Detection device

Abstract

To provide a detection device configured to accurately detect phase information by using simple configurations as much as possible.SOLUTION: A reception antenna 31 for receiving transmission power from a transmission antenna 22 for transmitting the transmission power is connected with a detection device 33 on a power reception side. The detection device 33 comprises: an antenna 32 for detecting the transmission power constituted separately from the reception antenna 31 to receive the transmission power; and a detection circuit 34 for detecting voltage received by the antenna 32 for detecting the transmission power by resistors RA1, RA2.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a detection device.

Background Art

[0002] As a technique for improving the power factor of a wireless power supply device, a method of compensating for reactance caused by effects such as misalignment of transmission and reception antennas has been proposed (see, for example, Patent Documents 1 and 2). According to this type of technique, a FET bridge type automatic compensation circuit including a capacitor and a switching element is provided on the power receiving side, and the bridge circuit is driven to output a voltage having a phase difference of 90 deg with respect to the phase of the transmission voltage, thereby automatically compensating for reactance. As a method for setting the phase of the bridge circuit, Patent Document 1 proposes a method of detecting an optimum point by phase sweep, and Patent Document 2 proposes a method of communicating a data signal including phase information of the transmission voltage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a method of detecting an optimum point by phase sweep as described in Patent Document 1 is used, the addition of a sweep function requires complex circuit elements. Further, in order to detect the optimum point, detectors such as received power and power factor and a determination circuit for the optimum point are required. When communicating a data signal including phase information of the transmission voltage as described in Patent Document 2, a dedicated transceiver for the data signal is separately required. Further, since problems occur in the operation of the bridge circuit when the transmission power from the transmission antenna is mixed into the receiver as noise, it is necessary to take noise countermeasures.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a detection device capable of accurately detecting phase information using a configuration as simple as possible.

Means for Solving the Problems

[0006] The invention according to claim 1 is directed to a detection device on the power receiving side including a receiving antenna that receives transmission power from a transmission antenna, and includes an antenna for detecting transmission power and a detection circuit. The antenna for detecting transmission power is configured separately from the receiving antenna and is configured to receive transmission power, and the detection circuit detects the voltage received by the antenna for detecting transmission power with a resistor.

[0007] According to the invention of claim 1, since the detection circuit detects the voltage received by the antenna for detecting transmission power with a resistor, the phase information of the voltage generated in the antenna for detecting transmission power can be directly detected. Further, the antenna for detecting transmission power configured separately from the receiving antenna can acquire phase information without taking noise countermeasures. Thereby, phase information can be accurately detected using a simple configuration.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0009] Hereinafter, several embodiments of a detection device in a wireless power feeding system will be described with reference to the drawings. For components having the same function among the embodiments, the same or similar reference numerals may be used and the description may be omitted.

[0010] (First Embodiment) As shown in FIG. 1, the wireless power feeding system 10 is a wireless power feeding system of an electric field coupling method, includes a power transmission device 20 and a power reception device 30, and is a system for feeding power from the power transmission device 20 to a load 40 via the power reception device 30.

[0011] The power transmission device 20 includes an AC power supply 21 and a transmission antenna 22. The AC power supply 21 generates an AC power signal with a predetermined frequency (for example, 6.78 MHz) and outputs it to the transmission antenna 22. The transmission antenna 22 converts the AC power signal into a power transmission wave and wirelessly supplies power to the outside. The transmission antenna 22 is composed of a plate-shaped antenna.

[0012] As shown in FIG. 2, a pair of transmission antennas 22 are configured. When wirelessly supplying power from the transmission antenna 22 of the power transmission device 20 to the power reception device 30, the reception antenna 31 of the power reception device 30 is arranged in the vicinity of the transmission antenna 22 of the power transmission device 20. The reception antenna 31 is also configured in a pair and each is composed of a plate-shaped antenna. Also, when the wireless power supply system 10 wirelessly supplies power from the power transmission device 20 to the power reception device 30, the power transmission power detection antenna 32 of the power reception device 30 is also arranged in the vicinity of the transmission antenna 22 of the power transmission device 20.

[0013] The power transmission power detection antenna 32 is configured separately from the reception antenna 31 and receives the power transmission power transmitted from the transmission antenna 22. The power transmission power detection antenna 32 is configured in a pair and each is composed of a plate-shaped antenna. At this time, the surfaces of the pair of power transmission power detection antennas 32 are respectively arranged facing the surfaces of the pair of transmission antennas 22.

