Charging device

Abstract

A charging device that contactlessly charges a power reception coil of a terminal device is provided with: a power transmission coil that transmits power to the terminal device; a power transmission instruction unit that causes the power transmission coil to transmit power; a transmitted power acquisition unit that acquires the magnitude of the transmitted power transmitted by the power transmission instruction unit; a received power acquisition unit that acquires the magnitude of the received power received by the power reception coil; a calculation unit that calculates the ratio of the received power to the transmitted power; and a charge state control unit that limits the transmitted power when the ratio is less than a threshold value.

Description

Technical Field

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

[0002] Recently, a charging device for contactless charging of terminal devices such as smartphones has been known. In such a charging device, an induced electromotive force is generated by electromagnetic induction by passing a magnetic flux generated by an alternating current flowing through a power transmission coil through a power receiving coil built into a terminal device placed on a charging stand. The terminal device is charged by the induced electromotive force generated in the power receiving coil.

[0003] In such a charging device, when the difference between the transmitted power on the charger side and the received power on the receiver side exceeds a predetermined threshold, it is determined that a foreign object is present between the charger and the receiver, and the transmitted power is cut off or limited (for example, Patent Document 1).

[0004] Furthermore, there is also known a charging device (for example, Patent Document 2) which determines that the position of the receiver has shifted when communication of received power from the receiver is disconnected, and corrects the position of the receiver.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: U.S. Patent No. 8039995

[0008] Patent Document 2: International Publication No. 2012 / 173128 Summary of the invention

[0009] The charging device disclosed in Patent Document 1 has a problem in that it is impossible to distinguish whether the power loss calculated based on the relationship between the transmitted power and the received power is caused by foreign matter or by the positional displacement of the receiver.

[0010] In addition, the charging device disclosed in Patent Document 2 has the following problem: the position deviation of the receiver cannot be determined in the area where the communication of the receiving power is not disconnected. There is also the following problem: when the area where the communication of the receiving power is disconnected is outside the foreign object detection range, the foreign object detection is activated before the position deviation of the receiver is detected, so the transmission power is cut off.

[0011] An object of the present disclosure is to provide a charging device that can continue charging as much as possible even if a power transmission coil and a power reception coil are misaligned or a foreign object is inserted between the power transmission coil and the power reception coil.

[0012] The charging device involved in the present disclosure is a terminal device equipped with a power receiving coil, which is placed on a charging seat to perform contactless charging on the terminal device, wherein the power receiving coil receives power transmitted wirelessly, and the charging device includes: a power transmitting coil, which transmits power to the terminal device; a power transmission indication unit, which causes the power transmitting coil to transmit power; a power transmission power acquisition unit, which acquires the size of the power transmission power transmitted by the power transmission indication unit; a power receiving power acquisition unit, which acquires the size of the power receiving power received by the power receiving coil; a calculation unit, which calculates the ratio of the power receiving power to the power transmitting power; and a charging state control unit, which limits the power transmitting power when the ratio is less than a threshold value.

[0013] Effects of the Invention

[0014] According to the charging device of the present disclosure, even if the power transmission coil and the power reception coil are misaligned or a foreign object is inserted between the power transmission coil and the power reception coil, charging can be continued as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a block diagram showing an example of a schematic configuration of a charging device according to an embodiment.

[0016] Figure 2 This is a diagram showing an example of a schematic structure of a charging stand.

[0017] Figure 3A This is a diagram showing an example of a power transmission state when a foreign object is present between the power transmission coil and the power reception coil.

[0018] Figure 3B This is a diagram showing an example of a power transmission state when a positional misalignment occurs between the power transmission coil and the power reception coil.

[0019] Figure 4 This is a functional block diagram showing an example of a functional configuration of a control unit included in the charging device according to the embodiment.

[0020] Figure 5 This is a diagram showing an example of the operation of the charging device when the position of the power receiving coil is misaligned.

[0021] Fig. 6A It is shown in Figure 5 FIG. 2 is a diagram showing an example of the positional relationship between the power receiving coil and the power transmitting coil at time t7.

[0022] Figure 6B It is shown in Figure 5 FIG. 4 is a diagram showing an example of a situation in which the charging device moves the position of the power transmission coil during the period from time t8 to time t13.

[0023] Figure 7This is a flowchart showing an example of the flow of processing performed by the charging device according to the embodiment.

[0024] Figure 8 This is a diagram showing an example of the operation of the charging device when a metallic foreign object is inserted between the power receiving coil and the power transmitting coil.

[0025] Fig.9A It is shown in Figure 8 FIG. 4 is a diagram showing an example of the positional relationship between the power receiving coil and the power transmitting coil at time t4.

[0026] Fig. 9B It is shown in Figure 5 FIG. 4 is a diagram showing an example of a situation in which the charging device moves the position of the power transmission coil during the period from time t5 to time t10.

[0027] Fig.10 This is a diagram showing an example of the operation of the charging device when a metallic foreign object is present between the power receiving coil and the power transmitting coil from the beginning.

[0028] Fig.11 This is a diagram showing an example of the operation of the charging device which continues charging even when the efficiency of the power receiving coil is originally low.

[0029] Fig.12 This is a diagram showing an example of the operation of the charging device when the user moves the position of the terminal device during charging.

[0030] Fig.13 This is a flowchart showing an example of the operation of the first modified example of the charging device according to the embodiment.

[0031] Fig.14 This is a flowchart showing an example of the operation of the second modified example of the charging device according to the embodiment.

[0032] Fig.15 This is a flowchart showing an example of the operation of the third modified example of the charging device according to the embodiment. DETAILED DESCRIPTION

[0033] (Implementation Method)

[0034] Hereinafter, embodiments of a charging device according to the present disclosure will be described with reference to the drawings.

