is maximized, the reference phase detection unit 156 adjusts the phase shift amount given by the phase shift circuit 153 while adjusting the phase shift amount. The operating point at which the voltage value detected by the voltmeter is maximized is detected, and the phase at that operating point is held in the internal memory as a reference phase.

Here, the clock output by the PLL 152 corresponds to the phase of the AC voltage due to the magnetic field resonance detected by the voltmeter 116. Therefore, adjusting the phase shift amount given by the phase shift circuit 153 to the clock output by the PLL 152 means that the phase shift circuit 153 controls the phase shift amount of the clock with respect to the voltage waveform detected by the voltmeter 116. Is.

The reference phase is the phase with respect to the AC voltage of the clocks CLK1 and CLK2 at which the maximum power receiving efficiency can be obtained. This reference phase is treated as 0 degree, and in order to adjust the received power, the phase difference between the phases of the clocks CLK1 and CLK2 with respect to the reference phase (0 degree) is adjusted by the phase shift circuit 153.

Here, since the phase of the AC voltage is not detected, the phase shift amount given by the phase shift circuit 153 to the clocks CLK1 and CLK2 when the maximum power receiving efficiency is obtained is treated as the reference phase.

Here, a mode in which the phase of the clock output from the PLL 152 is adjusted by the phase shift circuit 153 with respect to the AC voltage detected by the voltmeter 116 will be described, but an ammeter is used instead of the voltmeter 116. Therefore, the phase of the clock with respect to the alternating current may be adjusted by the phase shift circuit 153.

The voltmeter 155B is connected between the output terminals 160X and 160Y. The voltmeter 155B is used to calculate the received power of the power receiver 100. If the received power is obtained as described above based on the voltage V measured by the voltmeter 155B and the internal resistance value R of the battery 220, the loss is smaller than that in the case of measuring the current and measuring the received power. , A preferred measurement method. However, the received power of the power receiving device 100 may be obtained by measuring the current and the voltage. When measuring the current, it may be measured using a Hall element, a magnetoresistive element, a detection coil, a resistor or the like.

The processing unit 157 performs control processing such as output control of a reset signal for resetting the D-FF158C, output of a threshold value of the comparator 158D, and transmission of an abnormal signal indicating that an overvoltage has occurred to the transmitter 10. Further, the processing unit 157 monitors the SOC (State Of Charge) of the battery 220, and determines whether or not the battery 220 is fully charged.

The processing unit 157 outputs a reset signal (H (High) level reset signal) that resets the D-FF158C because the voltage detected by the detection unit 180 after the overvoltage occurs is a normal value (below a predetermined threshold value). If you return to. Since the output of the D-FF158C is fed back and input to the processing unit 157, the processing unit 157 can determine whether or not an overvoltage has occurred based on the output of the D-FF158C.

Further, the processing unit 157 constantly outputs a voltage value representing a threshold value to the comparator 158D while the power of the power receiver 100 is turned on. Further, when the voltage detected by the detection unit 180 becomes an overvoltage, the processing unit 157 transmits an abnormal signal indicating that the overvoltage has occurred to the transmitter 10 via the antenna 170.

In the OR circuit 158A, one input terminal is connected to the output terminal of the phase shift circuit 153, and the other input terminal is connected to the output terminal Q of the D-FF158C. The OR circuit 158A outputs a signal representing the logical sum of the clock CLK1 output from the phase shift circuit 153 and the output of the output terminal Q of the D-FF158C. The OR circuit 158A is an example of the first OR circuit.

When the output of the output terminal Q of the D-FF158C is at the L (Low) level, the OR circuit 158A outputs the clock CLK1 output from the phase shift circuit 153 as it is. On the other hand, when the output of the output terminal Q of the D-FF158C is H level, the OR circuit 158A outputs an H level signal regardless of the clock CLK1 output from the phase shift circuit 153. The output of the output terminal Q of the D-FF158C reaches the H level when an overvoltage occurs.

When the output of the output terminal Q of the D-FF158C is L level, the OR circuit 158B outputs the clock CLK2 input from the phase shift circuit 153 via the inverter 155A as it is. On the other hand, when the output of the output terminal Q of the D-FF158C is H level, the OR circuit 158B outputs an H level signal regardless of the clock CLK2 input from the phase shift circuit 153 via the inverter 155A. To do. The output of the output terminal Q of the D-FF158C reaches the H level when an overvoltage occurs. The OR circuit 158B is an example of a second OR circuit.

The D-FF158C has an input terminal S, an output terminal D, and a reset terminal R. The output terminal of the comparator 158D is connected to the input terminal S, one of the OR circuits 158A and 158B is connected to the output terminal D, and the processing unit 157 is connected to the reset terminal R. The D-FF158C reflects the level of the signal input to the input terminal S on the output terminal D and holds it at the output terminal D. The signal level of the output terminal D is reset to the L level when the reset signal becomes the H level. In the initial state in which the power of the power receiver 100 is turned on, the signal level of the output terminal D of the D-FF158C is the L level. D-FF158C is an example of a holding portion.

In the comparator 158D, the output terminal of the detection unit 180 is connected to the non-inverting input terminal (+), and the detection voltage of the detection unit 180 is input. Further, in the comparator 158D, an output terminal for outputting the threshold value of the processing unit 157 is connected to the inverting input terminal (−). The threshold value is a predetermined threshold value for determining the presence or absence of overvoltage. When the detection voltage input from the detection unit 180 is equal to or less than the threshold value, the voltage between both ends of the switches 131X and 131Y is normal, and when the detection voltage exceeds the threshold value, it becomes an overvoltage.

The comparator 158D outputs an L level signal when the detection voltage input from the detection unit 180 is equal to or less than the threshold value, and outputs an H level signal when the detection voltage exceeds the threshold value. The comparator 158D is an example of a comparator. The H level signal is an example of a signal representing the first level comparison result.

The DC-DC converter 210 is connected to the output terminals 160X and 160Y, and converts the voltage of the DC power output from the power receiver 100 into the rated voltage of the battery 220 and outputs the DC-DC converter 210. When the output voltage of the rectifier circuit 120 is higher than the rated voltage of the battery 220, the DC-DC converter 210 lowers the output voltage of the rectifier circuit 120 to the rated voltage of the battery 220. Further, when the output voltage of the rectifier circuit 120 is lower than the rated voltage of the battery 220, the DC-DC converter 210 boosts the output voltage of the rectifier circuit 120 to the rated voltage of the battery 220.

The battery 220 may be a secondary battery that can be recharged repeatedly, and for example, a lithium ion battery can be used. For example, when the power receiver 100 is built in an electronic device such as a tablet computer or a smartphone, the battery 220 is the main battery of such an electronic device.

The primary side coil 11, the primary side resonance coil 12, and the secondary side resonance coil 110 are manufactured, for example, by winding a copper wire. However, the material of the primary side coil 11, the primary side resonance coil 12, and the secondary side resonance coil 110 may be a metal other than copper (for example, gold, aluminum, etc.). Further, the materials of the primary side coil 11, the primary side resonance coil 12, and the secondary side resonance coil 110 may be different.

In such a configuration, the primary side coil 11 and the primary side resonance coil 12 are the power transmission side, and the secondary side resonance coil 110 is the power reception side.

By the magnetic field resonance method, electric power is transmitted from the transmitting side to the receiving side by utilizing the magnetic field resonance generated between the primary side resonance coil 12 and the secondary side resonance coil 110, so that the electric power is electromagnetically induced from the transmitting side to the receiving side. It is possible to transmit electric power over a longer distance than the electromagnetic induction method that transmits electric power.

The magnetic field resonance method has a higher degree of freedom than the electromagnetic induction method in terms of the distance or positional deviation between the resonance coils, and has the advantage of being position-free.

Next, the current path when the switches 131X and 131Y are driven by the drive signal will be described with reference to FIGS. 6 and 7.

FIG. 6 is a diagram showing current paths in the capacitor 115 and the adjusting unit 130. In FIG. 6, similarly to FIG. 4, the direction of the current flowing from the terminal 134X through the inside of the capacitor 115 or the adjusting unit 130 to the terminal 134Y is referred to as clockwise (CW (Clockwise)). Further, the direction of the current flowing from the terminal 134Y through the inside of the capacitor 115 or the adjusting unit 130 to the terminal 134X is referred to as counterclockwise (CCW (Counterclockwise)).

First, when both the switches 131X and 131Y are off and the current is clockwise (CW), a resonance current flows from the terminal 134X through the capacitor 133X and the diode 132Y toward the terminal 134Y, and at the same time, the resonance current flows from the terminal 115X to the capacitor 115. Resonant current flows through terminal 115Y. Therefore, a resonance current flows through the secondary resonance coil 110 in the clockwise direction.

