Non-contact power supply device

Abstract

A contactless power supply device (100) includes: a power output circuit (130) and a power supply unit (105). The power output circuit outputs AC power at a predetermined operating frequency, and the power supply unit supplies AC power to a receiving device. It also has a power resonant circuit (110) and a variable characteristic circuit (120). The power resonant circuit is composed of a power supply coil (112) and a resonant capacitor (116). The variable characteristic circuit is composed of a closed loop formed by a variable characteristic coil (122) magnetically coupled to the power supply coil (112) and a variable characteristic capacitor (126). When the variable characteristic circuit (120) supplies power from the power supply section (105) to the power receiving device, it has frequency characteristics with an operating frequency near the resonant frequency of the power supply resonant circuit (110). When it is not supplying power from the power supply section (105) to the power receiving device, it has frequency characteristics with the reactance of the power supply coil (112) at the operating frequency being greater than the reactance of the power supply coil (112) when supplying power.

Description

[0001] Citation of relevant applications

[0002] This application claims priority based on Japanese Patent Application No. 2019-227044, filed on December 17, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to a contactless power supply device. Background Technology

[0004] Japanese Patent Application Publication No. 2019-71719 discloses a wireless power supply system in which a current control element is arranged between a high-frequency power source and each power transmission coil. The current control element uses a component such as a saturated reactor, which increases impedance when the current flowing from the high-frequency power source to the power transmission coil is less than a threshold, and decreases impedance when the current flowing from the high-frequency power source to the power transmission coil is above the threshold. Therefore, the increased impedance of the current control element arranged on the power transmission coil, which is not opposite to the receiving coil, suppresses the supply of current from the high-frequency power source to the power transmission coil.

[0005] However, as with existing technologies, the structure of connecting the current control element in series with the power transmission coil is not suitable for power transmission resonant circuits that connect the power transmission coil in series with the power transmission resonant capacitor, resulting in low versatility. Furthermore, the reactance component of the current control element may affect the resonant characteristics of the power transmission resonant circuit, thus reducing its power transmission performance. Additionally, to increase impedance, the saturated reactor exemplified as a current control element requires a larger inductance; therefore, the saturated reactor used as a current control element may need to be larger. Summary of the Invention

[0006] According to one aspect of this disclosure, a contactless power supply device is provided for supplying electricity to a receiving device in a contactless manner. The contactless power supply device includes a power output circuit and a power supply section. The power output circuit outputs alternating current (AC) power at a predetermined operating frequency. The power supply section supplies the AC power to the receiving device. The device also includes a power resonant circuit and one or more variable characteristic circuits. The power resonant circuit is composed of a power supply coil and a resonant capacitor. The variable characteristic circuit is a closed loop formed by a variable characteristic coil magnetically coupled to the power supply coil and the variable characteristic capacitor. When power is supplied from the power supply section to the receiving device, the variable characteristic circuit has a frequency characteristic where the operating frequency is near the resonant frequency of the power supply resonant circuit. When power is not supplied from the power supply section to the receiving device, the variable characteristic circuit has a frequency characteristic where the reactance of the power supply coil at the operating frequency is greater than the reactance of the power supply coil during power supply.

[0007] According to this contactless power supply device, when not energized, the reactance of the power supply coil at the operating frequency is greater than that when energized, thereby suppressing the current supply from the power supply output circuit to the power supply section. This reduces losses and leakage flux in the power supply coil when not energized. Furthermore, like existing current control elements, it is possible to control the suppression of current supply from the power supply output circuit to the power supply section during energization and during non-energization without using a current control element connected in series with the power supply coil. Therefore, a more versatile technology than existing technologies can be provided. Attached Figure Description

[0008] The above-mentioned objects, other objects, features, and advantages of this disclosure will become clearer with reference to the accompanying drawings and the following detailed description. The accompanying drawings are described below.

[0009] Figure 1 This is a circuit diagram of the contactless power supply device according to the first embodiment.

[0010] Figure 2 This is an explanatory diagram illustrating an example of the configuration relationship between the power supply coil and the variable characteristic coil.

[0011] Figure 3 This is an explanatory diagram illustrating an example of the frequency characteristics of a power transmission coil.

[0012] Figure 4 This is an explanatory diagram showing the change in the variable width of the inductance of the power supply coil caused by the combination coefficient of the power supply coil and the variable characteristic coil.

[0013] Figure 5 This is an explanatory diagram showing the change in the variable width of the inductance of the power-transmitting coil caused by the Q value of the variable characteristic coil.

[0014] Figure 6 This is a circuit diagram of the contactless power supply device according to the second embodiment.

[0015] Figure 7 This is an explanatory diagram illustrating an example of the configuration relationship between the power supply coil and the variable characteristic coil.

[0016] Figure 8 This is an explanatory diagram illustrating an example of the frequency characteristics of a power transmission coil.

[0017] Figure 9 This is a circuit diagram of the contactless power supply device according to the third embodiment.

[0018] Figure 10 This is an explanatory diagram illustrating an example of the frequency characteristics of a power transmission coil.

[0019] Figure 11This is a schematic structural diagram of a contactless power supply device for vehicles that applies the contactless power supply device of the first embodiment. Detailed Implementation

[0020] A. First implementation method:

[0021] Figure 1 The structure of a contactless power supply device 100 according to a first embodiment, capable of supplying power to a power receiving device 200 in a contactless manner, is shown.