[0014] The facing area between the transmission antenna 22 and the power transmission power detection antenna 32 is arranged so as not to overlap the facing area between the transmission antenna 22 and the reception antenna 31. Thereby, while increasing the coupling capacitance C m3 (see FIG. 5) between the transmission antenna 22 and the power transmission power detection antenna 32, the coupling capacitance C m2 (see FIG. 5) between the power transmission power detection antenna 32 and the reception antenna 31 can be minimized.

[0015] As shown in FIG. 1, the power receiving device 30 includes a detection device 33. The detection device 33 of the power receiving device 30 includes a detection circuit 34 connected to a power transmission power detection antenna 32 that receives power transmission power from the transmission antenna 22. The detection circuit 34 detects the voltage received by the power transmission power detection antenna 32 and is composed of resistors (R in FIG. 5 A1 , R A2 ). The detection device 33 includes a drive signal generation unit 35. The drive signal generation unit 35 generates, for example, a rectangular drive signal that is a positive value when it exceeds zero and 0V when it is zero or less, and outputs it to the phase setting unit 36.

[0016] As shown in FIG. 3, the phase setting unit 36 changes the phase by a phase φ (for example, 90 deg) from the detected voltage of the power transmission voltage so as to compensate for the reactance caused by the positional deviation of the transmission / reception antenna, etc., and applies the rectangular drive signal to the bridge circuit 37.

[0017] As shown in FIG. 4, the bridge circuit 37 forms a bridge of MOS transistors FET1 and FET2. The drain-source terminals of the MOS transistors FET1 and FET2 are connected in series, and capacitors C1 and C2 are connected in series to these series connection nodes. The input terminal IN shown in FIG. 4 is connected to the power receiving electrode 31 side in FIG. 1, and the output terminal OUT is connected to the load 40 side. The bridge circuit 37 compensates for the reactance by turning on and off the respective MOS transistors FET1 and FET2 with a drive signal having the same frequency as the AC power supplied by the power transmission device 20. Here, the frequency of the AC power supplied by the power transmission device 20 is assumed to be, for example, in the MHz band. By detecting using the resistors (R in FIG. 5 A1 , R A2 ) of the detection circuit 34, as shown in FIG. 3, the phase shift between the power transmission voltage V TX and the detected voltage can be made approximately zero, and the phase of the power transmission voltage V TX can be directly detected.

[0018] Fig. 5 shows an equivalent circuit together with an electrical configuration example. When power is supplied from the power transmission device 20 to the power reception device 30, in the equivalent circuit shown in Fig. 5, the transmission antenna 22 and the reception antenna 31 are coupled by a coupling capacitance C m1 and. The transmission antenna 22 and the transmission power detection antenna 32 are coupled by a coupling capacitance C m3 and. The reception antenna 31 and the transmission power detection antenna 32 are coupled by a coupling capacitance C m2 and. Note that the parasitic capacitance generated near the transmission antenna 22 of the power transmission device 20 is defined as C p1 , and the parasitic capacitance generated near the reception antenna 31 of the power reception device 30 is defined as C p2 .

[0019] As shown in Fig. 5, the drive signal generation unit 35 of the detection device 33 is constituted by a comparator combining an operational amplifier OP and resistors R A1 , R A2 , R F1 , R F2 . Resistors R A1 and R A2 are connected in series between the inverting input terminal and the non-inverting input terminal of the operational amplifier OP. Resistors R A1 and R A2 are set to the same resistance value RA. The input capacitance of the operational amplifier OP is defined as C in . Between the positive power supply terminal of the operational amplifier OP and the ground, resistors R F1 and R F2 are connected in series, and the common connection point of resistors R F1 and R F2 is connected to the common connection point of resistors R A1 and R A2 . Resistors R F1 and R F2 are set to the same resistance value RF.

[0020] When the transmission antenna 22 transmits a transmission voltage V TX according to the configuration shown in Fig. 5, as shown in Fig. 3, the transmission power detection antenna 32 outputs a sinusoidal transmission voltage V TXcan be detected with almost no phase difference. As a result, the drive signal generation unit 35 can convert the input voltage into a rectangular drive signal and output it to the phase setting unit 36 without any phase change other than a certain phase delay caused by a comparator or internal wiring. The phase setting unit 36 sets the phase φ (= 90°) with respect to the transmission voltage V TX and outputs it to the bridge circuit 37. The power transmission device 20 supplies AC power to the load 40 via the bridge circuit 37.

