KR20130099152A - Power transmitting device, power receiving device, non-contact power transmission system, and method for controlling transmission power in non-contact power transmission system - Google Patents

Abstract

The non-contact electric power transmission system 1 of this invention is equipped with the power transmission apparatus 4 and the power receiving apparatus 7. The power transmission device 4 transfers AC power to the power reception device 7 on a carrier wave. The power receiving device 7 controls the power reception of AC power by changing the load of the power receiving device 7 and changing the resonance frequency of the power receiving antenna 20. The power transmission device 4 detects a modulation signal superimposed on a carrier wave of AC power in accordance with a change in the load of the power reception device 7, and performs power transmission control of AC power based on the detected modulation signal.

Description

Power transmission apparatus, power receiving apparatus, non-contact power transmission system, and control method of power transmission power in a non-contact power transmission system CONTACT POWER TRANSMISSION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact power transmission system that transmits power in a non-contact manner from a power transmission device to a power reception device. For example, the power receiving device is a portable electronic device, and the power transmission device is a charger for the portable electronic device.

If the load on the power receiving device side is too low compared to the assumed load, there is a possibility that the power receiving voltage becomes too high and the parts in the power receiving device may be destroyed.

Patent Literature 1 discloses a non-contact power transmission system that controls a transmission power from a power transmission device side by feeding back a power supply voltage to a power transmission device as a means for solving such a problem. This non-contact electric power transmission system includes coil pairs (transformers: antenna pairs) used for power transmission from a power transmitter to a power receiver, and auxiliary coil pairs used for transmission of feedback signals from a power receiver to a power transmitter. (Auxiliary Transformer: Auxiliary Antenna Pair).

Patent document 2 discloses a power receiving device (secondary side device) having a control circuit that performs voltage control. The power receiving device of Patent Document 2 does not feed the power supply voltage back to the power transmission device, but instead controls the power supply voltage level to be close to an appropriate value by changing the load in accordance with the power supply voltage.

Japanese Patent Laid-Open No. 2008-263779 Japanese Patent Laid-Open No. 2005-278400, Embodiment 6, Fig. 8

In the non-contact electric power transmission system of patent document 1, after a feedback signal is sent from a power receiving device to a power transmission device, a power transmission device controls power transmission power. That is, in the power receiving device, a certain time elapses from the occurrence of the overvoltage due to the low load until it is controlled. For this reason, there exists a possibility that the component in a power receiving device may be destroyed by the overvoltage in the meantime.

In the non-contact power transmission system including the power receiving device of Patent Document 2, the problem of the non-contact power transmission system of Patent Document 1 described above does not occur. However, the power transmission device is not aware of the control in the power reception device, and therefore cannot be optimized even if inefficient power transmission has been performed.

Accordingly, an object of the present invention is to provide a non-contact power transmission system capable of controlling the power supply voltage without timelag and transmitting the state of the power supply voltage to the power transmission device so that the power transmission power can be controlled at an appropriate level. do.

One aspect of the present invention is a power transmission device that transmits AC power by carrying a carrier wave to the power receiving device,

The power receiving device is capable of superimposing a modulated signal on the carrier wave of the AC power by varying the load of the power receiving device,

The power transmission device is:

With power transmission antenna;

A driver circuit for driving the power transmitting antenna to transfer the AC power to the carrier;

A power transmission control circuit for controlling the driver circuit;

A matching circuit provided between the driver circuit and the power transmission antenna, the matching circuit matching an output impedance of the driver circuit and an impedance of the power transmission antenna;

A detection circuit that detects the modulated signal superimposed on the carrier of the AC power and transmits the modulated signal to the power transmission control circuit;

The power transmission control circuit provides a power transmission device that controls the driver circuit based on the modulated signal.

Moreover, another aspect of this invention is a non-contact electric power transmission system provided with the above-mentioned power transmission apparatus and power receiving apparatus,

The power receiving device is:

A power receiving antenna;

A rectifier circuit for rectifying the AC power received by the power receiving antenna and converting the AC power into DC power;

A voltage detection circuit for detecting an output voltage of the rectifier circuit;

A resonant frequency changing circuit for varying the resonant frequency of the power receiving antenna by changing a load in accordance with the output of the voltage detection circuit to control the reception of the AC power and to superimpose the modulation signal on the carrier of the AC power;

It provides a non-contact power transmission system having a.

Moreover, another aspect of the present invention,

A control method of power transmission power in a non-contact power transmission system comprising a power reception device and a power transmission device that transmits AC power on a carrier wave with respect to the power reception device.