When both the switches 131X and 131Y are off and the current is counterclockwise (CCW), a resonant current flows from the terminal 134Y through the capacitor 133Y and the diode 132X toward the terminal 134X, and the capacitor 115 has a terminal from the terminal 115Y. Resonant current flows through 115X. Therefore, a resonance current flows through the secondary resonance coil 110 in the counterclockwise direction.

When the switch 131X is on, the switch 131Y is off, and the current is clockwise (CW), a current path is generated in the adjusting unit 130 from the terminal 134X to the terminal 134Y via the switch 131X and the diode 132Y. Since this current path is parallel to the capacitor 115, no current flows through the capacitor 115. Therefore, no resonance current flows through the secondary resonance coil 110. In this case, even if the switch 131Y is turned on, no resonance current flows through the secondary resonance coil 110.

When the switch 131X is on, the switch 131Y is off, and the current is counterclockwise (CCW), a resonance current flows in the adjusting unit 130 in the direction from the terminal 134Y to the terminal 134X via the capacitor 133Y and the switch 131X. A resonance current flows through the capacitor 115 from the terminal 115Y to the terminal 115X. Therefore, a resonance current flows through the secondary resonance coil 110 in the counterclockwise direction. A current also flows through the diode 132X parallel to the switch 131X.

When the switch 131X is off, the switch 131Y is on, and the current is clockwise (CW), a resonance current flows in the adjusting unit 130 in the direction from the terminal 134X to the capacitor 133X and the switch 131Y toward the terminal 134Y, and the capacitor. A resonance current flows through the terminal 115X to the terminal 115Y. Therefore, a resonance current flows through the secondary resonance coil 110 in the clockwise direction. A current also flows through the diode 132Y parallel to the switch 131Y.

When the switch 131X is off, the switch 131Y is on, and the current is counterclockwise (CCW), a current path is generated in the adjusting unit 130 from the terminal 134Y to the terminal 134X via the switch 131Y and the diode 132X. Since this current path is parallel to the capacitor 115, no current flows through the capacitor 115. Therefore, no resonance current flows through the secondary resonance coil 110. In this case, even if the switch 131X is turned on, no resonance current flows through the secondary resonance coil 110.

The capacitance that contributes to the resonance frequency of the resonance current is determined by the capacitor 115 and the capacitor 132X or 132Y. Therefore, it is desirable that the capacitances of the capacitors 132X and 132Y are equal.

FIG. 7 is a diagram showing an AC voltage generated in the secondary resonance coil 110 and two clocks included in the drive signal.

_{The AC voltage V 0} shown in FIGS. 7A and 7B is a waveform having the same frequency as the transmission frequency, for example, an AC voltage generated in the secondary resonance coil 110, and is detected by a voltmeter 116 (see FIG. 4). Will be done. Further, the clocks CLK1 and CLK2 are two clocks included in the drive signal. For example, the clock CLK1 is used for driving the switch 131X, and the clock CLK2 is used for driving the switch 131Y. The clocks CLK1 and CLK2 are examples of the first signal and the second signal, respectively.

In FIG. 7 (A), the clock CLK1, CLK2 is synchronized with the AC voltage _{V 0.} That is, the frequency of the clock CLK1, CLK2 is equal to the frequency of the AC voltage _{V 0,} the clock CLK1 phase is equal to the phase of the AC voltage _{V 0.} The clock CLK2 is 180 degrees out of phase with the clock CLK1 and has an opposite phase.

In FIG. 7A, _{the period T of the AC voltage V 0} is the reciprocal of the frequency f, and the frequency is 6.78 MHz.

As in FIG. 7 (A), the clock CLK1, CLK2 synchronized with the AC voltage _{V 0,} the switch 131X and 131Y in a state of turning off the power receiving unit 100 is receiving power from the power transmitter 10 secondary side resonance coil 110 The control unit 150 may generate the resonance current using the PLL 152 in a state where the resonance current is generated.

In FIG. 7B, the phases of the clocks CLK1 and CLK2 are delayed by θ degrees with respect to _{the AC voltage V 0.} As described above, the _{clocks CLK1 and CLK2 having a phase difference θ degree with respect to the AC voltage V 0} may be generated by the control unit 150 by using the phase shift circuit 153.

Control unit 150 adjusts the phase difference between the two clocks CLK1, CLK2 for alternating voltage _{V 0} to detect the phase of maximum power receiving efficiency can be obtained. Maximum power receiving efficiency can be obtained phase is the phase of the electric power receiving unit 100 is receiving is maximized, the phase difference between the two clocks CLK1, CLK2 for alternating voltage V _0, the resonance over the entire period of one cycle When it becomes, the received power becomes maximum. Therefore, the control unit 150, received power while increasing and decreasing the phase difference of the AC voltage two clocks CLK1 for V _0, CLK2 detects the phase difference becomes largest, handled detected phase difference as 0 degrees.

Then, the control unit 150 phased the phase difference between the two clocks with respect _{to the AC voltage V 0} based on the phase difference (0 degree) at which the received power is maximized and the data representing the phase difference received from the transmitter 10. It is set by the shift circuit 153.

Next, with reference to FIG. 8, the power receiving efficiency of the electric power received from the power transmitter 10 by the power receiving device 100 when the phase difference of the drive signal is adjusted will be described.

FIG. 8 is a diagram showing a simulation result showing the characteristics of the power receiving efficiency with respect to the phase difference of the drive signal. _{The phase difference on the horizontal axis is the phase difference between the two clocks with respect to the AC voltage V 0} when the phase difference at which the received power is maximized is 0 degrees, and the power receiving efficiency on the vertical axis is the AC power supply 1 (see FIG. 1). ) Is the ratio of the electric power (Pout) output by the power receiver 100 to the electric power (Pin) input to the transmitter 10. The power receiving efficiency is equal to the power transmission efficiency between the power transmitting device 10 and the power receiving device 100.

The frequency of the electric power transmitted by the power transmitter 10 is 6.78 MHz, and the frequency of the drive signal is also set to be the same. Further, in the state where the phase difference is 0 degrees, resonance due to magnetic field resonance occurs in the secondary resonance coil 110 over the entire period of one cycle of the resonance current, and the resonance current flows in the secondary resonance coil 110. Is. A large phase difference means that the period during which resonance does not occur in the secondary resonance coil 110 increases in one cycle of the resonance current. Therefore, in a state where the phase difference is 180 degrees, theoretically, no resonance current flows through the secondary resonance coil 110.

As shown in FIG. 8, as the phase difference is increased from 0 degrees, the power receiving efficiency decreases. When the phase difference is about 60 degrees or more, the power receiving efficiency is less than about 0.1. When the phase difference between the two clocks with respect to the AC voltage V ₀ is changed in this way, the power amount of the resonance current flowing through the secondary resonance coil 110 changes, so that the power receiving efficiency changes.

FIG. 9 is a diagram showing a power transmission device 80 and electronic devices 200A and 200B using the power transmission system 500 of the embodiment.

The power transmission device 80 is the same as the power transmission device 80 shown in FIG. 4, but in FIG. 9, components other than the primary coil 11, the control unit 15, and the antenna 16 in FIG. 4 are represented as the power supply unit 10A. is there. The power supply unit 10A collectively represents the primary resonance coil 12, the matching circuit 13, and the capacitor 14. The AC power supply 1, the primary resonance coil 12, the matching circuit 13, and the capacitor 14 may be collectively regarded as a power supply unit.

The antenna 16 may be any antenna capable of performing wireless communication at a short distance, such as Bluetooth (registered trademark). The antenna 16 is provided to receive data representing the received power and the rated output from the power receivers 100A and 100B included in the electronic devices 200A and 200B, and the received data is input to the control unit 15. The control unit 15 is an example of a control unit and an example of a third communication unit.

The electronic devices 200A and 200B are, for example, terminals such as a tablet computer or a smartphone, respectively. The electronic devices 200A and 200B include power receivers 100A and 100B, DC-DC converters 210A and 210B, and batteries 220A and 220B, respectively.

The power receivers 100A and 100B have the same configuration as the power receiver 100 shown in FIG. The DC-DC converters 210A and 210B are the same as the DC-DC converter 210 shown in FIG. 4, respectively. Further, the batteries 220A and 220B are the same as the batteries 220 shown in FIG. 4, respectively.

The power receiver 100A includes a secondary resonance coil 110A, a capacitor 115A, a rectifier circuit 120A, an adjusting unit 130A, a smoothing capacitor 140A, a control unit 150A, and an antenna 170A. The secondary side resonance coil 110A is an example of the first secondary side resonance coil.

The secondary resonance coil 110A, the capacitor 115A, the rectifying circuit 120A, the adjusting unit 130A, the smoothing capacitor 140A, and the control unit 150A are the secondary resonance coil 110, the capacitor 115, the rectifying circuit 120, and the adjusting unit 130, respectively, as shown in FIG. , Corresponds to the smoothing capacitor 140 and the control unit 150. In FIG. 9, the secondary resonance coil 110A, the rectifier circuit 120A, and the smoothing capacitor 140A are shown in a simplified manner, and the voltmeter 155B and the output terminals 160X and 160Y are omitted.

