Wireless power transmission system

Abstract

The invention discloses a wireless power transmission system. A wireless power transmission system includes a power transmission coil and a power reception coil that move relative to each other. The power transfer coil includes a first region for forming a coil having a first number of windings and a second region for forming a coil having a second number of windings. A first power transmitted to the power receiving coil in the first region is higher than a second power transmitted to the power receiving coil in the second region.

Description

Technical Field

[0001] The present invention relates to a wireless power transmission system for wireless power supply. Background Art

[0002] In recent years, wireless power transmission systems for wirelessly supplying power to moving bodies have been researched and developed.

[0003] For example, Japanese Patent Application Laid-Open No. 2013-014056 discusses a printer that wirelessly supplies power to a sliding ink cartridge using a narrow, long transmission coil. Wireless power transmission eliminates wear on the power cord caused by coil movement, improving product quality. Japanese Patent Application Laid-Open No. 2018-74855 discusses a coil configuration in which the number of windings depends on coil position, preventing variations in the coupling coefficient that occur with coil movement when facing solenoid-shaped coils are coupled.

[0004] However, the wireless power transmission systems discussed in Japanese Patent Application Laid-Open Nos. 2013-014056 and 2018-74855 are characterized by a nearly constant coupling coefficient and a nearly constant optimal load impedance, regardless of the coupling position between the power receiving coil and the power transmitting coil. Consequently, systems that transmit high power at specific coupling positions and low power at other coupling positions cannot achieve high power transmission efficiency at the coupling positions used for high power transmission. Consequently, the system exhibits significant overall losses, leading to increased coil temperature. Summary of the Invention

[0005] The present invention aims to provide a wireless power transmission system in which a power receiving coil moves on a power transmitting coil, the system maintaining high power transmission efficiency at a coupling position for transmitting high power to reduce coil temperature.

[0006] According to one aspect of the present invention, a wireless power transmission system includes a power transmission coil and a power receiving coil arranged to face each other and configured to move relative to each other. The power transmission coil includes a first transmission region for forming a coil having a first winding number and a second transmission region for forming a coil having a second winding number smaller than the first winding number. A first power transmitted to the power receiving coil in the first transmission region is greater than a second power transmitted to the power receiving coil in the second transmission region.

[0007] Further features of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 An example configuration of a wireless power transmission system according to an embodiment is shown.

[0009] Figure 2 An example circuit of the wireless power transmission system according to the first embodiment is shown.

[0010] Figure 3 An example relationship between the transmission power required by the wireless power transmission system according to the first embodiment and the moving distance of the power receiving coil is shown.

[0011] Figure 4A and Figure 4B An example configuration of a power transmission coil according to the prior art is shown.

[0012] Figure 5 Is to show about Figure 4A and Figure 4B Graph showing the relationship between the coupling coefficient between the power transmitting coil and the power receiving coil and the moving distance of the power receiving coil for the illustrated configuration.

[0013] Figure 6 Is to show about Figure 4A and Figure 4B Graph of the input impedance and power transfer efficiency of the power receiver for the shown configuration.

[0014] Figure 7 Is to show about Figure 4A and Figure 4B Graph of transmission efficiency and transmitted power versus travel distance for the configurations shown.

[0015] Figures 8A to 8C An example configuration of the power transmitting and power receiving coils according to the first embodiment is shown.

[0016] Figure 9 Is to show about Figures 8A to 8C Graph showing the relationship between the coupling coefficient (between the power transmitting and power receiving coils) and the moving distance of the power receiving coil for the configurations shown.

[0017] Figure 10 Is to show about Figures 8A to 8C Graph showing the relationship between travel distance and power / efficiency for the power receiving coils of the illustrated configurations.

[0018] Figure 11 It shows Figure 4A and 4B The configuration shown is the same as Figures 8A to 8C Graph showing the difference in power transfer efficiency between the configurations shown.

[0019] Figure 12A and Figure 12B Other examples of the power transmitting and power receiving coils according to the first embodiment are shown.

[0020] Figure 13A and Figure 13B An example configuration of a power transmission coil according to the second embodiment is shown.

[0021] Figure 14A and Figure 14B Shows about Figure 13A and Figure 13B Simulation results of the temperature distribution of the power transmission coil in the shown configuration.

