JP2014011928A - Non-contact power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission system in which a power-receiving device is reduced in size, thickness, or weight.SOLUTION: A non-contact power transmission system includes a power transmission device 1 that is provided with at least a primary coil 10, a primary power-transmission circuit section 11, and a voltage detection section 225; and a power-receiving device 2 that is provided with at least a secondary coil 20, a secondary communication circuit section 22, and a secondary power-receiving circuit section 21, and a load section 214. The non-contact power transmission system performs power transmission from the primary power-transmission circuit section 11 to the secondary coil 20 via the primary coil 10 when the electromotive force induced from the secondary communication circuit section 22 to the primary coil 10 via the secondary coil exceeds a predetermined value. The power received by the secondary coil 20 is supplied to the load section 214 via the secondary power-receiving circuit section 21.

Description

  The present invention relates to a non-contact power transmission system that performs non-contact power transmission from a power transmission device to a power reception device.

  Techniques have been developed to transmit power from a power transmission device to a power reception device in a contactless manner by electromagnetic induction.

  In particular, temporary power transmission is performed from the primary coil of the power transmission device, and the primary coil and secondary coil can transmit power by detecting the relative position of the primary coil and secondary coil from the induced voltage in the secondary coil of the power receiving device that received the temporary power transmission. Patent Document 1 discloses paragraph 0104, paragraph 0121, FIG. 3, FIG. 8, and FIG. 11 that perform ID authentication from the power receiving apparatus to the power transmitting apparatus and start power transmission from the power transmitting apparatus to the power receiving apparatus in the case of a facing arrangement. Etc. are disclosed.

JP 2009-189231 A

  In the technology described in Patent Document 1, ID authentication from the power receiving device side is used to determine whether the primary coil and the secondary coil are facing each other so that power can be transmitted. However, the primary coil and the secondary coil are not connected to the power receiving device. Since it is necessary to implement a function of detecting the relative position, there is a problem that the power receiving device is hindered from being reduced in size, thickness, or weight.

  Accordingly, an object of the present invention is to provide a non-contact power transmission system in which a power receiving device is reduced in size, thickness, or weight.

  To solve the above problems, the present invention provides a power transmission device including at least a primary coil, a primary power transmission circuit unit, and a voltage detection unit, and a power reception device including at least a secondary coil, a secondary communication circuit unit, a secondary power reception circuit unit, and a load unit. When the electromotive force induced in the primary coil from the secondary communication circuit unit through the secondary coil is detected by the voltage detection unit, and the electromotive force detected by the voltage detection unit exceeds a predetermined value Power is transmitted from the primary power transmission circuit unit to the secondary coil via the primary coil, and the power received by the secondary coil is solved by a contactless power transmission system supplied to the load via the secondary power reception circuit unit.

  The power transmission device further includes a primary communication circuit unit, transmits a communication signal from the primary communication circuit unit to the secondary communication circuit unit via the primary coil and the secondary coil, and the power reception device is an authentication signal corresponding to the communication signal. Is transmitted from the secondary communication circuit unit to the primary communication circuit unit through the secondary coil and the primary coil, and the power transmission device that receives the authentication signal detects the electromotive force induced in the primary coil by the voltage detection unit, When the electromotive force detected by the detection unit exceeds a predetermined value, a non-contact power transmission system that performs power transmission from the primary power transmission circuit unit to the secondary coil via the primary coil may be used.

  In addition, the power transmission device does not transmit power until a predetermined time elapses after the authentication signal is transmitted, and the power receiving device performs secondary communication from the secondary coil before the predetermined time elapses after the authentication signal is transmitted. A non-contact power transmission system that cuts off a power transmission path to the circuit unit may be used.

  In addition, when the power to be transmitted reaches the predetermined power while gradually increasing from the start of power transmission, and the electromotive force induced in the secondary coil in the power receiving apparatus exceeds a predetermined value, A non-contact power transmission system in which power transmission from the secondary coil to the secondary communication circuit unit is cut off may be used.

  Moreover, after starting electric power transmission, if the impedance of a primary coil is more than predetermined value, the non-contact electric power transmission system which stops electric power transmission may be sufficient.

  According to the present invention, it is possible to provide a non-contact power transmission system in which a power receiving device is reduced in size, thickness, or weight.