The power receiver 100B includes a secondary resonance coil 110B, a capacitor 115B, a rectifier circuit 120B, an adjustment unit 130B, a smoothing capacitor 140B, a control unit 150B, and an antenna 170B. The power receiver 100B is an example of another power receiver when viewed from the power receiver 100A. The secondary resonance coil 110B is an example of the second secondary resonance coil.

The secondary resonance coil 110B, the capacitor 115B, the rectifying circuit 120B, the adjusting unit 130B, the smoothing capacitor 140B, and the control unit 150B are the secondary resonance coil 110, the capacitor 115, the rectifying circuit 120, and the adjusting unit 130, respectively, as shown in FIG. , Corresponds to the smoothing capacitor 140 and the control unit 150. In FIG. 9, the secondary resonance coil 110B, the rectifier circuit 120B, and the smoothing capacitor 140B are shown in a simplified manner, and the voltmeter 155B and the output terminals 160X and 160Y are omitted.

The antennas 170A and 170B may be antennas capable of performing wireless communication at a short distance such as Bluetooth (registered trademark). The antennas 170A and 170B are provided for data communication with the antenna 16 of the transmitter 10, and are connected to the control units 150A and 150B of the receivers 100A and 100B, respectively. The control units 150A and 150B are examples of the drive control unit and are examples of the first communication unit and the second communication unit, respectively.

The control unit 150A of the power receiver 100A transmits the power received by the secondary resonance coil 110A and the data representing the rated output of the battery 220A to the transmitter 10 via the antenna 170A. Similarly, the control unit 150B of the power receiver 100B transmits the power received by the secondary resonance coil 110B and the data representing the rated output of the battery 220B to the transmitter 10 via the antenna 170B.

The electronic devices 200A and 200B can charge the batteries 220A and 220B in a state where they are arranged near the power transmission device 80, respectively, without contacting the power transmission device 80. The batteries 220A and 220B can be charged at the same time.

The power transmission system 500 is constructed by the transmitter 10 and the power receivers 100A and 100B among the components shown in FIG. That is, the power transmission device 80 and the electronic devices 200A and 200B employ a power transmission system 500 that enables power transmission in a non-contact state by magnetic field resonance.

Here, if the batteries 220A and 220B are charged at the same time, as described with reference to FIGS. 2 and 3, a state in which the power supply balance to the electronic devices 200A and 200B may not be good may occur.

Therefore, in order to improve the balance of power supply, the transmitter 10 adjusts the power receiving efficiency of the secondary resonance coil 110A, the rated output of the battery 220A, the power receiving efficiency of the secondary resonance coil 110B, and the rated output of the battery 220B. Based on this, the phase difference of the drive signals (clocks CLK1 and CLK2) that drive the adjusting units 130A and 130B with respect to the AC voltage V _{0 is set.}

FIG. 10 is a diagram showing the relationship between the phase difference of the drive signal and the power receiving efficiency of the power receivers 100A and 100B.

Here, in a state where the phase difference of the drive signal that drives the adjustment unit 130B of the power receiver 100B is fixed to the phase difference (0 degree) that maximizes the power receiving efficiency, the drive signal that drives the adjustment unit 130A of the power receiver 100A is used. A case where the phase difference is changed from the phase difference (0 degree) at which the power receiving efficiency is maximized will be described.

In FIG. 10, the horizontal axis represents the phase difference (θA, θB) of the drive signals that drive the adjusting units 130A and 130B of the power receivers 100A and 100B. The vertical axis on the left side shows the respective power receiving efficiencies of the power receiving devices 100A and 100B and the total value of the power receiving efficiencies of the power receiving devices 100A and 100B.

When the phase difference of the drive signal that drives the adjustment unit 130B of the power receiver 100B is fixed at 0 degrees, the phase difference of the drive signal that drives the adjustment unit 130A of the power receiver 100A is increased or decreased from 0 degrees. As shown in FIG. 10, the ratio of the power receiving efficiency of the power receiving device 100A decreases. The power receiving efficiency of the power receiving device 100A is maximum when the phase difference is 0 degrees. Further, as the power receiving efficiency of the power receiving device 100A decreases, the ratio of the power receiving efficiency of the power receiving device 100A increases.

When the phase difference of the drive signal that drives the adjusting unit 130A of the power receiver 100A is changed in this way, the amount of power received by the power receiver 100A decreases, so that the current flowing through the power receiver 100A also decreases. That is, the impedance of the power receiver 100A changes due to the change in the phase difference.

In the simultaneous power transmission using the magnetic field resonance, the electric power transmitted from the transmitter 10 to the receivers 100A and 100B by the magnetic field resonance is distributed between the receivers 100A and 100B. Therefore, if the phase difference of the drive signal that drives the adjusting unit 130A of the power receiver 100A is changed from 0 degrees, the power reception amount of the power receiver 100B increases by the amount that the power reception amount of the power receiver 100A decreases. ..

Therefore, as shown in FIG. 10, the ratio of the power receiving efficiency of the power receiving device 100A decreases. In addition, the ratio of the power receiving efficiency of the power receiving device 100B increases accordingly.

When the phase difference of the drive signal driving the adjusting unit 130A of the power receiving device 100A changes to about ± 90 degrees, the ratio of the power receiving efficiency of the power receiving device 100A drops to about 0, and the ratio of the power receiving efficiency of the power receiving device 100B becomes. Increases to about 0.8.

The sum of the power receiving efficiencies of the power receivers 100A and 100B is about 0.85 when the phase difference of the drive signals driving the adjusting unit 130A of the power receiving device 100A is 0 degrees, and the adjusting unit 130A of the power receiving device 100B is used. When the phase difference of the driving signals to be driven decreases to about ± 90 degrees, the sum of the power receiving efficiencies of the power receivers 100A and 100B becomes about 0.8.

In this way, with the phase difference of the drive signal driving the adjustment unit 130B of the power receiver 100A fixed at 0 degrees, the phase difference of the drive signal driving the adjustment unit 130A of the power receiver 100A is changed from 0 degrees. As it goes, the ratio of the power receiving efficiency of the power receiving device 100A decreases, and the ratio of the power receiving efficiency of the power receiving device 100B increases. The sum of the power receiving efficiencies of the power receivers 100A and 100B does not fluctuate significantly at a value of about 0.8.

In power transmission using magnetic field resonance, the power transmitted from the transmitter 10 to the receivers 100A and 100B by magnetic field resonance is distributed between the receivers 100A and 100B, so that even if the phase difference changes, the receiver The sum of the power receiving efficiencies of 100A and 100B does not fluctuate significantly.

Similarly, if the phase difference of the drive signal that drives the adjustment unit 130A of the power receiver 100A is fixed at 0 degrees, and the phase difference of the drive signal that drives the adjustment unit 130B of the power receiver 100B is reduced from 0 degrees. , The ratio of the power receiving efficiency of the power receiving device 100B decreases, and the ratio of the power receiving efficiency of the power receiving device 100A increases. The sum of the power receiving efficiencies of the power receivers 100A and 100B does not fluctuate significantly at a value of about 0.8.

Therefore, by adjusting the phase difference of the drive signal that drives either the adjusting unit 130A or 130B of the power receiver 100A or 100B, the ratio of the power receiving efficiency of the power receivers 100A and 100B can be adjusted.

As described above, when the phase difference of the drive signal for driving the adjusting unit 130A or 130B is changed, the ratio of the power receiving efficiencies of the secondary resonance coils 110A and 110B of the power receivers 100A and 100B changes.

Therefore, in the embodiment, the phase difference of one of the drive signals of the adjusting units 130A and 130B of the power receivers 100A and 100B is changed from the reference phase difference. For the reference phase difference, for example, the phase difference that maximizes the power receiving efficiency is defined as the reference phase difference (0 degree), and in this case, the phase difference of either one is changed from 0 degree.

At this time, which of the drive signals of the adjusting units 130A and 130B is to be changed from the reference phase difference is determined as follows.

First, the first value obtained by dividing the rated output of the battery 220A by the power receiving efficiency of the secondary resonance coil 110A and the second value obtained by dividing the rated output of the battery 220B by the power receiving efficiency of the secondary resonance coil 110B. And find the value of.

Then, the phase difference of the drive signal corresponding to the smaller of the first value and the second value (100A or 100B) is changed from 0 degrees to set an appropriate phase difference.

The value obtained by dividing the rated output by the power receiving efficiency represents the amount of power (required power transmission amount) transmitted by the power transmitter 10 to the power receiver (100A or 100B). The required power transmission amount is the amount of power transmitted from the power transmission 10 so that the power receiver (100A or 100B) can receive power without causing surplus power or shortage power.