[0022] The contactless power supply device 100 includes a power supply circuit 140, a power output circuit 130, and multiple power transmission units 105 connected in parallel with the power output circuit 130. Each power transmission unit 105 includes a power transmission resonant circuit 110 and a variable characteristic circuit 120. Each power transmission resonant circuit 110 is connected in parallel with the power output circuit 130.

[0023] The power supply resonant circuit 110 is a circuit that supplies power to the power receiving device 200 through resonance. The power supply resonant circuit 110, for example, includes a power supply coil 112 and a resonant capacitor 116 connected in series with the power supply coil 112. The power supply output circuit 130 is a circuit that converts the DC power supplied from the power supply circuit 140 into AC power at a predetermined operating frequency and supplies it to the power supply resonant circuit 110. The power supply output circuit 130 is, for example, configured as an inverter circuit. The power supply circuit 140 is, for example, configured as an AC / DC converter circuit that rectifies the AC voltage of an external power supply to output a DC voltage.

[0024] Furthermore, the power supply coils 112 of each power supply resonant circuit 110 are arranged, for example, with their respective coil surfaces arranged in a horizontal direction. The coil surfaces are surrounded by the wiring that forms the coils and function as surfaces that output magnetic flux corresponding to the current flowing through the coils.

[0025] The variable characteristic circuit 120, paired with the power transmission resonant circuit 110, is a closed circuit consisting of a variable characteristic coil 122 and a variable characteristic capacitor 126 connected in series. For example... Figure 2 As shown, the variable characteristic coil 122 of the variable characteristic circuit 120 itself is disposed on one side of the coil surface of the power supply coil 112 of the paired power supply resonant circuit 110, and is configured to be in a state of magnetic engagement with the power supply coil 112. Furthermore, in Figure 1 In the diagram, two parallel straight lines represent the magnetically coupled state of the power supply coil 112 and the variable characteristic coil 122.

[0026] Here, the configuration of the variable characteristic coil 122 is not limited to Figure 2The state shown can also be configured on the lateral side of the coil surface of the power transmission coil 112, or on the upper side of the coil surface of the power transmission coil 112. That is, the position of the variable characteristic coil 122 is not particularly limited as long as it is configured to be magnetically coupled with the power transmission coil 112 of the paired power transmission resonant circuit 110.

[0027] The different magnetic coupling states between the variable characteristic coil 122 and the power supply coil 112 are represented by different coupling coefficients. The coupling coefficient is a value greater than -1 and less than +1, depending on the configuration of the variable characteristic coil 122 relative to the power supply coil 112.

[0028] in addition, Figure 2 The power supply coil 112 shown is exemplified as a coil with a core structure in which a looped conductor 312 is formed on the core 310. The variable characteristic coil 122 is exemplified as a coil without a core structure composed of a looped conductor 322. Alternatively, the variable characteristic coil 122 may also be a coil with a core structure, similar to the power supply coil 112.

[0029] The power receiving device 200 is installed in various devices that use electricity to operate, such as electronic devices and electric vehicles. The power receiving device 200 includes a power receiving resonant circuit 210, a power receiving circuit 220, and a battery 230.

[0030] Similar to the power transmission resonant circuit 110, the power receiving resonant circuit 210 employs a single-series-second-series-series capacitor configuration (also known as the "SS configuration") for both the power transmission resonant circuit 110 and the power receiving resonant circuit 210, which have a power receiving coil 212 and a resonant capacitor 216 connected in series. Furthermore, a contactless power supply method is used, where the power transmission side is configured using a single-phase power transmission coil 112 and the power receiving side is configured using a single-phase power receiving coil 212. The power receiving resonant circuit 210 resonates at the same resonant frequency as the power transmission resonant circuit 110, and obtains AC power induced in the power receiving coil 212 in a resonant state where the power receiving coil 212 and the power transmission coil 112 are magnetically coupled.

[0031] The receiving circuit 220 is, for example, a circuit that converts the alternating current obtained from the receiving resonant circuit 210 into direct current and charges the battery 230, which serves as a load. The power used to charge the battery is used as electricity in the device equipped with the receiving device 200.

[0032] also, Figure 1An example is shown where the coil surface of the receiving coil 212 of the power receiving device 200 is positioned above the coil surface of the power supply coil 112 of the first power supply section 105 of the contactless power supply device 100. In this case, the receiving coil 212 is magnetically coupled with the first power supply coil 112 and the characteristic variable coil 122, while the characteristic variable coil 122 is magnetically coupled with the first power supply coil 112.

[0033] In the first power supply section 105 with the receiving coil 212 positioned above, the input impedance Zp of the power supply resonant circuit 110 is a small value Zp0, and a current of value Ip0 (hereinafter also referred to as "drive current Ip0") is supplied from the power supply output circuit 130 to the power supply coil 112 as the output current Ip at the operating frequency f0. In this case, a current at the operating frequency f0 induced by the resonant combination between the receiving coil 212 and the power supply coil 112 flows through the receiving coil 212 to perform the power supply from the power supply resonant circuit 110 to the power receiving device 200 via the receiving resonant circuit 210.

