JP2011193619A - Transceiver for radio power transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that in radio power transmission by a magnetic resonance method, the absence of impedance control of a transceiver leads to low efficiency, but incorporating an impedance control function into a small-sized device, such as portable device, results in a large circuit scale and size, thus bringing a negative effect on miniaturization. <P>SOLUTION: When a small-sized device serving as a receiver cannot mount an impedance control function, a transmitter determines the presence/absence of the impedance function and carries out impedance control by switching an impedance control method. As a result, radio power transmission can be carried out efficiently even if the receiver cannot mount the impedance control function. Hence radio power transmission performance is improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a configuration for improving power transmission efficiency between a transceiver in a transceiver for wireless power transmission that transmits and receives power in a space.

  2. Description of the Related Art In recent years, technological development of mobile phones and terrestrial digital broadcasting has progressed, and wireless receiving devices that receive data, voice, television broadcasts, etc. using wireless radio waves without using a wired connection have become widespread. On the other hand, many of the wireless receiving devices are supplied with electric power in a wired manner, and are used by charging a built-in rechargeable battery or the like. Meanwhile, efforts are being made to transmit power wirelessly as well as data. For example, in applications such as shavers and electric toothbrushes, wireless power transmission by electromagnetic induction has been commercialized and succeeded in improving user convenience.

  Prior document 1 shows a configuration of wireless power transmission using an electromagnetic induction method. As shown in FIG. 12, the power transmitter 1 on the power transmission side and the power receiver 2 on the reception side are provided with a transmission coil 111 and a reception coil 112 for transmitting power by electromagnetic induction. In wireless power transmission by electromagnetic induction, the magnetic flux that continues from the transmission coil 111 to the reception coil 112 does not propagate efficiently unless the positions of the central axes of the transmission coil 111 and the reception coil 112 exactly match each other. Therefore, as shown in FIG. 12, the transmission coil 111 of the power transmitter 1 is disposed in a cylindrical convex portion, the reception coil 112 of the power receiver 2 is disposed in a cylindrical concave portion, and the convex portion is aligned with the concave portion. Thus, by fixing the positional relationship between the transmission coil 111 and the reception coil 112, it is possible to maintain high transmission efficiency during wireless power transmission.

  However, in the electromagnetic induction type wireless power transmission, the positions of the transmission coil and the reception coil need to be close to each other, and as described above, the positions of the transmission coil and the reception coil are separated from each other. Transmission efficiency is greatly degraded (FIG. 5). Therefore, the convenience of the user such that the portable device is operated while wirelessly supplying power to the portable device, and the positions of the power transmitter 1 and the power receiver 2 need to be strictly fixed as described above. In recent years, development of a wireless power transmission technique using a magnetic resonance phenomenon has been promoted.

  A circuit element having a capacitor component is added to each of the transmission coil 111 and the reception coil 112 to form a circuit configuration having a resonance frequency, so that the transmission coil 111 and the reception coil 112 are in a state of magnetic resonance, and power is supplied between the coils. By transmitting, wireless power transmission can be realized. In the magnetic resonance type wireless power transmission, the change in transmission efficiency due to the change in the position of the transmission coil 111 and the reception coil 112 is smaller than that in the electromagnetic induction method, and the distance between the transmission and reception coils is large. Therefore, application to applications such as supplying wireless power while operating a portable device is being studied.

JP 2003-337655 A

  However, in order to maintain high transmission efficiency by the magnetic resonance method, it is necessary to appropriately control the impedance of the transmitter and the receiver. In the case of a configuration in which a capacitor is installed in series to operate as a resonator with respect to the transmission coil and the reception coil, as shown in FIG. 9, for a specific impedance value, as shown in FIG. There is a tendency for transmission efficiency to be maximized at specific distances. For this reason, when the transmission efficiency is B and the maximum efficiency is B with respect to the impedance A, the transmission efficiency seems to increase as the distance between the transmission coil and the reception coil decreases. However, as shown in FIG. If the above control is not performed, the transmission efficiency decreases even if the distance x approaches or moves away (FIG. 8). Therefore, the impedance of the transmitter and receiver must be controlled appropriately.

  However, considering an application where the receiving device is a portable device, if impedance control is installed in the receiving device, more control circuits, more capacitors and inductors with a higher withstand voltage are required, and the circuit scale and size As a result, the problem of adversely affecting the miniaturization of portable devices has arisen.