It is a circuit block diagram which shows Embodiment 1 in this invention. It is explanatory drawing regarding the power transmission judgment process in this invention. It is a circuit block diagram which shows Embodiment 2 in this invention. It is a circuit diagram which shows the example about the resonance part of Embodiment 3 in this invention. A resonance part is the resonance part 222 in FIG. It is a figure which shows the time chart and voltage amplitude waveform in Embodiment 3 in this invention. It is a circuit block diagram which shows Embodiment 4 in this invention. It is a figure which shows the time chart and voltage amplitude waveform in Embodiment 4 in this invention. It is a circuit block diagram which shows Embodiment 5 in this invention.

  An example of an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
The present invention includes, for example, a power transmission device including at least a primary coil, a primary power transmission circuit unit, and a voltage detection unit, and a power reception device including at least a secondary coil, a secondary communication circuit unit, a secondary power reception circuit unit, and a load unit. And when the electromotive force induced in the primary coil from the secondary communication circuit unit through the secondary coil exceeds a predetermined value, the primary power transmission circuit unit transmits power to the secondary coil through the primary coil. The power received by the secondary coil can take an embodiment of a non-contact power transmission system that is supplied to the load via the secondary power receiving circuit unit.

  Since the positional relationship between the primary coil and the secondary coil can be determined on the power transmitting device side by the electromotive force induced in the primary coil by the communication signal from the secondary coil, there is no need to provide a function for determining the positional relationship on the power receiving device side. .

  Accordingly, the power receiving device can be reduced in size, thickness, or weight, and the configuration of the present embodiment is particularly preferably applied when the power receiving device is a portable device such as a mobile phone.

  Furthermore, since the determination of the positional relationship is performed inside the power transmission device that is responsible for power transmission, it is possible to quickly determine whether power transmission is possible.

  In addition, if the power receiving device is a portable device that needs to be reduced in size, thickness, or weight, the power transmission function is often not implemented. An electromotive force is induced and no malfunction occurs.

  FIG. 1 is a circuit block diagram showing a first embodiment of the present invention.

  The power transmission device 1 amplifies power by the power amplification unit 112 using the AC voltage generated from the oscillation unit 111 in the primary power transmission circuit unit 11, and performs impedance matching by the resonance unit 113 configured by an LC parallel resonance circuit or the like while performing the primary coil 10 is configured to perform power transmission.

  In order to prevent an overvoltage from being applied to the primary coil 10, it is desirable that the power amplifying unit 112 be equipped with a power control function that supplies power having a constant voltage amplitude to the resonance unit 113.

  When power is transmitted in a non-contact manner from the primary coil 10 in the power transmission device 1 to the secondary coil 20 in the power reception device 2 by electromagnetic induction, the power received by the secondary coil 20 is impedance matched in the secondary power reception circuit unit 21. The power is transmitted to the load unit 214 via the resonance unit 211 that performs the above, the rectification unit 212 that converts the voltage into a DC voltage, and the power control unit 213 that performs power control such as step-up and step-down.

  In order to determine whether or not power transmission is possible, a communication signal is transmitted to the secondary coil 20 from the signal transmission unit 221 in the secondary communication circuit unit 22 in the power receiving device 2 via the resonance unit 222 that performs impedance matching, and electromagnetic induction is performed. Thus, a communication signal is detected in the primary coil 10 of the power transmission device 1.

  Furthermore, the communication signal is transmitted to the power transmission control unit 114 via the voltage detection unit 1001, and when the magnitude of the communication signal in the power transmission control unit 114 exceeds a threshold at which power can be transmitted from the primary coil 10 to the secondary coil 20. The oscillation unit 111 is controlled so that only power can be transmitted.

  FIG. 2 is an explanatory diagram regarding a power transmission determination process in the present invention.

  When performing non-contact power transmission by electromagnetic induction, in order to prevent heat generation due to loss of power transmission and generation of electromagnetic noise, power transmission efficiency of a certain level or more is required. For that purpose, the primary coil 10 and the secondary coil 20 face each other. However, it needs to be close to some extent.

  On the other hand, when performing communication by electromagnetic induction, it is sufficient that the primary coil 10 and the secondary coil 20 have the minimum magnetic coupling necessary for transmitting and receiving communication signals. Communication is possible even when the distance 20 cannot be transmitted.

  Therefore, as shown in FIG. 2, the power transmission possible area A by the primary coil 10 in the power transmitting device 1 is included in the communicable area B by the secondary coil 20 in the power receiving device 2.

  In the present embodiment, whether or not power transmission is possible is determined from the magnitude of the voltage at which the communication signal from the power reception device 2 is received on the power transmission device 1 side.