[0034] In contrast, in the second and subsequent power transmission sections 105 where the receiving coil is not positioned above, the input impedance Zp of the power transmission resonant circuit 110 is a value greater than Zp0, and only a current smaller than the drive current Ip0 flows through the power transmission coil 112 as the output current Ip. Therefore, in the power transmission resonant circuit 110 of the power transmission section 105 where the receiving coil 212 is not positioned above the power transmission coil 112, useless power consumption can be suppressed, and leakage flux can be reduced and power transmission efficiency improved.

[0035] Here, as explained below, the inductance Lp of the power supply coil 112 varies depending on the presence or absence of the characteristic variable circuit 120, i.e., the magnetic coupling between the characteristic variable coil 122 and the power supply coil 112.

[0036] like Figure 3 As shown by the double-dotted line, the inductance Lp of the power supply coil 112 is a constant value Lp0 in the absence of the characteristic variable circuit 120. In contrast, as... Figure 3 As shown by the solid and dashed lines, in the case of the variable characteristic circuit 120, the inductance Lp of the power supply coil 112 varies with frequency. The frequency characteristic of the inductance Lp of the power supply coil 112 is generated according to the frequency characteristic of the impedance of the variable characteristic circuit 120, exhibiting inductive characteristics at the low-frequency side of the resonant frequency fv of the variable characteristic circuit 120 and capacitive characteristics at the high-frequency side.

[0037] Furthermore, the inductance Lv of the variable characteristic coil 122 of the variable characteristic circuit 120 varies depending on whether the receiving coil 212 is positioned above it, i.e., whether there is magnetic interaction between the variable characteristic coil 122 and the receiving coil 212. Specifically, the inductance Lv of the variable characteristic coil 122 is larger when the receiving coil 212 is positioned above it compared to when the receiving coil 212 is not positioned above it. As a result, the resonant frequency fv of the variable characteristic circuit 120 is lower when the receiving coil 212 is positioned above it compared to when the receiving coil 212 is not positioned above it.

[0038] Therefore, as Figure 3 As shown, compared to the case where there is no receiving coil 212 above, the frequency characteristics of the inductance Lp of the power supply coil 112 are shifted to the low-frequency side when there is a receiving coil 212 above.

[0039] Therefore, in the first embodiment, as described below, the circuit constants of the power transmission resonant circuit 110 and the characteristic variable circuit 120 are set.

[0040] First, without the characteristic variable circuit 120, the reference values ​​of the inductance Lp of the power supply coil 112 and the capacitance Cp of the resonant capacitor 116 of the power supply resonant circuit 110 are set to values ​​that make the resonant frequency of the power supply resonant circuit 110 equal to the operating frequency f0. Here, "frequency equal to the operating frequency f0" not only means exactly the same, but also includes frequencies near the operating frequency f0 that will not cause interference, as frequencies equal to the operating frequency f0. In this example, the reference values ​​of the inductance Lp of the power supply coil 112 and the capacitance Cp of the resonant capacitor 116 are set to Lp = Lp0 and Cp = Cp0, and the reactance Xp of the power supply coil 112 at the operating frequency f0 is set to Xp = Xp0.

[0041] Furthermore, the inductance Ls of the receiving coil 212 and the capacitance Cs of the resonant capacitor 216 of the receiving resonant circuit 210 are also set to values ​​equal to the resonant frequency f0.

[0042] In addition, for the variable characteristic circuit 120, the inductance Lv of the variable characteristic coil 122 and the capacitance Cv of the variable characteristic capacitor 126 are set in the following manner.

[0043] Based on the presence or absence of magnetic connection between the variable characteristic coil 122 and the receiving coil 212 (hereinafter also referred to as "with or without the receiving coil 212"), the reference values ​​of the inductance Lv of the variable characteristic coil 122 and the capacitance Cv of the variable characteristic capacitor 126 are set so that the inductance Lp of the transmitting coil 112 changes to... Figure 3The solid and dashed lines illustrate the frequency characteristics. Furthermore, the reference values ​​for the inductance Lv of the variable characteristic coil 122 and the capacitance Cv of the variable characteristic capacitor 126 are the values ​​of the inductance Lv of the variable characteristic coil 122 and the capacitance Cv of the variable characteristic capacitor 126 when there is no energized coil 212. In this example, the reference values ​​for the inductance Lv of the variable characteristic coil 122 and the capacitance Cv of the variable characteristic capacitor 126 are set to Lv = Lvr and Cv = Cvr, respectively. At this time, the resonant frequency fv of the variable characteristic circuit 120 is set to a frequency higher than the value fv0, which is equal to the operating frequency f0. Furthermore, the reference value Cvr for the capacitance Cv of the variable characteristic capacitor 126 is the capacitance value Cv0, where the resonant frequency fv of the variable characteristic circuit 120, determined by the value Lv0 of the inductance Lv of the variable characteristic coil 122 and the value Cv of the capacitance Cv of the variable characteristic capacitor 126, is set to the value fv0, which is equal to the operating frequency f0.

[0044] The inductance Lv of the variable characteristic coil 122 with the receiving coil 212 varies depending on the magnetic coupling state between the receiving coil 212 and the variable characteristic coil 122, and is a value larger than a reference value Lvr that makes the resonant frequency fv of the variable characteristic circuit 120 equal to the operating frequency f0, which is lower than the frequency when the receiving coil 212 is not present. In this example, the value of the inductance Lv of the variable characteristic coil 122 with the receiving coil 212 is expressed as Lv = Lv0. In other words, the reference value Lvr, which is the value of the inductance Lv of the variable characteristic coil 122 without the receiving coil 212, is set to a value smaller than the value Lv0 when the receiving coil 212 is present.