[0021] In this way, by providing the power transmission power detection antenna 32, an appropriate drive signal can be supplied to the bridge circuit 37 without providing a dedicated electric circuit for searching for the optimum point of the phase or a dedicated communication means. As shown in FIG. 5, by adding only passive components such as the power transmission power detection antenna 32 and resistors R A1 , R A2 and a minimum number of operational amplifiers OP, an appropriate drive signal can be generated to drive the bridge circuit 37. As a result, the circuit scale can be suppressed as much as possible and the product cost can be reduced.

[0022] As described above, since the detection circuit 34 detects the voltage received by the power transmission power detection antenna 32 using the resistors R A1 , R A2 , the phase information on the power transmission side can be directly detected from the voltage generated in the power transmission power detection antenna 32. In addition, the power transmission power detection antenna 32 configured separately from the reception antenna 31 can acquire the phase information without taking noise countermeasures. Thereby, the phase information can be accurately detected using a simple configuration.

[0023] (Second Embodiment) (Regarding the power factor characteristics at the time of reflection according to the ratio of the coupling capacitances C m3 and C m2 ) If the coupling capacitances C m3 , C m2 are not appropriately set, the reflected power from the load 40 is applied to the coupling capacitance C m2There is a risk of intrusion into the input of the drive signal generation unit 35 (comparator) through []. If the setting is inappropriate, as shown in Fig. 6, the actual power transmission voltage V from the transmission antenna 22 TX There is a risk of a deviation occurring between the phase of [] and the phase of the detected detection voltage. The resulting phase shift may cause a decrease in the power factor of the wireless power supply.

[0024] Fig. 7 shows the coupling capacitance C between the transmission antenna 22 on the power transmission side and the power transmission power detection antenna 32 on the power reception side m3 and the coupling capacitance C between the reception antenna 31 on the power reception side and the power transmission power detection antenna 32 m2 ratio C of [] m3 / C m2 shows the power factor characteristics at the time of reflection according to []. As shown in this Fig. 7, it can be seen that the higher the ratio C m3 / C m2 becomes, the higher the power factor can be obtained. That is, it can be seen that the higher the coupling capacitance C between the power transmission power detection antenna 32 and the transmission antenna 22, or the lower the coupling capacitance C between the reception antenna 31 and the power transmission power detection antenna 32 m3 is, the higher the power factor can be obtained. m2

[0025] Therefore, it is desirable to set the ratio C of the coupling capacitance C between the power transmission power detection antenna 32 and the transmission antenna 22 to a value more than a predetermined multiple of the coupling capacitance Cm2 between the power transmission power detection antenna 32 and the reception antenna 31 m3 to be greater than or equal to a predetermined multiple. Then, the phase shift of the detection waveform due to the reflected power can be suppressed and the power factor decrease can be prevented. m3 / C m2

[0026] In general household appliances, for example, 0.85 is used as a predetermined value and it is normal to set the power factor so as to exceed the predetermined value. To configure so as to always satisfy such a regulation, it is desirable to set the predetermined multiple of the ratio C m3 / C m2 to 5 times or more. In this case, as shown in Fig. 8, the phase shift can be suppressed to less than 30° and the power factor decrease can be prevented. Further, for example, as shown in Fig. 7, in order to always obtain a characteristic with a power factor of 0.99 or more, the ratio C m3 / C​​m2 It is desirable to make it 30 times or more. As shown in FIG. 8, the phase shift can be suppressed to less than 8 to 9°, and further, the power factor reduction can be prevented.

[0027] (Third Embodiment) <Resistance R A1 、R A2 Regarding the resistance value RA of Also, as shown in FIG. 5, two resistors R A1 、R A2 are connected to the power transmission power detection antenna 32, and two resistors R A1 、R A2 are connected between the input terminals of the comparator of the drive signal generation unit 35. At this time, the total value 2×RA of the resistance values RA of the resistors R A1 、R A2 is desirably set to be larger than a predetermined multiple of the reactance X in of the input capacitance C Cin of the comparator.

[0028] If the values of each element are set in this way, even if the coupling capacitance C m3 between the power transmission power detection antenna 32 and the transmission antenna 22 changes, the detected voltage can obtain a phase equivalent to that of the power transmission voltage V TX . As a result, the phase shift of the detected voltage due to the characteristic change of the power transmission power detection antenna 32 can be suppressed, and the power factor reduction can be prevented.