A first process in which the power receiving device changes the load of the power receiving device to control the power receiving power in the power receiving device;

A second process in which the power transmission apparatus detects a modulated signal superimposed on the carrier of the AC power in accordance with a change in load of the power receiving apparatus, and controls the power transmission power based on the detected modulation signal;

Provided is a control method of transmission power.

According to the non-contact power transmission system of the present invention, the power receiving device is controlled by varying the load, and at the same time, based on the modulation signal superimposed on the carrier wave of AC power by load modulation in conjunction with the control of the power receiving voltage. The transmission power can be further controlled. Therefore, according to the present invention, it is possible to achieve both power supply voltage control without time lag and efficient power transfer control.

In addition, in this invention, since the modulated signal by load modulation mentioned above is used as a feedback signal, since it is not necessary to provide the system exclusively for feedback signal transmission, the non-contact power transmission system of this invention is the non-contact of patent document 1 Compared with an electric power transmission system, it can be set as a simple structure and therefore can be constructed in low cost.

By examining the following description of the best embodiments while referring to the accompanying drawings, the purpose of the present invention will be correctly understood and the structure thereof will be more fully understood.

1 is a block diagram showing a non-contact power transmission system according to a first embodiment of the present invention.
FIG. 2 is a circuit diagram showing a detection circuit in the non-contact power transmission system of FIG. 1.
FIG. 3 is a circuit diagram illustrating a resonant frequency changing circuit in the non-contact power transmission system of FIG. 1.
4 is a circuit diagram illustrating a voltage detection circuit in the non-contact power transmission system of FIG. 1.
FIG. 5 is a diagram schematically showing a feedback signal waveform and the like in the non-contact power transmission system of FIG. 1. The upper part schematically shows the feedback signal waveform which superimposed a modulation signal on a carrier wave, and the lower part shows the output waveform of a detection circuit typically.
6 is a block diagram showing a non-contact power transmission system according to a second embodiment of the present invention.
FIG. 7 is a circuit diagram illustrating a driver circuit and a current monitor circuit in the non-contact power transfer system of FIG. 1.
8 is a block diagram showing a non-contact power transmission system according to a third embodiment of the present invention.
9 is a diagram schematically illustrating a feedback signal waveform in the non-contact power transmission system of FIG. 8. The upper part schematically shows a waveform in which a modulated signal and an additional modulated signal are superimposed on a carrier wave, and the lower part A schematically shows an output waveform (modulated signal) of a first band pass filter, and the lower part B is a second one. The output waveform (additional modulated signal) of the band pass filter of is schematically shown.
FIG. 10 is a block diagram illustrating a modification of the power transmission device of the non-contact power transmission system of FIG. 8.

Although this invention can be implement | achieved with various deformation | transformation and various forms, the specific embodiment as shown to a figure as an example is demonstrated in detail below. The drawings and embodiments are not to be construed as limiting the invention to the specific forms disclosed herein, but are intended to include all modifications, equivalents, and alternatives within the scope specified in the appended claims. do.

(1st embodiment)

As shown in FIG. 1, the non-contact power transmission system 1 according to the first embodiment of the present invention includes a power transmission device 4 and a power reception device 7.

The power transmission device 4 includes a power transmission antenna 10 for transmitting electric power, a driver circuit 12 for driving the power transmission antenna 10, and a power transmission control circuit 11 for controlling power transmission by controlling the driver circuit 12. ), A matching circuit 13 for performing impedance matching between the power transmission antenna 10 and the driver circuit 12, and a detection circuit 14 for detecting a modulation signal (feedback signal: described later) transmitted by the power receiving device 7. ).

Here, the power transmission control circuit 11 includes a CPU (not shown) and the like, controls the output power of the power transmission power circuit (not shown), and generates a pulse signal for driving the driver circuit 12.

The power transmission antenna 10 electronically couples with the power receiving antenna 20 of the power receiving device 7 to transmit power to the power receiving device 7, and receives a modulated signal transmitted from the power receiving device 7. For example, a loop coil printed on a printed board can be used for the power transmission antenna 10.

The driver circuit 12 mainly consists of a bipolar transistor (not shown) or a field effect transistor (hereinafter referred to as FET), and generates a power transmission power waveform in accordance with the pulse signal generated by the power transmission control circuit 11. In other words, the driver circuit 12 drives the power transmission antenna 10 to load AC power on the carrier wave and to transmit the power to the power receiving device 7.

The matching circuit 13 is mainly comprised by the capacitor | condenser which is not shown in figure, and matches the impedance of the power transmission antenna 10 with the impedance of the power receiving antenna 20. FIG.