[0045] With the circuit constants of the power transmission resonant circuit 110 and the characteristic variable circuit 120 set as described above, the power transmission resonant circuit 110 of each power transmission unit 105 operates in the following manner depending on whether the receiving coil 212 is present or not.

[0046] like Figure 3 As shown by the solid line, the power supply coil 112 (refer to the first power supply section 105 arranged above the receiving coil 212) is a power supply coil 112. Figure 1 The inductance Lp of the power supply resonant circuit 110 is Lp0, which is the value of the resonant point of the power supply resonant circuit 110. Therefore, the resonant frequency fp of the power supply resonant circuit 110, including the power supply coil 112, becomes fp0, which is equal to the operating frequency f0. As a result, as... Figure 1 As shown, the input impedance Zp of the power transmission resonant circuit 110 at the operating point of the operating frequency f0 is a small value Zp0, and a large value of drive current Ip0 is supplied from the power transmission output circuit 130 as the output current Ip at the operating frequency f0. Therefore, power can be supplied from the power transmission resonant circuit 110, which has a power transmission coil 112 disposed above it, to the power receiving device 200 via the power receiving resonant circuit 210.

[0047] On the other hand, such as Figure 3 As shown by the dashed line, the inductance Lp of the power supply coil 112 of any of the other power supply units 105 arranged above the receiving coil 212 becomes a value that makes the resonant frequency fv of the resonant point of the power supply resonant circuit 110 higher than the value fp0. Therefore, the magnitude |Lp| of the inductance Lp at the operating point of the operating frequency f0 of this power supply coil 112 is a value Lp1 larger than the reference value Lp0 (refer to...). Figure 3 The reactance Xp at the operating frequency f0 is greater than the reference value Xp0 (refer to...). Figure 1 The result is, as Figure 1 As shown, the input impedance Zp of the power transmission resonant circuit 110 is greater than the value Zp0 when the receiving coil 212 is present, and only a current smaller than the driving current Ip0 flows through it as the output current Ip at the operating frequency f0. Therefore, in the power transmission resonant circuit 110 with the power transmission section 105 having the receiving coil 212 not positioned above the power transmission coil 112, useless power consumption can be suppressed, and leakage flux can be reduced and power transmission efficiency improved.

[0048] In the structure described above, when the receiving coil 212 of the receiving device 200 is magnetically coupled to the supply coil 112 of the supply resonant circuit 110, the input impedance Zp decreases to Zp = Zpo due to the resonance of the supply resonant circuit 110. Conversely, when the receiving coil 212 is not magnetically coupled to the supply coil 112, the input impedance Zp increases to Zp > Zp0 due to the non-resonance of the supply resonant circuit 110. Therefore, the supply output circuit 130 can supply a larger output current Ip = Ip0, corresponding to a smaller input impedance Zp = Zp0, to the supply resonant circuit 110 having the supply coil 112 magnetically coupled to the receiving coil 212. On the other hand, the supply output circuit 130 can suppress the supply of current to the supply resonant circuit 110 having the supply coil 112 not magnetically coupled to the receiving coil 212 by using the larger input impedance Zp > Zp0. Therefore, when driving the power transmission resonant circuit 110 of multiple power transmission sections 105 connected in parallel using a power transmission output circuit 130, it is possible to reduce the loss of useless power and the leakage flux in the power transmission coil 112 when no power is being transmitted. Furthermore, as with prior art current control elements, it is possible to control and suppress the current supply from the power transmission output circuit 130 to the power transmission section 105 during power transmission and the current supply from the power transmission output circuit 130 to the power transmission section 105 when not transmitting power, without using a current control element connected in series with the power transmission coil.

[0049] Here, Figure 4This represents the difference between the maximum and minimum values ​​of the inductance Lp of the power-transmitting coil 112, which varies depending on the frequency; that is, the characteristic variable width (refer to...). Figure 3 The relationship between the coupling coefficients of the power supply coil 112 and the characteristic variable coil 122. From Figure 4 It is understood that the larger the bonding coefficient, the larger the variable characteristic width. A larger variable characteristic width allows for a larger inductance Lp (i.e., reactance Xp) of the non-energizing power supply coil 112, resulting in a larger input impedance Zp of the non-energizing power supply resonant circuit 110 of the power supply section 105, thereby suppressing the current flowing through the power supply coil 112. From the above, it is ideal to design the variable characteristic coil 122 such that the bonding coefficient of the paired power supply coils 112 is larger. For example, it is ideal to arrange the variable characteristic coil 122 as close as possible to the power supply coil 112. Furthermore, it is ideal to arrange the variable characteristic coil 122 so that its axis is as aligned as possible with the axis of the power supply coil 112. Additionally, it is ideal to set the coil diameter of the variable characteristic coil 122 to be the same as the coil diameter of the power supply coil 112.