  Therefore, the present invention solves the above-described conventional problems, and considers wireless power transmission to a portable device, determines the presence or absence of an impedance control function of a receiver, and a method related to impedance control between a transmitter and a receiver. An object of the present invention is to provide a transmitter and receiver for wireless power transmission that can be applied from a stationary type to a portable device by adopting a switching method.

  In order to solve the above-described conventional problems, a wireless power transmission / reception device according to the present invention includes a power generation unit that converts power into a periodic signal in a wireless power transmission / reception device using a magnetic resonance method, and a periodic signal. A wireless power for transmitting power, comprising: a first impedance variable unit that converts impedance; a first impedance control unit that controls the first impedance variable unit; and a wireless transmission unit that transmits a periodic signal into space. Power is extracted from the output of the transmitter, the wireless receiver that receives the output from the wireless transmitter, the output from the wireless receiver, the second impedance variable unit that converts the impedance, and the second impedance variable unit A wireless power receiver configured to receive power, comprising: a power receiving unit; and a second impedance control unit that controls the second impedance variable unit. The presence or absence of the second variable impedance of the wireless power receiver, a first impedance control unit and switches the control method of the first variable impedance unit for controlling.

  Furthermore, in the transmitter / receiver for wireless power transmission according to the present invention, when the second impedance control unit is provided, the first impedance control unit and the second impedance control unit alternately control the impedance values in terms of time. Thus, an optimum impedance value is set, and when there is no second impedance control unit, the first impedance control unit always controls the impedance value.

  Furthermore, in the transmitter / receiver for wireless power transmission according to the present invention, the first impedance control unit does not have the control range of the impedance value when there is the second impedance variable unit of the wireless power receiver and the second impedance variable unit. The control range of the impedance value in this case is different.

  Further, in the transmitter / receiver for wireless power transmission according to the present invention, the wireless transmission unit includes a reflected signal detection unit that detects a reflected signal that is reflected back to the wireless transmission unit, and the first impedance control unit includes the reflected signal. The impedance value of the first impedance variable unit is determined using the output of the detection unit.

  Furthermore, in the transmitter / receiver for wireless power transmission according to the present invention, the reflected signal detection unit detects the amplitude in a plurality of circuit portions, and the first impedance control unit adjusts the impedance value to minimize the difference between the amplitude values. It is characterized by doing.

  Furthermore, in the transmitter / receiver for wireless power transmission according to the present invention, the impedance value controlled by the first impedance control unit is wider when the impedance value is not present than when the second impedance control unit is provided. It is characterized by that.

  As a result, when wireless power transmission is applied to a portable device, even when the receiver side cannot be equipped with an impedance control function, the transmitter side determines the presence or absence of the impedance control function and switches the impedance control method. As a result, wireless power transmission can be performed efficiently, and the performance of wireless power transmission can be improved.

The figure which shows the structure of the transmitter / receiver for wireless power transmission of this invention Operation flow chart of transceiver for wireless power transmission of the present invention The figure which shows the structure of the transmitter / receiver for wireless power transmission of this invention (when there is no impedance control on the receiving side) The figure which shows an example (the 1) of the positional relationship of the transmission / reception coil of this invention The figure which shows an example (the 2) of the positional relationship of the transmission / reception coil of this invention The figure which shows the structure of the transmitter for wireless power transmission shown with the portable 2 of implementation of this invention The figure which shows an example of the reflection detection part of the transmitter for wireless power transmission of this invention The figure which shows an example (the 1) of the distance dependence of the efficiency of the wireless power transmission of this invention The figure which shows an example (the 1) of the distance dependence of the impedance of the wireless power transmission of this invention The figure which shows an example (the 2) of distance dependence of the efficiency of the wireless power transmission of this invention The figure which shows an example (the 2) of the distance dependence of the impedance of the wireless power transmission of this invention The figure which shows the structure and positional relationship of the transmitter / receiver for the conventional wireless power transmission

(Embodiment 1)
1 to 3 are a block configuration and an operation flowchart of a transceiver for wireless power transmission according to Embodiment 1 of the present invention. A wireless power transmission system including a power transmitter 1 and a power receiver 2 for wireless power transmission according to the present embodiment includes a power transmitter 1, a power receiver 2, a wireless transmission unit 11, a wireless reception unit 12, and a control signal. The transmission / reception units 21 and 22, the reflection detection unit 211, the impedance variable units 31 and 32, the impedance control units 41 and 42, the power generation unit 51, and the power reception unit 52 are configured.

