Charging device

Abstract

The present invention provides a charging device that can improve power efficiency in wireless charging compared to conventional devices. [Solution] The charging device according to this disclosure is a charging device that performs wireless charging by placing a terminal device equipped with a receiving coil for receiving wirelessly transmitted power on a charging base. The charging device includes a power transmission coil for transmitting power to the terminal device, an acquisition unit for acquiring the operating voltage of the charging device and the power received by the terminal device after the charging device has started wireless charging to the terminal device, a positional misalignment characteristic calculation unit for calculating a first reference voltage of the charging device, and a determination unit for determining the positional misalignment between the power transmission coil and the power receiving coil according to a first voltage difference indicating the difference between the operating voltage of the charging device and the first reference voltage.

Description

Technical Field

[0001] The present disclosure relates to a charging device.

Background Art

[0002] Conventionally, there has been known a charging device that moves a power transmission coil to a position corresponding to a power reception coil of a terminal device with a built-in battery, and performs wireless charging on the terminal device via the power transmission coil. In such a charging device, induced electromotive force is generated by electromagnetic induction by allowing magnetic flux generated by an alternating current supplied to the power transmission coil to pass through the power reception coil built in the terminal device placed on a charging stand. Then, the terminal device is charged by the induced electromotive force generated in the power reception coil.

[0003] For example, in a charging device, when determining foreign matter existing between the charging device and the terminal device, the foreign matter determination is performed in consideration of the received power of the terminal device.

Prior Art Literature

Patent Literature

[0004]

Patent Literature 1

Summary of Invention

Problem to be Solved by Invention

[0005] For example, when positional displacement occurs between the power transmission coil and the power reception coil, or when foreign matter enters between the power transmission coil and the power reception coil, power efficiency decreases. Therefore, there is still room for further improvement in order to improve power efficiency in wireless charging.

[0006] One of the problems to be solved by the present disclosure is to provide a charging device that can improve power efficiency in wireless charging more than conventional charging devices.

Means for Solving the Problem

[0007] The charging device according to this disclosure is a charging device that performs wireless charging by placing a terminal device equipped with a receiving coil for receiving wirelessly transmitted power on a charging base. The charging device includes a power transmission coil for transmitting power to the terminal device, an acquisition unit for acquiring the operating voltage of the charging device and the power received by the terminal device after the charging device starts wireless charging to the terminal device, a positional misalignment characteristic calculation unit for calculating a first reference voltage of the charging device, and a determination unit for determining the positional misalignment between the power transmission coil and the power receiving coil according to a first voltage difference indicating the difference between the operating voltage of the charging device and the first reference voltage. [Effects of the Invention]

[0008] According to this disclosure, power efficiency in wireless charging can be improved compared to conventional methods. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows an example of a schematic configuration of a charging system according to an embodiment. [Figure 2] Figure 2 is a block diagram showing an example of the functional configuration of the control unit according to the embodiment. [Figure 3] Figure 3 is a schematic diagram illustrating the displacement characteristics according to the embodiment. [Figure 4] Figure 4 is a schematic diagram illustrating the displacement characteristics according to the embodiment. [Figure 5] Figure 5 is a schematic diagram illustrating the misalignment between the transmitting coil and the receiving coil according to this embodiment. [Figure 6] Figure 6 is a schematic diagram illustrating the positional misalignment between the power transmission coil and the power reception coil according to this embodiment. [Figure 7] Figure 7 is a schematic diagram illustrating the positional misalignment between the power transmission coil and the power reception coil according to this embodiment. [Figure 8] Figure 8 is a schematic diagram illustrating the positional misalignment between the power transmission coil and the power reception coil according to this embodiment. [Figure 9]FIG. 9 is a schematic diagram for explaining the content of misalignment between a power transmission coil and a power receiving coil according to the embodiment. [Figure 10] FIG. 10 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 11] FIG. 11 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 12] FIG. 12 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 13] FIG. 13 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 14] FIG. 14 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 15] FIG. 15 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 16] FIG. 16 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 17] FIG. 17 is a flowchart illustrating an example of a flow of processing executed by the charging device according to the embodiment. [Figure 18] FIG. 18 is a flowchart illustrating an example of a flow of processing executed by a charging device according to a first modification. [Figure 19] FIG. 19 is a diagram illustrating an example of a hardware configuration of a charging system according to the embodiment and the modification. DETAILED DESCRIPTION OF EMBODIMENTS

[0010] (Embodiment) Hereinafter, embodiments of the charging device according to the present disclosure will be described with reference to the drawings.

[0011] In the description of the present disclosure, components that have the same or substantially the same functions as those described above with respect to the previously shown drawings are denoted by the same reference numerals, and the description thereof may be omitted as appropriate. In addition, even when representing the same or substantially the same parts, the dimensions and ratios may be shown differently in different drawings. Further, for example, from the viewpoint of ensuring visibility of the drawings, in the description of each drawing, only main components are provided with reference numerals, and even components that have the same or substantially the same functions as those described above in the previously shown drawings may not be provided with reference numerals.

[0012] In the description of the present disclosure, components having the same or substantially the same functions may be distinguished by adding alphanumeric characters to the end of reference numerals. Alternatively, when a plurality of components having the same or substantially the same functions are not distinguished, they may be described collectively by omitting the alphanumeric characters added to the end of the reference numerals.

[0013] Conventionally, there has been known a charging device that moves a power transmission coil to the position of a power reception coil of a terminal device with a built-in battery, and performs wireless charging on the terminal device by the power transmission coil. In such a charging device, induced electromotive force is generated by electromagnetic induction by allowing magnetic flux generated by an alternating current flowing through the power transmission coil to pass through the power reception coil built in the terminal device placed on a charging stand. The terminal device is then charged by the induced electromotive force generated in the power reception coil.

[0014] For example, in a charging device, when determining whether there is a foreign object between the charging device and the terminal device, the foreign object determination is performed in consideration of the received power of the terminal device. For example, when positional misalignment occurs between the power transmission coil and the power reception coil, or when a foreign object is inserted between the power transmission coil and the power reception coil, the power efficiency decreases. Therefore, in wireless charging, there is room for further improvement to improve power efficiency.

[0015] Furthermore, for example, in charging equipment mounted on a vehicle, vibrations from road conditions (such as curves and road surface conditions) can cause the terminal device placed on the charging bay to shift, reducing the power efficiency of wireless charging. By accurately detecting the positional shift between the charging equipment and the terminal device, the charging equipment can improve charging stability and robustness.

[0016] Furthermore, for example, charging devices require high alignment accuracy between the transmitting and receiving coils in the Qi standard. If the receiving coil is misaligned with the transmitting coil, the power efficiency decreases, causing the device to switch from high-power charging to low-power charging. Therefore, it is desirable to quickly detect even slight misalignments, correct them, and continue high-power charging.

[0017] Therefore, this disclosure describes a charging device that can improve power efficiency in wireless charging compared to conventional devices.

[0018] (Embodiment) Figure 1 is a diagram showing an example of the schematic configuration of a charging system 100 according to an embodiment. As shown in Figure 1, the charging system 100 has a charging device 10 and a terminal device 30. The charging device 10 is mounted on a vehicle. Here, the vehicle may be, for example, a passenger car, a truck, a bus, a motorcycle, an electric scooter, construction machinery, agricultural machinery, an aircraft, etc. In this embodiment, a configuration in which one charging device 10 is provided for one vehicle will be described.

[0019] The charging device 10 is a device that performs contactless charging, or wireless charging, on the terminal device 30. Here, wireless charging means charging by wireless means. In this disclosure, a form in which wireless charging means charging by electromagnetic induction is described as an example.

[0020] The Qi standard, developed by the Wireless Power Consortium (WPC), is an international standard for wireless charging. The Qi standard specifies two types of charging: low-power charging and high-power charging. For example, low-power charging is performed at a maximum of 5W, and high-power charging is performed at a maximum of 15W. Low-power transmission is called BPP (Baseline Power Profile), and high-power charging is called EPP (Extended Power Profile).

[0021] In such wireless charging, as an example, with the terminal device 30 to be charged placed on the upper surface of the charging device 10's mounting section, the power transmission coil 16 of the charging device 10 is moved by the moving mechanism 17 to bring it closer to the power receiving coil 31 of the terminal device 30, thereby aligning the power transmission coil 16 and the power receiving coil 31.

[0022] In wireless charging, the closer the power transmission coil 16 of the charging device 10 and the power receiving coil 31 of the terminal device 30 to be charged are to face each other, the more efficient the charging becomes. Within the Qi standard, there is a trend towards standardizing MPP (Magnetic Power Profile), a high-speed charging method that uses magnets for alignment. For this reason, the charging device 10 according to this disclosure may have a magnet arranged together with the power transmission coil 16.

