Power receiving device and non-contact power supply system

Abstract

To achieve a non-contact power supply system in which power loss and cost are reduced as compared with the conventional art by a simple circuit configuration.SOLUTION: A power receiving device receives electric power from a power transmission coil device by non-contact power supply, and includes a power reception coil and at least one intermediate tap. The power receiving coil includes a plurality of loops. The at least one intermediate tap is led out from the middle of the plurality of loops of the power receiving coil by at least one coil wiring, and divides and outputs a voltage generated in the power receiving coil by the non-contact power supply.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power receiving device and a contactless power supply system. [Background technology]

[0002] In recent years, the development of contactless power transfer systems has progressed. A contactless power transfer system is a system that has a power transmission device (power transfer device) and a power receiving device, and the power transmission device supplies power to the power receiving device in a contactless manner. In conventional systems, in order to receive power with high efficiency, a method was used to increase efficiency by receiving power with a separate coil via a resonance coil, but since the coil is a separate body, there are issues with the weight and the coil area being increased.

[0003] For example, when mounting a power receiving device on an electric drone and feeding power via a wireless power transfer system, it is desirable to make the power receiving device as small and lightweight as possible. In conventional wireless power transfer systems, there is room for improvement in making the power receiving device smaller and lighter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5843309 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem that the invention aims to solve is to achieve further miniaturization and weight reduction of a power receiving device in a contactless power supply system. [Means for solving the problem]

[0006] A power receiving device according to one embodiment is a power receiving device that receives power from a power transmitting coil device by contactless power supply, and includes a power receiving coil and at least one center tap. The power receiving coil includes a plurality of loops. The at least one center tap is drawn from the middle of the plurality of loops of the power receiving coil by at least one coil wire, and divides and outputs a voltage generated in the power receiving coil by contactless power supply. Effect of the Invention

[0007] According to one aspect of the power receiving device disclosed in the present application, it is possible to achieve further miniaturization and weight reduction of the power receiving device in a contactless power supply system. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a contactless power supply system according to an embodiment, and the configurations of a power supply device and a power receiving device included in the contactless power supply system. [Diagram 2] FIG. 2 is a diagram for explaining the configuration of a power receiving coil circuit of a power receiving device and the configuration of a power transmitting coil circuit of a power transmitting device according to an embodiment. [Diagram 3] FIG. 3 is a diagram for explaining the configuration of a power receiving coil circuit of a power receiving device and the configuration of a power transmitting coil circuit of a power transmitting device according to Comparative Example 1. In FIG. [Figure 4] FIG. 4 is a diagram for explaining the configuration of a power receiving coil circuit of a power receiving device and the configuration of a power transmitting coil circuit of a power transmitting device according to Comparative Example 2. In FIG. [Diagram 5] FIG. 5 is a graph for explaining the transmission efficiency of the contactless power supply system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Each embodiment will be described in detail below with reference to the drawings.

[0010] FIG. 1 is a diagram showing an example of the configuration of a contactless power supply system S according to the embodiment, and the configurations of a power transmitting device 1 and a power receiving device 2 included in the contactless power supply system S. As shown in FIG.

[0011] As shown in Fig. 1, a contactless power supply system S includes a power transmission device 1 and a power receiving device 2 to which power is contactlessly supplied by the power transmission device 1. Note that Fig. 1 illustrates one power receiving device 2 as an example of a device to which the power transmission device 1 contactlessly supplies power. However, the power transmission device 1 may supply power to a plurality of power receiving devices 2.

[0012] The power receiving device 2 can be mounted on a mobile device, for example, and can supply power to an apparatus (electrically driven device) mounted on the mobile device. Here, the electrically driven device may be an electrically driven mobile body such as an electrically driven drone, an AGV (Automatic Guided Vehicle), an electrically driven vehicle, a trolley such as a medical cart or a wheelchair, or an electrically driven mobile robot. The electrically driven device is not limited to the above-mentioned examples of an object mounted on a mobile device, an electrically driven mobile body, etc. The electrically driven device may be, for example, an electric motor such as an electric tool, or any device that does not move but requires charging. Also, tablet computers, smartphones, projectors, displays, etc. can be targets for power supply.