  The power generation unit 51 of the power transmitter 1 converts the power into a specific frequency signal, and the frequency signal is output to the reflection detection unit 211 via the impedance variable unit 31 connected to the power generation unit 51 and changing the output impedance. The The output of the reflection detection unit 211 is input to the wireless transmission unit 11 and transmits power into the space. Here, the reflection detection unit 211 has a function of only detecting a signal transmitted from the impedance variable unit 31 to the wireless transmission unit 11, and no impedance change occurs in the block of the reflection detection unit 211.

  In the magnetic resonance type wireless power transmission, the wireless transmission unit 11 and the wireless reception unit 12 are resonators using inductors, capacitors, and the like, and are configured to resonate with respect to a specific frequency. Even in a state where the receiving unit 12 is spatially separated from the receiving unit 12, the power transmission efficiency can be maintained high.

  Here, what is important in the magnetic resonance method is that the output impedance of the power generation unit 51 connected to the wireless transmission unit 11 that is a resonator and the input impedance of the power reception unit 52 connected to the wireless receiver 12 are appropriate. If it is a value, the power transmission efficiency is high, but if both impedance values are not appropriate values, the power transmission efficiency is lowered even if the wireless transmission unit 11 and the wireless reception unit 12 resonate. . At this time, an impedance control function is always added to the power transmitter 1 on the transmission side, but there is a selection as to whether or not the impedance control function is added to the power receiver 2 on the reception side. If the device that receives power is a small device such as a portable device, the need for a larger number of control circuits, capacitors or inductors with a high withstand voltage will increase the circuit scale and size, and the portable device will become smaller. It becomes difficult. As shown in the example of FIG. 1, the power transmission efficiency can be maintained higher when both the power transmitter 1 and the power receiver 2 are equipped with the function of controlling the impedance value, but in the example of FIG. As shown, even when the power transmitter 1 is provided with an impedance control function and the power receiver 2 is not equipped with an impedance control function, the power transmission efficiency is higher than when both transmission and reception are equipped with an impedance control function. Although it deteriorates, the power transmission efficiency can be greatly improved as compared with the case where both do not have the impedance control function.

  FIG. 10 shows the dependence of power transmission efficiency and distance on the three patterns when impedance is controlled optimally for both transmission and reception, when impedance control is not performed for both transmission and reception, and when impedance control is performed only on the transmission side. FIG. 11 is a graph showing the dependence of the distance between the distance and the distance. If the impedance at which the transmission efficiency is maximum at the distance x is fixed, a high efficiency is obtained at the distance x. On the other hand, when both the transmission and reception impedances are controlled, the transmission efficiency increases as the distance approaches, and the transmission efficiency can be obtained only at a specific distance as in the case where impedance control is not performed. When impedance control is performed only on the transmission side, transmission efficiency is degraded compared to when both transmission and reception impedances are controlled, but the characteristics are greatly improved compared to when impedance control is not performed, and transmission is performed only at a specific distance. There is no such thing as inefficiency.

  The impedance control function of the power transmitter 1 switches the control method depending on whether or not the power receiver 2 is equipped with the impedance control function, so that whether or not the power receiver 2 is equipped with the impedance control function. Therefore, it is possible to improve the power transmission efficiency.

  FIG. 2 shows an operation flowchart of the power transmitter 1 and the power receiver 2. First, at the start of wireless power transmission, the operation flow branches depending on whether or not the power receiver has an impedance control function. When the power receiver 2 has an impedance control function as shown in FIG. 1, the power receiver 2 performs impedance control after a predetermined time elapses when the power transmitter 1 performs impedance control. Specifically, the impedance control unit 41 controls the impedance variable unit 31 and determines an impedance value to be controlled from the reflection signal component detected by the reflection detection unit 211.