[0035] (Schematic Structure of Charging Device)

[0036] use Figure 1 A schematic structure of the charging device 10 will be described. Figure 1 This is a block diagram showing an example of a schematic configuration of a charging device according to an embodiment.

[0037] The charging device 10 performs contactless charging (hereinafter referred to as charging) on ​​the terminal device 30. The terminal device 30 is, for example, a smartphone. 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 reception coil position detection circuit 20, a foreign object detection circuit 21, and a control unit 22.

[0038] The DC power source 11 supplies DC power for operating the charging device 10 .

[0039] The DC-DC converter 12 steps up or down the DC voltage of the DC power source 11 to a predetermined DC voltage.

[0040] The bridge circuit 13 converts the DC voltage boosted or stepped down by the DC-DC converter 12 into an AC voltage. In addition, the bridge circuit 13 may be a full-bridge circuit or a half-bridge circuit.

[0041] The voltage detection circuit 14 detects the DC voltage stepped up or down by the DC-DC converter 12 .

[0042] The current detection circuit 15 detects the output current of the bridge circuit 13 .

[0043] The power transmission coil 16 generates magnetic flux according to the AC voltage applied from the bridge circuit 13 by using the principle of electromagnetic induction. The generated magnetic flux passes through the power receiving coil 31 of the terminal device 30 placed in a manner overlapping the power transmission coil 16, thereby generating an induced electromotive force in the power receiving coil 31. The built-in battery of the terminal device 30 is charged by the induced electromotive force generated at this time. That is, power is transmitted from the power transmission coil 16 to the power receiving coil 31. In addition, the power receiving coil 31 performs communication based on the Qi standard to transmit the power received by the power receiving coil 31 to the power transmission coil 16.

[0044] The moving mechanism 17 moves the position of the power transmission coil 16 within a two-dimensional coordinate system including the coil surface. The structure of the moving mechanism 17 will be described in detail later (see Figure 2 ). That is, the power transmission coil 16 can change its position by the moving mechanism 17. Therefore, in the following description, the power transmission coil 16 may also be referred to as a movable coil.

[0045] The position detection controller 18 includes a plurality of pattern coils, and the reception coil position detection circuit 20 detects reflected waves that vary depending on the coupling states of the plurality of pattern coils and the reception coil 31 based on pulses output from a pulse output circuit (not shown) connected to each pattern coil.

[0046] The power transmission coil 16, the moving mechanism 17, and the position detection controller 18 are included in the charging stand 19. The upper surface of the charging stand 19 forms a plane on which the terminal device 30 can be placed.

[0047] The power receiving coil position detection circuit 20 acquires the reflected wave from the position detection controller 18 to detect the center position of the power receiving coil 31 .

[0048] The foreign object detection circuit 21 detects whether there is a metal foreign object at a position overlapping with the power transmission coil 16 when the charging device 10 is not charging. More specifically, when the bridge circuit 13 applies an AC voltage to the power transmission coil 16 with a changed frequency, the foreign object detection circuit 21 calculates the sharpness (Q value) of the series resonance state generated by the capacitance component (capacitance) of the capacitor C connected in series between the bridge circuit 13 and the power transmission coil 16 and the resistance component (inductance) of the power transmission coil 16. And, the foreign object detection circuit 21 determines that there is a metal foreign object between the power transmission coil 16 and the power receiving coil 31 by detecting that the calculated Q value is lower than the expected Q value. In addition, a more detailed detection method is disclosed in, for example, Patent Document 2.

[0049] The control unit 22 performs various controls related to the charging state of the charging device 10 .

[0050] The control unit 22 includes a calculation unit 22a, a calculation result comparison unit 22b, a calculation result storage unit 22c, and a power transmission coil position control unit 22d.

[0051] The calculation unit 22 a calculates the power transmitted to the power transmission coil 16 based on the voltage detected by the voltage detection circuit 14 and the current detected by the current detection circuit 15 .

[0052] Furthermore, the calculation unit 22 a calculates the received power of the power receiving coil 31 based on the communication data received by the power transmitting coil 16 from the power receiving coil 31 .

[0053] The calculation unit 22a calculates the ratio of the received power Rp(t) calculated at the same time t to the calculated transmitted power Pout(t), that is, the efficiency E(t)(=Rp(t) / Pout(t)). In addition, the calculation unit 22a may calculate the difference (Pout(t)-Rp(t)) between the transmitted power Pout(t) calculated at the same time t and the calculated received power Rp(t).

[0054] The calculation result comparison unit 22b compares the calculated efficiency E(t) with the preset threshold value Eth. In addition, the calculation result comparison unit 22b instructs the DC-DC converter 12 and the bridge circuit 13 to start or end charging. In addition, the calculation result comparison unit 22b instructs the DC-DC converter 12 and the bridge circuit 13 to continue charging with normal power or to continue charging with limited power. In addition, the calculation result comparison unit 22b instructs the power transmission coil position control unit 22d to move the position of the power transmission coil 16.

[0055] The calculation result storage unit 22c sequentially updates and stores the maximum value of the efficiency E(t) calculated by the calculation unit 22a.

[0056] The power transmission coil position control unit 22d instructs the moving mechanism 17 to move the power transmission coil 16 based on the current position of the power reception coil 31 detected by the power reception coil position detection circuit 20 and the movement instruction of the power transmission coil 16 issued by the calculation result comparison unit 22b.

[0057] In addition, the configuration in which the charging station 19 is provided with a power transmission coil 16 (movable coil) whose position is variable may be described here, but the power transmission coil 16 may also be provided with a plurality of fixed coils. In the case of providing the power transmission coil 16 with a plurality of fixed coils, it is not necessary to Figure 2 The position detection controller 18 and the power receiving coil position detection circuit 20 in the embodiment are replaced by a power supply control unit having a function of selecting one fixed coil from a plurality of fixed coils and supplying power thereto. Figure 2 In the moving mechanism 17, the power transmission coil position control unit 22d gives an instruction to the energization control unit to change the fixed coil to be energized.