Therefore, if the power supply amount to the power receiver (100A or 100B) having the smaller required power transmission amount is reduced, the power supply amount to the power receiver (100A or 100B) having the larger required power transmission amount can be increased. As a result, the balance of the amount of power supplied to the power receivers 100A and 100B can be improved.

As can be seen from FIG. 10, when the phase difference of either of the power receivers (100A or 100B) is changed, the amount of power received by the power receiver (100A or 100B) decreases. Further, in either of the other power receivers (100A or 100B), the amount of power received increases in a state where the phase difference is fixed at 0 degrees.

Therefore, if the phase difference of the drive signal corresponding to the power receiver (100A or 100B) with the smaller required power transmission amount is changed from the reference phase difference (0 degree), the power receiver with the smaller required power transmission amount (100A or 100B) The amount of power supplied to 100A or 100B) is narrowed down, and the amount of power supplied to the receiver (100A or 100B) having the larger required power transmission amount can be increased.

In this way, the balance of the amount of power supplied to the power receivers 100A and 100B may be improved. The specific method of setting the phase difference will be described later.

Next, a method in which the transmitter 10 obtains data representing the power receiving efficiency and the rated output from the power receivers 100A and 100B will be described with reference to FIG.

FIG. 11 is a task diagram showing a process executed by the transmitter 10 and the receivers 100A and 100B to set the phase difference. This task is performed by controls 15, 150A, and 150B (see FIG. 9).

First, the power receiver 100A transmits data representing the received power to the power transmitter 10 (step S1A). Similarly, the power receiver 100B transmits data representing the received power to the power transmitter 10 (step S1B). As a result, the transmitter 10 receives data representing the received power from the receivers 100A and 100B (step S1).

The data representing the received power may be transmitted, for example, by the control units 150A and 150B via the antennas 170A and 170B in response to a request from the transmitter 10. Further, the data representing the received power may include an identifier that identifies the power receivers 100A and 100B.

The data representing the received power may be acquired as follows. First, a signal for setting both switches (131X and 131Y in FIG. 4) of the adjustment unit 130B to be turned on is transmitted from the transmitter 10 to the power receiver 100B by wireless communication, and the adjustment unit 130A is transmitted from the transmitter 10 to the power receiver 100A. A signal that sets both switches to off is transmitted by wireless communication.

Here, when both switches of the adjusting unit 130B are turned on, resonance does not occur in the adjusting unit 130B, and the power receiver 100B is in a state of not receiving electric power. That is, the power receiver 100B is turned off. Further, when both switches of the adjusting unit 130A are turned off, a resonance current flows through the secondary resonance coil 110A.

Then, a predetermined electric power is transmitted from the transmitter 10 to the power receiver 100A by magnetic field resonance, and the electric power is received by the power receiver 100A. At this time, if a signal representing the amount of electric power received by the power receiver 100A is transmitted to the power transmission 10, the power reception efficiency of the power receiver 100A can be measured by the power transmission 10.

Further, in order to measure the power receiving efficiency of the power receiving device 100B, a signal for setting both switches of the adjusting unit 130A to be turned on is transmitted from the transmitter 10 to the power receiving device 100A by wireless communication, and the power receiving device 10 sends the signal to the power receiving device 100B. A signal for setting both switches of the adjusting unit 130B to be turned off is transmitted by wireless communication. If a predetermined power is transmitted from the transmitter 10 to the receiver 100B by magnetic field resonance and a signal indicating the amount of electric power received by the receiver 100B is transmitted to the transmitter 10, the power receiving efficiency of the receiver 100B is measured by the transmitter 10. can do.

Next, the power receiver 100A transmits data representing the rated output to the power transmitter 10 (step S2A). Similarly, the power receiver 100B transmits data representing the rated output to the power transmitter 10 (step S2B). As a result, the transmitter 10 receives data representing the rated output from the receivers 100A and 100B (step S2).

The data representing the rated output of the electronic devices 200A and 200B is stored in advance in the internal memory of the control units 150A and 150B, for example, and after sending the data indicating the power receiving efficiency, the control units 150A and 150B perform the antennas 170A and 170B. It suffices to transmit to the transmitter 10 via.

Next, the transmitter 10 sets the power receivers 100A and 100B based on the data representing the power receiving efficiency and the rated output of the power receiving device 100A and the data representing the power receiving efficiency and the rated output of the power receiving device 100B. The phase difference of the corresponding drive signal is calculated (step S3). The phase difference of either one is the reference phase difference (0 degree) at which the power receiving efficiency is maximized, and the other phase difference is the phase difference optimized by changing from the reference phase difference (0 degree). is there. Details of step S3 will be described later with reference to FIG.

Next, the transmitter 10 transmits data representing the phase difference to the receivers 100A and 100B (step S4). Then, the power receivers 100A and 100B receive the phase difference (steps S4A and S4B).

Here, the control unit 15 of the transmitter 10 is set to transmit data representing the phase difference to the receivers 100A and 100B via the antenna 16 after calculating the phase difference.

The control units 150A and 150B of the power receivers 100A and 100B set the phase difference in the drive signal (steps S5A and S5B).

The power transmission 10 starts power transmission (step S6). The process of step S6 may be executed, for example, when the transmitter 10 is notified that the control units 150A and 150B have completed the setting of the phase difference to the drive signal. The processing when an overvoltage occurs will be described later.

Here, a method of acquiring data representing the power receiving efficiency of the power receiving devices 100A and 100B will be described with reference to FIGS. 12 and 13.

FIG. 12 is a diagram showing an equivalent circuit of the power transmission device 80 and the electronic devices 200A and 200B. The equivalent circuit shown in FIG. 12 corresponds to the power transmission device 80 and the electronic devices 200A and 200B shown in FIG. However, here, it is assumed that the power transmission device 80 does not include the primary side coil 11 and the primary side resonance coil 12 is directly connected to the AC power supply 1. Further, the power receivers 100A and 100B include voltmeters 155BA and 155B, respectively.

In FIG. 12, the secondary resonance coil 110A is a coil L _RA and a resistor R _RA , and the capacitor 115A is a capacitor C _RA . The smoothing capacitor 140A is a capacitor C _SA , and the DC-DC converter 210A and the battery 220A are resistors R _LA .

Similarly, the secondary side resonance coil 110B is a coil _{L RB} and the resistor _{R RB,} capacitors 115B is a capacitor _{C RB.} Also, the smoothing capacitor 140B is a capacitor _{C SB,} DC-DC converter 210B and the battery 220B is a resistor _{R LB.}

The primary side resonance coil 12 of the power transmission device 80 is a resistor _{R T} and the coil _{L T,} the AC power source 1 is a power supply _{V S} and resistor _{R S.} The capacitor 14 is a capacitor _{C T.}

The mutual inductance of the power transmission device 80 and the electronic apparatus 200A _{M TA,} the mutual inductance of the power transmission device 80 and the electronic apparatus 200B _{M TB,} the mutual inductance between the electronic device 200A and 200B and _{M AB.}

Here, when comparing the mutual inductance _{M TA} and mutual inductance _{M TB,} since the mutual inductance _{M AB} enough negligible small, here, a mutual inductance _{M TA} and mutual inductance discuss _{M TB.}

The mutual inductance _MTA is determined by the power receiving efficiency between the power transmission device 80 and the power receiver 100A of the electronic device 200A. This is because the power receiving efficiency is determined by the position (distance) and the posture (angle) of the power receiving device 100A with respect to the power transmitting device 80. Similarly, the mutual inductance _MTB is determined by the power receiving efficiency between the power transmission device 80 and the power receiver 100B of the electronic device 200B.

The power receiving efficiency of the power receiving device 100A can be obtained by transmitting power from the power transmitting device 10 to the power receiving device 100A with the power receiving device 100B turned off and measuring the amount of power received by the power receiving device 100A. Similarly, the power receiving efficiency of the power receiving device 100B can be obtained by transmitting power from the power transmitting device 10 to the power receiving device 100B with the power receiving device 100A turned off and measuring the amount of power received by the power receiving device 100B. it can.

Therefore, if the power receiving efficiency of the power receivers 100A and 100B is obtained independently, the mutual inductance _MTA and the mutual inductance _MTB can be obtained.

In the embodiment, the phase difference of the drive signal for driving the adjusting unit 130A or 130B is changed in order to change the ratio of the power receiving efficiency of the secondary resonance coils 110A and 110B of the power receivers 100A and 100B.

Therefore, table data in which the phase difference is associated with the relationship between the mutual inductance _{MTA and the mutual inductance MTB} is prepared in advance, and the phase difference of the drive signal is adjusted by using such table data. ..

FIG. 13 is a diagram showing table data in which the phase difference is associated with the relationship between the _{mutual inductance MTA} and the mutual inductance _MTB.