[0050] in addition, Figure 5 The variable width characteristic of the inductance Lp of the power transmission coil 112 is shown (see reference). Figure 3 The relationship between the characteristic variable coil 122 and the Q value. From Figure 5 It is known that the larger the Q value of the variable characteristic coil 122, the wider the variable characteristic width. From the above, it is ideal to design the Q value of the variable characteristic coil 122 to be larger. For example, to increase the reactance of the variable characteristic coil 122, it is ideal to use a coil with a core structure, or to increase the number of turns to increase the self-inductance. Furthermore, to reduce the equivalent series resistance (ESR) of the coil, it is ideal to use stranded wire or other conductors with excellent high-frequency and temperature characteristics in the coil windings, or to increase the cross-sectional area of ​​the coil windings, or to shorten the coil length.

[0051] B. Second implementation method:

[0052] Figure 6 The contactless power supply device 100B of the second embodiment shown includes a power transmission unit 105B, which replaces the contactless power supply device 100 of the first embodiment (see reference). Figure 1 The power transmission unit 105B differs from the power transmission unit 105 in that it includes multiple, in this example, two variable characteristic circuits 120_1 and 120_2.

[0053] like Figure 7As shown, the characteristic variable coil 122 of the first characteristic variable circuit 120_1 is arranged transversely with respect to the power transmission coil 112 in the same manner as in the first embodiment (refer to Figure 2 ). As Figure 7 shown, the characteristic variable coil 122 of the second characteristic variable circuit 120_2 is arranged perpendicular to the power transmission coil 112 in a state of being magnetically coupled to the power transmission coil 112. In this configuration, the magnetic coupling between the characteristic variable coil 122 of the first characteristic variable circuit 120_1 and the power transmission coil 112 is a differential coupling (Japanese: 差動結合), that is, a coupling with a negative coupling coefficient, and the magnetic coupling between the characteristic variable coil 122 of the second characteristic variable circuit 120_2 and the power transmission coil 112 is a sum coupling (Japanese: 和動結合), that is, a coupling with a positive coupling coefficient.

[0054] Even in the case of a structure having two characteristic variable circuits 120_1 and 120_2, as Figure 8 shown by the solid line and the dotted line, the inductance Lp of the power transmission coil 112 also has a frequency characteristic that varies according to the frequency. In addition, similar to the frequency characteristic of the inductance Lp of the power transmission coil 112 in the first embodiment (refer to Figure 3 ), the frequency characteristic of the inductance Lp of the power transmission coil 112 shifts to the low-frequency side in the case of having the power reception coil 212 arranged above compared to the case without the power reception coil 212 arranged above.

[0055] Therefore, similar to the first embodiment, the circuit constants of the power transmission resonant circuit 110 and the characteristic variable circuits 120_1 and 120_2 are set (refer to Figure 6 ). The reference values of the inductance Lp of the power transmission coil 112 and the capacitance Cp of the resonant capacitor 116 are set to Lp = Lp0 and Cp = Cp0, and the reactance Xp at the operating frequency f0 of the power transmission coil 112 is set to Xp = Xp0.

[0056] Furthermore, the reference values ​​for the inductance Lv1 of the variable coil 122 and the capacitance Cv1 of the variable capacitor 126 in the first variable characteristic circuit 120_1 are set to Lv1 = Lvr1 < Lv0_1 and Cv1 = Cv0_1. Similarly, the reference values ​​for the inductance Lv2 of the variable coil 122 and the capacitance Cv2 of the variable capacitor 126 in the second variable characteristic circuit 120_2 are set to Lv2 = Lvr2 < Lv0_2 and Cv2 = Cv0_2. Moreover, when Lv0_1 and Cv0_1 are arranged above the receiving coil 212, they are set such that the resonant frequency of the power supply resonant circuit 110 is the operating frequency f0. Furthermore, when Lv0_2 and Cv0_2 are arranged above the receiving coil 212, they are also the values ​​of the inductance Lv2 of the characteristic variable coil 122 and the capacitance Cv2 of the characteristic variable capacitor 126 of the second characteristic variable circuit 120_2, which are set in such a way that the resonant frequency of the power supply resonant circuit 110 is the operating frequency f0.

[0057] By setting the circuit constants of the power transmission resonant circuit 110 and the characteristic variable circuits 120_1 and 120_2 as described above, such as Figure 8 As shown by the solid line, the inductance Lp of the power supply coil 112, on which the receiving coil 212 is positioned, is set to a value Lp0 such that the resonant frequency of the power supply resonant circuit 110 is equal to the operating frequency f0 of the operating point. Thus, as... Figure 6 As shown, a large value of drive current Ip0 can be supplied from the power supply output circuit 130 as the output current Ip at the operating frequency f0.

[0058] In addition, such as Figure 8 As shown by the dashed line, the frequency characteristic of the inductance Lp of the power supply coil 112 (where the receiving coil 212 is not positioned above) can be shifted towards a higher frequency side. Therefore, the inductance Lp of the power supply coil 112 at the operating point of the operating frequency f0 can be set to a value |Lp| greater than the reference value Lp0 by -Lp2 (refer to...). Figure 8 This allows the reactance Xp at the operating frequency f0 to be larger than the reference value Xp0 (refer to...). Figure 6 As a result, only a current smaller than the drive current Ip0 can flow as the output current Ip at the operating frequency f0. Thus, in the power transmission resonant circuit 110 of the power transmission section 105, in which the power transmission coil 112 is not positioned above the receiving coil 212, the consumption of useless power can be suppressed, and leakage flux can be reduced and power transmission efficiency can be improved.