[0058] (Charging station structure)

[0059] use Figure 2 The schematic structure of the charging stand 19 will be described. Figure 2 1 is a diagram showing an example of a schematic structure of a charging stand. In addition, the case where the charging stand 19 is provided with a power transmission coil 16 whose position is variable will be described below.

[0060] The charging stand 19 is enclosed by a housing 40 and includes a moving mechanism 17 inside. The moving mechanism 17 moves the power transmission coil 16 along the upper surface of the charging stand 19 in the X-axis direction and the Y-axis direction. The moving mechanism 17 moves the power transmission coil 16 along the X-axis and the Y-axis by the action of the servo motor 32 controlled by the position control circuit 38. The servo motor 32 includes an X-axis servo motor 32a and a Y-axis servo motor 32b. The X-axis servo motor 32a is an actuator that moves the power transmission coil 16 along the X-axis. The Y-axis servo motor 32b is an actuator that moves the power transmission coil 16 along the Y-axis.

[0061] The X-axis servo motor 32a drives a pair of X-axis screws 33a arranged parallel to each other along the X-axis to rotate the pair of X-axis screws 33a. Belts 35 are respectively mounted on both ends of the pair of X-axis screws 33a, and the pair of X-axis screws 33a rotate synchronously in a direction corresponding to the rotation direction of the X-axis servo motor 32a. X-axis nuts 34a are respectively screwed on the pair of X-axis screws 33a. In addition, Figure 2 A guide rod not shown in the figure, which is arranged parallel to a pair of X-axis screws 33a and is used to assist the movement of the X-axis nut member 34a along the X-axis, passes through the X-axis nut member 34a. The X-axis nut members 34a screwed on the pair of X-axis screws 33a are connected to each other through the Y-axis screw 33b and the guide rod 36 arranged parallel to each other. The power transmission coil 16 is constructed in a manner in which a wire is wound on a core 37 composed of a magnetic body such as ferrite. An AC voltage is supplied to the power transmission coil 16 from a power supply circuit 39. A Y-axis nut member 34b is arranged on the back side of the core 37, and the Y-axis screw 33b is screwed into the Y-axis nut member 34b. In addition, the guide rod 36 passes through the core 37 in parallel with the Y-axis screw 33b.

[0062] When the pair of X-axis screws 33a rotates with the rotation of the X-axis servo motor 32a, the pair of X-axis nuts 34a moves in a direction corresponding to the rotation direction of the X-axis screws 33a. Accordingly, the power transmission coil 16 moves along the X-axis.

[0063] The Y-axis servo motor 32b is provided on an X-axis nut member 34a, and drives the Y-axis screw 33b provided along the Y-axis to rotate the Y-axis screw 33b. When the Y-axis screw 33b rotates with the rotation of the Y-axis servo motor 32b, the Y-axis nut member 34b moves in a direction corresponding to the rotation direction of the Y-axis screw 33b. Accordingly, the power transmission coil 16 moves along the Y-axis. In addition, the above is an example, and the power transmission coil moving mechanism can also be realized by other structures, only one of the X-axis and the Y-axis.

[0064] Furthermore, the charging stand 19 may be configured to include a plurality of power transmission coils whose installation positions are fixed, instead of the moving mechanism 17 including the power transmission coil 16 .

[0065] (Positional Relationship between Transmitting Coil and Receiving Coil)

[0066] use Figure 3A , Figure 3B The positional relationship between the power transmission coil 16 and the power reception coil 31 will be described. Figure 3A This is a diagram showing an example of a power transmission state when a foreign object is present between the power transmission coil and the power reception coil. Figure 3B This is a diagram showing an example of a power transmission state when a positional misalignment occurs between the power transmission coil and the power reception coil.

[0067] like Figure 3A As shown, when the metallic foreign object 90 is present between the power transmission coil 16 and the power reception coil 31 , power loss occurs between the transmission power transmitted by the power transmission coil 16 and the reception power received by the power reception coil 31 .

[0068] That is, in Figure 3A In this case, part of the magnetic flux generated by the power transmission coil 16 passes through the metal foreign matter 90 and is consumed as eddy current, so that the efficiency of the magnetic coupling between the power transmission coil 16 and the power receiving coil 31 is reduced. Figure 3A A portion of the magnetic flux in the upward arrow (indicated by the arrow in FIG. 1 ) does not reach the center position of the power receiving coil 31, so the efficiency E(t) of power transmission decreases.

[0069] For example, in Figure 3A , the power transmission power Pout(t) of the power transmission coil 16 is set to 14.5W, and the power reception power Rp(t) of the power reception coil 31 is set to 10W. In addition, a certain power loss will occur between the power transmission power Pout(t) of the power transmission coil 16 and the power reception power Rp(t) of the power reception coil 31 even in the absence of the metal foreign matter 90. The power loss is set to 2W. As a result, the power transmission power of the charging device 10 loses 2W due to the power loss, and loses 2.5W due to the metal foreign matter 90.

[0070] The metal foreign object 90 absorbs the 2.5 W of power and generates heat. Due to the heat generated by the metal foreign object 90, there is a risk of contact with the charging device 10 or the terminal device 30 causing burns, burns caused by the heat generated by the metal foreign object 90, deterioration of the charging device 10 or the terminal device 30, or fire. Therefore, the charging by the charging device 10 is usually stopped when the loss of the transmitted power exceeds a threshold.

[0071] on the other hand, Figure 3B The diagram shows a state where charging is performed in a state where the center positions of the power transmission coil 16 and the power reception coil 31 are offset from each other.