FIG. 13A is table data for adjusting the phase difference of the drive signal driving the adjusting unit 130A in a state where the phase difference of the driving signal driving the adjusting unit 130B is fixed at 0 degrees.

The mutual inductance M _TA 1, M _TA 2, M _TA 3, ... Actually take a specific value of the _{mutual inductance M TA.} Similarly, the mutual inductance M _TB 1, M _TB 2, M _TB 3, ... Actually take a specific value of the _{mutual inductance M TB.} Phase difference PD1A, PD2A, PD3A, ..., PD11A, PD12A, PD13A, ... Specifically, take a specific phase difference value obtained by simulation or experiment.

FIG. 13B is table data for adjusting the phase difference of the drive signal driving the adjusting unit 130B in a state where the phase difference of the driving signal driving the adjusting unit 130A is fixed at 0 degrees.

The mutual inductances M _TA 1, M _TA 2, M _TA 3 ... And the mutual inductances M _TB 1, M _TB 2, M _TB 3 ... Are the same as in FIG. 13 (A). Phase difference PD1B, PD2B, PD3B, ..., PD11B, PD12B, PD13B, ... Specifically, take a specific phase difference value obtained by simulation or experiment.

In order to experimentally obtain the table data shown in FIGS. 13 (A) and 13 (B), the mutual inductances of the receivers 100A and 100B with respect to the transmitter 10 are changed in various ways, and the mutual inductances are set to _MTA and M. It can be created by optimizing the phase difference while measuring _TB.

FIG. 14 is _{table data in which the mutual inductances M TA} and M _TB are associated with the power receiving efficiency. (A) of FIG. 14, the mutual inductance _{M TA,} a table data that associates a power receiving efficiency of the power receiving device 100A, (B) in FIG. 14, the mutual inductance _{M TB,} a power receiving efficiency of the power receiving device 100B Is the table data associated with.

Mutual inductance _{M TA, M TB,} respectively, the power transmission device 80, the power receiver 100A, the power receiving efficiency _E A of 100B, determined by _{E B.}

In (A) of FIG. 14, the mutual inductance _M TA _{1, M} TA _2, and ..., power reception efficiency of the power receiving device 100A _{E A1, E} A2, and ... are associated. Further, in (B) of FIG. 14, the mutual inductance _{M TB1, M TB2,} and ..., power reception efficiency of the power receiving device 100B _{E B1, E} B2, and ... are associated.

_{If the mutual inductances M TA} and M _TB of the power receivers 100A and 100B and the power receiving efficiency are measured in advance by an experiment or the like, and table data as shown in FIGS. 14A and 14B is created. From the power receiving efficiency of the power receiving devices 100A and 100B, the mutual inductances M _TA and M _TB of the power receiving devices 100A and 100B can be obtained. _{Alternatively, the mutual inductances M TA} and M _TB of the power receivers 100A and 100B may be obtained from the power reception efficiency of the power receivers 100A and 100B by simulation.

Next, a method of setting the phase difference will be described with reference to FIG.

FIG. 15 is a flowchart showing a method in which the transmitter 10 of the embodiment sets the phase difference of the receiver 100A or 100B. This flow represents the processing executed by the control unit 15 of the transmitter 10, and shows the details of the processing contents of step S3 of FIG.

The control unit 15 receives signals representing the received power from the power receivers 100A and 100B to obtain the power receiving efficiency, receives signals representing the rated output from the power receivers 100A and 100B, and proceeds to step S3, as shown in FIG. Start processing.

The control unit 15 divides the rated output of the battery 220A by the first value obtained by dividing the rated output of the battery 220A by the power receiving efficiency of the secondary resonance coil 110A and the rated output of the battery 220B by the power receiving efficiency of the secondary resonance coil 110B. The second value to be obtained is obtained, and it is determined whether or not the first value is larger than the second value (step S31).

When the control unit 15 determines that the first value is larger than the second value (S31: YES), the control unit 15 sets the phase difference of the drive signal for driving the adjustment unit 130A of the power receiver 100A to 0 degrees (step S31A). ).

Next, the control unit 15 sets the phase difference of the drive signal that drives the adjustment unit 130B of the power receiver 100B (step S32A). Specifically, the control unit 15, based on the table data shown in (A) and (B) in FIG. 14, respectively, the power receiver 100A, 100B power receiving efficiency _E A, the power receiver 100A from _{E B,} 100B mutual Obtain the inductances M _TA and M _TB. Then, the control unit 15, the table data shown in (B) of FIG. 13, the power receiver 100A, the mutual inductance _M TA of _100B, based on the _{M TB,} position of the drive signal for driving the adjusting portion 130B of the power receiver 100B Find the phase difference.

When the process of step S32A is completed, the control unit 15 advances the flow to step S4 (see FIG. 11).

Further, when the control unit 15 determines that the first value is smaller than the second value (S31: NO), the control unit 15 sets the phase difference of the drive signal for driving the adjustment unit 130B of the power receiver 100B to 0 degrees (S31: NO). Step S31B).

Next, the control unit 15 sets the phase difference of the drive signal that drives the adjustment unit 130A of the power receiver 100A (step S32B). Specifically, the control unit 15, based on the table data shown in (A) and (B) in FIG. 14, respectively, the power receiver 100A, 100B power receiving efficiency _E A, the power receiver 100A from _{E B,} 100B mutual Obtain the inductances M _TA and M _TB. Then, the control unit 15, the table data shown in (A) of FIG. 13, the power receiver 100A, the mutual inductance _M TA of _100B, based on the _{M TB,} position of the drive signal for driving the adjusting portion 130A of the power receiver 100A Find the phase difference.

When the process of step S32B is completed, the control unit 15 advances the flow to step S4 (see FIG. 11).

As described above, the control unit 15 sets the phase difference of the drive signal that drives the adjustment units 130A and 130B of the power receivers 100A and 100B.

As described above, the required power transmission amount to the power receivers 100A and 100B is obtained from the power reception efficiency of the secondary resonance coils 110A and 110B of the power receivers 100A and 100B and the rated output of the electronic devices 200A and 200B.

Then, the phase difference of the drive signal corresponding to the power receiver (100A or 100B) having the smaller required power transmission amount among the power receivers 100A and 100B is changed from the reference phase difference.

As a result, the power supply amount to the power receiver (100A or 100B) having the smaller required power transmission amount can be narrowed down, and the power supply amount to the power receiver (100A or 100B) having the larger required power transmission amount can be increased. .. As a result, the balance of the amount of power supplied to the power receivers 100A and 100B can be improved.

FIG. 16 is a diagram showing the relationship between the clock CLK1, the output of the D-FF158C, and the output of the OR circuit 158A. The output of D-FF158C represents the level (H or L) of the signal output from the output terminal D. FIG. 16A shows the relationship between the clock CLK1 and the output of the OR circuit 158A when the level of the signal output from the output terminal D is L level, and FIG. 16B shows the output from the output terminal D. The relationship between the clock CLK1 and the output of the OR circuit 158A when the level of the signal to be output is H level is shown.

As shown in FIG. 16A, when the level of the signal output from the output terminal D is L level, the signal level of the clock CLK1 is directly reflected in the output of the OR circuit 158A. On the other hand, as shown in FIG. 16B, when the level of the signal output from the output terminal D is H level, the signal level of the clock CLK1 is not reflected in the output of the OR circuit 158A, and the OR circuit 158A The output becomes H level.

Here, the relationship between the output of the clock CLK1 and the D-FF158C and the output of the OR circuit 158A has been described. However, since the clock CLK2 has a signal level in which the clock CLK1 is inverted, the clock CLK2 and the D-FF158C have a signal level. The relationship between the output and the output of the OR circuit 158B is the same.

While the voltage across the switch 131X or 131Y is overvoltage, the output of the OR circuit 158A is held at the H level, so that the outputs of the OR circuits 158A and 158B are both held at the H level. Therefore, the switches 131X and 131Y can be held in the ON state.

When the switches 131X and 131Y are held in the ON state, the current flowing through the secondary resonance coil 110 (see FIG. 4) does not flow through the capacitor 115, but flows through the switches 131X and 131Y having the lowest impedance. .. In this case, resonance does not occur in the secondary resonance coil 110.

FIG. 17 is a diagram showing simulation results of the transmission voltage of the primary resonance coil 12, the voltages of the terminals 112X and 112Y of the secondary resonance coil 110 (voltages between terminals), and the time change of the received power of the power receiver 100. .. Since the received power is 6.78 MHz as an example, the sine wave system is compressed in the horizontal axis direction.

The power transmission voltage is an AC voltage applied to the primary resonance coil 12. The voltage between the terminals 112X and 112Y is the total value of the voltage across each of the switches 131X and 131Y. The received power is the power input to the DC-DC converter 210 from the output terminals 160X and 160Y.