[0023] The terminal device 30 to be charged by the charging device 10 can be any electronic device with a built-in battery, such as a smartphone, tablet, audio player, or mobile phone.

[0024] The charging device 10 includes a DC power supply 11, a DC-DC converter 12, a bridge circuit 13, a voltage detection circuit 14, a current detection circuit 15, a power transmission coil 16, a moving mechanism 17, a position detection controller 18, a power receiving coil position detection circuit 20, a foreign object detection circuit 21, and a control unit 22.

[0025] The DC power supply 11 supplies DC power to operate the charging device 10.

[0026] The DC-DC converter 12 boosts or lowers the DC voltage of the DC power supply 11 to a predetermined DC voltage.

[0027] The bridge circuit 13 converts the DC voltage boosted or stepped down by the DC-DC converter 12 into an AC voltage. The bridge circuit 13 may be a full bridge circuit or a half bridge circuit.

[0028] The voltage detection circuit 14 detects the DC voltage that has been boosted or stepped down by the DC-DC converter 12.

[0029] The current detection circuit 15 detects the output current of the bridge circuit 13.

[0030] The transmitting coil 16 generates magnetic flux by the principle of electromagnetic induction in response to the AC voltage applied from the bridge circuit 13. The generated magnetic flux passes through the receiving coil 31 of the terminal device 30, which is mounted so as to overlap with the transmitting coil 16, thereby generating an induced electromotive force in the receiving coil 31. The induced electromotive force generated at this time charges the built-in battery of the terminal device 30. In other words, power is transmitted from the transmitting coil 16 to the receiving coil 31. In addition, communication based on the Qi standard is performed from the receiving coil 31 to the transmitting coil 16, and for example, the amount of power received by the receiving coil 31 is transmitted.

[0031] The moving mechanism 17 moves the position of the power transmission coil 16 within a two-dimensional coordinate system that includes the coil surface. The moving mechanism 17 moves the power transmission coil 16 along the X and Y axes by the operation of a servo motor controlled by a position control circuit 38, which will be described later. The servo motor is, for example, an actuator.

[0032] The position detection controller 18 is equipped with multiple pattern coils, and the reflected wave, which changes according to the coupling state between the multiple pattern coils and the power receiving coil 31, is detected by the power receiving coil position detection circuit 20 in response to pulses output from pulse output circuits (not shown) connected to each pattern coil.

[0033] The power transmission coil 16, the moving mechanism 17, and the position detection controller 18 are all housed within the charging base 19. The top surface of the charging base 19 is a flat surface on which the terminal device 30 can be placed.

[0034] The power receiving coil position detection circuit 20 detects the position of the power receiving coil 31. For example, the power receiving coil position detection circuit 20 acquires the reflected wave from the position detection controller 18 and detects the center position of the power receiving coil 31.

[0035] The foreign object detection circuit 21 performs foreign object detection processing. Specifically, when the bridge circuit 13 applies an AC voltage to the power transmission coil 16 while changing the frequency, the foreign object detection circuit 21 calculates the sharpness (Q value) of the series resonance state due to the capacitance component of the capacitor 23 connected in series between the bridge circuit 13 and the power transmission coil 16 and the inductive component (inductance) of the power transmission coil 16.

[0036] The control unit 22 performs various controls related to the charging state by the charging device 10.

[0037] The control unit 22 includes a calculation unit 221, a calculation result comparison unit 222, a calculation result storage unit 223, and a power transmission coil position control unit 224.

[0038] The calculation unit 221 calculates the power transmitted to the power transmission coil 16 from the voltage detected by the voltage detection circuit 14 and the current detected by the current detection circuit 15.

[0039] Furthermore, the calculation unit 221 calculates the power received by the receiving coil 31 based on the communication data received by the transmitting coil 16 from the receiving coil 31.

[0040] Furthermore, the calculation unit 221 calculates the ratio of the received power Rp(t) to the transmitted power Pout(t) calculated at the same time t, i.e., the efficiency E(t) (=Rp(t) / Pout(t)). Alternatively, the calculation unit 221 may calculate the difference between the transmitted power Pout(t) and the received power Rp(t) calculated at the same time t (Pout(t)-Rp(t)).

[0041] The calculation result comparison unit 222 compares the calculated efficiency E(t) with a preset threshold Eth. The calculation result comparison unit 222 also instructs the DC-DC converter 12 and the bridge circuit 13 to start or stop charging. The calculation result comparison unit 222 also instructs the DC-DC converter 12 and the bridge circuit 13 to continue charging at normal power or to continue charging at limited power. The calculation result comparison unit 222 also instructs the power transmission coil position control unit 224 to move the position of the power transmission coil 16.

[0042] The calculation result storage unit 223 stores the maximum value of efficiency E(t) calculated by the calculation unit 221, updating it sequentially.

[0043] The power transmission coil position control unit 224 instructs the movement mechanism 17 to move the power transmission coil 16 to a specific position, based on the current position of the power receiving coil 31 detected by the power receiving coil position detection circuit 20 and the movement instruction for the power transmission coil 16 issued by the calculation result comparison unit 222.

[0044] (Positional relationship between the transmitting coil and the receiving coil) Next, the transmission efficiency depending on the positional relationship between the transmitting coil 16 and the receiving coil 31 will be explained. For example, if the receiving coil 31 is misaligned with the transmitting coil 16 by 6 mm or more, the transmission efficiency will decrease by 10% or more. Since it is easy to determine a 10% decrease in transmission efficiency, it is also easy to determine a 6 mm misalignment. On the other hand, for example, in the MPP standard, if the charging device 10 is misaligned by 2 mm or more during high-power charging, it may switch from high-power charging to low-power charging. In that case, the decrease in transmission efficiency is about 1%.

[0045] Here, if the power received by the terminal device 30 is 15W, a transmission efficiency of 1% corresponds to 150mW, which falls within the normal range of power variation. Therefore, if the misalignment between the transmitting coil 16 and the receiving coil 31 is determined simply from the transmission efficiency of the power received by the terminal device 30, the charging device 10 will not be able to continue high-power charging. To address this, the charging device 10 in this embodiment determines the misalignment between the transmitting coil 16 and the receiving coil 31 based on the value of the operating voltage of the charging device 10. Specifically, the charging device 10 sets a reference voltage for the charging device 10 corresponding to the misalignment determination, and determines the misalignment by comparing the relative value of the operating voltage of the transmitting coil 16 with the said reference voltage.

[0046] For example, if a misalignment occurs between the transmitting coil 16 and the receiving coil 31 in the terminal device 30, the received power decreases. Therefore, the terminal device 30 requests an increase in transmitting power from the charging device 10 in an attempt to restore the original high power. In this case, with a small misalignment, the transmission efficiency remains almost unchanged, but the operating voltage of the charging device 10 increases significantly.

[0047] Therefore, the charging device 10 determines that a misalignment is occurring if the power received by the terminal device 30 does not increase before and after the increase in the operating voltage of the power transmission coil 16. Also, the charging device 10 determines that a charging power increase is occurring if the power received by the terminal device 30 increases before and after the increase in the operating voltage of the power transmission coil 16. Furthermore, the charging device 10 determines that a subsequent increase in the operating voltage is immediately due to a misalignment if the power received was stable (for example, reached the contracted power) before the change in the operating voltage of the power transmission coil 16. The details of what the charging device 10 processes will be explained below.

[0048] (Functional Configuration) Figure 2 is a block diagram showing an example of the functional configuration of the control unit 22 according to the embodiment. The control unit 22 includes a terminal position detection unit 51, a power transmission coil position setting unit 52, a position deviation characteristic calculation unit 53, a foreign object detection unit 54, a charging state control unit 55, a power transmission instruction unit 56, an acquisition unit 57, a parameter setting unit 58, and a determination unit 59. However, the functions of the control unit 22 are not limited to these.

[0049] The terminal position detection unit 51 detects the position of the terminal device 30 when the terminal device 30 is placed on the charging base 19.

[0050] The power transmission coil position setting unit 52 sets the position of the power transmission coil 16 to a position opposite the power transmission coil 31, based on the position of the power receiving coil 31 detected by the power receiving coil position detection circuit 20. Then, the power transmission coil 16 is moved by the movement mechanism 17 to the position set by the power transmission coil position setting unit 52, and various authentications are performed between the charging device 10 and the terminal device 30.

[0051] Furthermore, the power transmission coil position setting unit 52 determines whether to utilize the positional misalignment characteristic. If the power transmission coil position setting unit 52 determines that the positional misalignment characteristic should be utilized, after detecting the position of the terminal device 30, it sets the power transmission coil 16 to move to a predetermined position in order to calculate the positional misalignment characteristic. After the positional misalignment characteristic calculation unit 53 performs PING transmission / SIG reception, it sets the power transmission coil 16 again to move to a position where there is no positional misalignment with the power receiving coil 31.