[0022] Figure 15A and Figure 15B An example configuration of other power transmission coils according to the second embodiment is shown. DETAILED DESCRIPTION

[0023] The wireless power transmission system according to the present invention employs a method for transmitting power using a magnetic field, or both an electric field and a magnetic field, known as an electromagnetic induction / magnetic field resonance method. Embodiments of the present invention will be described below with reference to the accompanying drawings. Each embodiment of the present invention described below may be implemented individually or as a combination of multiple embodiments or features thereof, where necessary or where combining elements or features from various embodiments in a single embodiment is beneficial.

[0024] Figure 1 The configuration of the wireless power transmission system according to the first embodiment is shown. The power transmission system 100 includes a power transmission coil 110, a power transmitter 111, a power receiving coil 120, a power receiver 121, and a constant voltage circuit 122. The power transmitter 111 includes a known power transmission circuit used when adopting an electromagnetic induction method or a magnetic field resonance method. More specifically, the power transmitter 111 uses a switching (SW) circuit to convert the direct current (DC) voltage supplied from the power supply unit 106 into a current having a frequency suitable for power transmission (hereinafter referred to as a carrier frequency), and outputs the DC voltage to the power transmission coil 110. In other words, the power transmitter 111 converts the DC voltage into alternating current (AC), and the power transmission coil 110 generates an AC magnetic field.

[0025] The power receiver 121 also includes a known power receiving circuit used when adopting an electromagnetic induction method or a magnetic field resonance method. More specifically, the power receiver 121 converts the AC magnetic field received from the power receiving coil 120 into a DC voltage via a rectifier circuit serving as the power receiver 121. The constant voltage circuit 122 converts the DC voltage into a desired voltage and supplies the voltage to the load 123.

[0026] In order to efficiently wirelessly transmit the energy supplied from power supply unit 106, the input impedance of power receiver 121 must be matched to that of power transmission coil 110 and power receiving coil 120. The wireless power transmission system according to the present invention assumes a configuration suitable for a load 123 that slides and moves in a predetermined direction. As load 123 slides and moves, power receiving coil 120, power receiver 121, and constant voltage circuit 122 similarly slide and move. In this case, power transmission coil 110 also extends in the predetermined direction, and power transmission coil 110 and power receiving coil 120 always face each other, maintaining a coupled state.

[0027] Figure 2 It shows Figure 1 The input impedance (R L ) 207. The power transmission coil 110 includes an inductance component (L1) 201, a resistance component (r1) 202, and a power transmission capacitor (C1) 203 that resonates in series with the inductance component (L1) 201 at the carrier frequency. The power reception coil 120 includes an inductance component (L2) 204, a resistance component (r2) 205, and a power reception capacitor (C2) 206 that resonates in series with the inductance component (L2) 204 at the carrier frequency. Figure 2 Also shown are a current source 208 serving as the power transmitter 111 , and a coupling coefficient (k) 209 between the power transmission coil 110 and the power reception coil 120 .

[0028] Formula (1) indicates Figure 2 The power transmission efficiency η of the circuit diagram in FIG. Formula (1) assumes that the power transmission capacitor 203 and the power reception capacitor 206 satisfy the resonance condition with respect to the inductance component (L1) 201 and the inductance component (L2) 204, respectively.

[0029]

[0030] In order to Figure 2 In order to transmit power with the highest efficiency in the circuit configuration, the condition (impedance matching condition) expressed by the following formula (2) must be satisfied. L_opt represents the input impedance (R L )207. The Q value (Q1) of the power transmission coil 110 and the Q value (Q2) of the power reception coil 120 are calculated using formula (3). ω is calculated using formula (4). When these impedance matching conditions are met, the power transmission system provides the theoretical maximum efficiency. The theoretical maximum efficiency is calculated using formula (5).

[0031]

[0032] r2, r1, L1, L2, and the Q values ​​of the power transmission coil 110 and the power reception coil 120 are constants that are uniquely determined when the shapes of these coils are determined.

[0033] Figure 3 The figure shows an example relationship between the transmission power required by the wireless power transmission system 100 of the present invention and the travel distance d of the power receiving coil 120. For example, the system receives 300 W (watts) of power in an area 320 where the travel distance d of the power receiving coil 120 is 10 mm (millimeters) or less, and receives 130 W (or more) of power in an area 321 where the travel distance d of the power receiving coil 120 is longer than 10 mm. The present invention assumes that the direction of movement of the power receiving coil 120 is substantially aligned with the direction of extension of the power transmitting coil 110, and that the power receiving coil 120 always faces the power transmitting coil 110.