17 (A) shows the voltage waveform when the amplitude of the power transmission voltage of the primary side resonance coil 12 is increased from 0 V to 10 V, and FIGS. 17 (B) and 17 (C) show FIG. 17 (A). As shown, the voltage between terminals and the received power when the transmission voltage is increased are shown.

17 (C) shows a voltage waveform when the amplitude of the AC voltage (transmission voltage) applied to the primary side resonance coil 12 is increased from 0 V to 25 V, and FIGS. 17 (D) and 17 (E) show. As shown in FIG. 17C, the voltage between terminals and the received power when the transmission voltage is increased are shown. The predetermined threshold value for determining the overvoltage is 40V.

When the amplitude of the transmission voltage is gradually increased from 0V to 10V as shown in FIG. 17 (A), the amplitude of the inter-terminal voltage is gradually increased from 0V to about 25V as shown in FIG. 17 (B). However, as shown in FIG. 17C, the received power gradually increases. When the amplitude of the transmission voltage becomes constant at 10V when about 100 μs (microseconds) elapses from the start of power transmission (0 seconds), the amplitude of the voltage between terminals becomes constant at about 25V and the received power is about 2.7W. Become constant.

Further, when the amplitude of the transmission voltage is gradually increased from 0 V as shown in FIG. 17 (D), the amplitude of the inter-terminal voltage is gradually increased from 0 V as shown in FIG. 17 (E). As shown in 17 (F), the received power gradually increases. When the amplitude of the transmission voltage reaches about 20V and the amplitude of the voltage between terminals exceeds 40V at the time of about 75 μs (microseconds) from the start of power transmission (0 seconds), the detection voltage input from the detection unit 180 to the comparator 158D becomes Exceed the threshold. That is, an overvoltage occurs. At this point, the received power is about 1.8W,
As a result, the outputs of the OR circuits 158A and 158B are both at the H level, and the switches 131X and 131Y are both turned on. Therefore, the voltage between terminals shown in FIG. 17 (E) instantly drops to 0V at about 75 μs. ..

Further, when the voltage between terminals becomes 0 V, as shown in FIG. 17 (F), the received power gradually decreases from about 1.8 W. The voltage between terminals instantly becomes 0V when both switches 131X and 131Y are turned on, while the received power gradually decreases due to the influence of the capacity of the smoothing capacitor 140.

As described above, when an overvoltage occurs in the switches 131X and / or 131Y, the voltage between the terminals instantly drops to 0V, so that the switches 131X and 131Y can be protected from the overvoltage.

Next, the processing performed by the power receiver 100 and the transmitter 10 when an overvoltage occurs will be described. FIG. 18 is a task diagram showing a process performed by the power receiver 100 and the transmitter 10 when an overvoltage occurs. The task diagram shown in FIG. 18 shows the power receiver 100 and the power transmission 10 after steps S5A and S5B (phase difference setting process) and step S6 (power transmission start process) of the task diagram shown in FIG. 11 are performed. It is a process performed in.

Here, the processing performed by one receiver 100 and the transmitter 10 instead of the two receivers 100A and 100B will be described. Therefore, the process of setting the phase difference is shown as step S5. When there are a plurality of power receivers 100, the power transmitter 10 performs the same processing as each power receiver 100 and the processing described below.

As a precondition, the power transmission 10 starts power transmission in a state where it can communicate with the power receiver 100 (step S6). Further, in the power receiver 100, the processing unit 157 outputs a reset signal to reset the D-FF158C in a state where it can communicate with the power transmitter 10, and the detection unit 180 receives the voltage detected by the voltmeters 181X and 181Y. It is assumed that it has been entered.

The control unit 15 of the transmitter 10 determines whether or not an abnormal signal has been received from the receiver 100 (step S11). The abnormal signal is transmitted to the transmitter 10 together with the unique identifier of the receiver 100.

When the control unit 15 determines that the abnormal signal has been received (S11: YES), the control unit 15 stops power transmission (step S12).

Next, the control unit 15 identifies the power receiver 100 that has transmitted the abnormality signal based on the identifier, transmits an abnormality recognition notification indicating that the abnormality of the power receiver 100 has been recognized, to the power receiver 100, and determines the state (. Step S13). The determination of the state is a process of confirming which power receiver 100 has generated the overvoltage.

The control unit 15 returns the flow to step S1 in order to reset the transmitted power.

Further, when the control unit 15 determines that the abnormality signal has not been received (S11: NO), it determines whether or not the end notification has been received from the power receiver 100 (step S14). The process of step S14 is repeatedly executed until the end notification is received.

When the control unit 15 determines that the end notification has been received (S14: YES), the control unit 15 stops power transmission (step S15).

Next, the control unit 15 ends a series of processes (end).

Further, the processing unit 157 of the control unit 150 of the power receiving device 100 detects the detection voltage input from the detection unit 180 in the state where the phase difference is set in step S5 (step S101).

Next, the processing unit 157 determines whether or not the detected voltage is equal to or lower than a predetermined value (step S102). The processing of step S102 is performed by the processing unit 157 determining whether or not the output of the output terminal Q of the D-FF158C is at the L level.

When the processing unit 157 determines that the detected voltage is equal to or lower than a predetermined value (S102: YES), the processing unit 157 drives the switches 131X and 131Y with the drive signal for which the phase difference is set (step S103).

The processing unit 157 determines whether or not charging is completed (step S104). Whether or not charging is completed may be determined by whether or not the SOC input from the battery 220 has reached a level indicating full charge.

Here, in step S104, a mode for determining whether or not charging is completed will be described, but in addition to determining whether or not charging is completed, or determining whether or not charging is completed. Instead of, a signal indicating that charging is completed is input to the processing unit 157 from the electronic device including the battery 220, and the determination process of step S104 is performed based on the signal indicating that charging is completed. May be good.

When the processing unit 157 determines that charging is completed (S104: YES), the processing unit 157 transmits a completion notification to the transmitter 10 (step S105). The end notification is a signal indicating the end (completion) of charging, and is transmitted from the power receiver 100 to the transmitter 10.

When the processing unit 157 transmits the end notification to the transmitter 10, the processing unit 157 ends a series of processing (end).

When the processing unit 157 determines that charging is not completed (S104: NO), the processing unit 157 returns the flow to step S101.

Further, when the processing unit 157 determines that the detected voltage is not equal to or lower than the predetermined value (S102: NO), the processing unit 157 confirms that the output of the D-FF158C is at the H level, and the overvoltage of the voltage across the switch 131X or 131Y is increased. An abnormal signal indicating that the occurrence has occurred is transmitted to the transmitter 10 (step S106). As a result of the output of the D-FF158C becoming the H level, the outputs of the OR circuits 158A and 158B are held at the H level, and the switches 131X and 131Y are held in the ON state. The abnormality signal may include information indicating that the switches 131X and 131Y are held in the ON state. Further, a signal indicating that the switches 131X and 131Y are held in the ON state may be transmitted from the power receiver 100 to the transmitter 10 together with the abnormality signal.

Next, the processing unit 157 determines whether or not the abnormality recognition notification has been received (step S107). The process of step S107 is repeated until the processing unit 157 receives the abnormality recognition notification. When the processing unit 157 finishes the processing of step S107, the processing unit 157 returns the flow to step S1A or S1B. As a result, the process of transmitting the received power is performed.

As described above, in the power receiver 100, when an overvoltage occurs in the voltage between both ends of the switch 131X or 131Y, the switches 131X and 131Y are held in the ON state, so that the current resonance does not occur in the secondary resonance coil 110. , The voltage across the switches 131X and 131Y becomes 0V.

Therefore, it is possible to provide a power receiver 100, a power transmission system 500, and a power receiving method that can protect the switches 131X and 131Y that adjust the power receiving efficiency. The switches 131X and 131Y are realized by FET. Since the allowable voltage of the FET is lower than that of the capacitors 133X and 133Y and the diodes 132X and 132Y, the FET may be damaged by the overvoltage.

Therefore, the switch 131X and 131Y can be protected from the overvoltage by monitoring the overvoltage with the comparator 158D and keeping the switches 131X and 131Y in the ON state when the overvoltage occurs.

Further, in the above, the power to the power receivers 100A and 100B is reduced by reducing the phase difference of the drive signal corresponding to the power receiver (100A or 100B) having the smaller required power transmission amount among the two power receivers 100A and 100B. The mode for improving the balance of the supply amount was explained.

However, there are cases where three or more receivers are charged at the same time. In such a case, the phase difference of the drive signals of the receivers other than the receiver having the maximum required power amount (the amount of power obtained by dividing each rated power by each power receiving efficiency) may be reduced.

Further, in the above, the form in which the electronic devices 200A and 200B are terminals such as a tablet computer or a smartphone has been described as an example, but the electronic devices 200A and 200B are, for example, a notebook type PC (Personal Computer) or a mobile phone. It may be an electronic device having a built-in rechargeable battery such as a telephone terminal, a portable game machine, a digital camera, or a video camera.