[0059] Here, in the first embodiment, as Figure 3As shown, the inductance Lp of the power supply coil 112 when the receiving coil 212 is not positioned above can only be set to a value more positive than the value Lp0 at the resonant point when the receiving coil 212 is positioned above, i.e., a value on the inductive side. In contrast, in the second embodiment, as... Figure 8 As shown, the inductance Lp of the power supply coil 112, where the receiving coil 212 is not positioned above, can also be set to a value on the capacitive side. Furthermore, since the circuit constants and configuration of the variable characteristic circuits 120_1 and 120_2 can be adjusted to regulate the shift amount of the frequency characteristic corresponding to the presence or absence of the receiving coil 212, the inductance Lp of the power supply coil 112, where the receiving coil 212 is not positioned above, can be set to any value from the inductive side to the capacitive side, thereby expanding the setting range.

[0060] also, Figure 8 The inductance Lp of the power transmission coil 112 shown has multiple resonant points, depending on the frequency characteristics synthesized from the impedance frequency characteristics of the variable characteristic circuits 120_1 and 120_2. Furthermore, Figure 8 The frequency characteristics of the inductance Lp of the power transmission coil 112 shown vary depending on the setting state of the circuit constants of the variable characteristic circuits 120_1 and 120_2, and the combination state caused by the configuration state of the power transmission coil 112 and the variable characteristic coil 122.

[0061] Therefore, the configuration of the variable characteristic coil 122 is not limited to Figure 7 The state shown can be set to various positional relationships. That is, the characteristic variable coil 122 is configured to be in a state of magnetic connection with the power supply coil 112 of the paired power supply resonant circuit 110, and the connection coefficient between the power supply coil 112 and the characteristic variable coil 122 and the connection coefficient between the characteristic variable coils 122 are respectively configured to obtain the desired characteristics as the frequency characteristics of the power supply coil 112.

[0062] In addition, the number of variable characteristic circuits is not limited to two; it can also be a structure that includes three or more variable characteristic circuits.

[0063] Alternatively, ideally, at least one variable coil of a plurality of variable characteristic circuits is configured to have differential magnetic coupling with the power supply coil, i.e., a coupling with a negative coupling coefficient, while at least one other variable coil is configured to have synchronous magnetic coupling with the power supply coil, i.e., a coupling with a positive coupling coefficient. In this case, the frequency characteristic of the power supply coil's inductance can be set to have multiple resonant points, and the inductance value of the power supply coil can be set to any value from the inductive side to the capacitive side, thereby expanding the setting range.

[0064] Furthermore, as mentioned above, the inductance of the power transmission coil has multiple resonant points due to the frequency characteristics synthesized from the frequency characteristics of the impedances of the multiple variable characteristic circuits. The frequency characteristics of each of the multiple variable characteristic circuits are determined by its resonant frequency. Therefore, it is ideal to design that the resonant frequencies of the multiple variable characteristic circuits are different. If this is the case, the frequency characteristic of the power transmission coil's inductance can be set to have multiple resonant points, and the value of the power transmission coil's inductance can be set to any value from the inductive side to the capacitive side, thereby expanding the setting range.

[0065] Furthermore, in the second embodiment, similar to the first embodiment, it is preferable to design a larger coupling coefficient between the variable characteristic coil and the paired power-generating coils. Additionally, it is preferable to design a larger Q value for the variable characteristic coil.

[0066] C. Third implementation method:

[0067] Figure 9 The contactless power supply device 100C of the third embodiment shown includes a power supply unit 105C, which replaces the contactless power supply device 100 of the first embodiment (see reference). Figure 1 The power transmission section 105 is described above. The power transmission section 105C differs from the power transmission section 105 in that it includes a characteristic variable circuit 120C instead of a characteristic variable circuit 120. The characteristic variable circuit 120C differs from the characteristic variable circuit 120 in that it includes a characteristic variable coil 122C instead of a characteristic variable coil 122. The characteristic variable coil 122C uses a variable inductor with varying inductance.

[0068] Similar to the first embodiment, the reference values ​​of the inductance Lp of the power transmission coil 112 and the capacitance Cp of the resonant capacitor 116 of the power transmission resonant circuit 110 are set to Lp = Lp0 and Cp = Cp0, and the reactance Xp of the power transmission coil 112 at the operating frequency f0 is set to Xp = Xp0.

[0069] The reference value of the capacitance Cv of the variable capacitor 126 in the variable characteristic circuit 120C is set to Cv = Cvr = Cv0. The inductance Lv of the variable characteristic coil 122C is set as follows.

[0070] When the receiving coil 212 is positioned above the transmitting coil 112, the inductance Lv of the variable characteristic coil 122C is set to Lv = Lv0, so that the inductance Lp of the transmitting coil 112 is Lp = 0, and the resonant frequency fv of the variable characteristic circuit 120C becomes a value fv0 equal to the operating frequency f0.

[0071] In contrast, when the receiving coil 212 is not positioned above the transmitting coil 112, the inductance Lv of the characteristic variable coil 122C is set to Lv < Lv0 or Lv > Lv0, so that the resonant frequency fv of the characteristic variable circuit 120C becomes fv > fv0 or fv < fv0.

[0072] Furthermore, changes to the setting of the variable characteristic coil 122C can be made, for example, by detecting the presence or absence of the receiving coil 212 of the receiving device 200 disposed above the receiving coil 112 using an object detection sensor (not shown) included in each power supply unit 105C.