[0034] In having Figure 3 In the system shown in the graph, priority should be given to transmission efficiency when receiving 300W power, rather than 130W. For example, if the transmission efficiency is 80% when receiving 300W power, the loss is 75W. If the transmission efficiency is 80% when receiving 130W power, the loss is 32.5W. This means that even with the same transmission efficiency, the loss is at least twice as great. Since the loss is proportional to the increase in coil temperature, it is necessary to maximize the transmission efficiency when receiving 300W power to simplify the radiation mechanism.

[0035] about Figure 3 The relationship between the transmission power and the moving distance d is shown below. The configuration for achieving efficient power transmission will be further considered with reference to the formula.

[0036] Formulas (6) to (13) are calculated by introducing the following two different assumptions:

[0037] (a) The effective value of the current flowing through the power transmission coil 110 is constant.

[0038] (b) The waveform of the current flowing in the power transmission coil 110 is a sine wave having a single frequency.

[0039] The relationship between the current I1 flowing in the power transmission coil 110 and the current I2 flowing in the power reception coil 120 is expressed by Formula (6).

[0040]

[0041] Generally, the resistance component (r2) of the power receiving coil 120 is much larger than the input impedance (R L). Therefore, the current value can be approximated as expressed by formula (7).

[0042] According to the above-mentioned assumption (a), the approximate value I′ 1 of the current I 1 flowing in the power transmission coil 110 is also constant.

[0043]

[0044] Output voltage of the power receiving coil 120 (input voltage of the power receiver 121) V o It is expressed by formula (8).

[0045]

[0046] Referring to formula (8), all values ​​except the coupling coefficient k are treated as constants. This means that the output voltage V of the power receiving coil 120 is o Proportional to the coupling coefficient k and independent of the input impedance R of the power receiver 121 L .

[0047] By using the output voltage V obtained by formula (8) o and the input impedance R of the power receiver 121 L , the transmission power P can be calculated by formula (9) o .

[0048]

[0049] According to formula (9), when r2, r1, L1, L2 and I'1 are constants, the transmitted power P o The coupling coefficient k or the input impedance R of the power receiver 121 L Sure.

[0050] By using V expressed by formula (8) o , calculate the transmission power P with the optimal load by formula (10) o_opt .

[0051]

[0052] The constants r2, r1, L1, and L2 and the Q values ​​of the power transmission coil 110 and the power reception coil 120 are uniquely determined by the coil shapes. Therefore, the proportional relationship in formula (11) is satisfied by formula (10).

[0053]

[0054] The Q value of a general power transmission coil and a general power reception coil is approximately 10 to 1000, so it is assumed that the relationship in formula (12) is satisfied.

[0055] k 2 Q1Q2>>1 (12)

[0056] When the relationship in formula (12) is satisfied, formula (13) can be obtained by approximating the denominator of formula (11).

[0057] P o_opt ∝k (13)

[0058] In other words, formula (13) shows that the transmission power P with the optimal load o_opt Proportional to the coupling coefficient k.

[0059] In a wireless power transmission system that provides different powers with different coil positions, the coupling coefficient k will vary according to the coil positions to provide the desired power accordingly.

[0060] The configurations of the prior art and this embodiment will be compared below.

[0061] First, the configuration of the related art will be described. Figure 4A An example configuration of a conventional power transmission coil is shown. Power transmission coil 300 includes a pattern 302 formed on a substrate 301. Power transmission coil 300 has a total length of 200 mm and a width of 20 mm. Similarly, power reception coil 310 includes a pattern 311 formed on a substrate 312. Power reception coil 310 has a total length of 30 mm and a width of 20 mm, the same as the width of power transmission coil 300.

[0062] Each of the power transmission coil 300 and the power reception coil 310 forms a 2-winding coil using two different layers in the z direction.

[0063] Figure 4B The moving distance d of the power receiving coil 310 in the x direction relative to the power transmitting coil 300 is shown. The region 320 corresponds to the transmission region for transmitting high power according to this embodiment. The region 321 corresponds to the transmission region for transmitting low power according to this embodiment.