Further, in the above, the mode in which the phase difference is obtained according to the power receiving efficiency and the rated output of the two power receivers 100A and 100B and the control unit 150A or 150B adjusts the phase difference of the drive signal for driving the switches 131A and 131B will be described. did.

However, when power is transmitted between one transmitter 10 and one receiver 100 (see FIG. 4), the control unit 150 of the receiver 100 obtains a phase difference previously obtained in an experiment or the like. It may be used to drive switches 131A and 131B. In this case, it is not necessary to store the data representing the rated output of the battery 220 in the internal memory of the control unit 150.

Further, when power is transmitted between one transmitter 10 and one receiver 100 (see FIG. 4), the control unit 150 of the receiver 100 adjusts the phase difference between the clocks CLK1 and CLK2. , The received power can be adjusted. In this case, it is not necessary to detect the phase difference that maximizes the power received by the power receiver 100.

Further, in the above, the mode in which the control unit 150 of the power receiving device 100 adjusts the received power by adjusting the phase difference between the clocks CLK1 and CLK2 has been described, but the method of adjusting the received power is limited to such a method. It is not something that can be done. For example, the received power may be adjusted by adjusting the duty ratio of the clocks CLK1 and CLK2 with the phase difference of the clocks CLK1 and CLK2 set to a certain phase difference.

Further, in the above, the mode in which the power receivers 100A and 100B charge the batteries 220A and 220B at the same time has been described. However, the electronic devices 200A and 200B may operate by directly consuming the electric power received by the power receivers 100A and 100B without including the batteries 220A and 220B. Since the power receivers 100A and 100B can efficiently receive power at the same time, the electronic devices 200A and 200B can be driven at the same time even when the electronic devices 200A and 200B do not include the batteries 220A and 220B. This is one of the merits when receiving power at the same time because it is impossible when receiving power in a time-division manner. In such a case, the phase difference may be set by using the rated output required for driving the electronic devices 200A and 200B.

Further, in the above description, the mode in which the control unit 15 of the power transmission 10 generates a drive signal and transmits it to the power receivers 100A and 100B has been described, but data representing the power transmission power of the power transmission device 10 is transmitted to the power receivers 100A and 100B. Then, the drive signal may be generated on the power receivers 100A and 100B. In this case, data communication is performed between the power receivers 100A and 100B, the power receiver 100A or 100B determines which power received is larger, and the power receiver (100A or 100B) having the smaller power is used. At least one of the power receivers (100A or 100B) may generate the drive signal so as to increase the phase difference of the drive signal.

Further, the power transmission 10 receives data representing the received power and the rated output from the power receivers 100A and 100B, and causes a phase difference to the control unit (150A or 150B) of the power receiver (100A or 100B) having the smaller required power transmission amount. May be adjusted. In this case, the data required for adjusting the phase difference may be stored in the internal memory by the control unit (150A or 150B).

Further, the directions of the diodes 131X and 131Y of the adjusting unit 130 may be opposite to the directions shown in FIG.

Further, although the mode in which the processing unit 157 inputs the voltage representing the threshold value to the comparator 158D has been described above, as shown in FIG. 19, a circuit that outputs the voltage representing the threshold value may be used. FIG. 19 is a diagram showing a threshold output circuit 159E. The threshold output circuit 159E includes a shunt regulator 159E1, a voltage divider resistor 159E2, and a resistor 159E3.

In the shunt regulator 159E1, the cathode is connected to the power supply VCS via the resistor 159E3, and the anode is grounded. The voltage dividing resistor 159E2 is connected in parallel to the shunt regulator 159E1, and the midpoint is connected to the reference terminal of the shunt regulator 159E1. Such a threshold value output circuit 159E outputs a voltage representing a threshold value from the cathode of the shunt regulator 159E1. The voltage value is set by the voltage value of the power supply VCS, the resistance value of the voltage dividing resistor 159E2, and the resistance value of the resistor 159E3.

Further, the power receiver 100 (see FIG. 4) may be deformed like the power receiver 100C shown in FIG. FIG. 20 is a diagram showing a power receiver 100C of a modified example of the embodiment.

The power receiver 100C has a configuration in which a switch 190C connected in parallel to the switches 131X and 131Y is added to the power receiver 100 shown in FIG. 4, and the control unit 150 is replaced with the control unit 150C.

The switch 190C is an example of a third switch, and on / off control is performed by the control unit 150C. The switch 190C is a switch that is turned on (normally on) without a drive signal being input from the control unit 150C. When the drive signal is not input from the control unit 150C to the switch 190C, the power of the power receiver 100 is off. The state in which the power supply of the power receiver 100 is off can be regarded as a state in which the drive signal input from the control unit 150C to the switch 190C is off (L level). When the power of the power receiver 100 is turned on, the control unit 150C inputs an H level drive signal to the switch 190C, and the switch 190C is turned off.

If such a switch 190C is used, the switch 190C is on even if the receiver 100 is located near the power transmitter 10 transmitting power while the power of the receiver 100 is turned off. Since resonance does not occur in the secondary resonance coil 110, damage to the switches 131X and 131Y can be suppressed.

Further, the control unit 150 (see FIG. 5) may be deformed like the control unit 150D shown in FIG. FIG. 21 is a diagram showing a control unit 150D of a modified example of the embodiment.

The control unit 150D adds a switch 159A, a voltage adjustment unit 159B, and a standby power supply 159C to the control unit 150 shown in FIG. 5, and replaces the processing unit 157 with the processing unit 157D. The switch 159A, the voltage adjusting unit 159B, and the standby power supply 159C are examples of the holding signal output unit.

The switch 159A is inserted between the phase shift circuit 153 and the inverter 155 and the OR circuits 158A and 158B. The switch 159A receives the input of one of the input terminals (upper input terminal in FIG. 21) of the OR circuits 158A and 158B from the output (clock) of the phase shift circuit 153 and the inverter 155 and the voltage adjusting unit 159B. It is a circuit that switches between the voltage (voltage corresponding to the H level drive signal). Such switching is performed by the processing unit 157D. When the switch 159A switches the input of one of the input terminals of the OR circuits 158A and 158B (the upper input terminal in FIG. 21) to the voltage input from the voltage adjusting unit 159B, one of the input terminals of the OR circuits 158A and 158B Is input with the voltage input from the voltage adjusting unit 159B.

The voltage adjusting unit 159B is a circuit that adjusts the voltage input from the standby power supply 159C to a voltage corresponding to the H level drive signal and inputs it to the switch 159A. Such a voltage adjusting unit 159B is realized by, for example, a voltage dividing resistor.

The standby power supply 159C is a power supply that outputs a predetermined voltage higher than the voltage corresponding to the H level drive signal. The standby power supply 159C may have a rated capacity capable of outputting a voltage when the power receiver 100 is off.

When the power of the power receiver 100 is turned off, the processing unit 157D switches the switching device 159A so that the switching device 159A outputs the voltage input from the voltage adjusting unit 159B to the OR circuits 158A and 159B. The power of the power receiver 100 is turned off in a state where the output of the switch 159A is switched in this way.

When the output voltage of the voltage adjusting unit 159B is input to one of the input terminals of the OR circuits 158A and 159B, the outputs of the OR circuits 158A and 159B are both held at the H level, so that the switches 131X and 131Y are turned on. Be retained.

When the power of the power receiver 100 is turned on, the processing unit 157D switches the output of the switch 159A to the clock output from the phase shift circuit 153 and the inverter 155. As a result, when the power of the power receiver 100 is turned on, a clock is input from the phase shift circuit 153 and the inverter 155 to one terminal of the OR circuits 158A and 158B.

By using such a switch 159A, a voltage adjusting unit 159B, and a standby power supply 159C, the power receiving device 100 is located near the power transmitting device 10 transmitting power while the power receiving device 100 is turned off. Even so, since the switches 131X and 131Y are on, resonance does not occur in the secondary resonance coil 110, and damage to the switches 131X and 131Y can be suppressed.

Although the power receiver, the power transmission system, and the power receiving method of the exemplary embodiment of the present invention have been described above, the present invention is not limited to the specifically disclosed embodiments, and claims for patent. Various modifications and changes are possible without departing from the range of.