[0073] like Figure 10 As shown, when fv > f0, the frequency characteristic of the inductance Lp of the power transmission coil 112 can be shifted to the higher frequency side, so that the inductance Lp at the operating frequency f0 is the inductive side value where Lp > Lp0. Conversely, when fv < f0, the frequency characteristic of the inductance Lp of the power transmission coil 112 can be shifted to the lower frequency side, so that the inductance Lp at the operating frequency f0 is the capacitive side value where Lp < Lp0, and its magnitude |Lp| is |Lp| > Lp0 and its reactance Xp is Xp > Xp0.

[0074] In the third embodiment, when the receiving coil 212 is not positioned above, the inductance Lv of the variable characteristic coil 122C can be set to Lv < Lv0 or Lv > Lv0, so that the resonant frequency fv of the variable characteristic circuit 120C becomes fv > fv0 or fv < fv0. Therefore, the value of the inductance Lp of the supply coil 112, where the receiving coil 212 is not positioned above, can be set to any value from the inductive side to the capacitive side, thereby expanding the setting range.

[0075] Furthermore, in the above embodiment, the structure of changing the resonant frequency of the variable characteristic circuit by using a variable inductor in a variable characteristic coil was described as an example. However, it is not limited to this; a variable capacitor may also be used, and the resonant frequency of the variable characteristic circuit may be changed by changing the capacitance of the variable characteristic capacitor. Alternatively, the resonant frequency of the variable characteristic circuit may be changed by changing both the inductance of the variable characteristic coil and the capacitance of the variable characteristic capacitor.

[0076] Furthermore, in the third embodiment, similar to the first embodiment, it is preferable to design a larger coupling coefficient between the variable characteristic coil and the paired power-generating coils. Additionally, it is preferable to design a larger Q value for the variable characteristic coil.

[0077] D. Fourth Implementation Method:

[0078] The contactless power supply device 100 of the first embodiment (see reference) Figure 1 The contactless power supply device 100D can be applied to vehicle contactless power supply systems.

[0079] Figure 11 The contactless power supply system for vehicles shown is a power supply system capable of supplying power from a contactless power supply device 100D laid along the travel route RS to a power receiving device 200D installed in the vehicle VH.

[0080] With contactless power supply device 100 (reference) Figure 1 Similarly, the contactless power supply device 100D includes a plurality of power supply units 105, a power supply output circuit 130 that supplies AC power to the plurality of power supply units 105, and a power supply circuit 140 that supplies DC power to the power supply output circuit 130.

[0081] Each power transmission unit 105 includes a power transmission resonant circuit 110 and a characteristic variable circuit 120.

[0082] The power transmission resonant circuit 110 has a power transmission coil 112 (not shown) and a resonant capacitor 116 (see reference) laid on the vehicle travel path RS. Figure 1 The power supply coils 112 of each power supply resonant circuit 110 are laid sequentially along the travel path of the vehicle RS.

[0083] Figure 11 In the diagram, the x-direction represents the horizontal direction of the power transmission coil 112 arranged with the power transmission resonant circuit 110, the y-direction represents the horizontal direction perpendicular to the x-direction, and the z-direction represents the upward direction perpendicular to both x and y.

[0084] With power receiving device 200 (reference) Figure 1 Similarly, the power receiving device 200D installed in the vehicle VH includes a power receiving resonant circuit 210, a power receiving circuit 220, and a battery 230.

[0085] The receiving resonant circuit 210 has a receiving coil 212 and a resonant capacitor 216 (see reference). Figure 1 At least the receiving coil 212 is connected to the power supply resonant circuit 110 with the power supply coil 112 (see reference). Figure 1 It is positioned at the bottom of the vehicle's VH in a relatively opposite manner.

[0086] The power receiving circuit 220 is a circuit that converts the alternating current (AC) power obtained using the power receiving resonant circuit 210 into direct current (DC) power and charges the battery 230, which serves as a load. The power charged to the battery 230 is used to drive an electric motor (not shown) or similar device.

[0087] The same effect as the contactless power supply device described above can also be achieved in the contactless power supply device of the vehicle contactless power supply system.

[0088] Furthermore, although illustrations and descriptions are omitted, the contactless power supply device 100B of the second embodiment and the contactless power supply device 100C of the third embodiment (see reference) can also be used as contactless power supply devices for vehicle contactless power supply systems. Figure 6 , Figure 9 ).

[0089] E. Other implementation methods:

[0090] (1) The contactless power supply device described in the above embodiment is illustrated using a structure including multiple power transmission resonant circuits as an example, but it is not limited to this and may also include a structure including a single power transmission resonant circuit. In this structure, it is also possible to reduce the loss of useless power in the power transmission coil when no power is being transmitted and to reduce leakage flux. In addition, as with the current control elements of the prior art, it is possible to control the suppression of the current supply from the power transmission output circuit to the power transmission section during power transmission and the current supply from the power transmission output circuit to the power transmission section when not transmitting power, without using a current control element connected in series with the power transmission coil.

[0091] (2) In the above embodiments, a power transmission resonant circuit and a power receiving resonant circuit utilizing series resonance were described as examples. However, the embodiments are not limited to this. A power transmission resonant circuit and a power receiving resonant circuit utilizing parallel resonance can also be configured, or a resonant circuit in which one party utilizes series resonance and the other party utilizes parallel resonance can also be configured. Therefore, the embodiments are applicable not only to structures utilizing parallel resonance but also to structures utilizing series resonance. Thus, a technology with higher versatility than the prior art can be provided.