[0013] The power transmitting device 1 includes a control circuit 100, a DC / DC converter 101, an oscillator circuit 103, a resonant circuit 105, and a power transmitting coil circuit 107.

[0014] The control circuit 100 is a microcomputer or a CPU (Central Processing Unit) that controls the oscillation circuit 103 .

[0015] The DC / DC converter 101 receives a DC voltage supplied from, for example, an AC / DC conversion circuit (not shown), converts it into a voltage within a predetermined range, and supplies the converted voltage to the oscillation circuit 103 .

[0016] In response to a control signal (drive signal) from the control circuit 100, the oscillator circuit 103 continuously outputs an AC voltage (high frequency voltage).

[0017] The resonant circuit 105 is provided between the oscillation circuit 103 and the power transmitting coil circuit 107, and has an LC circuit. The inductance of the coil and the capacitance of the capacitor of the LC circuit of the resonant circuit 105 are adjusted in advance according to the inductance of the power transmitting coil circuit 107 to be connected. The resonant circuit 105 controls the AC voltage output by the oscillation circuit 103.

[0018] The power transmitting coil circuit 107 has a plurality of loops arranged in one direction (array direction), for example. The power transmitting coil circuit 107 spatially transmits the power output from the resonant circuit 105 to the power receiving device. Note that the loop means an area whose boundary is formed by a coil wire.

[0019] The power receiving device 2 includes a power receiving coil circuit 201 , a resonant circuit 202 , and a rectifier circuit 203 .

[0020] The receiving coil circuit 201 receives the power transmitted through space from the transmitting coil circuit 107 by electromagnetic induction. The receiving coil circuit 201 has, for example, a plurality of loops arranged in one direction (array direction). The receiving coil circuit 201 also has at least one center tap drawn out from the middle position of the plurality of loops. The specific configuration of the receiving coil circuit 201 will be described in detail later.

[0021] The resonant circuit 202 is provided between the power receiving coil 201 and the rectifier circuit 203, and has an LC circuit. The inductance of the coil and the capacitance of the capacitor of the LC circuit of the resonant circuit 202 are adjusted in advance according to the inductance of the connected power receiving coil 201. The resonant circuit 202 controls the AC voltage output by the power receiving coil 201.

[0022] The rectifier circuit 203 rectifies the voltage from the resonance coil 202 .

[0023] FIG. 2 is a diagram for explaining the configuration of a power receiving coil circuit 201 of the power receiving device 2 and the configuration of a power transmitting coil circuit 107 of the power transmitting device 1 according to the embodiment.

[0024] As shown in FIG. 2, the power transmitting coil circuit 107 of the power transmitting device 1 includes a first capacitor 107a, a second capacitor 107b, and a power transmitting coil 107c having a plurality of loops.

[0025] The first capacitor 107a is connected in series to the power transmitting coil 107c, and the second capacitor 107b is connected in parallel to the power transmitting coil 107c. The resonant frequency of the power transmitting coil circuit 107 can be adjusted by adjusting the capacitance of the first capacitor 107a and the second capacitor 107b. It is also possible to use only one of the first capacitor 107a and the second capacitor 107b. It is also possible to add more of the first capacitor 107a and the second capacitor 107b as necessary.

[0026] As shown in FIG. 2, the power receiving coil circuit 201 of the power receiving device 2 includes a third capacitor 201a, a power receiving coil 201B having a plurality of loops, and a center tap 201c.

[0027] The third capacitor 201a is connected, for example, in series to the power receiving coil 201B. By adjusting the capacitance of the third capacitor 201a, it is possible to adjust the resonant frequency of the power receiving coil circuit 201. Note that the capacitor connected to the power receiving coil 201B can also be added in series or parallel as necessary.

[0028] Intermediate tap 201c is a terminal of a coil wire drawn from the middle of the winding of power receiving coil 201B, and is connected to rectifier circuit 203. Note that Fig. 2 illustrates an example in which there is one intermediate tap 201c. However, this is not limiting, and multiple intermediate taps 201c can be formed by multiple coil wires drawn from multiple positions in the middle of the winding of power receiving coil 201B.