[0052] The misalignment characteristic calculation unit 53 calculates the misalignment characteristic. Specifically, after detecting the position of the terminal device 30, the unit 53 performs PING transmission / SIG reception on the power transmission coil 16, which has moved to a predetermined position set by the power transmission coil position setting unit 52, and calculates the misalignment characteristic. Here, the misalignment characteristic represents the rate of change in the operating voltage of the charging device 10 with respect to the amount of misalignment when the terminal device 30 is misaligned, and is the limit value of the operating voltage corresponding to the allowable amount of misalignment. The misalignment characteristic will be explained using Figures 3 and 4.

[0053] Figures 3 and 4 are schematic diagrams illustrating the misalignment characteristics according to the embodiment. In Figure 3, the horizontal axis represents the misalignment amount [mm] between the transmitting coil 16 and the receiving coil 31, and the vertical axis represents the SS value (Signal Strength Value) received in the SIG packet. As described above, after detecting the position of the terminal device 30, the transmitting coil position setting unit 52 sets the transmitting coil 16 to move to a predetermined position in order to calculate the misalignment characteristics, and then performs PING transmission / SIG reception. Here, the predetermined position is set to 4 [mm] as the misalignment amount to be detected.

[0054] As shown in Figure 3, the SS value at a misalignment of 4 mm is 146. Furthermore, after the power transmission coil 16 moves as indicated by arrow M1 and is aligned, i.e., at a misalignment of 0 mm, the SS value is 156. The SS ratio at a misalignment of 4 mm is 94% (=146 / 156).

[0055] The positional displacement characteristic calculation unit 53 determines a first estimation formula fv(x) = a*x + b for estimating the reference voltage for the charging start position, i.e., the power-voltage characteristic without positional displacement. Here, the coefficients a and b are determined, for example, using the least squares method, resulting in a = 0.651 and b = 7718. In other words, the positional displacement characteristic calculation unit 53 determines the first estimation formula fv(x) = 0.651*x + 7718. Note that x [unit: W] in the first estimation formula is a value to which the received power is substituted. Note that the coefficients a and b are not limited to these and are determined according to the charging device 10.

[0056] Next, the misalignment characteristic calculation unit 53 uses the first estimation formula to derive a second estimation formula for estimating the limit value of the operating voltage of the charging device 10 corresponding to the misalignment characteristic. The second estimation formula is, for example, fvk(x) = a(k)*x + b(k). Here, the coupling coefficient k is calculated from the relationship between coefficient a and coupling coefficient k and the relationship between coefficient b and coupling coefficient k. The coupling coefficient k indicates the degree of inductive coupling between the transmitting coil 16 and the receiving coil 31, and takes a value between 0 and 1.

[0057] Figure 4 shows the coupling coefficient on the horizontal axis, coefficient a on the first vertical axis, and coefficient b on the second vertical axis. Here, the relationship between coefficient a and coupling coefficient k is given as a(k) = -7.0757*k + 6.1412 in Figure 4, and this is represented by graph G2. Also, the relationship between coefficient b and coupling coefficient k is given as b(k) = 12819*k - 1353, and this is represented by graph G3.

[0058] Here, using the relationship between coefficient a and coupling coefficient k, substituting the coefficient a determined in the first estimation formula into a(k), we get 0.651 = -7.0757*k + 6.1412, so the coupling coefficient k = 0.78. Also, since the SS ratio is 94% when the positional displacement is 4 [mm], the coupling coefficient k becomes k = 0.78 * 0.94 = 0.73.

[0059] Assuming the coupling coefficient is 94%, the coefficient a(k) in the second estimation formula is a(k) = -7.0757 * 0.73 + 6.1412 = 0.976. Also, the coefficient b(k) in the second estimation formula is b(k) = 12819 * 0.73 - 1353 = 8005. Thus, the positional displacement characteristic calculation unit 53 derives the second estimation formula fvk(x) = 0.976 * x + 8005. By substituting the received power for x in this second estimation formula, the limit value of the operating voltage of the charging device 10 can be estimated.

[0060] Returning to Figure 2, the explanation continues. The positional displacement characteristic calculation unit 53 determines whether there is enough data to use the first estimation formula. Here, the required number of data is the number of data points obtained by the acquisition unit 57, which will be described later, when acquiring the operating voltage of the charging device 10 and the power received by the terminal device 30. If there is enough data to use the first estimation formula, the positional displacement characteristic calculation unit 53 derives the first estimation formula using the operating voltage of the charging device 10 and the power received by the terminal device 30 acquired by the acquisition unit 57.

[0061] The positional misalignment characteristic calculation unit 53 determines whether to apply the calculated positional misalignment characteristic. If the positional misalignment characteristic calculation unit 53 determines not to apply the calculated positional misalignment characteristic, it substitutes the power received by the terminal device 30 acquired by the acquisition unit 57 into x in the first estimation formula to calculate the reference voltage of the charging device 10. Hereinafter, in this specification, when the positional misalignment characteristic is applied as appropriate, after detecting the position of the terminal device 30, the power transmission coil 16 moves to a predetermined position set by the power transmission coil position setting unit 52, performs PING transmission / SIG reception, and the reference voltage of the charging device 10 calculated based on the limit value of the operating voltage of the charging device 10 is referred to as the first reference voltage, and when the positional misalignment characteristic is not applied, the reference voltage of the charging device 10 calculated using the first estimation formula is referred to as the second reference voltage.

[0062] On the other hand, when the positional misalignment characteristic calculation unit 53 determines that the calculated positional misalignment characteristic should be applied, it uses the data acquired by the acquisition unit 57 of the operating voltage of the charging device 10 and the power received by the terminal device 30 to calculate the coupling coefficient k using graphs G1 and G2 shown in Figure 4, and determines the coefficients a(k) and b(k). Furthermore, the positional misalignment characteristic calculation unit 53 calculates the limit value of the operating voltage of the charging device 10 from the second estimation formula determined again.

[0063] The foreign object detection unit 54 detects the absence of foreign objects between the power transmitting coil 16 and the power receiving coil 31 based on the coupling state of the power transmitting coil 16 and the power receiving coil 31 when the charging device 10 is not charging and the power receiving coil 31 is placed in a position where it is not misaligned with the power transmitting coil 16. Here, foreign objects are conductive objects such as metal pieces. For example, when wireless charging is performed, a current flows through the foreign object, causing it to overheat. In other words, foreign objects are objects that pose a risk of fire during wireless charging. Furthermore, when wireless charging is performed, a current flows through the foreign object, causing power loss.

[0064] The charging state control unit 55 suppresses power to the power transmission coil 16 when the foreign object detection unit 54 determines that there is a foreign object between the power transmission coil 16 and the power receiving coil 31. The charging state control unit 55 may also stop power to the power transmission coil 16 if it determines that there is a foreign object between the power transmission coil 16 and the power receiving coil 31. In this case, the charging device 10 may notify the user of the possibility of a foreign object being inserted using an indicator, monitor, buzzer, speaker, etc. (not shown in Figure 1). Furthermore, if the terminal device 30 conforms to the MPP standard, the charging device 10 may perform a CLOAK operation on the terminal device 30.

[0065] After the determination unit 59 (described later) determines the positional misalignment between the power transmitting coil 16 and the power receiving coil 31, the charging state control unit 55 controls at least one of the following: stopping power to the power transmitting coil 16 or closing it. After stopping power to the power transmitting coil 16 or closing it, the charging state control unit 55 detects the position of the power receiving coil 31 using the power receiving coil position detection circuit 20, and after the power transmitting coil 16 is moved by the movement mechanism 17 to the position set by the power transmitting coil position setting unit 52, the charging state control unit 55 controls the power transmission instruction unit 56 to resume charging the terminal device 30.

[0066] Furthermore, the charging state control unit 55 controls the power transmission instruction unit 56 to start charging the terminal device 30. Specifically, when the foreign object detection unit 54 determines that there is no foreign object between the power transmission coil 16 and the power receiving coil 31, the charging state control unit 55 controls the power transmission instruction unit 56 to start charging the terminal device 30. The charging state control unit 55 controls the power transmission instruction unit 56 to start charging the terminal device 30 after the foreign object detection unit 54 has determined that there is no foreign object between the power transmission coil 16 and the power receiving coil 31 and has suppressed the power to the power transmission coil 16.

[0067] Furthermore, the charging state control unit 55 determines whether the terminal device 30 has reached a full charge. Specifically, the charging state control unit 55 determines that the terminal device 30 has reached a full charge when it receives an EPT (End Power Transfer) packet from the terminal device 30, or when the average value of RP (Received Power Packet) packets, which notify the received power, over a certain period is extremely low. Once the charging state control unit 55 determines that the terminal device 30 has reached a full charge, it stops charging.