[0064] Figure 5 Graph 3 shows the change in the coupling coefficient k between the power transmission coil 300 and the power reception coil 310 with respect to the moving distance d varying from 0 to 55 mm. Figure 5 As shown, in Figure 4A and Figure 4B In the exemplary configuration of the power transmission coil 300 according to the related art shown, the coupling coefficient k changes very slightly with respect to changes in the moving distance d.

[0065] exist Figure 4A and Figure 4BIn the example configuration in Figure 5 As shown in FIG. 1 , the coupling coefficient k is almost constant with respect to the change of the moving distance d. Therefore, it is necessary to change the input impedance R of the power receiver 121. L To control the transmission power P o Table 1 shows the Figure 4A and 4B The electrical performance of the example configuration of the prior art power transmission coil 300 is shown. The coupling coefficient k shown in Table 1 is a representative value. Substituting these values ​​into formula (1), the input impedance R of the power receiver 121 is obtained. L The relationship between η and power transmission efficiency.

[0066]

Table 1

[0067]

[0068]

[0069] This relationship is caused by Figure 6 The curve 601 in FIG. 1 shows that the input impedance R of the power receiver 121 is obtained by substituting the values ​​shown in Table 1 into formula (9). L and transmit power P o This relationship is determined by Figure 6 The curve 602 in FIG. 6 shows the maximum transmission efficiency of 79.8%. The point 622 provides the transmission power P of the relevant timing. o 310 W. These points indicate the operating state of the power transmission system in the transmission area for transmitting high power according to the prior art. Increasing the input impedance R of the power receiver 121 L Can reduce transmission power P o Point 621 provides 132W of transmission power P o Point 622 provides a transmission efficiency of 72.8% at the relevant timing. These points indicate the operating state of the power transmission system in the transmission area for transmitting low power according to the prior art.

[0070] Figure 7 It is shown that by using the power transmission coil 300 according to the prior art, when the input impedance R of the power receiver 121 is L Transmission efficiency 701 and transmission power 711 as they change according to the moving distance d. Point 702 provides the maximum transmission efficiency of 79.8%. Point 712 provides the transmission power P at the relevant timing. o It is 310 W. These points indicate the operating states of the power transmission system in the transmission area for transmitting high power according to the related art.

[0071] Point 713 provides 132W of transmission power P oPoint 703 provides a transmission efficiency of 72.8% at the relevant timing. These points indicate the operating status of the power transmission system in the transmission area for transmitting low power according to the prior art.

[0072] An example configuration of the power transmission coil 300 in this embodiment.

[0073] like Figure 4A and Figure 4B As shown, in a system that receives 300 W of power in a transmission area for high power transmission and transmits 130 W (or more) of power in a transmission area for low power transmission, the ratio of the power in the transmission area for high power transmission to the power in the transmission area for low power transmission is approximately 2.3. In other words, referring to formula (13), by configuring the transmitting coil and the receiving coil so that the ratio of the coupling coefficient k in the transmission area for high power transmission to the coupling coefficient k in the transmission area for low power transmission is approximately 2.3, efficient power transmission can be achieved.

[0074] Figures 8A to 8C Specific examples of the power transmission coil and the power reception coil according to the present embodiment are shown. Figure 8A Schematic diagram showing power transmission and power receiving coils. The long coil is the power transmission coil 801 and the short coil is the power receiving coil 802. Figures 8A to 8C In the power transmission coil 801 and the power receiving coil 802, the transmission area 321 for transmitting low power is formed by a two-winding coil, and the transmission area 320 for transmitting high power is formed by a four-winding coil. Figure 8B and Figure 8C An example arrangement of actual power transmission of the power transmission coil 801 and the power reception coil 802 according to the present embodiment is shown.

[0075] Table 2 shows Figures 8A to 8C The electrical performance of the specific example of the power transmission coil 801 and the power receiving coil 802 according to this embodiment is shown in Table 2. The coupling coefficient k shown in Table 2 high and k low are representative values ​​of the coupling coefficients in the transmission region 320 for transmitting high power and the transmission region 321 for transmitting low power, respectively. high and coupling coefficient k low The ratio is about 2.37.