[0072] exist Figure 3B In the example, the power transmission power Pout(t) of the power transmission coil 16 is 14.5W, and the power reception power Rp(t) of the power reception coil 31 is 10W. In this case, a power loss of 2W is also generated as in the normal case. Figure 3B In this case, the center position of the power transmission coil 16 and the center position of the power receiving coil 31 are offset, so that the efficiency of magnetic coupling is reduced, that is, the magnetic flux ( Figure 3BThe state where a part of the magnetic flux in the upward arrow of the power transmission coil 16 does not reach the center position of the power receiving coil 31. In addition, due to the positional deviation between the power transmission coil 16 and the power receiving coil 31, a power loss of 2.5 W is generated.

[0073] also, Figure 3B An example is shown in which the coil surface of the power receiving coil 31 moves on a plane parallel to the coil surface of the power transmitting coil 16, but the same is true for the case where the coil surface of the power transmitting coil 16 moves in a direction away from the coil surface of the power receiving coil 31. For example, when the terminal device 30 to be charged is installed with a thicker case, the distance between the power transmitting coil 16 and the power receiving coil 31 becomes larger when placed on the charging stand 19 compared to the case without a case. In such a case, power loss also occurs. In addition, when a camera lens is provided on the back of the terminal device 30, that is, on the side where the power receiving coil 31 is provided, the outer frame of the lens sometimes protrudes from the back of the terminal device 30. In such a case, when the terminal device 30 is placed on the charging stand 19, the terminal device 30 is tilted and lifted due to the influence of the outer frame of the lens, destroying the parallelism of the coil surface of the power transmitting coil 16 and the coil surface of the power receiving coil 31. In such a case, power loss also occurs.

[0074] When the general Figure 3A and Figure 3B When compared, the power loss caused by the metal foreign matter 90 is equal to the power loss caused by the positional deviation between the power transmission coil 16 and the power reception coil 31. Figure 3B In the case where power loss occurs due to the positional misalignment between the power transmission coil 16 and the power reception coil 31 , there is no need to stop charging because there is no heat generation by the metallic foreign matter 90 .

[0075] In such Figure 3A When a metallic foreign object 90 is present between the power transmission coil 16 and the power reception coil 31, the charging device 10 of this embodiment continues charging as much as possible while limiting the transmission power Pout(t) in order to suppress the heating of the metallic foreign object 90. Figure 3B In the case where there is a positional misalignment between the power transmission coil 16 and the power receiving coil 31, the power transmission coil 16 is moved or a power transmission coil 16 with a higher coupling state is selected to continue charging as much as possible. In addition, when the presence of a metal foreign object 90 is detected, power transmission can also be stopped and the user can be instructed to remove the metal foreign object 90.

[0076] (Functional Structure of Charging Device)

[0077] use Figure 4 The functional structure of the charging device 10 will be described. Figure 4This is a functional block diagram showing an example of a functional configuration of a control unit included in the charging device according to the embodiment.

[0078] The control unit 22 of the charging device 10 includes Figure 4 That is, the control unit 22 includes a transmission coil position setting unit 41, a transmission instruction unit 42, a transmission power acquisition unit 43, a reception power acquisition unit 44, a reception efficiency calculation unit 45, a reception efficiency comparison unit 46, a transmission power control unit 47, a transmission coil position search unit 48, a charging state control unit 49, and a foreign object detection unit 50.

[0079] Each of these functional parts may be realized by software installed as a control program in the control unit 22, or by dedicated hardware. Alternatively, each of these functional parts may be realized by a hybrid structure of software and dedicated hardware.

[0080] When the terminal device 30 is placed on the charging stand 19, the power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position where there is no positional deviation from the power receiving coil 31. In the case where the charging device 10 is configured to include a power transmission coil 16 (movable coil) whose position is variable, the power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position facing 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 transmission coil 16 is moved to the position set by the power transmission coil position setting unit 41 by the moving mechanism 17. On the other hand, in the case where the charging device 10 is configured to include a plurality of fixed coils as the power transmission coil 16, the power transmission coil position setting unit 41 sequentially energizes each fixed coil and sets the position of the fixed coil with the best power receiving efficiency as the position of the power transmission coil 16.

[0081] The power transmission instruction unit 42 controls the DC-DC converter 12 and the bridge circuit 13 based on the instructions of the power transmission power control unit 47 and / or the charging state control unit 49 described later. As a result, power is supplied to the power transmission coil 16. Specifically, the power transmission instruction unit 42 generates magnetic flux in the power transmission coil 16 by instructing the DC-DC converter 12 and the bridge circuit 13 to be energized, thereby causing the power transmission coil 16 to transmit power. The magnetic flux generated by the power transmission coil 16 generates an induced electromotive force in the power receiving coil 31, so that the terminal device 30 is charged.

[0082] The transmission power acquisition unit 43 acquires the magnitude of the transmission power Pout(t) transmitted by the transmission coil 16 caused by the transmission instruction unit 42. The transmission power acquisition unit 43 acquires the magnitude of the transmission power Pout(t) by multiplying the voltage detected by the voltage detection circuit 14 and the current detected by the current detection circuit 15 at the same time t.

[0083] The received power acquisition unit 44 acquires the magnitude of the received power Rp(t) received by the receiving coil 31 at time t from the terminal device 30. More specifically, the received power acquisition unit 44 receives information including the received power Rp(t), the received power target value, etc., which is transmitted from the terminal device 30 by packet communication. The received power acquisition unit 44 acquires the received power Rp(t) by demodulating the received information.

[0084] The power reception efficiency calculation unit 45 calculates the efficiency E(t) of the received power Rp(t) relative to the transmitted power Pout(t). The efficiency E(t) is an example of a ratio in the present disclosure. The power reception efficiency calculation unit 45 is an example of a calculation unit in the present disclosure.