[0068] The power transmission instruction unit 56 controls the DC-DC converter 12 and the bridge circuit 13 based on the instructions from the charge state control unit 55. This supplies power to the power transmission coil 16. Specifically, the power transmission instruction unit 56 instructs the DC-DC converter 12 and the bridge circuit 13 to energize, thereby generating a magnetic flux in the power transmission coil 16 and transmitting power to it. The magnetic flux generated in the power transmission coil 16 induces an electromotive force in the power receiving coil 31, and the terminal device 30 is charged.

[0069] The acquisition unit 57 acquires the operating voltage of the charging device 10 and the power received by the terminal device 30. Specifically, at time t, the acquisition unit 57 periodically acquires the DC voltage that the DC-DC converter 12 has boosted or stepped down, as detected by the voltage detection circuit 14.

[0070] For example, the acquisition unit 57 acquires the magnitude of the received power Rp(t) received by the receiving coil 31 at time t from the terminal device 30. Alternatively, for example, the acquisition unit 57 receives information including the received power Rp(t) and the received power target value CEP (Control Error Packet) sent from the terminal device 30 via packet communication. The acquisition unit 57 then acquires the received power Rp(t) by demodulating the received information.

[0071] Furthermore, the acquisition unit 57 determines whether the power received by the terminal device 30 is stable. Here, "stable power received by the terminal device 30" means that the power is constant, at least for a short period of time, and the amount of change in the power received is within a certain range. Here, "certain range" means, for example, that the absolute value of the packets instructing CEP from the terminal device 30 is 1 or less. However, the "certain range" is not limited to this. For example, the "certain range" includes the case where the power received has already reached the contracted power.

[0072] The acquisition unit 57 then determines whether the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to a voltage threshold. Here, for example, Vout1 is the operating voltage when there is no misalignment, and Vout2 is the operating voltage at the amount of misalignment for which misalignment should be determined. The voltage threshold is set in advance to (Vout2-Vout1) and is stored in the memory unit, based on measured values ​​from a standard machine / actual machine or a value calculated from a simulation model, etc.

[0073] Furthermore, the acquisition unit 57 determines whether there has been an increase in the power received by the terminal device 30. For example, the acquisition unit 57 determines that there has been no increase in the power received by the terminal device 30 when the difference between the power received by the terminal device 30 and the reference power received by the terminal device 30 is within a certain range.

[0074] Furthermore, the acquisition unit 57 determines whether there is a decrease in the power received by the terminal device 30. For example, if the acquisition unit 57 determines that the power received by the terminal device 30 is unstable and that the amount of change in the power received is less than a predetermined threshold, it determines that there is a decrease in the power received by the terminal device 30. Here, the predetermined threshold is a threshold for determining the power decrease. This predetermined threshold is set based on the amount of power decrease when the positional displacement exceeds the amount that should be determined when the operating voltage is not changed.

[0075] The acquisition unit 57 then determines whether the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is equal to or greater than the operating voltage of the charging device 10. Specifically, if the acquisition unit 57 determines that there is a decrease in the power received by the terminal device 30, and the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is equal to or greater than the voltage within a certain range of the change in power received.

[0076] When the charging state control unit 55 instructs the power transmission instruction unit 56 to start wireless charging to the terminal device 30, the parameter setting unit 58 initializes the parameters for determining the misalignment. Here, the parameters include the reference voltage of the charging device 10 and the reference power received by the terminal device 30, which are used as a reference when determining the misalignment.

[0077] Furthermore, the parameter setting unit 58 sets parameters after wireless charging has started. Specifically, the parameter setting unit 58 determines whether the reference voltage of the charging device 10 is undetermined after wireless charging has started. If the reference voltage of the charging device 10 is undetermined after wireless charging has started, the parameter setting unit 58 sets the parameters as follows: (reference voltage of charging device 10) = (operating voltage of charging device 10) and (reference power received by terminal device 30) = (power received by terminal device 30).

[0078] Furthermore, the parameter setting unit 58 updates the parameters. Specifically, after wireless charging has started, the parameter setting unit 58 updates the parameters if the voltage difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10 is less than the voltage threshold. Also, after wireless charging has started, the parameter setting unit 58 updates the parameters if the voltage difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10 is greater than or equal to the voltage threshold, and the power received by the terminal device 30 is not stable.

[0079] Furthermore, the parameter setting unit 58 updates the parameters if the determination unit 59 determines that the voltage difference is less than the voltage threshold. Then, after wireless charging has started, the parameter setting unit 58 updates the parameters if the determination unit 59 determines that the operating voltage of the charging device 10 is less than the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula.

[0080] The parameter setting unit 58 sets the following when the operating voltage of the charging device 10 is greater than (reference voltage + first change) and the received power is greater than (reference received power + second change): (reference voltage of charging device 10) = (operating voltage of charging device 10) and (reference received power of terminal device 30) = (received power of terminal device 30). Also, the parameter setting unit 58 sets the following when the operating voltage of the charging device 10 is less than (reference voltage - first change) and the received power is less than (reference received power - second change): (reference voltage of charging device 10) = (operating voltage of charging device 10) and (reference received power of terminal device 30) = (received power of terminal device 30).

[0081] The determination unit 59 determines the misalignment between the transmitting coil 16 and the receiving coil 31 according to the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device. Specifically, the determination unit 59 determines the misalignment between the transmitting coil 16 and the receiving coil 31 when the received power is stable. Furthermore, when the received power is stable, if the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to a voltage threshold, the determination unit 59 determines that there is a misalignment between the transmitting coil 16 and the receiving coil 31. In addition, when the received power is stable, if the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to a voltage threshold, and determines that there is no increase in the received power of the terminal device 30, the determination unit 59 determines that there is a misalignment between the transmitting coil 16 and the receiving coil 31. Here, the determination unit 59 determines that there is a misalignment between the power transmission coil 16 and the power receiving coil 31, and this will be explained using Figure 5.

[0082] Figure 5 is a schematic diagram illustrating the misalignment state between the power transmission coil 16 and the power receiving coil 31 according to the embodiment. Figure 5 is a graph with time on the horizontal axis and the operating voltage Vout and power received RP of the charging device 10 on the vertical axis. Figure 5 also shows the reference voltage Vref for determining the misalignment, the voltage threshold Vth, the reference power received Pref when the reference voltage Vref is determined, and the change in power received ΔRP when the power is stable.

[0083] For example, as shown in Figure 5, after the received power RP stabilizes, when a misalignment occurs, the operating voltage Vout of the charging device 10 rises and the received power RP falls, making it unstable. Also, immediately before misalignment detection T61, the operating voltage Vout of the charging device 10 rises and the received power RP rises, making it unstable. Furthermore, immediately after misalignment detection T62, the operating voltage Vout of the charging device 10 rises and the received power RP remains constant and stable. In addition, before and after misalignment detection, the difference between the operating voltage Vout of the charging device 10 and the reference voltage Vref of the charging device 10 is greater than or equal to the voltage threshold Vth.

[0084] Returning to Figure 2, the explanation continues. When the determination unit 59 determines that the received power RP has decreased and that the voltage difference between the operating voltage Vout of the charging device 10 and the reference voltage Vref of the charging device 10 is equal to or greater than or equal to that of the receiving coil 31, it determines that there is a misalignment between the transmitting coil 16 and the receiving coil 31. Here, the details of how the determination unit 59 determines that there is a misalignment between the transmitting coil 16 and the receiving coil 31 will be explained using Figure 6.

[0085] Figure 6 is a schematic diagram illustrating the positional misalignment between the power transmission coil 16 and the power receiving coil 31 according to this embodiment. Figure 6 is a graph with time on the horizontal axis and the operating voltage Vout and power received RP of the charging device 10 on the vertical axis. Figure 6 also shows a reference voltage Vref for determining the positional misalignment, the change in the operating voltage Vout ΔV when the power is stable, the reference power received Pref when the reference voltage Vref is determined, and a threshold Pth for determining the power decrease.

[0086] For example, as shown in Figure 6, when a misalignment occurs, the operating voltage Vout of the charging device 10 rises and the received power RP falls, but since it is greater than the threshold Pth for determining power reduction, the received power can be said to be constant. Also, at the time of misalignment detection T63, the operating voltage Vout of the charging device 10 rises and the received power RP rises, but since it is less than the threshold Pth for determining power reduction, the received power can be said to be decreasing. Furthermore, before and after the detection of misalignment, the difference between the operating voltage Vout of the charging device 10 and the reference voltage Vref of the charging device 10 is equal to or greater than the change in the operating voltage Vout ΔV during power stabilization. Therefore, the determination unit 59 determines a misalignment when, in a state where the received power RP is decreasing, the voltage difference representing the difference between the operating voltage Vout of the charging device 10 and the reference voltage Vref of the charging device 10 is greater than or equal to the voltage within a certain range of change in the received power RP.