[0076]

Table 2

[0077] <![CDATA[L1]]> 2.3μH <![CDATA[L2]]> 0.26μH <![CDATA[r1]]> 360mΩ <![CDATA[r2]]> 45mΩ <![CDATA[k high ]]> 0.45 <![CDATA[k low ]]> 0.19

[0078] Figure 9Shown are changes in the coupling coefficient between the power transmitting coil and the receiving coil (ie, the power transmitting coil 900 and the power receiving coil 910 ) according to the present embodiment with respect to the movement distance d varying from 0 to 55 mm.

[0079] Reference Figure 5 , relative to the change in the moving distance d, the change in the coupling coefficient between the power transmission coil 300 and the power receiving coil 310 is very small.

[0080] In contrast, Figures 8A to 8C The variation in the coupling coefficient between the power transmitting coil 801 and the power receiving coil 802 shown decreases with movement from the transmission area 320 for transmitting high power to the transmission area 321 for transmitting low power, and converges to an almost constant value within a range of a movement distance d of 40 mm or longer.

[0081] Substituting the electrical properties in Table 2 into formulas (5) and (9), we can obtain Figures 8A to 8C The relationship between the moving distance of the power transmission coil 801 and the power receiving coil 802 and the power and efficiency. Figure 10 Transmission efficiency 1000 and transmission power 1010 are shown.

[0082] Point 1001 provides the maximum transmission efficiency of 87%. Point 1011 provides the transmission power P of the relevant timing. o is 330 W. These points indicate the operating states of the power transmission system according to the present embodiment using the power transmission coil 801 and the power reception coil 802 in a transmission area for transmitting high power.

[0083] Point 1012 provides 136W of transmission power P o Point 1002 provides a transmission efficiency of 72.3% at the relevant timing. These points indicate the operating state of the power transmission system using the power transmission coil 801 and the power reception coil 802 in a transmission area for transmitting low power according to the present embodiment.

[0084] Figure 11The difference in transmission efficiency between the prior art and this embodiment is shown. This means that when curve 1100 is positive, the transmission efficiency of the power transmission coil 801 and the power receiving coil 802 according to this embodiment exceeds that of the power transmission coil 300 according to the prior art. In the transmission region 320 for high power transmission, the transmission efficiency improves by 7.5%. Assuming a transmitted power of 300 W, this corresponds to a loss reduction of approximately 33.3 W. For low-power transmitting and receiving coils, a loss reduction of 33.3 W offers a major advantage from the perspectives of simplifying the radiation mechanism and reducing costs. This means that in the transmission region 320 for high power transmission, the transmission efficiency is significantly improved (loss reduction). At the same time, in the transmission region 321 for low power transmission, a localized deterioration in transmission efficiency of up to approximately 4% occurs near a travel distance d of approximately 33 mm. Assuming a transmitted power of 130 W, this corresponds to an increase in loss of approximately 6 W. However, this loss decreases as the travel distance d increases, becoming almost zero when the travel distance d exceeds 55 mm. In other words, the system reduces the total losses in the coil and also reduces the temperature rise in the coil.

[0085] Figure 12A and Figure 12B Other examples of power transmission and power reception coils according to the present embodiment are schematically shown. Figure 12A and Figure 12B The transmission area 321 for transmitting low power is formed by a two-winding coil, and the transmission area 320 for transmitting high power is formed by a four-winding coil. Figure 12A The figure shows a configuration in which the width (in the vertical and horizontal directions) of the transmission region 320 for transmitting high power is different from the width of the transmission region 321 for transmitting low power. From another perspective, the transmission region 320 for transmitting high power (a region with a large number of windings) is contained within the transmission region 321 for transmitting low power (a region with a small number of windings). Figure 12B A configuration is shown in which the width (in the vertical and horizontal directions) of the transmission area 320 for transmitting high power is different from the width of the transmission area 321 for transmitting low power, and the width of the transmission area 320 for transmitting high power is greater than the width of the transmission area 321 for transmitting low power.

[0086] The relationship between the transmission power and the moving distance according to the present embodiment is considered to be illustrative. The configuration of the present invention is also applicable to a case where the area of ​​the transmission area for transmitting high power is larger than the area of ​​the transmission area for transmitting low power.

[0087] According to this embodiment, the number of windings of the power transmission coil is changed to change the coupling coefficient in the transmission area 320 for transmitting high power and the coupling coefficient in the transmission area 321 for transmitting low power. As a result, the wireless power transmission system is adjusted to operate near the optimal load.