[0085] The power receiving efficiency comparison unit 46 compares the efficiency E(t) calculated during the charging process with a preset threshold value Eth. When the efficiency E(t) is less than the threshold value Eth, the power receiving efficiency comparison unit 46 determines that the position of the terminal device 30 has shifted or the metal foreign object 90 has been inserted. In addition, when the power transmission coil 16 is moved in a state where the power transmission power control unit 47 limits the power transmission power Pout(t) to the power transmission coil 16, the power receiving efficiency comparison unit 46 compares the efficiencies E(t) calculated over time and stores the highest efficiency E(t). In addition, the power receiving efficiency comparison unit 46 compares the efficiency E(t) at the start of charging with the highest efficiency E(t) obtained when the power transmission coil 16 is moved.

[0086] In addition, it is desirable to set a threshold value Eth for each terminal device 30 to be charged. For example, when the charging device 10 is used in a state of being mounted on a vehicle, since the type of terminal device 30 charged by the charging device 10 is limited by the vehicle owner and family, the efficiency E(t) is measured in advance for each terminal device 30 to be charged, and the terminal device 30 is stored in association with the threshold value Eth in advance.

[0087] When the terminal device 30 is placed on the charging device 10 and charging starts, information that can identify the model of the terminal device 30 is sent from the terminal device 30 to the charging device 10, so that the charging device 10 can determine the model of the placed terminal device 30. In addition, the charging device 10 can also call and set the threshold Eth associated with the determined model. In addition, the user can also use Figure 1 The operating system (not shown) is used to input identification information for specifying the terminal device 30 mounted on the charging device 10. Furthermore, the charging device 10 may call and set the threshold value Eth associated with the terminal device 30 from the input identification information.

[0088] The transmission power control unit 47 controls the power transmitted from the transmission coil 16 to the reception coil 31. The transmission power control unit 47 controls the limitation and release of the transmission power Pout(t) based on instructions from the charging state control unit 49 described later.

[0089] The power transmission coil position search unit 48 searches for the position of the power transmission coil 16 where the efficiency E(t) calculated by the power receiving efficiency calculation unit 45 is the highest by moving the position of the power transmission coil 16 when the efficiency E(t) is less than the threshold value Eth while the power transmission power Pout(t) is limited by the power transmission power control unit 47. In the case where the charging device 10 is a structure including a power transmission coil 16 (movable coil) whose position is variable, the power transmission coil position search unit 48 searches for the position of the power transmission coil 16 where the efficiency E(t) is the highest by moving the position of the power transmission coil 16 by the moving mechanism 17. In the case where the charging device 10 is a structure including a plurality of fixed coils as the power transmission coil 16, the power transmission coil position search unit 48 sequentially energizes each fixed coil and searches for the fixed coil where the efficiency E(t) is the highest. In addition, the power transmission coil position search unit 48 is an example of a power transmission position search unit in the present disclosure.

[0090] When the efficiency E(t) at the position of the power transmission coil 16 searched by the power transmission coil position search unit 48 is greater than the threshold value Eth, the charging state control unit 49 causes the power transmission power control unit 47 to release the restriction on the power transmission power Pout(t) at the position of the power transmission coil 16 searched by the power transmission coil position search unit 48 and continue charging.

[0091] When the efficiency E(t) at the position of the power transmission coil 16 found by the power transmission coil position search unit 48 is smaller than the threshold value Eth, the charging state control unit 49 stops charging by cutting off the power supply to the power transmission coil 16 .

[0092] In addition, the charging state control unit 49 determines whether the terminal device 30 is in a fully charged state. Specifically, the charging state control unit 49 determines that the terminal device 30 is in a fully charged state when a packet such as EPT (End Power Transfer) is received from the terminal device 30, or a packet such as CEP (Control Error Packet) indicating a target value of received power has an extremely low average value during a certain period of time.

[0093] When the charging device 10 is not charging, the foreign object detector 50 detects whether there is a metal foreign object 90 between the power transmitting coil 16 and the power receiving coil 31 based on the coupling state between the power transmitting coil 16 and the power receiving coil 31 when the power receiving coil 31 is placed at a position not offset from the power transmitting coil 16.

[0094] (Charging device operation example (1))

[0095] use Figure 5 , Fig. 6A , Figure 6B A first operation example of the charging device 10 will be described. Figure 5 This is a diagram showing an example of the operation of the charging device when the position of the power receiving coil is misaligned. Fig. 6A It is shown in Figure 5 FIG. 2 is a diagram showing an example of the positional relationship between the power receiving coil and the power transmitting coil at time t7. Figure 6B It is shown in Figure 5 The figure shows an example of a situation in which the charging device moves the position of the power transmission coil during the period from time t8 to time t13. Figure 7 The flowchart shown corresponds to the following.

[0096] Figure 5 The time t=t1 indicates a state where the power transmission coil 16 is set to a position without positional deviation from the power reception coil 31 when the terminal device 30 is placed on the charging stand 19 and charging is started.

[0097] At this time, it is assumed that the charging device 10 transmits power Pout(t1)=13.0 W and the terminal device 30 receives power Rp(t1)=10.0 W. That is, the efficiency E(t1) is 77%. Thereafter, the charging device 10 continues to charge the terminal device 30.

[0098] For example, when the charging device 10 is used in a vehicle, the terminal device 30 is simply placed on the charging stand 19, so the position of the terminal device 30 may change due to the vibration of the vehicle. Figure 5 In the example, from time t=t4 to time t=t6, the position of the terminal device 30 moves. At this time, the loss of the transmitted power Pout(t) of the charging device 10 increases, so Figure 5 As shown in FIG. 1 , the efficiency E(t) decreases. Furthermore, it is assumed that at time t=t6, the efficiency E(t) is lower than a preset threshold value Eth (e.g., 70%). In addition, when the efficiency E(t) decreases, the power transmission instruction unit 42 increases the transmission power Pout(t) to obtain the desired reception power Rp(t). Therefore, as shown in FIG. Figure 5 As shown, from time t=t4 to time t=t6, the transmitted power Pout(t) increases.