The detection circuit 14 detects a modulated signal transmitted by the power receiving device 7 and receives it as a feedback signal. The detected modulation signal is transmitted to the power transmission control circuit 11 and used for power transmission control. As the detection circuit 14, an envelope detection circuit using a diode can be used, for example.

Specifically, as shown in FIG. 2, the detection circuit 14 according to the present embodiment connects the anode to the power transmission antenna 10 and simultaneously connects the cathode to the transmission and reception control circuit 11. And a coil 16 connected between the anode of the diode 15 and the ground, and a resistor 17 and a capacitor 18 connected between the cathode of the diode 15 and the ground.

Referring again to FIG. 1, the power receiving device 7 includes a power receiving antenna 20 for receiving AC power from the power transmission device 4 and a resonant frequency changing circuit 21 for changing the resonant frequency of the power receiving antenna 20. ), A rectifier circuit 22 for rectifying and converting AC power received by the power receiving antenna 20 into DC power, a voltage detecting circuit 23 for detecting an output voltage of the rectifying circuit 22, and a power receiving device. The load 24 to which electric power is supplied from (7) is provided.

Here, the power receiving antenna 20 electronically couples with the power transmitting antenna 10 to receive power from the power transmission device 4 and transmits a modulation signal (to be described later) to the power transmission device 4. As the power receiving antenna 20, for example, a loop coil laid out on a printed board can be used.

The resonance frequency changing circuit 21 is configured by combining at least a plurality of capacitors, FETs, and resistors, respectively.

Specifically, as shown in FIG. 3, the resonance frequency changing circuit 21 according to the present embodiment includes a first impedance 41, a second impedance 42, and a third impedance 43. ), FETs 44 and 45, and a resistor 46.

In the present embodiment, the first impedance 41, the second impedance 42 and the third impedance 43 are all capacitors, and the second impedance 42 and the third impedance 43 ) Have the same capacitance as each other.

One end of the second impedance 42 is connected to the drain of the FET 44, and the other end of the second impedance 42 is connected to the terminal a1 of the power receiving antenna 20. Similarly, one end of the third impedance 43 is connected to the drain of the FET 45, and the other end of the third impedance 43 is connected to the terminal a2 of the power receiving antenna 20.

Gates and sources of the FETs 44 and 45 are connected to each other, and the center tap CT is drawn out from the source. The resistor 46 is connected between the gate and the source of the FETs 44 and 45, and the center tap CT is connected to the ground.

That is, the resonant frequency changing circuit 21 has the center tap CT as the circuit center and is symmetrical with respect to the center tap CT.

When the FETs 44 and 45 are on, the resonant frequency changing circuit 21 connects the second series of impedances 42 and the third series of impedances 43 and the equivalent series resistance due to the on resistance of the FET in series. It is equivalent to the circuit formed by connecting a circuit and the 1st impedance 41 in parallel.

On the other hand, when the FETs 44 and 45 are off, the resonant frequency changing circuit 21 is parasitic due to the second impedance 42 and the third impedance 43 and the FETs 44 and 45. ) It is equivalent to the circuit which connected the capacitance in series, and the circuit which connects the 1st impedance 41 in parallel.

In this way, since the impedances connected between the terminals a1 and a2 of the power receiving antenna 20 change when the FETs 44 and 45 are on and off, the resonance frequency also changes.

In this embodiment, the impedance is adjusted so that the power receiving efficiency is the highest when the FETs 44 and 45 are off, and the power receiving voltage is lowered when the FETs 44 and 45 are on.

That is, when the load 24 is heavy, the resonance frequency is set in advance so as to maximize the power receiving efficiency, and when the load 24 becomes light and the power receiving voltage rises, the resonance frequency changing circuit 21 operates to switch the resonance frequency. It is a constitution. Switching the resonant frequency lowers the power receiving efficiency and lowers the power receiving voltage.

The resonant frequency changing circuit 21 is connected to the rectifier circuit 22 at the terminals b1 and b2.

The rectifier circuit 22 is a single-layer bridge rectifier circuit constructed using four diodes. In other words, the rectifier circuit 22 according to the present embodiment is a full-wave rectifier circuit, and has a good efficiency compared with that of Patent Document 2. The rectifier circuit 22 further has a rectification output terminal Vd and a ground terminal (not shown). The rectifier output terminal Vd is connected to the voltage detection circuit 23 and the load 24, and the ground terminal is connected to the center tap CT of the resonance frequency change circuit 21 described above.

The voltage detection circuit 23 has hysteresis characteristics and is constituted by at least a plurality of transistors, a resistor, and a zener diode.

Specifically, as shown in FIG. 4, the voltage detection circuit 23 according to the present embodiment includes zener diodes ZDs and a gate driving circuit 60.