[0088] If the above adjustments are insufficient, the load value can be adjusted. In this case, for example, the system may include a position detection unit for detecting the position of the power receiving coil and a load control unit for controlling the load. The position detection unit can detect that the power receiving coil is in the transmission area 320 for high power transmission, and the load control unit can then control the load value.

[0089] The second embodiment will now be described centering on a configuration for further reducing the temperature rise of the entire coil. Figure 13A and Figure 13B A specific example of the power transmission coil including the substrate having multiple layers according to the second embodiment is shown.

[0090] Figure 13A The first configuration of this embodiment is shown. Power transmission coil 110 is formed from a four-layer substrate, a three-winding conductor pattern in transmission region 320 for transmitting high power, and a single-winding conductor pattern in transmission region 321 for transmitting low power. These two different conductor patterns are formed on the substrate. A support member 1300 is positioned below power transmission coil 110. When current flows through power transmission coil 110, the heat generated is transferred to support member 1300, thereby reducing the temperature of power transmission coil 110. Support member 1300 is a magnet or a metal with an insulating surface.

[0091] Figure 13B The second configuration of this embodiment is shown. Figure 13A In addition to the configuration in FIG, a conductor pattern having the same shape as the conductor pattern of winding 1 is formed on all layers of the substrate in the transmission area 321 for transmitting low power, and the multiple layers are connected with conductors (such as one or more through holes). Generally, the resistance of a conductor is inversely proportional to its cross-sectional area. Therefore, Figure 13B The configuration shown increases the cross-sectional area and reduces the resistance. In addition, the resistance of a conductor is proportional to the temperature of the conductor.

[0092] More specifically, the resistance value increases as the conductor temperature increases and decreases as the conductor temperature decreases. This means that even during high-power transmission, the temperature of the conductor pattern must be kept low. The thermal conductivity of the conductor is generally higher than that of substrates such as FR-4. Therefore, by replacing the substrate material of all layers of the substrate in the transmission area 321 used for low-power transmission with the conductor pattern, the radiation performance of the support member 1300 can be improved.

[0093] Figure 14A and Figure 14B The results of a temperature distribution simulation of the power transmission coil 110 according to the present embodiment are shown. Figure 14A Shown in the application Figure 13A The temperature distribution in the configuration prior to this embodiment is shown. In this case, the power receiving coil 120 is arranged facing the transmission region 321 for low power transmission. The temperature in the transmission region 320 for high power transmission is the highest (up to 85°C) and decreases toward the transmission region 321 for low power transmission. Figure 14B Shows the application Figure 13B The temperature distribution in the configuration of this embodiment is shown. The temperature of the transmission region 320 for transmitting high power is the highest (up to 55°C) and decreases toward the transmission region 321 for transmitting low power. The above results ensure that this embodiment can reduce the temperature of the power transmission coil 110.

[0094] The power transmission coil 110 may also be configured by only a conductor, such as an edgewise coil. Figure 15A and Figure 15B An example of a power transmission coil formed of a conductor according to the present embodiment is shown. Figure 15A The configuration before the present embodiment is applied is shown. The power transmission coil 110 includes three winding conductors in a transmission region 320 for transmitting high power, and includes one winding conductor in a transmission region 321 for transmitting low power.

[0095] The support member 1300 is disposed below the power transmission coil 110. When current flows in the power transmission coil 110, generated heat is transferred to the support member 1300, thereby lowering the temperature of the power transmission coil 110.

[0096] The supporting member 1300 is a magnet or a metal having an insulation-treated surface. Figure 15B The configuration to which this embodiment is applied is shown. Figure 15A The thickness of the conductor in transmission region 321 for low power transmission is greater than the thickness of the conductor in the first winding, so that the thickened conductor contacts support member 1300. The thermal conductivity of a conductor is generally higher than that of air. Therefore, by replacing the air in transmission region 321 for low power transmission with a conductor, radiation performance to support member 1300 can be improved.

[0097] The disclosure of this embodiment also includes the following configurations.

[0098] (Configuration 1)

[0099] A wireless power transmission system, comprising:

[0100] a power transmission coil and a power reception coil, arranged to face each other and configured to move relative to each other,

[0101] wherein the power transmission coil includes a first transmission area for forming a coil having a first winding number and a second transmission area for forming a coil having a second winding number smaller than the first winding number, and

[0102] Here, a first electric power transmitted to the power receiving coil in the first transmission area is greater than a second electric power transmitted to the power receiving coil in the second transmission area.