[0099] At this time, there may be a metal foreign object 90 between the power transmission coil 16 and the power receiving coil 31. Therefore, in order to suppress the heat generation of the metal foreign object 90, the charging state control unit 49 causes the power transmission power control unit 47 to limit the power transmission power Pout(t) transmitted to the power transmission coil 16. In addition, it is desirable to set the limit amount of the power transmission power to, for example, about half of the initial power transmission power Pout(t). Figure 5 In the example shown in FIG. 1 , the transmitted power Pout(t) is limited to 8.0W.

[0100] In addition, it is assumed that at time t=t7, the power transmission coil 16 and the power reception coil 31 (terminal device 30) are in Fig. 6A That is, the terminal device 30 is displaced relative to the power transmission coil 16 in the direction of 4:30 of the analog clock.

[0101] At time t=t7, when the transmitted power Pout(t) is limited to 8.0 W, the power reception efficiency calculation unit 45 calculates the efficiency E(t7). The calculated efficiency E(t7) is stored in the calculation result storage unit 22c.

[0102] Then, the power transmission coil position search unit 48 moves the position of the power transmission coil 16 while the power transmission power control unit 47 limits the transmission power Pout(t), and searches for the position of the power transmission coil 16 where the efficiency E(t) calculated by the power reception efficiency calculation unit 45 is the maximum.

[0103] There is no limitation on the movement mode of the power transmission coil 16. Figure 5 In the example, the center position of the power transmission coil 16 at time t=t7, that is, position P1 (refer to Figure 6B ) moves to the outer edge of the power transmission coil 16, i.e., position P2, in the direction of 12 o'clock at time t=t8. Then, as time t passes, the center position of the power transmission coil 16 moves counterclockwise along the outer edge position of the power transmission coil 16 at time t=t7.

[0104] That is, the center position of the power transmission coil 16 moves to position P3 at time t=t9. Also, it moves to position P4 at time t=t10, and moves to position P5 at time t=t11. The power receiving efficiency calculation unit 45 calculates the efficiency E(t) for each position to which the power transmission coil 16 moves, while limiting the transmission power Pout(t). Figure 5 The sampling interval of the efficiency E(t) shown is determined by the received power packet interval notified from the terminal device 30. That is, the efficiency E(t) is calculated at any time while the power transmission coil 16 is moving.

[0105] exist Figure 5In the example, it is assumed that the power transmission coil position search unit 48 finds that there is a position where the efficiency E(t) is maximum between the efficiency E(t10) at time t=t10 and the efficiency E(t11) at time t=t11. At this time, the power transmission coil position search unit 48 moves the power transmission coil 16 to the position P6 at 4:30, which is the middle point between the position P4 at time t=t10 and the position P5 at time t=t11, at time t=t12.

[0106] Since the efficiency E(t12) at position P6 is a high value, the power transmission coil position search unit 48 searches for a position with higher efficiency E(t). For example, at time t=t13, the power transmission coil 16 is moved to position P7 outside 4:30.

[0107] The efficiency E(t13)=78% at the position P7 is the maximum value exceeding the threshold value Eth, so the charging device 10 determines that the position P7 is the position where the terminal device 30 is offset. In addition, since the efficiency E(t13) exceeds the threshold value Eth, the charging device 10 determines that there is no metal foreign matter between the power transmission coil 16 and the power reception coil 31.

[0108] Next, at time t= t14 , the charging state control unit 49 cancels the limitation on the transmission power Pout(t) by the transmission power control unit 47 and continues charging.

[0109] When the charging device 10 includes a plurality of fixed coils instead of the movable power transmission coil 16 , the fixed coils are sequentially selected and energized to search for the position of the power reception coil 31 in the same manner as described above.

[0110] (Processing Flow of Charging Device)

[0111] use Figure 7 The flow of processing performed by charging device 10 will be described. Figure 7 FIG. 1 is a flowchart showing an example of a process flow performed by the charging device according to the embodiment. Figure 7 In the flowchart shown, the charging device 10 monitors the efficiency E(t) after the start of charging, and when it is not determined that the efficiency E(t) is greater than the threshold, the power transmission power is limited in consideration of the possibility that a metal foreign object is present between the power transmission coil 16 and the power receiving coil 31. Furthermore, in a state where the power transmission power is limited, the power transmission coil 16 is moved to search for a position where the efficiency E(t) is greater than the threshold, thereby eliminating the positional deviation between the power transmission coil 16 and the power receiving coil 31. When the efficiency E(t) is not improved to a value greater than the threshold even when the power transmission coil 16 is moved, it is estimated that there is a possibility that a metal foreign object is present between the power transmission coil 16 and the power receiving coil 31, and therefore the power is cut off.

[0112] exist Figure 7In the embodiment of the present invention, when the terminal device 30 is placed on the charging stand 19, the charging device 10 detects the position of the terminal device 30 (step S11). Specifically, when the terminal device 30 is placed on the charging stand 19, the power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position where there is no positional deviation from the power receiving coil 31. In the case where the charging device 10 is a structure having a power transmission coil 16 (movable coil) whose position is variable, the power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position facing 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 transmission coil 16 is moved to the position set by the power transmission coil position setting unit 41 by the moving mechanism 17, and various authentications are performed between the charging device 10 and the terminal device 30. On the other hand, in the case where the charging device 10 is a structure having a plurality of fixed coils as the power transmission coil 16, the power transmission coil position setting unit 41 sequentially energizes each fixed coil and sets the position of the fixed coil with the best power receiving efficiency as the position of the power transmission coil 16. Then, when the position of the power transmission coil is set, various authentications are performed between the charging device 10 and the terminal device 30 .

[0113] The foreign object detector 50 detects whether or not there is a metallic foreign object 90 between the power transmission coil 16 and the power reception coil 31 when charging is not being performed (step S12 ).