(Embodiment 2)
In the present invention, the power transmission device further includes a primary communication circuit unit, the communication signal is transmitted from the primary communication circuit unit to the secondary communication circuit unit via the primary coil and the secondary coil, and the power receiving device corresponds to the communication signal. The power transmission device that transmits the authentication signal from the secondary communication circuit unit to the primary communication circuit unit via the secondary coil and the primary coil, and the electromotive force induced in the primary coil exceeds the predetermined value In this case, an embodiment of a non-contact power transmission system that performs power transmission by induced electromotive force from the primary power transmission circuit unit to the secondary coil via the primary coil can be taken.

  Since the positional relationship between the primary coil and the secondary coil is determined using a communication signal when the power receiving device authenticates the power receiving device, a slight design change may be required when applying this embodiment to the non-contact power transmission system. .

  FIG. 3 is a circuit block diagram showing a second embodiment of the present invention.

  The first embodiment is different from FIG. 1 in that it includes a primary communication circuit unit 12 that mainly enables communication from the power transmission device 1 to the power transmission device 2.

  In the present embodiment, the power transmission device 1 determines whether power transmission is possible by using a signal for the power transmission device 1 to authenticate the power reception device 2 according to the following procedure.

  First, a polling signal is transmitted from the communication coil 101 at regular intervals through the switching unit 122 and the resonance unit 123 from the signal transmission unit 121 in the primary communication circuit unit 12 inside the power transmission device 1.

  Here, the switching unit 122 has a function of transmitting a signal from the signal transmission unit 121 to the resonance unit 123 and transmitting a signal from the resonance unit 123 to the signal reception unit 124 and the voltage detection unit 1001. The switching unit 122 can be configured by a circulator, for example.

  When the secondary coil 20 in the power receiving device 2 receives the polling signal from the power transmitting device 1, the polling signal is transmitted to the signal receiving unit 224 via the resonance unit 222 and the switching unit 223 in the secondary communication circuit unit 22. The

  Here, the switching unit 223 has a function of transmitting a signal from the resonance unit 222 to the signal reception unit 224 and transmitting a signal from the signal transmission unit 221 to the resonance unit 222.

  When the signal reception unit 224 receives the polling signal, the authentication signal is transmitted from the signal transmission unit 221 to the secondary coil 20 via the switching unit 223 and the resonance unit 222.

  When the communication coil 101 in the power transmission device 1 receives the authentication signal from the power reception device 2, the authentication signal is transmitted to the signal reception unit 124 and the voltage detection unit 1001 via the resonance unit 123 and the switching unit 122 in the primary communication circuit unit 12. Is transmitted to.

  The signal received by the signal receiving unit 124 is transmitted to the authentication determining unit 1002 and collated with an authentication signal stored in advance, and if they match, a power transmission permission signal is transmitted to the power transmission control unit 114.

  The signal received by the signal receiving unit 124 is also transmitted to the voltage detecting unit 1001. When the magnitude of the authentication signal exceeds a threshold that allows power transmission from the primary coil 10 to the secondary coil 20 in advance, voltage detection is performed. The power transmission enabling signal is transmitted from the unit 1001 to the power transmission control unit 114.

  When the power transmission control unit 114 receives the power transmission permission signal and the power transmission enabling signal, the power transmission control unit 114 controls the oscillation unit 111 to perform power transmission in the same procedure as in the first embodiment.

  When a semiconductor switch such as an FET is provided between the resonance unit 113 and the power transmission coil 102 and between the secondary coil 20 and the resonance unit 211 in advance, and communication is performed between the communication coil 101 and the secondary coil 20. In addition, by disconnecting the circuit by turning off the semiconductor switch, the AC voltage amplitude of the power transmission coil 102 and the secondary coil 20 may be increased to improve the communication sensitivity.

(Embodiment 3)
In the present invention, the power transmission device does not transmit power until a predetermined time has elapsed after the transmission of the authentication signal, and the power receiving device transmits the authentication signal and before the predetermined time elapses, the secondary coil An embodiment of a non-contact power transmission system in which power transmission to the secondary communication circuit unit is cut off can be taken.

  When the power transmission device side determines that power transmission is possible based on a communication signal from the power reception device, protection is performed by cutting off the secondary communication circuit unit from the secondary coil on the power reception device side before power transmission is performed. The circuit block in the present embodiment is the same as that in FIG. 3 in the second embodiment, except that a blocking unit that prevents power transmission from being performed to the switching unit 223 is provided in the resonance unit 222.