  FIG. 7 shows an example of the configuration of the reflection detection unit 211. Inside the reflection detection unit 211, a first amplitude detection unit 2111, a second amplitude detection unit 2112, and an nth amplitude detection unit 211n are provided. Each amplitude detector is installed with a predetermined distance from each other. When wireless power transmission is performed from the power transmitter 1 to the power receiver 2, the power transmission efficiency varies depending on the impedance and distance as described above. When the efficiency is low, that is, the reflected wave returns to the power transmitter 1, and therefore a standing wave is generated. For this reason, when the amplitude is detected by a plurality of amplitude detection units having a predetermined distance, the amplitude detected by each amplitude detection unit differs when a standing wave is generated by the reflected wave, and the amplitude difference is detected by the amplitude difference detection unit 221. It is possible to detect a standing wave and detect the magnitude of the reflected wave therefrom. Thus, the magnitude of the reflected wave detected by the reflection detection unit 211 is detected, and the impedance is controlled so that the component of the reflected wave is minimized (the output of the amplitude difference detection unit 221 is minimized).

  When the control of the impedance control unit 41 is completed, the control signal transmission / reception unit 21 outputs a control signal indicating that the control is completed in the space. When the control signal transmission / reception unit 22 receives the control signal from the control signal transmission / reception unit 21 and confirms that the impedance control of the power transmitter 1 is completed, the power receiver 2 starts impedance control after a predetermined time has elapsed. . The impedance control unit 42 controls the impedance variable unit 32 and outputs a control signal notifying that the impedance control of the power receiver 2 is completed to the control signal transmission / reception unit 22, and the control signal transmission unit 22 transmits the control signal in space. Output to. When the control signal transmission / reception unit 21 of the power transmitter 1 receives the control signal from the control signal transmission / reception unit 22 and confirms that the impedance control of the power receiver 2 is completed, the power transmitter 1 again after a predetermined time elapses. The impedance control is always performed, and then the control of the power receiver 2 is repeated, so that the optimum impedance control is always realized.

  On the other hand, when the power receiver 2 does not have an impedance control function as shown in FIG. 3, the power receiver 2 does not perform impedance control after the power transmitter 1 performs impedance control. Naturally does not return a control signal indicating that the impedance control function of the power receiver 2 has been completed. Therefore, if a control signal is not returned even after a predetermined time has elapsed, the impedance control unit 41 of the power transmitter 1 determines that the power receiver 2 does not have an impedance control function, and the impedance control unit 41 is always on. Implement impedance control.

  As described above, the power receiver 2 has the impedance control function in order to maintain higher power transmission efficiency by switching the impedance control method of the power transmitter 1 depending on whether or not the power receiver 2 has the impedance control function. Even in the case where it is provided, or since wireless power is transmitted to the portable device, wireless power can be efficiently transmitted even when the impedance control function is not provided for downsizing the device.

  In the first embodiment, the component of the reflected wave is detected by detecting the amplitude difference at each location of the power transmitter 1 like the reflection detector 211, but an antenna that receives the reflected wave separately, etc. The receiver may be provided to detect the component of the reflected wave.

  In the first embodiment, the control signal is transmitted from the control signal transmitting / receiving unit 21 to 22 in order to notify that the impedance control of the power transmitter 1 is completed. The configuration may be such that the control signal is multiplexed with the frequency signal for transmitting power to the receiving unit 12.

(Embodiment 2)
FIG. 6 is a block configuration of a transceiver for wireless power transmission according to Embodiment 2 of the present invention. In FIG. 6, the same components as those in FIGS. In the first embodiment, the impedance controlled by the impedance control unit 41 is not different from the presence or absence of the impedance control function of the power receiver 2, but in the present embodiment, the impedance control function of the power receiver 2 is not different. A different impedance value set in advance is selected depending on the presence or absence.

  FIG. 10 shows that the power transmission efficiency can be maintained high by controlling the impedance of both transmission and reception or only on the transmission side. However, the impedance value to be controlled differs greatly between the case of controlling both transmission and reception and the case of controlling only the transmission side (FIG. 11). For example, when both transmission and reception are controlled under a certain condition, when the range of impedance control is 10 to 100Ω, when only the transmission side is controlled, 10 to 1 kΩ is controlled only on the transmission side. In this case, a larger impedance control range is required, and a difference occurs in the control range. In addition, as an actual configuration for performing the impedance control, a circuit configuration in which the impedance value is not discontinuously changed with respect to the above-described impedance control range but the impedance having a discrete numerical value is taken. Conceivable. In this case, the discrete impedance tables prepared for impedance control for both transmission and reception and for the case of controlling only the transmission side are greatly different. Then, from the detection result of the reflection detection unit 211, when impedance is to be controlled, it is necessary to select in advance which impedance table should be used for impedance control.