[0114] The foreign object detector 50 determines whether a foreign object is detected (step S13). If it is determined that a foreign object is detected (step S13: Yes), the process proceeds to step S14. On the other hand, if it is determined that a foreign object is not detected (step S13: No), the process proceeds to step S15.

[0115] If it is determined in step S13 that a foreign object has been detected, the charging state control unit 49 cuts off the power supply to the power transmission coil 16 (step S14). Figure 7 In addition, at this time, the charging device 10 can also Figure 1 An indicator, monitor, buzzer, speaker, etc. (not shown) is used to notify that a metal foreign object 90 may have been inserted.

[0116] When it is determined in step S13 that a foreign object is not detected, the charging state control unit 49 causes the power transmission instruction unit 42 to start charging the terminal device 30 (step S15 ).

[0117] The power reception efficiency calculation unit 45 calculates the efficiency E(t) (step S18 ). Specifically, the power reception efficiency calculation unit 45 calculates the efficiency E(t) based on the transmitted power Pout(t) acquired by the transmitted power acquisition unit 43 and the received power Rp(t) acquired by the received power acquisition unit 44 .

[0118] The power receiving efficiency comparison unit 46 determines whether the efficiency E(t) calculated in step S18 is greater than or equal to the threshold value Eth (step S19). If it is determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S19: Yes), the process proceeds to step S20. On the other hand, if it is not determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S19: No), the process proceeds to step S21.

[0119] If it is determined in step S19 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging state control unit 49 determines whether the terminal device 30 is fully charged (step S20). If it is determined that the terminal device 30 is fully charged (step S20: Yes), the charging device 10 ends the charging process. Figure 7 On the other hand, when it is not determined that the terminal device 30 has reached the fully charged state (step S20: No), the process returns to step S18.

[0120] When it is not determined in step S19 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging state control unit 49 causes the transmission power control unit 47 to limit the transmission power Pout(t) transmitted by the transmission coil 16 (step S21 ).

[0121] The power receiving efficiency calculation unit 45 calculates the efficiency E(t) when the power transmission power Pout(t) is limited, and stores it in the calculation result storage unit 22c. In addition, the efficiency E(t) stored at this time is set as the efficiency Q (step S22). In addition, at this time, the position of the power transmission coil 16 is also stored in the calculation result storage unit 22c.

[0122] Next, the power transmission coil position search unit 48 starts moving the power transmission coil (step S23 ). The power transmission coil position search unit 48 moves the power transmission coil 16 based on a predetermined rule to search for the position of the power transmission coil 16 that maximizes the efficiency E(t).

[0123] The power receiving efficiency calculation unit 45 calculates the efficiency E(t) at predetermined time intervals while the power transmission coil 16 is moving (step S24 ).

[0124] The power receiving efficiency comparison unit 46 determines whether the efficiency E(t) calculated in step S24 is greater than the efficiency Q (step S25). If it is determined that the efficiency E(t) is greater than the efficiency Q (step S25: Yes), the process proceeds to step S26. On the other hand, if it is not determined that the efficiency E(t) is greater than the efficiency Q (step S25: No), the process proceeds to step S27.

[0125] When it is determined in step S25 that the efficiency E(t) is greater than the efficiency Q, the power receiving efficiency comparison unit 46 replaces the efficiency Q with the efficiency E(t) calculated in step S24 (step S26). The replaced efficiency Q value is stored in the calculation result storage unit 22c together with the position of the power transmission coil 16 at that time.

[0126] The power transmission coil position search unit 48 determines whether the power transmission coil 16 has been moved within the prescribed range (step S27). When it is determined that the power transmission coil 16 has been moved within the prescribed range (step S27: "Yes"), the process proceeds to step S28. On the other hand, when it is not determined that the power transmission coil 16 has been moved within the prescribed range (step S27: "No"), the process returns to step S24. That is, the processes of step S24 to step S26 are repeated until the power transmission coil 16 is moved within the prescribed range. Since the power transmission coil 16 is moved while changing its position within the prescribed range and the efficiency E(t) is monitored, when the position of the receiving coil is offset after the start of charging, the power transmission coil 16 can be aligned with the power receiving coil 31 of the terminal device 30 without performing position detection of the terminal device 30 by the receiving coil position detection circuit 20.

[0127] When it is determined in step S27 that the power transmission coil 16 has been moved within the predetermined range, the power reception efficiency comparison unit 46 determines whether the efficiency Q is greater than or equal to the threshold value Eth used in step S19 (step S28). When it is determined that the efficiency Q is greater than or equal to the threshold value Eth (step S28: Yes), the process proceeds to step S29. On the other hand, when it is not determined that the efficiency Q is greater than or equal to the threshold value Eth (step S28: No), the process proceeds to step S31.

[0128] When it is determined in step S28 that the efficiency Q is equal to or greater than the threshold value Eth, the power transmission coil position search unit 48 moves the power transmission coil 16 to the position where the efficiency Q is maximized (step S29 ).

[0129] The charging state control unit 49 cancels the restriction on the transmitted electric power performed in step S21 (step S30 ), and then returns to step S18 .

[0130] If it is not determined in step S28 that the efficiency Q is equal to or greater than the threshold value Eth, the charging state control unit 49 cuts off the power supply to the power transmission coil 16 (step S31). Figure 7 processing.

[0131] In addition, Figure 7 In all the steps of the charging device 10, the charging device 10 always monitors whether the communication with the terminal device 30 is continuing. In addition, if the communication with the terminal device 30 is detected to be disconnected, the charging device 10 transfers to step S11 and performs the communication again. Figure 7processing.

[0132] (Charging device operation example (2))

[0133] use Figure 8 , Fig.9A , Fig. 9B A second operation example of the charging device 10 will be described. Figure 8 This is a diagram showing an example of the operation of the charging device when a metallic foreign object is inserted between the power receiving coil and the power transmitting coil. Fig.9A It is shown in Figure 8 FIG. 4 is a diagram showing an example of the positional relationship between the power receiving coil and the power transmitting coil at time t4. Fig. 9B It is shown in Figure 8 The second operation example is similar to the above-mentioned Figure 7 The flowchart shown corresponds to the following.