The illustrated gate drive circuit 60 includes bipolar transistors 61 and 62, resistors R1 to R5, and zener diodes ZDc and ZDp. The gate drive circuit 60 uses the DC voltage after rectification (that is, the output voltage of the rectifier circuit 22) as a drive power supply. If the output voltage of the rectifier circuit 22 is excessively high, the FETs 44 and 45 may be destroyed, so the breakdown voltage of the zener diode ZDp is set to the gate of the FET used in the resonance frequency change circuit 21. It is preferable to set it as below withstand voltage between sources.

A resistor R1 is connected in the middle of the base of the bipolar transistor 61 and the anode of the zener diodes ZDs, and a resistor R2 in the middle of the rectifier output terminal Vd and the collector of the bipolar transistor 61. Is connected. In addition, the resistor R3 is connected between the rectifier output terminal Vd and the collector of the bipolar transistor 62, and the resistor R4 is provided between the base of the bipolar transistor 61 and the ground terminal GND. This connection is made, and the resistor R5 is connected between the emitter of the bipolar transistor 61 and the ground terminal GND.

The base of the bipolar transistor 62 is connected to the collector of the bipolar transistor 61, and the emitter of the bipolar transistor 62 is connected to the emitter of the bipolar transistor 61.

The cathode of the zener diode ZDp is connected to the collector of the bipolar transistor 62, and the anode is connected to the ground terminal GND. The cathode of the zener diode ZDc is connected to the collector of the bipolar transistor 62, and the anode is connected to the FETs 44 and 45 as the terminal c1.

For example, since the load 24 is lightened, the DC voltage after rectification rises, and when a voltage exceeding the breakdown voltage of the zener diodes ZDs is applied, the zener diodes ZDs break down. At this time, the voltage applied to the base of the bipolar transistor 61 is determined by dividing the voltage drop by the zener diodes ZDs by the resistors R1 and R4 from the DC voltage after rectification.

The voltage applied to the base of the bipolar transistor 61 is the emitter potential VE of the bipolar transistor 61 with respect to the ground terminal GND, and the bipolar transistor necessary for the switch of the bipolar transistor 61 ( When the sum of the base-emitter voltage VBE of 61) is equal to or greater than VE + VBE, current flows in the base, and the bipolar transistor 61 is turned on. In the present embodiment, the resistor R1 and the resistor R4 are selected so that the bipolar transistor 61 is turned on when the zener diodes ZDs conduct.

The on / off of the bipolar transistor 61 and the bipolar transistor 62 are inverted from each other. That is, when the bipolar transistor 61 is off, the bipolar transistor 62 is on, and when the bipolar transistor 61 is on, the bipolar transistor 62 is off.

When the bipolar transistor 61 is on, the emitter potential VE of the bipolar transistor 61 is determined by the voltage division ratio between the resistor R2 and the resistor R5 and the DC voltage after rectification.

On the other hand, when the bipolar transistor 61 is off, the emitter potential VE of the bipolar transistor 61 is determined by the divided voltage ratio of the resistor R3 and the resistor R5 and the DC voltage after rectification.

That is, the emitter potential VE of the bipolar transistor 61 can be changed when the bipolar transistor 61 is on and off.

In the present embodiment, when the resistor R2 is set larger than the resistor R3, the resistor R3 is set larger than the resistor R5, and the resistor R5 is set to a value sufficiently smaller than the resistor R2, When the bipolar transistor 61 is on, the emitter potential VE is closer to the ground potential.

When the bipolar transistor 62 is on, the FETs 44 and 45 of the resonant frequency changing circuit 21 shown in Fig. 3 are divided from voltages obtained by dividing the DC voltage after rectification by the resistors R3 and R5. The voltage obtained by subtracting the voltage drop caused by the zener diode ZDc is applied. In this embodiment, this voltage is set lower than the voltage required for turning on the FETs 44 and 45. That is, when the bipolar transistor 62 is on, the resonance frequency is in an initial state.

When a voltage exceeding the breakdown voltage of the zener diodes ZDs is applied, and the bipolar transistor 62 is turned off, the zener diode ZDp is formed from the breakdown voltage of the zener diode ZDp between the gate and the source of the FETs 44 and 45. The voltage minus the voltage drop by ZDc) is applied.

That is, when a voltage exceeding the breakdown voltage of the zener diodes ZDs is applied, the voltage applied between the gate and the source of the FETs 44 and 45 is almost constant. In this embodiment, this voltage is set to the value which can reliably turn on the FETs 44 and 45. That is, when the FETs 44 and 45 are turned on, the resonance frequency changing circuit 21 switches the resonance frequency because the receiving voltage is lowered.