[0087] Returning to Figure 2, the explanation continues. When the determination unit 59 determines that the received power RP has increased, it determines whether there is enough data to derive the first estimation formula. Also, when the determination unit 59 determines that the received power RP has decreased and the voltage difference indicating the difference between the operating voltage Vout of the charging device 10 and the reference voltage Vref of the charging device 10 is less than or equal to the same value, the positional displacement characteristic calculation unit 53 determines whether there is enough data to derive the first estimation formula fv(x) = a*x + b.

[0088] Then, the determination unit 59 determines that there is a positional misalignment between the power transmission coil 16 and the power receiving coil 31 if the voltage difference, which represents the difference between the operating voltage of the power transmission device 10 acquired by the acquisition unit 57 and the reference voltage of the power transmission device 10 calculated by the positional misalignment characteristic calculation unit 53 using the first estimation formula, is greater than or equal to a voltage threshold.

[0089] Figure 7 is a schematic diagram illustrating the positional misalignment between the power transmission coil 16 and the power receiving coil 31 according to this embodiment. Figure 7 is a graph with time on the horizontal axis and the operating voltage Vout of the charging device 10 on the vertical axis. Here, the power received RP of the terminal device 30 acquired by the acquisition unit 57 is substituted into the first estimation formula fv(x) = a*x + b, and the change in the reference voltage Vref of the charging device 10 is shown as graph G5. Furthermore, the result of adding the voltage threshold Vth to graph G5 is shown as graph G6. Here, the voltage threshold Vth is assumed to be a fixed value.

[0090] For example, as shown in Figure 7, at positional misalignment detection time T64, the operating voltage Vout of the charging device 10 is above graph G6. In other words, the difference between the reference voltage of the charging device 10 calculated using the first estimation formula and the Vout is greater than or equal to the voltage threshold.

[0091] Figure 8 is a schematic diagram illustrating the positional misalignment between the power transmission coil 16 and the power receiving coil 31 according to this embodiment. Figure 8 is a graph with time on the horizontal axis and the operating voltage Vout of the charging device 10 on the vertical axis. Here, the power received RP of the terminal device 30 acquired by the acquisition unit 57 is substituted into the first estimation formula fv(x) = a*x + b, and the change in the reference voltage Vref of the charging device 10 is shown as graph G7. Furthermore, the result of adding the voltage threshold Vth to graph G7 is shown as graph G8. Here, the voltage threshold Vth is assumed to be a linked value that is linked to the power received.

[0092] For example, as shown in Figure 8, at positional misalignment detection time T65, the operating voltage Vout of the charging device 10 is above graph G8. In other words, the voltage difference, which represents the difference from the reference voltage of the charging device 10 calculated using the first estimation formula, is above the voltage threshold.

[0093] Returning to Figure 2, the explanation continues. The determination unit 59 determines that there is a positional misalignment between the power transmitting coil 16 and the power receiving coil 31 if the operating voltage of the charging device 10 acquired by the acquisition unit 57 is greater than or equal to the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula determined again by the positional misalignment characteristic calculation unit 53. Here, the details of how the determination unit 59 determines that there is a positional misalignment between the power transmitting coil 16 and the power receiving coil 31 will be explained using Figure 9.

[0094] Figure 9 is a schematic diagram illustrating the positional misalignment between the power transmission coil 16 and the power receiving coil 31 according to the embodiment. Figure 9 is a graph with time on the horizontal axis and the operating voltage Vout of the charging device 10 on the vertical axis. Here, the first estimation equation is denoted as graph G9. Furthermore, using the positional misalignment characteristics, the power received by the terminal device 30 acquired by the acquisition unit 57 is substituted into fvk(x)=a(k)*x+b(k), and the change in the limit value of the operating voltage Vout of the charging device 10 corresponding to the positional misalignment characteristics is denoted as graph G10.

[0095] For example, as shown in Figure 9, at positional displacement detection time T66, the operating voltage Vout of the charging device 10 exceeds graph G10. In other words, the operating voltage of the charging device 10 is greater than or equal to the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula determined again by the positional displacement characteristic calculation unit 53.

[0096] Furthermore, in this embodiment, the charging device 10 performs positional misalignment determination after wireless charging begins. If the foreign object detection circuit 21 detects that there is a metallic foreign object between the transmitting coil 16 and the receiving coil 31, it is desirable to prioritize the foreign object detection process.

[0097] Figure 10 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 10 explains the contents of the processing performed by the charging device 10 until wireless charging begins.

[0098] The terminal position detection unit 51 detects the position of the terminal device 30 when the terminal device 30 is placed on the charging base 19 (step S11). Next, the power receiving coil position detection circuit 20 detects the position of the power receiving coil 31 (step S12). Subsequently, the power transmitting coil position setting unit 52 sets the position of the power transmitting coil 16 to a position opposite the power receiving coil 31 based on the position of the power receiving coil 31 detected by the power receiving coil position detection circuit 20. Then, the power transmitting coil 16 is moved by the moving mechanism 17 to the position set by the power transmitting coil position setting unit 52 (step S13).

[0099] Next, the foreign object detection circuit 21 performs a foreign object detection process (step S14). Subsequently, the foreign object detection unit 54 detects whether there is any foreign object between the power transmission coil 16 and the power receiving coil 31 based on the coupling state of the power transmission coil 16 and the power receiving coil 31 when the power receiving coil 31 is placed in a position where it is not misaligned with the power transmission coil 16 while the charging device 10 is not performing a charge (step S15). If the foreign object detection unit 54 detects that there is no foreign object between the power transmission coil 16 and the power receiving coil 31 (step S15: Yes), the process proceeds to step S17. On the other hand, if the foreign object detection unit 54 detects that there is a foreign object between the power transmission coil 16 and the power receiving coil 31 (step S15: No), the process proceeds to step S16.

[0100] In step S16, the charging state control unit 55 suppresses power to the power transmission coil 16 (step S16). In step S17, the charging state control unit 55 instructs the power transmission instruction unit 56 to start charging the terminal device 30 (step S17). Subsequently, the parameter setting unit 58 initializes the parameters for positional misalignment determination when the charging state control unit 55 instructs the power transmission instruction unit 56 to start charging the terminal device 30 (step S18). Subsequently, the positional misalignment characteristic calculation unit 53 calculates the positional misalignment characteristics (step S19). When the processing in step S19 is completed, the charging device 10 proceeds to process A.

[0101] Figure 11 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 11 shows the content of the processing that describes step S13 in more detail in order to perform step S19 shown in Figure 10.

[0102] The power transmission coil position setting unit 52 determines whether to utilize the misalignment characteristics (step S131). If the power transmission coil position setting unit 52 determines that the misalignment characteristics will not be utilized (step S131: No), the charging device 10 proceeds to step S134. On the other hand, if the power transmission coil position setting unit 52 determines that the misalignment characteristics will be utilized (step S131: Yes), the device proceeds to step S132. In step S132, after detecting the position of the terminal device 30, the power transmission coil position setting unit 52 sets the power transmission coil 16 to move to a predetermined position in order to calculate the misalignment characteristics (step S132).

[0103] Next, the positional misalignment characteristic calculation unit 53 performs PING transmission / SIG reception (step S133). Subsequently, the power transmission coil position setting unit 52 sets the power transmission coil 16 to a position where there is no positional misalignment with the power receiving coil 31 (step S134). By executing the processes from step S131 to step S134, the charging device 10 can perform step S19 shown in Figure 10.

[0104] Figure 12 is a flowchart illustrating an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 12 corresponds to process A shown in Figure 10. Furthermore, Figure 12 describes the processing performed by the charging device 10 from the start of wireless charging until the positional misalignment between the transmitting coil 16 and the receiving coil 31 is determined.

[0105] The acquisition unit 57 acquires the operating voltage of the charging device 10 and the power received by the terminal device 30 (step S21). Next, the acquisition unit 57 determines whether the power received by the terminal device 30 is stable (step S22). If the acquisition unit 57 determines that the power received by the terminal device 30 is not stable (step S22: No), the process proceeds to D. On the other hand, if the acquisition unit 57 determines that the power received by the terminal device 30 is stable (step S22: Yes), the process proceeds to step S23. In step S22, the power received by the terminal device 30 is considered stable if the absolute value of the packets instructing CEP from the terminal device 30 is 1 or less.