  FIG. 4 is a circuit diagram showing an example of the resonance unit according to the third embodiment of the present invention. A resonance part is the resonance part 222 in FIG.

  Both ends of the secondary coil 20 are connected to the resonance unit 222 via terminals 201 and 202. The AC voltage input from the secondary coil 20 is expanded in voltage amplitude by a parallel resonance circuit composed of an inductor 2221 and a capacitor 2222, and an AC voltage signal is transmitted to the switching unit 223 in FIG. 2 via terminals 2223 and 2224. Is done.

  Here, a semiconductor switch 2225 such as an FET and a capacitor 2226 are connected in parallel with the parallel resonance circuit, and by turning on the semiconductor switch 2225, the resonance point of the parallel resonance circuit is removed and the secondary coil 20 to the switching unit 223. The transmission of the AC voltage signal can be cut off.

  FIG. 5 is a diagram showing a time chart and a voltage amplitude waveform in the third embodiment of the present invention.

  As in the second embodiment, the polling signal I1 is transmitted from the communication coil 101 in the power transmission device 1, the polling signal I1 is received by the secondary coil 20 in the power reception device 2, and then the authentication signal I2 is transmitted. The power transmission device 1 that has received the authentication signal I2 from the communication coil 101 executes power transmission P when it is determined that power transmission is possible in the procedure of the second embodiment.

  Here, during execution of the above procedure, the semiconductor switch 2225 is in an OFF state, that is, a non-conductive state, and after transmitting the authentication signal I2, the semiconductor switch 2225 is turned on, that is, in a conductive state after a predetermined time t2.

  On the power transmission device 1 side, the secondary communication circuit unit on the power reception device 2 side is protected by the semiconductor switch 2225 by making the time t1 until the start of power transmission after receiving the authentication signal I2 longer than the predetermined time t2. Power transmission will be performed later.

  Note that the primary communication circuit unit 12 may be protected from overvoltage during power transmission by operating the semiconductor switch in the procedure of FIG. 5 with the resonance unit 123 in FIG. In this case, the communication coil 101 and the power transmission coil 102 can be integrated into one primary coil.

(Embodiment 4)
The present invention further provides a case where the power to be transmitted reaches a predetermined power while gradually increasing from the start of power transmission, and the electromotive force induced in the secondary coil in the power receiving apparatus exceeds a predetermined value. An embodiment of a non-contact power transmission system in which power transmission from the secondary coil to the secondary communication circuit unit is interrupted can be taken.

  By taking the above embodiment, when power transmission that is not expected by the power receiving device is performed, before the electromotive force induced in the secondary coil exceeds the allowable upper limit of the secondary communication circuit unit, By blocking the connection between the secondary coil and the secondary communication circuit unit, the secondary communication circuit unit can be protected.

  Furthermore, by gradually increasing the power transmitted from the power transmission device side from the start of power transmission, it is possible to reliably disconnect the secondary communication circuit unit before exceeding the allowable upper limit.

  FIG. 6 is a circuit block diagram showing a fourth embodiment of the present invention.

  3 is different from FIG. 3 in that a voltage detection unit 225 is provided.

  In the present embodiment, similarly to the third embodiment, at least the resonance unit 222 is provided with a semiconductor switch as shown in FIG. 4 to protect the secondary communication circuit from an overvoltage during power transmission.

  Further, the present embodiment is different from the third embodiment in that the semiconductor switch of the resonance unit 222 is controlled by the voltage detection unit 225 that detects the voltage amplitude of the secondary coil 20.

  FIG. 7 is a diagram showing a time chart and a voltage amplitude waveform in the fourth embodiment of the present invention.

  The polling signal I1 and the authentication signal I2 are transmitted and received in the same procedure as in the third embodiment. When the power transmission apparatus determines that power transmission is possible according to the procedure of the second and third embodiments, the power transmission P is performed so that the transmission power is gradually increased after reaching the power transmission and reaches a predetermined power. By performing power transmission P in this way, the voltage amplitude induced in the secondary coil also gradually increases.

  During the execution of the above procedure, the semiconductor switch 2225 in FIG. 4 is in an OFF state or non-conductive state, and when the voltage amplitude induced in the secondary coil exceeds a predetermined value VL, the semiconductor switch 2225 is ON or conductive. State.

  With this configuration, it is possible to protect the secondary communication circuit unit from an overvoltage generated by the power transmission P.