Here, when the resistor R2 is made sufficiently larger than the resistor R5, the voltage generated at both ends of the resistor R5 when the bipolar transistor 62 is off becomes sufficiently small compared with the voltage of the rectified output terminal Vd. The threshold of the bipolar transistor 61 is substantially equal to the base-emitter voltage VBE of the bipolar transistor 61 required for switching the bipolar transistor 61.

At this time, even when the receiving voltage decreases because the bipolar transistor 62 is turned off, when the base voltage of the bipolar transistor 61 is greater than the base-emitter voltage VBE, the bipolar transistor 61 is in an on state. The bipolar transistor 61 is turned off and the bipolar transistor 62 is turned on only after the base voltage becomes lower than the base-emitter voltage VBE.

As described above, the relationship between the voltage applied to the input of the gate driving circuit 60, that is, the base of the bipolar transistor 61, and the output of the gate driving circuit 60, that is, the anode potential of the zener diode ZDc. It can be seen that there is hysteresis. Therefore, the resonant frequency changing circuit 21 does not react to a temporary voltage drop, and after switching the resonant frequency sufficiently, the resonant frequency can be returned to the initial value.

In this way, the hysteresis is applied to the input / output of the gate driving circuit 60, so that the FETs 44 and 45 are operated until the effect of the resonance frequency adjustment is obtained when a voltage exceeding the breakdown voltage of the zener diodes ZDs is applied. Can be driven certainly.

As described above, when the voltage converted into the direct current by the rectifier circuit 22 exceeds a predetermined threshold, the resonant frequency changing circuit 21 operates to switch the resonant frequency. When the resonant frequency is switched, the power receiving voltage drops and falls below the threshold, the resonant frequency changing circuit 21 stops operating, and the resonant frequency returns to its original state and the power receiving voltage increases. As described above, in the present embodiment, since the power reception voltage is controlled on the power receiving device 7 side based on the DC voltage after rectification, the element due to the time lag as concerned in the case of Patent Document 1 The problem of destruction of the back does not occur.

In addition, by repeating the above switching operation of the resonant frequency (that is, the load changing operation), the voltage detection circuit 23 pulses the resonant frequency changing circuit 21. This pulse period depends on the power receiving voltage, and when the power receiving voltage is high, the pulse period is short, and when the power receiving voltage is low, the pulse period is long. In other words, the pulse signal generated by the voltage detection circuit 23 and the resonance frequency change circuit 21 can be used as a pulse width modulation signal corresponding to the power receiving voltage. This pulse width modulation signal is superimposed on a carrier wave as a load modulation signal (feedback signal) by the ON / OFF of the resonance frequency change circuit 21, and is transmitted to the power transmission apparatus 4 (refer FIG. 5 (a)). The detection circuit 14 detects this modulated signal (see FIG. 5 (b)) and transfers it to the power transmission control circuit 11. Thereby, the power transmission control circuit 11 controls the driver circuit 12 based on the modulation signal transmitted from the detection circuit 14, and can perform more efficient, ie, less wasteful power transfer.

Thus, in this embodiment, since a system dedicated to the transmission of the feedback signal is not required, the configuration can be simplified. In addition, when the frequency for power transmission and the frequency for feedback signal transmission are different, it is necessary to take a noise countermeasure for the feedback signal, but it is not necessary to implement such a noise countermeasure in the present embodiment. Therefore, according to this embodiment, an inexpensive non-contact electric power transmission system can be obtained.

(Second embodiment)

As shown in FIG. 6, the non-contact power transmission system 2 according to the second embodiment of the present invention includes a power transmission device 5 and a power reception device 8. Hereinafter, the difference from the 1st Embodiment mentioned above is demonstrated.

The power transmission device 5 includes a power transmission antenna 10 for transmitting electric power, a driver circuit 12 for driving the power transmission antenna 10, and a power transmission control circuit 11 for controlling power transmission by controlling the driver circuit 12. ) And a current monitor circuit 80 for monitoring the current input to the driver circuit 12 in addition to the matching circuit 13 for performing impedance matching between the power transmission antenna 10 and the driver circuit 12.

Here, the current monitor circuit 80 is composed of a resistor, a current transformer, an amplifier circuit, and the like, and outputs a voltage corresponding to the current input to the driver circuit 12.

7 shows a specific example of the driver circuit 12 and the current monitor circuit 80 schematically. The driver circuit 12 is connected to a power supply line Vp, a resistor 81, a choke coil 82 connected to a resistor 81, and a choke coil 82, and a power transmission control circuit 11. The drive FET 83 which is controlled by this is provided. The current monitor circuit 80 detects a change in the current input to the driver circuit 12 from the drop voltage at both ends of the resistor 81 as a modulation signal and transmits it to the power transmission control circuit 11.