[0106] In step S23, the parameter setting unit 58 sets the parameters (step S23). Next, the acquisition unit 57 determines whether the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to the voltage threshold (step S24). If the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is less than the voltage threshold (step S24: No), the process proceeds to step B. On the other hand, if the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to the voltage threshold (step S24: Yes), the process proceeds to step S25.

[0107] In step S25, the acquisition unit 57 determines whether the power received by the terminal device 30 is stable (step S25). If the acquisition unit 57 determines that the power received by the terminal device 30 is not stable (step S25: No), the process proceeds to step S26. On the other hand, if the acquisition unit 57 determines that the power received by the terminal device 30 is stable (step S25: Yes), the process proceeds to step S27. In step S25, the power received by the terminal device 30 being stable means that the power received has already reached the contracted power.

[0108] In step S26, the acquisition unit 57 determines whether there is an increase in the power received by the terminal device 30 (step S26). If the acquisition unit 57 determines that there is an increase in the power received by the terminal device 30 (step S26: No), the process proceeds to step B. On the other hand, if the acquisition unit 57 determines that there is no increase in the power received by the terminal device 30 (step S26: Yes), the process proceeds to step S27. In step S27, the determination unit 59 determines that there is a misalignment between the power transmission coil 16 and the power receiving coil 31 (step S27). After the process in step S27 is completed, the charging device 10 proceeds to process C.

[0109] Figure 13 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 13 shows the processing content that explains step S23 shown in Figure 12 in more detail.

[0110] The parameter setting unit 58 determines whether the reference voltage of the charging device 10 is undetermined (step S231). If the parameter setting unit 58 determines that the reference voltage of the charging device 10 is not undetermined (is determined) (step S231: No), the process proceeds to step S24 shown in Figure 12. On the other hand, if the parameter setting unit 58 determines that the reference voltage of the charging device 10 is undetermined (step S231: Yes), the process proceeds to step S232.

[0111] In step S232, the parameter setting unit 58 sets the parameters as follows: (reference voltage of charging device 10) = (operating voltage of charging device 10) and (reference power received by terminal device 30) = (power received by terminal device 30) (step S232). When the processing in step S232 is completed, the charging device 10 proceeds to the processing in step S24 shown in Figure 12.

[0112] Figure 14 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 14 corresponds to the processing D shown in Figure 12. Note that the processing of step S27 shown in Figure 14 is the same as the processing of step S27 shown in Figure 12, so a detailed explanation is omitted.

[0113] The acquisition unit 57 determines whether there is a decrease in the power received by the terminal device 30 (step S31). If the acquisition unit 57 determines that there is no decrease in the power received by the terminal device 30 (step S31: No), the process proceeds to step S33. On the other hand, if the acquisition unit 57 determines that there is a decrease in the power received by the terminal device 30 (step S31: Yes), the process proceeds to step S32.

[0114] In step S32, the acquisition unit 57 determines whether the voltage difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10 is equal to or greater than or equal to (step S32). If the acquisition unit 57 determines that the voltage difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10 is equal to or greater than or equal to (step S32: Yes), the process proceeds to step S27. On the other hand, if the acquisition unit 57 determines that the voltage difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10 is less than or equal to (step S32: No), the process proceeds to step S33.

[0115] In step S33, the positional displacement characteristic calculation unit 53 determines whether there is enough data to use the first estimation formula (step S33). If the positional displacement characteristic calculation unit 53 determines that there is not enough data to use the first estimation formula (step S33: No), the process proceeds to step B. On the other hand, if the positional displacement characteristic calculation unit 53 determines that there is enough data to use the first estimation formula (step S33: Yes), the process proceeds to step S34.

[0116] In step S34, the misalignment characteristic calculation unit 53 derives a first estimation formula using the operating voltage of the charging device 10 and the power received by the terminal device 30 acquired by the acquisition unit 57 (step S34). Next, the misalignment characteristic calculation unit 53 determines whether to apply the calculated misalignment characteristics (step S35). If the misalignment characteristic calculation unit 53 determines to apply the calculated misalignment characteristics (step S35: Yes), the process proceeds to step S38. On the other hand, if the misalignment characteristic calculation unit 53 determines not to apply the calculated misalignment characteristics (step S35: No), the process proceeds to step S36.

[0117] In step S36, if the positional misalignment characteristic calculation unit 53 determines that the calculated positional misalignment characteristic should not be applied, it substitutes the power received by the terminal device 30 acquired by the acquisition unit 57 into x in the first estimation formula to calculate the reference voltage of the charging device 10 (step S36). Next, the determination unit 59 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 acquired by the acquisition unit 57 and the reference voltage of the charging device 10 calculated by the positional misalignment characteristic calculation unit 53 using the first estimation formula, is greater than or equal to the voltage threshold (step S37). Here, if the determination unit 59 determines that the voltage difference is greater than or equal to the voltage threshold (step S37: Yes), it proceeds to step S27. On the other hand, if the determination unit 59 determines that the voltage difference is less than the voltage threshold (step S37: No), it proceeds to process B.

[0118] In step S38, the positional misalignment characteristic calculation unit 53 uses the data acquired by the acquisition unit 57 for the operating voltage of the charging device 10 and the power received by the terminal device 30 to calculate the coupling coefficient k using graphs G1 and G2 shown in Figure 4, determine the coefficient a(k) and coefficient b(k), and then determine the second estimation formula again (step S38). Subsequently, the positional misalignment characteristic calculation unit 53 calculates the limit value of the operating voltage of the charging device 10 from the second estimation formula that was determined again (step S39).

[0119] Next, the determination unit 59 determines whether the operating voltage of the charging device 10 acquired by the acquisition unit 57 is equal to or greater than the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula determined again by the positional deviation characteristic calculation unit 53 (step S40). If the determination unit 59 determines that the operating voltage of the charging device 10 is equal to or greater than the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula (step S40: Yes), the process proceeds to step S27. On the other hand, if the determination unit 59 determines that the operating voltage of the charging device 10 is less than the limit value of the operating voltage of the charging device 10 calculated from the second estimation formula (step S40: No), the process proceeds to process B.

[0120] Figure 15 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 15 corresponds to processing B shown in Figures 12 and 14.

[0121] The parameter setting unit 58 updates the parameters (step S51). Next, the charging state control unit 55 determines whether the terminal device 30 is fully charged (step S52). If the charging state control unit 55 determines that the terminal device 30 is not fully charged (step S52: No), the process proceeds to A. On the other hand, if the charging state control unit 55 determines that the terminal device 30 is fully charged (step S52: Yes), the process proceeds to step S53.

[0122] In step S53, the charging state control unit 55 determines that the terminal device 30 is fully charged and stops charging (step S53). When the process in step S53 is completed, the charging device 10 terminates wireless charging.

[0123] Figure 16 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 16 shows the processing content that explains step S51 shown in Figure 15 in more detail.

[0124] The parameter setting unit 58 determines whether the operating voltage of the charging device 10 is greater than (reference voltage + first change) and the received power is greater than (reference received power + second change) (step S511). If the parameter setting unit 58 determines that the conditions that the operating voltage of the charging device 10 is greater than (reference voltage + first change) and the received power is greater than (reference received power + second change) are met (step S511: Yes), the process proceeds to step S513. On the other hand, if the parameter setting unit 58 determines that the conditions that the operating voltage of the charging device 10 is greater than (reference voltage + first change) and the received power is greater than (reference received power + second change) are not met (step S511: No), the process proceeds to step S512.

[0125] In step S512, the parameter setting unit 58 determines whether the operating voltage of the charging device 10 is less than (reference voltage - first change) and the received power is less than (reference received power - second change) (step S512). If the parameter setting unit 58 determines that the conditions that the operating voltage of the charging device 10 is less than (reference voltage - first change) and the received power is less than (reference received power - second change) are not met (step S512: No), this process ends. On the other hand, if the parameter setting unit 58 determines that the conditions that the operating voltage of the charging device 10 is less than (reference voltage - first change) and the received power is less than (reference received power - second change) are met (step S512: Yes), the process proceeds to step S513.

[0126] In step S513, the parameter setting unit 58 sets (reference voltage of charging device 10) = (operating voltage of charging device 10) and (reference power received by terminal device 30) = (power received by terminal device 30) (step S513). When the processing in step S513 or the processing in step S512:No is completed, the charging device 10 terminates the parameter update process.