[0029] The power receiving coil 201B is separated into a first sub-coil 201b1 and a second sub-coil 201b2 by an intermediate tap 201c. The first sub-coil 201b1 and the second sub-coil 201b2 may have the same shape or different shapes. The shapes of the first sub-coil 201b1 and the second sub-coil 201b2 can be adjusted by the position of the intermediate tap 201c in the power receiving coil 201B, the loop diameter of each sub-coil, and the density of the number of turns.

[0030] The voltage generated across the power receiving coil 201B due to the power transmitted through space from the power transmitting coil 107c is divided by the intermediate tap 201c. The voltage generated across the power receiving coil 201B can be reduced to a desired value and output to the downstream rectifier circuit 203 by a voltage division ratio according to the position of the intermediate tap 201c in the power receiving coil 201B.

[0031] Fig. 3 is a diagram for explaining the configuration of a contactless power supply system S1 according to Comparative Example 1. As shown in Fig. 3, the contactless power supply system S1 includes a power transmitting device 4 and a power receiving device 5. The power transmitting device 4 includes a primary coil 43. The power receiving device 5 includes a secondary coil 53 having a size approximately equal to that of the primary coil 43.

[0032] The efficiency of power transmission through space between the primary coil (transmitting coil) and the secondary coil (receiving coil) can be evaluated using the index α=kQ, where k is the coupling constant due to electromagnetic induction between the receiving coil and the transmitting coil, Q is the quality factor on the receiving side, and Q=ωL / R=(L / C). 1 / 2 / R, where ω is the resonant frequency on the power receiving device side, L is the inductance of the power receiving coil, and R is the resistance on the power receiving device side.

[0033] In the contactless power supply system S1 according to Comparative Example 1 shown in Fig. 3, the power receiving coil and the power transmitting coil have approximately the same size. In this case, the coupling constant k due to electromagnetic induction is largely dependent on the positional relationship (distance) between the secondary coil 53 and the primary coil 43. That is, when the distance between the secondary coil 53 and the primary coil 43 is short, the coupling constant k becomes relatively large. On the other hand, when the distance between the secondary coil 53 and the primary coil 43 is long, the coupling constant k becomes relatively small.

[0034] In the contactless power supply system S1 according to the comparative example 1, when the distance between the secondary coil 53 and the primary coil 43 is long, the index α becomes relatively small and the transmission efficiency decreases. For this reason, for example, in order to transmit power from the primary coil 43 through space at a high voltage and not to lower the Q value, it is necessary to receive the power at a high voltage at the secondary coil 53 having a large L value (inductance) and convert it to a required voltage by a step-down circuit such as a transformer. Therefore, the entire contactless power supply system S1 or the downstream side of the power transmission device 4 becomes relatively large, and there is a limit to the size and weight reduction of the device. In addition, when the voltage is lowered without using a step-down circuit such as a transformer, the coil 53 has a low number of turns, the L value becomes relatively small, and the Q value decreases, which hinders highly efficient power transmission over a long distance.

[0035] Fig. 4 is a diagram for explaining the configuration of a contactless power supply system S2 according to Comparative Example 2, which is an improvement on the contactless power supply system S1 according to Comparative Example 1. As shown in Fig. 4, the contactless power supply system S2 has a matching coil device 7, which is separate from the power receiving device 5, between the power receiving device 5 and the power transmitting device 4.

[0036] The matching coil device 7 includes a matching coil 72 serving as a booster coil. In the contactless power supply system S2 according to the comparative example 2 shown in FIG. 4 , the matching coil 72 performs additional matching on the magnetic flux generated in the primary coil 43 of the power transmitting device 4, and efficiently transmits the magnetic flux from the matching coil 72 to the secondary coil 53 of the power receiving device 5.

[0037] On the other hand, the contactless power supply system S2 according to the comparative example 2 requires a matching coil device 7 (matching coil 72) that is separate from the power receiving device 5, between the power receiving device 5 and the power transmitting device 4. Therefore, the entire contactless power supply system S2, or the downstream side of the power transmitting device 4, becomes a relatively large configuration, and there is a limit to the size and weight reduction of the device.