As in the first embodiment, when the load 24 becomes light in the power receiving device 8 and the power receiving voltage rises, the resonance frequency changing circuit 21 operates to switch the resonance frequency. At this time, in conjunction with the operation of the resonant frequency changing circuit 21, the current input to the driver circuit 12 of the power transmission device 5 fluctuates. The power transmission control circuit 11 receives the fluctuation of this current from the current monitor circuit 80 as a modulation signal (feedback signal), thereby monitoring the presence or absence of the operation of the resonant frequency changing circuit 21, and on the other hand, the resonant frequency changing circuit. Power transmission control based on the operation of (21) can be performed. In addition, with a simple configuration, control of the power transmission voltage can be realized.

(Third embodiment)

As shown in FIG. 8, the non-contact power transmission system 3 according to the third embodiment of the present invention includes the power transmission device 6 and the power reception device 9. Hereinafter, the difference from 1st Embodiment is demonstrated.

The power transmission device 6 includes a power transmission antenna 10 for transmitting electric power, a driver circuit 12 for driving the power transmission antenna 10, and a power transmission control circuit 11 for controlling power transmission by controlling the driver circuit 12. And a matching circuit 13 for impedance matching between the power transmission antenna 10 and the driver circuit 12, the detection circuit 14 for detecting a modulated signal and the output of the detection circuit 14 The first band pass filter 72a and the second band pass filter 72b are provided. The input of the detection circuit 14 is connected to the power transmission antenna 10. The first band pass filter 72a and the second band pass filter 72b have different frequency characteristics. The first band pass filter 72a corresponds to the frequency band (first frequency band) of the modulation signal that the power receiver 9 overlaps with the carrier wave, and the second band pass filter 72b load modulates. The circuit 74 is adjusted to correspond to the frequency band (second frequency band) of the additional modulation signal (to be described later) superimposed on the carrier wave.

On the other hand, the power receiving device 9 includes a power receiving antenna 20 for receiving AC power from the power transmission device 4, a resonant frequency changing circuit 21 for changing the resonant frequency of the power receiving antenna 20, and a power receiving antenna. In addition to the rectifier circuit 22 for rectifying and converting the AC power received at 20 into DC power, and the voltage detection circuit 23 for detecting the output voltage of the rectifier circuit 22, an additional modulated signal is added to the carrier wave. The power receiving control circuit 76 which performs the power receiving control of the secondary side including the overlapping load modulation circuit 74, and the power supply circuit 75 which stabilizes a power receiving voltage are provided.

The power receiving control circuit 76 includes a CPU (not shown) and the like, and controls the power receiving device 9 and drives the load modulation circuit 74.

The load modulation circuit 74 mainly consists of a capacitor | condenser (not shown), FET, and a resistor, and superimposes an additional modulation signal on a carrier according to the output signal of the power reception control circuit 76. As shown in FIG. This load modulation circuit 74 can have the same structure as the resonance frequency change circuit 21 shown in FIG. In addition, you may replace the 2nd impedance 42 and the 3rd impedance 43 with a resistance element.

When the resonance frequency of the power receiving antenna 20 and the impedance of the power receiving antenna 20 are changed by turning on / off the FETs 44 and 45 of the resonance frequency changing circuit 21 according to the output of the power receiving control circuit 76, As described above, a modulated signal is superimposed on a carrier wave.

Similarly, when the load modulation circuit 74 is operated in accordance with the output of the power receiving control circuit 76 to change the resonance frequency of the power receiving antenna 20 and the impedance of the power receiving antenna 20, an additional modulated signal is superimposed on the carrier wave. .

In the present embodiment, the resonant frequency changing circuit 21 has a frequency band (first frequency band) of the modulated signal superimposed on the carrier wave and the frequency of the additional modulated signal superimposed by the load modulating circuit 74. It is designed differently from the frequency band (second frequency band).

As shown in Fig. 9A, the power transmission device 6 is sent with a modulated signal A and an additional modulated signal B superimposed on a carrier wave. By processing this with the first band pass filter 72a and the second band pass filter 72b, respectively, the modulated signal A and the additional modulated signal B are detected as signal waveforms independent of each other, and power transmission control. It is transmitted to the circuit 11 (see FIG. 9 (b)).

As a result, for example, the power receiving device 9 superimposes the feedback of the power receiving voltage on the carrier as a modulation signal, and simultaneously superimposes the ID information of the power receiving device 9 on the carrier as an additional modulation signal and transmits the power transmission device ( 6), the power transmission power can be controlled in a state where the power transmission device 6 recognizes which power reception device 9 is controlling based on the ID information or the like.