[0127] In other words, when the received power is decreasing (step S31: Yes), the parameter setting unit 58 sets the operating voltage to the second reference voltage and the received power to the reference received voltage (step S513) if the second voltage difference, which represents the difference between the operating voltage of the charging device 10 and the second reference voltage corresponding to the positional misalignment determination, is less than the voltage threshold that represents the difference between the first operating voltage of the charging device 10 when there is a positional misalignment and the second operating voltage of the charging device 10 when there is no positional misalignment (step S32: No), and the operating voltage of the charging device 10 is greater than the sum of the second reference voltage and the first change amount, and the received power is greater than the sum of the reference received power and the second change amount. Then, the parameter setting unit 58 sets the operating voltage to the second reference voltage and the received power to the reference received power (step S513) if the second voltage difference, which indicates the difference between the operating voltage of the charging device 10 and the second reference voltage, is less than the voltage threshold that indicates the difference between the first operating voltage of the charging device 10 when there is a misalignment and the second operating voltage of the charging device 10 when there is no misalignment (step S32: No), and the operating voltage of the charging device 10 is less than the difference between the second reference voltage and the first change amount, and the received power is less than the difference between the reference received power and the second change amount (step S512: Yes).

[0128] Figure 17 is a flowchart showing an example of the processing flow performed by the charging device 10 according to this embodiment. Figure 17 corresponds to process A shown in Figure 12. In other words, Figure 17 shows the processing after the charging device 10 has determined the positional misalignment between the power transmission coil 16 and the power receiving coil 31. Steps S12 and S13 shown in Figure 17 are the same as steps S12 and S13 shown in Figure 10, so their explanation is omitted.

[0129] In step S61, the charging state control unit 55, when the determination unit 59 (described later) determines the misalignment between the transmitting coil 16 and the receiving coil 31, stops or closes the power supply to the transmitting coil 16 (step S61).

[0130] In step S64, the charging state control unit 55 instructs the power transmission instruction unit 56 to resume charging the terminal device 30 (step S64). After the processing in step S64 is completed, the charging device 10 proceeds to process A.

[0131] As described above, a charging device 10 according to one aspect of the present disclosure is a charging device that performs wireless charging by placing a terminal device 30 equipped with a power receiving coil 31 that receives wirelessly transmitted power on a charging base 19. The charging device 10 includes a power transmission coil 16 that transmits power to the terminal device 30, an acquisition unit 57 that acquires the operating voltage of the charging device 10 and the power received by the terminal device 30 after the charging device 10 starts wireless charging of the terminal device 30, a positional misalignment characteristic calculation unit 53 that calculates a first reference voltage of the charging device 10, and a determination unit 59 that determines the positional misalignment between the power transmission coil 16 and the power receiving coil 31 according to a first voltage difference that indicates the difference between the operating voltage of the charging device 10 and the first reference voltage.

[0132] For example, if the charging device 10 detects positional misalignment using the difference in transmission efficiency and transmitted / received power, it needs to use the communication data transmitted from the terminal device 30. Furthermore, the accuracy of the power information included in the communication data may affect the detection accuracy of positional misalignment detection. In addition, when the received power of the terminal device 30 is stable, the transmission efficiency changes according to the load state of the terminal device 30, but the voltage value of the charging device 10 increases or decreases due to the CEP from the terminal device 30. Therefore, simply monitoring the change in the voltage value of the charging device 10 may lead to false detections if positional misalignment detection is determined in response to the increase in transmitted power that occurs during normal operation.

[0133] The charging device 10 according to this disclosure can determine the misalignment between the transmitting coil 16 and the receiving coil 31 using only the voltage value of the charging device 10. Therefore, it is not affected by communication data from the terminal device 30 or increases in transmitted power. As a result, the charging device 10 can detect even slight misalignments between the transmitting coil 16 and the receiving coil 31, and after detection, correct the misalignment again to continue high-power charging. Consequently, the charging device 10 can improve the power efficiency of wireless charging compared to conventional devices.

[0134] The embodiments described above can also be modified and implemented as appropriate by changing some of the configurations or functions of each of the devices described above. Therefore, several modifications of the embodiments described above will be described below as other embodiments. In the following, we will mainly describe the differences from the embodiments described above, and will omit detailed explanations of points that are common with what has already been described.

[0135] (First variation) For example, the charging device 10 may determine the misalignment between the power transmission coil 16 and the power receiving coil 31 using a different process for the process from step S25 onward as described in Figure 12 above.

[0136] For example, the determination unit 59 determines the misalignment if, while the power RP received by the terminal device 30 is stable, the first voltage difference is greater than or equal to a voltage threshold indicating the difference between the first operating voltage of the charging device 10 when there is a misalignment and the second operating voltage of the charging device 10 when there is no misalignment, and the first voltage difference is greater than or equal to the first threshold. The determination unit 59 also determines the misalignment if, while the power RP received by the terminal device 30 is stable, the first voltage difference is greater than or equal to a voltage threshold indicating the difference between the first operating voltage of the charging device 10 when there is a misalignment and the second operating voltage of the charging device 10 when there is no misalignment, and the first voltage difference is greater than or equal to the second threshold.

[0137] Figure 18 is a flowchart showing an example of the processing flow performed by the charging device 10 according to the first modified example. The processes from steps S21 to S25 and step S27 shown in Figure 18 are the same as the processes from steps S21 to S25 and step S27 shown in Figure 12, so no explanation is provided.

[0138] In step S71, the acquisition unit 57 determines whether the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to a first threshold (step S71). The first threshold is, for example, 1[V]. However, the value of the first threshold is not limited to this. If the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to the first threshold (step S71:Yes), the process proceeds to step S27. On the other hand, if the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is less than the first threshold (step S71:No), the process proceeds to process B.

[0139] In step S72, the acquisition unit 57 determines whether the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to the second threshold (step S72). The second threshold is, for example, less than or equal to the first threshold. If the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is greater than or equal to the second threshold (step S72: Yes), the process proceeds to step S27. On the other hand, if the acquisition unit 57 determines that the voltage difference, which represents the difference between the operating voltage of the charging device 10 and the reference voltage of the charging device 10, is less than the second threshold (step S72: No), the process proceeds to process B.

[0140] (Second variation) For example, if the charging device 10 conforms to the MPP standard, there is a procedure for estimating the coupling coefficient k at the start of wireless charging, and the second estimation formula may be derived using the estimated coupling coefficient. For example, the positional misalignment characteristic calculation unit 53 estimates the coupling coefficient k3 at time t1. The positional misalignment characteristic calculation unit 53 also estimates the coupling coefficient k4 at time t2. Here, the positional misalignment characteristic calculation unit 53 calculates the future coupling coefficient k using the formula k = α*k3 + β*k4, where α + β = 1.

[0141] As a result, the positional displacement characteristic calculation unit 53 can derive the second estimation formula without using graphs G2 and G3 shown in Figure 4. Therefore, the charging device 10 can estimate the limit value of its operating voltage at an earlier timing.

[0142] (Third variation) In the embodiments described above, the charging device 10 was described as having a voltage threshold Vth that is linked to the received power, as shown in Figure 8, but it is not limited to this. For example, the voltage threshold Vth is updated by sequential determination at each step, but extremely small deviations within an acceptable range that do not affect the position deviation determination may accumulate. If extremely small deviations continue to accumulate in the voltage threshold Vth, the accuracy of the position deviation determination may decrease.

[0143] Therefore, a reference voltage threshold Vth is set as the voltage threshold Vth that is linked to the received power. If the voltage threshold Vth is lower than the reference voltage threshold, the charging device 10 performs positional deviation determination based on the voltage threshold Vth. Also, if the voltage threshold Vth is higher than the reference voltage threshold, the charging device 10 performs positional deviation determination based on the reference voltage threshold. The reference voltage threshold may be set in advance, or it may be set using a coupling coefficient k.

[0144] (Fourth variation) For example, the charging device 10 may arrange multiple magnetic field sensors on the charging base 19 so as to surround the receiving coil 31, and detect the misalignment between the transmitting coil 16 and the receiving coil 31 by acquiring the balance of magnetic field strength output by these magnetic field sensors. In this way, the charging device 10 can detect the misalignment during wireless charging by arranging multiple magnetic field sensors.

[0145] (Fifth variation) For example, the charging device 10 may determine the positional displacement using the efficiency E(t). Specifically, the charging device 10 moves the power transmission coil 16 according to a predetermined procedure (for example, up, down, left, and right). The charging device 10 also calculates the power received by the power receiving coil 31 based on the communication data received by the power transmission coil 16 from the power receiving coil 31. Furthermore, the charging device 10 compares the efficiency E(t) calculated during wireless charging with a pre-set threshold Eth. The charging device 10 then determines that a positional displacement of the terminal device 30 has occurred when the efficiency E(t) is less than the threshold Eth.

[0146] (Sixth variation) For example, the charging device 10 may include a plurality of detection coils for detecting the position of the power receiving coil 31 of the terminal device 30 placed on the charging base 19. For example, the plurality of detection coils may be positioned opposite the power receiving coil 31 of the terminal device 30 placed on the charging base 19. Alternatively, the plurality of detection coils may be arranged in a matrix in directions that intersect each other.