[0029] As shown in the second embodiment, by sufficiently increasing the ratio C m3 / C m2 to sufficiently reduce the influence of the coupling capacitance C m2 , the power factor reduction caused by the phase shift between the phase of the power transmission voltage V TX and the phase of the detected waveform can be suppressed. Considering the actual physical relationship of the transmission antenna 22, the reception antenna 31, and the power transmission power detection antenna 32, the coupling capacitance C m3 between the power transmission power detection antenna 32 and the transmission antenna 22 is assumed to be significantly smaller than the coupling capacitance C m1 between the transmission antenna 22 and the reception antenna 31. In actual operation, the coupling capacitance C m3 = 1p to several fF, the coupling capacitance Cm2 is almost zero, coupling capacitance C m1 is desirably set to about several tens of pF. When actually designing, for elements other than the coupling capacitance C m2 , that is, for the coupling capacitance C m1 , C m3 and the resistors R A1 , R A2 , and the input capacitance C in , it is desirable to consider their values.

[0030] In FIG. 9, the numerical range that the coupling capacitance C m3 can take is set to 10 fF to 90 pF, and the minimum power factor value within this numerical range, the total value of the resistors R A1 , R A2 (2×RA), and the ratio of the reactance X Cin (2×RA / X Cin ) are shown.

[0031] In general electrical appliances, for example, with 0.85 as a predetermined value, it is normal to set the power factor so as to exceed the predetermined value. To always satisfy such a regulation, it is desirable to set the ratio 2×RA / X Cin to 1.6 times or more. In this case, as shown in FIG. 10, the maximum phase shift can be suppressed to less than 30°, and a decrease in the power factor can be prevented. Further, for example, as shown in FIG. 9, to always obtain a characteristic with a power factor of 0.99 or more, it is desirable to make the ratio 2×RA / X Cin 7 times or more. In this case, as shown in FIG. 10, the maximum phase shift can be suppressed to less than 8 to 9°, and a decrease in the power factor can be further prevented.

[0032] (Other Embodiments) The present disclosure is not limited to the foregoing embodiments, and for example, the following modifications or extensions are possible. Although a form applied to a wireless power supply device using the electric field coupling method has been shown, it may also be applied to a wireless power supply device using the magnetic field coupling method.

[0033] Although the present disclosure has been described in accordance with embodiments, it is understood that the present disclosure is not limited to such embodiments or structures. The present disclosure also encompasses various modifications and variations within the equivalent scope. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element thereof, are within the scope and spirit of the present disclosure.

Description of Reference Numerals

[0034] In the drawings, 10 is a wireless power supply system, 22 is a transmission antenna, 31 is a reception antenna, 32 is a transmission power detection antenna, 33 is a detection device, 34 is a detection circuit, 35 is a drive signal generation unit, C m1 ~C m3 is a coupling capacitance, R A1 , R A2 is a resistance, which are shown.

Claims

1. A power receiving side detection device (33) that connects a receiving antenna (31) for receiving the power transmission power from a transmission antenna (22) that transmits the power transmission power, A power transmission power detection antenna (32) that is configured separately from the receiving antenna and receives the power transmission power, A detection circuit (34) that detects the voltage received by the power transmission power detection antenna with a resistor, A detection device comprising the above.

2. Mounted on a wireless power feeding system using the electric field coupling method, The coupling capacitance (C ｍ３ ) between the power transmission power detection antenna and the transmission antenna, with respect to the coupling capacitance (C ｍ２ ) between the power transmission power detection antenna and the reception antenna, the ratio (C ｍ３ / C ｍ２ ) is set to be greater than or equal to a predetermined multiple. The detection device according to claim 1.

3. The detection device according to claim 2, wherein the opposing regions of the transmission antenna and the power transmission power detection antenna are arranged so as not to overlap the opposing regions of the transmission antenna and the receiving antenna.

4. The detection device according to claim 2, wherein the predetermined multiple is 5 times or more.

5. Mounted on a wireless power feeding system using the electric field coupling method, Composed by connecting a drive signal generation unit (35) having a comparator with characteristics of a predetermined input capacitance, The detection circuit is configured by connecting the two resistors between the input terminals of the comparator, The detection device according to claim 1, wherein the total value of the resistance values of the resistors is set to be larger than the reactance of the input capacitance by a predetermined multiple or more.

6. The detection device according to claim 5, wherein the predetermined multiple is 1.6 times or more.

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