[0038] In contrast, in the contactless power supply system S according to the embodiment, the power receiving device 2 includes a power receiving coil 201B having a plurality of loops and at least one intermediate tap 201c. The at least one intermediate tap 201c is drawn from the middle of the power receiving coil 201B by at least one coil wire, and divides the voltage generated in the power receiving coil 210B by contactless power supply and outputs the divided voltage to the rectifier circuit 203.

[0039] Therefore, the entire power receiving coil 201B receives power from the primary coil (power transmitting coil) with high efficiency. Meanwhile, the power generated in the entire power receiving coil 201B can be extracted at a required voltage using intermediate wiring by the intermediate tap 201c. Also, by adjusting the position of the intermediate tap 201c, the power generated in the power receiving coil 201B can be extracted at a desired voltage.

[0040] In other words, there is no need for a step-down circuit such as a transformer for extracting the spatially transmitted power at a desired voltage on the power receiving side, nor for a matching coil device that is separate from the power receiving device. Therefore, it is possible to achieve further miniaturization and weight reduction compared to conventional power receiving devices and contactless power transfer systems.

[0041] FIG. 5 is a graph showing the change in transmission efficiency of the contactless power supply system S according to the embodiment and the change in transmission efficiency of the contactless power supply system S1 according to the comparative example 1 depending on the distance between the primary coil and the secondary coil.

[0042] 5, the transmission efficiency of the contactless power supply system S1 according to Comparative Example 1 drops significantly when the distance between the primary coil and the secondary coil is close to D1. In contrast, the transmission efficiency of the contactless power supply system S according to the embodiment drops gently even when the distance between the primary coil and the secondary coil exceeds D1. That is, the contactless power supply system S according to the embodiment achieves a transmission efficiency that is less affected by the distance between the primary coil and the secondary coil than the contactless power supply system S1 according to Comparative Example 1.

[0043] (Variation 1) In the above embodiment, the power receiving coil 201B is an ordinary coil having a plurality of loops arranged in the array direction. However, the power receiving coil 201B may include at least one pattern coil having a printed pattern.

[0044] (Variation 2) The power receiving coil 201B may be configured to include a magnetic body disposed on the back surface (the surface opposite to the power transmitting coil 107C). ​​With such a configuration, the L value (reactance) of the power receiving coil 201B can be increased, and the Q value and the α value can be increased, thereby improving the transmission efficiency.

[0045] Although the embodiments of the present disclosure have been described above in detail, these embodiments are presented as examples, and the present disclosure is not intended to be limited to the individual embodiments described above. These new embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications are possible without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0046] 1 Power transmission equipment 2 Power receiving device 100 Control circuit 101 DC / DC Converter 103 Oscillator Circuit 105 Resonant circuit 107 Transmitting coil circuit 107a first capacitor 107b Second capacitor 107c Transmitting coil 201 Receiving coil circuit 201a Third capacitor 201B Receiving coil 201b1 First sub-coil 201b2 Second sub-coil 201c Center Tap 202 Resonant circuit 203 Rectifier circuit S Non-contact power supply system

Claims

1. A power receiving device that receives power from a power transmitting coil device by non-contact power supply, A receiving coil having a plurality of loops; at least one center tap that is drawn from the middle of the plurality of loops of the power receiving coil by at least one coil wire and divides and outputs a voltage generated in the power receiving coil by contactless power supply; A power receiving device comprising:

2. The receiving coil is divided into a plurality of sub-coils by at least one of the center taps, The plurality of sub-coils are of the same shape. The power receiving device according to claim 1 .

3. The receiving coil is divided into a plurality of sub-coils by at least one of the center taps, the plurality of sub-coils are of different shapes; The power receiving device according to claim 1 .

4. The receiving coil includes at least one layer of pattern coil printed with a pattern. The power receiving device according to claim 1 .

5. The receiving coil includes at least one capacitor connected in series or parallel. The power receiving device according to claim 1 .

6. The receiving coil has a magnetic body disposed on a rear surface thereof. The power receiving device according to claim 1 .

7. a power transmitting coil device including a power transmitting coil having a plurality of loops; a power receiving device including: a power receiving coil having a plurality of loops; and at least one center tap that is drawn from the middle of the plurality of loops of the power receiving coil by at least one coil wire and divides and outputs a voltage generated in the power receiving coil by contactless power supply; A non-contact power supply system comprising:

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