[0147] (Hardware configuration) Figure 19 shows an example of the hardware configuration of the charging system 100 according to the embodiment and modified example. In the charging device 10 and terminal device 30 of the charging system 100 according to the embodiment and modified example, the processor 41, main memory 42, auxiliary memory 43, and device I / F 44 are interconnected by a bus 45, etc., and the hardware configuration is that of a normal computer.

[0148] The processor 41 is, for example, a CPU, and is an arithmetic unit that controls the charging device 10 and terminal device 30 of the above embodiment and modified examples. The main memory 42 is, for example, RAM, and stores data necessary for various processes performed by the processor 41. The auxiliary memory 43 is, for example, ROM, and stores programs and the like that realize information processing by the processor 41. The main memory 42 and the auxiliary memory 43 are examples of storage units.

[0149] The device interface 44 is an interface for various inputs / outputs and / or communications of the charging device 10 and the terminal device 30. For example, the device interface 44 may include a communication interface configured to allow connection of an external communication device that communicates with the charging device 10 and the terminal device 30, or configured to function as such a communication device.

[0150] As for communication interfaces, wired communication circuits such as USB (Universal Serial Bus®) and Ethernet®, or wireless communication circuits compatible with various standards such as 3G, LTE, 4G, 5G, 6G, Wi-Fi®, and Bluetooth® can be used as appropriate.

[0151] In the above embodiment and modified versions of the charging device 10 and terminal device 30, the processor 41 reads a program from the auxiliary storage device 43 onto the main storage device 42 and executes it, thereby realizing each of the above-mentioned functional units on the computer.

[0152] Furthermore, the programs for executing the above-mentioned processes performed by the charging device 10 and terminal device 30 of the above embodiment and modified version may be stored in an HDD (hard disk drive). Alternatively, the programs for executing the above-mentioned processes performed by the charging device 10 and terminal device 30 of the above embodiment and modified version may be pre-installed and provided in an auxiliary storage device 43.

[0153] Furthermore, the program for executing the above-mentioned processing performed by the charging device 10 and terminal device 30 of the above-described embodiment and modified version may be provided as a computer program product by being stored in an installable or executable file format on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD (Digital Versatile Disk), or flexible disk (FD). Alternatively, the program for executing the above-mentioned information processing performed by the charging device 10 and terminal device 30 of the above-described embodiment and modified version may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Furthermore, the program for executing the above-mentioned information processing performed by the charging device 10 and terminal device 30 of the above-described embodiment and modified version may be provided or distributed via a network such as the Internet.

[0154] According to at least one embodiment described above, power efficiency in wireless charging can be improved compared to conventional methods.

[0155] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0156] 10 Charging device 16 Power transmission coil 30 Terminal devices 31 Power receiving coil 51 Terminal location detection unit 52 Power transmission coil position setting unit 53 Positional displacement characteristic calculation unit 54 Foreign object detection unit 55 Charging State Control Unit 56 Power transmission instruction unit 57 Acquisition Department 58 Parameter setting section 59 Decision Section

Claims

1. A charging device that performs wireless charging by placing a terminal device equipped with a receiving coil for receiving wirelessly transmitted power on a charging base, A power transmission coil for transmitting power to the terminal device, After the charging device starts wireless charging to the terminal device, an acquisition unit acquires the operating voltage of the charging device and the power received by the terminal device. A positional misalignment characteristic calculation unit calculates a first reference voltage of the charging device corresponding to the positional misalignment determination, A determination unit that determines the positional misalignment between the power transmission coil and the power receiving coil according to a first voltage difference that indicates the difference between the operating voltage of the charging device and the first reference voltage, A charging device equipped with the following features.

2. The determination unit, when the received power is stable, If the first voltage difference is greater than or equal to a voltage threshold representing the difference between the first operating voltage of the charging device when there is a misalignment and the second operating voltage of the charging device when there is no misalignment, the misalignment is determined. The charging device according to claim 1.

3. The determination unit, when the received power is stable, If the first voltage difference is greater than or equal to the voltage threshold and there is no increase in the received power, the positional shift is determined. The charging device according to claim 2.

4. The determination unit, in a state where the received power is decreasing, If the first voltage difference is greater than or equal to the voltage within a certain range of the change in the received power, the positional shift is determined. The charging device according to claim 1.

5. The positional misalignment characteristic calculation unit calculates a second reference voltage of the charging device corresponding to the positional misalignment determination when the received power is decreasing. The determination unit determines the positional misalignment if the second voltage difference, which represents the difference between the operating voltage of the charging device and the second reference voltage, is greater than or equal to a voltage threshold that represents the difference between the first operating voltage of the charging device when there is a positional misalignment and the second operating voltage of the charging device when there is no positional misalignment. The charging device according to claim 1.

6. The positional displacement characteristic calculation unit calculates the limit value of the operating voltage of the charging device when the received power is decreasing. The determination unit determines the positional misalignment if the operating voltage of the charging device is greater than or equal to the limit value. The charging device according to claim 1.

7. The determination unit, when the received power is stable, If the first voltage difference is greater than or equal to a voltage threshold representing the difference between the first operating voltage of the charging device when there is a misalignment and the second operating voltage of the charging device when there is no misalignment, and the first voltage difference is greater than or equal to the first threshold, the misalignment is determined. The charging device according to claim 1.

8. The determination unit, when the received power is stable, If the first voltage difference is greater than or equal to a voltage threshold representing the difference between the first operating voltage of the charging device when there is a misalignment and the second operating voltage of the charging device when there is no misalignment, and the first voltage difference is greater than or equal to the second threshold, the misalignment is determined. The charging device according to claim 1.

9. The system includes a parameter setting unit for setting parameters including the first reference voltage and the reference power received by the terminal device, The parameter setting unit initializes the parameters after starting the wireless charging. The charging device according to claim 1.

10. The parameter setting unit, when the received power is stable and the parameters are undetermined, sets the first reference voltage to the operating voltage and the reference received power to the received power. The charging device according to claim 9.

11. The parameter setting unit, when the received power is increasing, The operating voltage is greater than the sum of the first reference voltage and the first change, If the received power is greater than the sum of the reference received power and the second change, The first reference voltage is set to the operating voltage, and the reference power received is set to the power received. The charging device according to claim 9.

12. The parameter setting unit, when the received power is increasing, The operating voltage is smaller than the difference between the first reference voltage and the first change amount, If the received power is smaller than the difference between the reference received power and the second change, The first reference voltage is set to the operating voltage, and the reference power received is set to the power received. The charging device according to claim 9.

13. The positional misalignment characteristic calculation unit calculates a second reference voltage of the charging device corresponding to the positional misalignment determination when the received power is decreasing. The parameter setting unit is, The second voltage difference, which represents the difference between the operating voltage of the charging device and the second reference voltage, is less than the voltage threshold that represents the difference between the first operating voltage of the charging device when there is a misalignment and the second operating voltage of the charging device when there is no misalignment, and The operating voltage is greater than the sum of the second reference voltage and the first change, If the received power is greater than the sum of the reference received power and the second change, The operating voltage is set to the second reference voltage, and the received power is set to the reference received power. The charging device according to claim 9.

14. The positional misalignment characteristic calculation unit calculates a second reference voltage of the charging device corresponding to the positional misalignment determination when the received power is decreasing. The parameter setting unit is, The second voltage difference, which represents the difference between the operating voltage of the charging device and the second reference voltage, is less than the voltage threshold that represents the difference between the first operating voltage of the charging device when there is a misalignment and the second operating voltage of the charging device when there is no misalignment, The operating voltage is smaller than the difference between the second reference voltage and the first change amount, If the received power is smaller than the difference between the reference received power and the second change, The operating voltage is set to the second reference voltage, and the received power is set to the reference received power. The charging device according to claim 9.

15. The positional displacement characteristic calculation unit calculates the limit value of the operating voltage of the charging device when the received power is decreasing. The parameter setting unit is, The operating voltage of the charging device is less than the limit value, and The operating voltage is greater than the sum of the first reference voltage and the first change, If the received power is greater than the sum of the reference received power and the second change, The first reference voltage is set to the operating voltage, and the reference power received is set to the power received. The charging device according to claim 9.

16. The positional displacement characteristic calculation unit calculates the limit value of the operating voltage of the charging device when the received power is decreasing. The parameter setting unit is, The operating voltage of the charging device is less than the limit value, and The operating voltage is smaller than the difference between the first reference voltage and the first change amount, If the received power is smaller than the difference between the reference received power and the second change, The first reference voltage is set to the operating voltage, and the reference power received is set to the power received. The charging device according to claim 9.

17. After the determination unit determines the positional misalignment, the system includes a charge state control unit that controls at least one of the following: stopping the power to the power transmission coil or performing a CLOAK process. The charging device according to claim 1.

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