  Note that the resonance unit 123 in FIG. 6 may also have a configuration for similarly protecting the primary communication circuit.

(Embodiment 5)
Furthermore, the present invention can take an embodiment of a power transmission system that stops power transmission if the impedance of the primary coil is equal to or higher than a predetermined value after power transmission is started.

  When power transmission is normally performed, the power transmitted by the load on the power receiving device side is consumed, and thus the impedance of the primary coil that performs power transmission to the secondary coil is lower than a predetermined value.

  On the other hand, when the load unit is a secondary battery and the battery is fully charged, the load unit does not accept power transmission, and thus the impedance of the primary coil when performing power transmission is equal to or greater than a predetermined value.

  Therefore, by specifying the upper limit of the impedance of the primary coil when power transmission is normally performed and taking the above embodiment set as a predetermined value, the power transmission is performed when the load unit does not require power transmission. It is possible to stop and prevent problems such as overvoltage on the power receiving apparatus side and power loss due to unnecessary power transmission.

  FIG. 8 is a circuit block diagram showing a fifth embodiment of the present invention.

  FIG. 6 is different from FIG. 6 in that an impedance detection unit 1003 is provided in the power transmission device 1.

  When power is transmitted from the power transmission coil 102, the impedance detection unit 1003 detects the impedance based on, for example, the ratio of the AC current amplitude and the AC voltage amplitude of the power transmission coil 102.

  When the magnitude of the impedance detected by the impedance detection unit 1003 exceeds a predetermined value, a signal for stopping power transmission is transmitted to the power transmission control unit 114.

Power transmission device 1
Power receiving device 2
Primary coil 10
Primary power transmission circuit section 11
Primary communication circuit section 12
Secondary coil 20
Secondary power receiving circuit part 21
Secondary communication circuit unit 22
Communication coil 101
Power transmission coil 102
Oscillator 111
Power amplifier 112
Resonant part 113, 123, 211, 222
Power transmission control unit 114
Signal transmitter 121, 221
Switching unit 122, 223
Signal receiver 124, 224
Terminals 201, 202, 2223, 2224
Rectifier 212
Power control unit 213
Load section 214
Voltage detector 225
Voltage detection unit 1001
Authentication judgment unit 1002
Impedance detection unit 1003
Inductor 2221
Capacitors 2222 and 2226
Semiconductor switch 2225
Power transmission area A
Communication area B
Time t1, t2
Polling signal I1
Authentication signal I2
Power transmission P
Predetermined value VL

Claims (5)

A power transmission device including a primary coil, a primary power transmission circuit unit, and a voltage detection unit;
And a power receiving device including at least a secondary coil, a secondary communication circuit unit, a secondary power receiving circuit unit, and a load unit,
An electromotive force induced in the primary coil from the secondary communication circuit unit through the secondary coil is detected by the voltage detection unit,
When the electromotive force detected by the voltage detection unit exceeds a predetermined value, power is transmitted from the primary power transmission circuit unit to the secondary coil through the primary coil,
The electric power received by the secondary coil is supplied to the load via the secondary power receiving circuit unit. The power transmission device further includes a primary communication circuit unit,
A communication signal is transmitted from the primary communication circuit unit to the secondary communication circuit unit through the primary coil and the secondary coil,
The power receiving device transmits an authentication signal corresponding to the communication signal from the secondary communication circuit unit to the primary communication circuit unit via the secondary coil and the primary coil,
The power transmission device that has received the authentication signal detects an electromotive force induced in the primary coil by the voltage detection unit,
The power transmission is performed from the primary power transmission circuit unit to the secondary coil via the primary coil when an electromotive force detected by the voltage detection unit exceeds a predetermined value. Non-contact power transmission system. The power transmission device does not perform the power transmission until a predetermined time elapses after the authentication signal is transmitted,
3. The power receiving device according to claim 2, wherein after the authentication signal is transmitted, the power receiving device blocks a power transmission path from the secondary coil to the secondary communication circuit unit before the predetermined time elapses. Non-contact power transmission system. The power transmitted power reaches a predetermined power while gradually increasing from the start of the power transmission,
The power transmission from the secondary coil to the secondary communication circuit unit is cut off when an electromotive force induced in the secondary coil in the power receiving device exceeds a predetermined value. The non-contact electric power transmission system in any one of Claims 1-3.   5. The non-contact power transmission system according to claim 1, wherein, after the power transmission is started, the power transmission is stopped if an impedance of the primary coil is equal to or higher than a predetermined value. .

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