In addition, instead of providing a plurality of band pass filters like the first band pass filter 72a and the second band pass filter 72b, as shown in FIG. 10, one frequency characteristic can be switched. The band pass filter 72c may be used to switch the frequency characteristics of the band pass filter 72c to receive the modulated signal and the additional modulated signal, respectively.

[Industrial Availability]

The present invention can be applied to, for example, a non-contact power transmission system for charging a secondary battery mounted on portable electronic devices such as mobile phones, electric shavers, and digital cameras.

The present invention is based on Japanese Patent Application No. 2011-207736, filed with the Japan Patent Office on September 22, 2011, and Japanese Patent Application No. 2012-093769, filed with the Japan Patent Office on April 17, 2012. The contents constitute part of this specification by reference.

While the best embodiments of the present invention have been described, it will be apparent to those skilled in the art that modifications may be made to the embodiments without departing from the spirit thereof, and such embodiments fall within the scope of the present invention. will be.

1, 2, 3 non-contact power transmission system
4, 5, 6, 6a power transmission unit
7, 8, 9 faucet
10 power transmission antenna
11 power transmission control circuit
12 driver circuit
13 matching circuit
14 Detection Circuit
15 diodes
16 coils
17 resistance
18 condenser
20 power receiving antenna
21 resonant frequency change circuit
22 rectifier circuit
23 voltage detection circuit
24 load
41 primary impedance
42 second impedance
43 third impedance
44, 45 FET
46 resistance
60 gate driving circuit
61, 62 Bipolar Transistors
72a first band pass filter
72b second band pass filter
72c bandpass filter
74 load modulation circuit
75 power circuit
76 faucet control circuit
80 current monitor circuit
81 resistance
82 choke coils
83 drive FET
CT Center Tab
R1, R2, R3, R4, R5 Resistance
a1, a2, b1, b2, c1 terminals
GND ground terminal
ZDc, ZDp, ZDs Zener Diodes
A modulated signal
B additional modulated signal
Vd rectified output terminal
Vp power line

Claims (15)