  Therefore, in the present embodiment, the first storage unit 231 storing the impedance value when the power receiver 2 has the impedance control function and the impedance value when the power receiver 2 does not have the impedance control function are obtained. A second storage unit 232 stored therein, and the impedance control unit 41 selects either the first storage unit 231 or the second storage unit 232 depending on the presence or absence of the impedance control function of the power receiver 2. The switching unit 241 has an optimum value among the discrete impedance values stored in the first storage unit 231 or the second storage unit 232 based on the result detected by the reflection detection unit 211. The impedance value is selected, and the impedance value is changed by the impedance variable unit 31.

  From the above, it is determined whether or not the power receiver 2 has an impedance control function, and as a result, a necessary impedance table is selected from two storage units having different discrete impedance tables, and an impedance value is obtained. By controlling, it is possible to realize a transceiver for wireless power transmission that efficiently performs wireless power transmission.

  In this embodiment, for easy understanding, different impedance tables are stored in two storage units. However, different impedance tables are stored in one storage unit, and from the storage unit, The configuration may be such that a necessary impedance table is read depending on the presence or absence of a control function.

  The transmitter / receiver for wireless power transmission according to the present invention is controlled by switching the impedance control method by determining whether the transmitter side has the impedance control function when the portable device on the receiving side cannot be equipped with the impedance control function. Therefore, even when the impedance control function cannot be installed on the receiver side, it has a feature that enables efficient wireless power transmission, and not only data but also power is transmitted and received wirelessly to stationary devices and portable devices This is useful for many electrical products.

DESCRIPTION OF SYMBOLS 1 Power transmitter 2 Power receiver 11 Wireless transmission part 12 Wireless reception part 21, 22 Control signal transmission / reception part 31, 32 Impedance variable part 41, 42 Impedance control part 51 Power generation part 52 Power reception part 111 Transmission coil 112 Reception coil 211 Reflection detection unit 221 Amplitude difference detection unit 2111, 2112, 211n Amplitude detection unit

Claims (6)

In the transmitter and receiver for wireless power transmission using the magnetic resonance method,
A power generator for converting power into a periodic signal;
A first impedance variable section for converting impedance of the periodic signal;
A first impedance control unit for controlling the first impedance variable unit;
A wireless transmission unit for transmitting the periodic signal into space;
A wireless power transmitter for transmitting power comprising:
A wireless receiver for receiving an output from the wireless transmitter;
A second impedance variable unit for converting the output from the wireless reception unit;
A power receiving unit for extracting power from the output of the second impedance variable unit;
A second impedance control unit for controlling the second impedance variable unit;
A wireless power receiver for receiving power comprising:
Transmission / reception for wireless power transmission, wherein the control method of the first impedance variable unit controlled by the first impedance control unit is switched according to the presence or absence of the second impedance variable unit of the wireless power receiver vessel. When there is the second impedance control unit, the first impedance control unit and the second impedance control unit alternately control the impedance value in terms of time to set an optimum impedance value. ,
When the second impedance control unit is not provided, the first impedance control unit always controls the impedance value.
The wireless power transmission transceiver according to claim 1. The first impedance control unit has an impedance value control range when the second impedance variable unit of the wireless power receiver is present and an impedance value control range when the second impedance variable unit is not present. Different,
The transceiver for wireless power transmission according to any one of claims 1 and 2. The wireless transmission unit further includes a reflection signal detection unit that detects a reflection signal reflected and returned to the wireless transmission unit,
The first impedance control unit determines an impedance value of the first impedance variable unit using an output of the reflected signal detection unit.
The transceiver for wireless power transmission according to any one of claims 1 and 2. The reflected signal detection unit detects amplitude in a plurality of circuit portions, and the first impedance control unit adjusts the impedance value to minimize the difference between the amplitude values.
The transceiver for wireless power transmission according to claim 3. The impedance value controlled by the first impedance control unit has a wider control range of the impedance value when there is no impedance value than when the second impedance control unit is present.
The transceiver for wireless power transmission according to claim 3.

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