The following additional notes will be further disclosed with respect to the above embodiments.
(Appendix 1)
A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic field resonance or electric field resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A second detector that detects the voltage between the first switch or the second switch,
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance Includes a control unit that adjusts the amount of power received by the coil
A power receiver that holds the first switch and the second switch in an on state when the voltage across the ends detected by the second detection unit exceeds a predetermined threshold value.
(Appendix 2)
When the voltage between both ends detected by the second detection unit becomes equal to or less than a predetermined threshold value, the holding of the first switch and the second switch in the on state is released.
The power receiver according to Appendix 1, wherein when the holding of the second switch in the ON state is released, the control unit adjusts the amount of electric power received by the secondary resonance coil.
(Appendix 3)
A comparator that compares the voltage between both ends detected by the second detection unit with the predetermined threshold value, and outputs a signal indicating the first level comparison result when the voltage between both ends exceeds the predetermined threshold value. When,
When the signal output from the comparator reaches the first level, the holding unit that holds the first level and the holding unit
A first logical sum circuit that switches on / off the first switch with a first logical sum signal that represents the logical sum of the first signal and the output signal of the holding unit.
Further including a second logical sum circuit for switching on / off of the second switch with a second logical sum signal representing the logical sum of the second signal and the output signal of the holding unit.
When the voltage between both ends detected by the second detection unit exceeds a predetermined threshold value, the first level signal output from the comparer is held by the holding unit, and the first OR circuit and the first OR circuit are held. 2. The first logical sum signal and the second logical sum signal output by the OR circuit are brought to the first level, so that the first switch and the second switch are held in the ON state. Power receiver.
(Appendix 4)
When the voltage between both ends detected by the second detection unit becomes equal to or lower than a predetermined threshold value, the control unit resets the holding unit that holds the first level.
When the holding unit is reset, the first OR circuit switches on / off the first switch with the first signal, and the second OR circuit uses the second signal to switch on the second switch. The power receiver according to Appendix 3, wherein the amount of power received by the secondary resonance coil is adjusted by the control unit by switching on / off.
(Appendix 5)
A third switch, which is connected in parallel to the first switch and the second switch, is turned on when the power of the receiver is off, and is turned off when the power of the receiver is on is further included.
The power receiver according to any one of Supplementary note 1 to 4, wherein the first switch and the second switch are switches of a type that are turned off when the power of the power receiver is off.
(Appendix 6)
When the power of the power receiver is off, the first signal and the second signal are input to the first OR circuit and the second OR circuit, respectively, instead of the first signal and the second signal, and the first switch and the second switch are used. The power receiver according to Appendix 3 or 4, further comprising a holding signal output unit that outputs a first holding signal and a second holding signal that keeps the power on.
(Appendix 7)
A communication unit that performs data communication with a transmitter including the primary resonance coil is further included.
When the first switch and the second switch are held in the on state, the communication unit transmits data indicating that the first switch and the second switch are held in the on state to the transmitter, any one of Supplementary note 1 to 6. The power receiver described in the section.
(Appendix 8)
The control unit controls the first signal and the second signal so as to adjust the phase difference between the voltage or current detected by the first detection unit and the first signal and the second signal. The first signal and the second signal so as to adjust the length of the period during which both the first switch and the second switch are turned on, or in a state where the phase difference is adjusted to a predetermined phase difference. The power receiver according to any one of Supplementary note 1 to 7, wherein the amount of power received by the secondary side resonance coil is adjusted by controlling the above.
(Appendix 9)
A transmitter with a primary resonance coil and
A power transmission system including a power receiver that receives power from the power transmitter.
The power receiver
A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic field resonance or electric field resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A second detector that detects the voltage between the first switch or the second switch,
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance It has a control unit that adjusts the amount of power received by the coil.
A power transmission system that keeps the first switch and the second switch in an ON state when the voltage between both ends detected by the second detection unit exceeds a predetermined threshold value.
(Appendix 10)
A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic field resonance or electric field resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A method for receiving power in a power receiver including the first switch or a second detection unit that detects a voltage between both ends of the second switch.
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance Adjust the amount of power received by the coil,
A power receiving method for holding the first switch and the second switch in an on state when the voltage between both ends detected by the second detection unit exceeds a predetermined threshold value.

10 Transmitter 11 Primary side coil 12 Primary side resonance coil 13 Matching circuit 14 Capacitor 15 Control unit 100, 100A, 100B, 100C, 101, 101-1-101-N, 103 Power receiver 110, 110A, 110B Secondary side resonance Coil 120, 121, 122, 123, 124 Rectifying circuit 130, 130A, 130B Adjusting unit 131X, 131Y Switch 132X, 132Y Diode 133X, 133Y Capacitor 134X, 134Y Terminal 140, 140A, 140B Smoothing capacitor 150, 150A, 150B Control unit 157 Processing unit 158A, 158B OR circuit 158C D-FF
158D Comparator 159A Switch 159B Voltage regulator 159C Standby power supply 160X, 160Y Output terminal 170A, 170B Antenna 180 Detector 181X, 181Y Voltmeter 190C Switch 200A, 200B Electronic equipment 210, 210A, 210B DC-DC converter 220, 220A, 220B Battery 500 power transmission system

Claims (9)

A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A second detector that detects the voltage between the first switch or the second switch,
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance Includes a control unit that adjusts the amount of power received by the coil
A power receiver that holds the first switch and the second switch in an on state when the voltage between both ends detected by the second detection unit becomes equal to or higher than a predetermined threshold value. When the voltage between both ends detected by the second detection unit becomes less than a predetermined threshold value, the holding of the first switch and the second switch in the on state is released.
The power receiver according to claim 1, wherein when the holding of the second switch in the ON state is released, the control unit adjusts the amount of electric power received by the secondary resonance coil. A comparator that compares the voltage between both ends detected by the second detection unit with the predetermined threshold value, and outputs a signal indicating the first level comparison result when the voltage between both ends becomes equal to or higher than the predetermined threshold value. When,
When the signal output from the comparator reaches the first level, the holding unit that holds the first level and the holding unit
A first logical sum circuit that switches on / off the first switch with a first logical sum signal that represents the logical sum of the first signal and the output signal of the holding unit.
Further including a second logical sum circuit for switching on / off of the second switch with a second logical sum signal representing the logical sum of the second signal and the output signal of the holding unit.
When the voltage between both ends detected by the second detection unit becomes equal to or higher than a predetermined threshold value, the first level signal output from the comparer is held by the holding unit, and the first OR circuit and the first OR circuit are held. 2. The first logical sum signal and the second logical sum signal output by the two OR circuits are brought to the first level, so that the first switch and the second switch are held in the ON state, according to claim 1. Power receiver. When the voltage between both ends detected by the second detection unit becomes less than a predetermined threshold value, the control unit resets the holding unit that holds the first level.
When the holding unit is reset, the first OR circuit switches on / off the first switch with the first signal, and the second OR circuit uses the second signal to switch on the second switch. The power receiver according to claim 3, wherein the amount of power received by the secondary resonance coil is adjusted by the control unit by switching on / off. A third switch, which is connected in parallel to the first switch and the second switch, is turned on when the power of the receiver is off, and is turned off when the power of the receiver is on is further included.
The power receiver according to any one of claims 1 to 4, wherein the first switch and the second switch are switches of a type that are turned off when the power of the power receiver is off. When the power of the power receiver is off, the first signal and the second signal are input to the first OR circuit and the second OR circuit, respectively, instead of the first signal and the second signal, and the first switch and the second switch are used. The power receiver according to claim 3 or 4, further comprising a holding signal output unit that outputs a first holding signal and a second holding signal that keeps the power on. A communication unit that performs data communication with a transmitter including the primary resonance coil is further included.
Any one of claims 1 to 6, wherein when the first switch and the second switch are held in the on state, the communication unit transmits data indicating that the first switch and the second switch are held in the on state to the transmitter. The power receiver described in item 1. A transmitter with a primary resonance coil and
A power transmission system including a power receiver that receives power from the power transmitter.
The power receiver
A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A second detector that detects the voltage between the first switch or the second switch,
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance It has a control unit that adjusts the amount of power received by the coil.
A power transmission system that holds the first switch and the second switch in an on state when the voltage between both ends detected by the second detection unit becomes equal to or higher than a predetermined threshold value. A secondary resonance coil having a resonance coil portion and receiving power from the primary resonance coil by magnetic resonance generated between the primary resonance coil and the primary resonance coil.
A capacitor inserted in series with the resonance coil portion of the secondary resonance coil,
A series circuit of the first switch and the second switch connected in parallel to the capacitor,
A first rectifying element connected in parallel to the first switch and having a first rectifying direction,
A second rectifying element connected in parallel to the second switch and having a second rectifying direction opposite to the first rectifying direction.
A first detector that detects the voltage or current supplied to the secondary resonance coil, and
A method for receiving power in a power receiver including the first switch or a second detection unit that detects a voltage between both ends of the second switch.
By controlling the first signal and the second signal for switching on / off of the first switch and the second switch, respectively, based on the voltage or current detected by the first detection unit, the secondary side resonance Adjust the amount of power received by the coil,
A power receiving method for holding the first switch and the second switch in an on state when the voltage between both ends detected by the second detection unit becomes equal to or higher than a predetermined threshold value.

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