As a power transmission device that transfers AC power to a carrier wave and transmits power to a power reception device,
The power receiving device is capable of superimposing a modulated signal on the carrier wave of the AC power by varying the load of the power receiving device,
The power transmission device is:
With power transmission antenna;
A driver circuit for driving the power transmitting antenna to transfer the AC power to the carrier;
A power transmission control circuit for controlling the driver circuit;
A matching circuit provided between the driver circuit and the power transmission antenna, the matching circuit matching an output impedance of the driver circuit and an impedance of the power transmission antenna;
A detection circuit that detects the modulated signal superimposed on the carrier of the AC power and transmits the modulated signal to the power transmission control circuit;
And a power transmission control circuit for controlling the driver circuit based on the modulated signal. The method of claim 1,
The detection circuit includes a detection circuit connected to the power transmission antenna,
The detection circuit detects the modulated signal and transmits a detection result to the power transmission control circuit. The method of claim 1,
The detection circuit includes a current monitor circuit connected to the driver circuit and configured to monitor a current input to the driver circuit,
And the current monitor circuit detects the modulated signal as a change in the current, and transmits a detection result to the power transmission control circuit. A non-contact power transmission system comprising the power transmission device according to any one of claims 1 to 3 and a power reception device,
The power receiving device is:
A power receiving antenna;
A rectifier circuit for rectifying the AC power received by the power receiving antenna and converting the AC power into DC power;
A voltage detection circuit for detecting an output voltage of the rectifier circuit;
A resonant frequency changing circuit for varying the resonant frequency of the power receiving antenna by changing a load in accordance with the output of the voltage detection circuit to control the reception of the AC power and to superimpose the modulation signal on the carrier of the AC power;
Non-contact power transmission system having a. 5. The method of claim 4,
The resonant frequency changing circuit of the power receiving device includes a condenser element and a switch for connecting / cutting the condenser element and the antenna in accordance with an output of the voltage detection circuit. 4. The method according to any one of claims 1 to 3,
The modulated signal has a frequency belonging to the first frequency band,
Wherein the receiving circuit is further capable of superimposing an additional modulated signal having a frequency belonging to a second frequency band different from the modulated signal to the carrier of the AC power,
The detection circuit includes a detection circuit connected to the power transmission antenna, a first band pass filter connected to the detection circuit to pass the first frequency band, and a second frequency band connected to the detection circuit. And a second band pass filter through which
The first band pass filter and the second band pass filter each deliver a filter output to the power transmission control circuit,
The power transmission control circuit is configured to perform power transmission control based on the filter output. 4. The method according to any one of claims 1 to 3,
The modulated signal has a frequency belonging to the first frequency band,
Wherein the receiving circuit is further capable of superimposing an additional modulated signal having a frequency belonging to a second frequency band different from the modulated signal to the carrier of the AC power,
The detection circuit includes a detection circuit connected to the power transmission antenna, a band pass filter switchable between the first frequency band and the second frequency band connected to the detection circuit,
The band pass filter delivers a filter output to the power transmission control circuit,
The power transmission control circuit is configured to perform power transmission control based on the filter output. A non-contact power transmission system comprising the power transmission device according to claim 6 or 7, and a power reception device,
The power receiving device is:
A power receiving antenna;
A rectifier circuit for rectifying the AC power received by the power receiving antenna and converting the AC power into DC power;
A voltage detection circuit for detecting an output voltage of the rectifier circuit;
The resonance frequency of the power receiving antenna is varied by changing the load in accordance with the output of the voltage detection circuit to control the reception of the AC power, and the frequency having the frequency belonging to the first frequency band with respect to the carrier of the AC power. A resonant frequency changing circuit for superposing a modulated signal;
A load modulating circuit for superimposing an additional modulated signal having a frequency belonging to a second frequency band different from said modulated signal onto said carrier of said AC power;
A load modulation control circuit for controlling the load modulation circuit;
Non-contact power transmission system having a. The method of claim 8,
The resonant frequency changing circuit of the power receiving device includes a condenser element and a switch for connecting / cutting the condenser element and the antenna in accordance with an output of the voltage detection circuit. A power receiving device for receiving the AC power from the power transmission device according to claim 6 or 7,
A power receiving antenna;
A rectifier circuit for rectifying the AC power received by the power receiving antenna and converting the AC power into DC power;
A voltage detection circuit for detecting an output voltage of the rectifier circuit;
The resonance frequency of the power receiving antenna is varied by changing the load in accordance with the output of the voltage detection circuit to control the reception of the AC power, and the frequency having the frequency belonging to the first frequency band with respect to the carrier of the AC power. A resonant frequency changing circuit for superposing a modulated signal;
A load modulating circuit for superimposing an additional modulated signal having a frequency belonging to a second frequency band different from said modulated signal onto said carrier of said AC power;
A load modulation control circuit for controlling the load modulation circuit;
A power receiving device having a. The method of claim 10,
The resonant frequency changing circuit includes a capacitor element and a switch for connecting / cutting the capacitor element and the antenna in accordance with an output of the voltage detection circuit. A control method of power transmission power in a non-contact power transmission system comprising a power reception device and a power transmission device that transmits AC power on a carrier wave with respect to the power reception device.
A first process in which the power receiving device changes the load of the power receiving device to control the power receiving power in the power receiving device;
A second process in which the power transmission apparatus detects a modulated signal superimposed on the carrier of the AC power in accordance with a change in load of the power receiving apparatus, and controls the power transmission power based on the detected modulation signal;
A control method of transmission power. 13. The method of claim 12,
The power receiving device includes a power receiving antenna and a rectifying circuit for rectifying and converting the AC power received by the power receiving antenna into DC power.
The first processing includes a process of outputting a pulse width modulated signal having a different pulse period when the output voltage of the rectifier circuit is low and high, and receiving the pulse width modulated signal to change the load, and the power receiving antenna A method of controlling transmission power, comprising a process of changing a resonance frequency of the circuit. The method according to claim 12 or 13,
The modulated signal belongs to the first frequency band,
The first processing further includes a process of further superimposing an additional modulated signal having a frequency belonging to a second frequency band different from the first frequency band to the carrier wave of the AC power,
The second processing uses the band pass filter that is compatible with both the first frequency band and the second frequency band to set the modulated signal using the corresponding frequency band of the band pass filter as the first frequency band. Processing for receiving the additional modulated signal using the corresponding frequency band of the band pass filter as the second frequency band, and based on the modulated signal and the additional modulated signal. A control method of transmission power, which controls transmission power. The method according to claim 12 or 13,
The modulated signal belongs to the first frequency band,
The first processing further includes a process of further superimposing an additional modulated signal having a frequency belonging to a second frequency band different from the first frequency band to the carrier wave of the AC power,
The second processing is a process of acquiring the modulated signal using a first band pass filter corresponding to the first frequency band, and the additional process using a second band pass filter corresponding to the second frequency band. And a processing for acquiring a modulated signal, wherein the power transmission control is performed based on the modulated signal and the additional modulated signal.

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