[0092] (3) In the above embodiment, the example described is that both the power supply coil 112 on the power supply side and the power receiving coil 212 on the power receiving side are single-phase. However, this is not a limitation. The power supply side can also be configured as a multi-phase power supply coil. In addition, the power receiving side can also be configured as a multi-phase power receiving coil. For example, it can be configured such that the power supply side is a single-phase power supply coil and the power receiving side is a multi-phase power receiving coil with two or more phases. Alternatively, the power supply side can be configured as a multi-phase power supply coil with two or more phases, and the power receiving side can be a single-phase or multi-phase power receiving coil.

[0093] (4) In the above embodiment, the case of a variable capacitor that includes a variable characteristic circuit as an independent component was described as an example, but the structure of using the parasitic capacitance of the variable characteristic coil as the variable characteristic capacitor can also be adopted.

[0094] This disclosure is not limited to the embodiments described above, and can be implemented through various structures without departing from the above-described spirit. For example, the technical features in the embodiments corresponding to the technical features in the various methods described in the summary section can be appropriately replaced or combined to solve part or all of the above-described technical problems, or to achieve part or all of the above-described effects. Furthermore, the above-described technical features can be appropriately deleted unless they are described as essential structures in this specification.

Claims

1. A contactless power supply device, wherein the contactless power supply device supplies electricity to a receiving device in a contactless manner, characterized in that, include: A power output circuit that outputs AC power at a predetermined operating frequency; as well as The power transmission unit supplies AC power to the power receiving device and includes a power transmission resonant circuit and one or more variable characteristic circuits. The power transmission resonant circuit consists of a power transmission coil and a resonant capacitor. The variable characteristic circuit consists of a closed loop formed by a variable characteristic coil magnetically coupled to the power transmission coil and a variable characteristic capacitor. The variable characteristic circuit When power is supplied from the power supply unit to the power receiving device, it has frequency characteristics where the operating frequency is near the resonant frequency of the power supply resonant circuit. In the non-powered state, when no power is being supplied from the power supply unit to the power receiving device, the frequency characteristic of the power supply coil having a reactance greater at the operating frequency than the reactance of the power supply coil during power supply is present. In the power supply mode where power is supplied from the power supply unit to the power receiving device, the power supply coil of the power supply unit and the power receiving coil of the power receiving device are magnetically coupled. The variable characteristic circuit, in the state of magnetic coupling between the power supply coil and the power receiving coil, i.e., in the power supply mode, has a frequency characteristic where the operating frequency is near the resonant frequency of the power supply resonant circuit. The variable characteristic circuit, in the non-magnetically coupled state of the power supply coil and the power receiving coil (i.e., the non-power supply mode), makes the reactance of the remaining power supply coil of the power supply section greater than the reactance of the power supply coil. The variable characteristic circuit changes the reactance of the power supply coil according to the magnetic coupling state with the power receiving coil, and increases the reactance of the power supply coil and suppresses the current flowing through the power supply coil when there is no magnetic coupling with the power receiving coil.

2. The contactless power supply device as described in claim 1, characterized in that, Multiple power supply units are connected in parallel with the power supply output circuit.

3. The contactless power supply device as described in claim 1 or 2, characterized in that, The frequency characteristics of the variable circuit vary with the state during power supply and the state during non-power supply, which are related to the magnetic coupling between the power supply coil and the power receiving coil included in the power receiving device.

4. The contactless power supply device as described in claim 1 or 2, characterized in that, The change in the frequency characteristics of the variable circuit during power supply and during non-power supply is performed by changing at least one of the inductance of the variable coil and the capacitance of the variable capacitor.

5. The contactless power supply device as described in claim 1 or 2, characterized in that, The power transmission unit has multiple circuits with the aforementioned variable characteristics. The inductance of the power transmission coil has frequency characteristics that enable the power transmission resonant circuit to generate multiple resonant frequencies.

6. The contactless power supply device as described in claim 5, characterized in that, At least one of the variable characteristic coils of the variable characteristic circuit has a magnetic coupling with the power supply coil, which is a dynamic coupling; at least one other variable characteristic coil has a magnetic coupling with the power supply coil, which is a differential coupling.

7. The contactless power supply device as described in claim 5, characterized in that, At least one variable characteristic coil of the variable characteristic circuit is arranged in a vertical direction relative to the power supply coil, and at least one other variable characteristic coil of the variable characteristic circuit is arranged in a horizontal direction relative to the power supply coil.

8. The contactless power supply device as described in claim 5, characterized in that, The resonant frequencies of each variable characteristic circuit are set to different frequencies.

9. The contactless power supply device as described in any one of claims 1, 2, 6, 7, and 8, characterized in that, The inductance of the power transmission coil During power transmission, the circuit exhibits the characteristic of making the operating frequency the resonant frequency of the power transmission resonant circuit. When not powered, it has inductive or capacitive characteristics at the operating frequency.

10. The contactless power supply device as described in any one of claims 1, 2, 6, 7, and 8, characterized in that, The variable capacitor in the variable characteristic circuit is the parasitic capacitance of the variable characteristic coil.

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