[0103] (Configuration 2)

[0104] The wireless power transmission system according to Configuration 1, wherein a first coupling coefficient between the power transmitting coil and the power receiving coil in the first transmission area is greater than a second coupling coefficient between the power transmitting coil and the power receiving coil in the second transmission area.

[0105] (Configuration 3)

[0106] The wireless power transmission system according to Configuration 1 or 2, wherein an area of ​​the first transmission region is different from an area of ​​the second transmission region.

[0107] (Configuration 4)

[0108] The wireless power transmission system according to any one of Configurations 1 to 3, wherein power transmission efficiency in the first transmission area is higher than power transmission efficiency in the second transmission area.

[0109] (Configuration 5)

[0110] The wireless power transmission system according to any one of configurations 1 to 4, wherein the number of the first windings is four and the number of the second windings is two.

[0111] (Configuration 6)

[0112] The wireless power transmission system according to any one of Configurations 1 to 5, further including: a position detection unit configured to detect whether the power receiving coil is located in the first transmission area or the second transmission area.

[0113] (Configuration 7)

[0114] The wireless power transmission system according to any one of Configurations 1 to 6, further including: a load control unit configured to control a value of a load according to the transmission power.

[0115] (Configuration 8)

[0116] The wireless power transmission system according to any one of Configurations 1 to 7, further including a member for supporting the power transmission coil.

[0117] (Configuration 9)

[0118] The wireless power transmission system according to any one of Configurations 1 to 7, wherein a conductor thickness of the power transmission coil in the second transmission area is greater than a conductor thickness of the power transmission coil in the first transmission area.

[0119] (Configuration 10)

[0120] The wireless power transmission system according to any one of Configurations 1 to 8, wherein the power transmission coil includes a substrate formed of multiple layers, and the conductor pattern formed in the second transmission area is formed of two or more layers.

[0121] (Configuration 11)

[0122] The wireless power transmission system according to Configuration 10, wherein the conductor pattern formed in the second transmission area and formed of two or more layers is connected to a conductor.

[0123] While the present invention has been described with reference to embodiments, it is to be understood that the invention is not limited to the disclosed embodiments and that the scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A wireless power transmission system, comprising: a power transmission coil and a power reception coil, arranged to face each other and configured to move relative to each other, wherein the power transmission coil includes a first transmission area for forming a coil having a first winding number and a second transmission area for forming a coil having a second winding number smaller than the first winding number, and Here, a first electric power transmitted to the power receiving coil in the first transmission area is greater than a second electric power transmitted to the power receiving coil in the second transmission area.

2. The wireless power transmission system according to claim 1, wherein: A first coupling coefficient between the power transmitting coil and the power receiving coil in the first transmission area is greater than a second coupling coefficient between the power transmitting coil and the power receiving coil in the second transmission area.

3. The wireless power transmission system according to claim 1, wherein: An area of ​​the first transmission region is different from an area of ​​the second transmission region.

4. The wireless power transmission system according to claim 1, wherein: The power transmission efficiency in the first transmission area is higher than the power transmission efficiency in the second transmission area.

5. The wireless power transmission system according to claim 1, wherein: The number of the first windings is four, and the number of the second windings is two.

6. The wireless power transmission system according to claim 1, further comprising: A position detection unit is configured to detect whether the power receiving coil is located in the first transmission area or the second transmission area.

7. The wireless power transmission system according to claim 1, further comprising: A load control unit is configured to control a value of a load according to the transmission power. 8 . The wireless power transmission system according to claim 1 , further comprising a member for supporting the power transmission coil.

9. The wireless power transmission system according to claim 1, wherein: A conductor thickness of the power transmission coil in the second transmission area is greater than a conductor thickness of the power transmission coil in the first transmission area.

10. The wireless power transmission system according to claim 1, wherein: The power transmission coil includes a substrate formed of multiple layers, and a conductor pattern formed in the second transmission area is formed of two or more layers.

11. The wireless power transmission system according to claim 10, wherein: A conductor pattern formed in the second transmission region and formed of two or more layers is connected to a conductor.

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