[0134] Figure 8 The time t=t1 indicates a state where the power transmission coil 16 is set to a position without positional deviation from the power reception coil 31 when the terminal device 30 is placed on the charging stand 19 and charging is started.

[0135] At this time, the charging state control unit 49 transmits the transmission power Pout(t1)=13.0 W, and the terminal device 30 receives the reception power Rp(t1)=10.0 W. That is, the efficiency E(t1) is 77%. Thereafter, the charging state control unit 49 continues to charge the terminal device 30.

[0136] For example, when the charging device 10 is used in a vehicle, the terminal device 30 is only placed on the charging stand 19, so metal foreign objects such as coins or gum wrappers (aluminum foil) may be inserted between the terminal device 30 and the charging stand 19 due to the vibration of the vehicle. Figure 8 In the example, it is assumed that the metal foreign object 90 is inserted at time t=t4. At this time, the loss of the transmitted power Pout(t) of the charging device 10 becomes large, so Figure 8 Here, when the efficiency E(t) decreases, the power transmission instruction unit 42 increases the transmission power Pout(t) to obtain the desired reception power Rp(t). Figure 8 As shown, at time t=t4, the transmitted power Pout(t) increases.

[0137] Furthermore, it is assumed that: at time t=t4, the efficiency E(t4) is lower than a preset threshold value Eth (e.g., 70%) of the efficiency E(t). At this time, there may be a metal foreign object 90 between the power transmission coil 16 and the power receiving coil 31. Or, the positional relationship between the power transmission coil 16 and the power receiving coil 31 may be offset. Therefore, in order to suppress the heating of the metal foreign object 90, the charging state control unit 49 causes the power transmission power control unit 47 to limit the power transmission power Pout(t) transmitted to the power transmission coil 16. In addition, it is desirable to set the limit amount of the power transmission power to, for example, approximately half of the initial power transmission power Pout(t). Figure 8 In the example shown in FIG. 1 , the transmitted power Pout(t) is limited to 8.0W.

[0138] At time t=t5, when the transmitted power Pout(t) is limited to 8.0 W, the power reception efficiency calculation unit 45 calculates the efficiency E(t5). The calculated efficiency E(t5) is stored in the calculation result storage unit 22c.

[0139] Then, the power transmission coil position search unit 48 moves the position of the power transmission coil 16 while the power transmission power control unit 47 limits the transmission power Pout(t), and searches for the position of the power transmission coil 16 where the efficiency E(t) calculated by the power reception efficiency calculation unit 45 is the maximum.

[0140] There is no limitation on the movement mode of the power transmission coil 16. Figure 8 In the example, the center position of the power transmission coil 16 at time t=t5, that is, position P11 (refer to Fig. 9B ) moves to the outer edge of the power transmission coil 16, i.e., position P12, in the direction of 12 o'clock at time t=t6. Then, as time t passes, the center position of the power transmission coil 16 moves counterclockwise along the outer edge position of the power transmission coil 16 at time t=t5.

[0141] That is, the center position of the power transmission coil 16 moves to position P13 at time t=t7. Also, it moves to position P14 at time t=t8, and moves to position P15 at time t=t9. The power receiving efficiency calculation unit 45 calculates the efficiency E(t) for each position to which the power transmission coil 16 moves, while limiting the transmission power Pout(t). Figure 8 The sampling interval of the efficiency E(t) shown is determined by the received power packet interval notified from the terminal device 30. That is, the efficiency E(t) is calculated at any time while the power transmission coil 16 is moving.

[0142] exist Figure 8In the example, the power transmission coil position search unit 48 finds that there is a position where the efficiency E(t) is maximum between the efficiency E(t6) at time t=t6 and the efficiency E(t7) at time t=t7. At this time, the power transmission coil position search unit 48 moves the power transmission coil 16 to the position P16 at 10:30, which is the middle point between the position P12 at time t=t6 and the position P13 at time t=t7, at time t=t10.

[0143] The power transmission coil position search unit 48 also searches for a position with a higher efficiency E(t) near the position P16. As a result, the maximum value (65%) of the efficiency E(t11) is obtained at time t=t11.

[0144] Since the efficiency E(t11) at time t=t11 is equal to the efficiency E(t5) at time t=t5, the charging state control unit 49 determines that the efficiency E(t) has not been improved. In other words, the charging device 10 determines that the positional misalignment between the power transmission coil 16 and the power reception coil 31 has not occurred, but that the metal foreign object 90 has been inserted between the power transmission coil 16 and the power reception coil 31.

[0145] Then, at time t=t12, the charging state control unit 49 cuts off the power supply to the power transmission coil 16. At this time, the charging device 10 may notify that the power supply is cut off because a metallic foreign object may have been inserted.

[0146] When the charging device 10 includes a plurality of fixed coils instead of the movable power transmission coil 16 , the fixed coils are sequentially selected and energized to search for the position of the power reception coil 31 in the same manner as described above.

[0147] (Charging device operation example (3))

[0148] use Fig.10 A third operation example of the charging device 10 will be described. Fig.10 is a diagram showing an example of the operation of the charging device when a metallic foreign object is initially present between the power receiving coil and the power transmitting coil. Figure 7 The flowchart shown corresponds to the following.

[0149] Fig.10 The time t=t1 indicates that the power transmission coil 16 is set to a position without positional deviation from the power reception coil 31 and charging is started when the terminal device 30 is placed on the charging stand 19. At the time t=t1, the efficiency E(t1) calculated by the power reception efficiency calculation unit 45 is a value less than the threshold value Eth (e.g., 70%).

[0150] Since the efficiency E(t1) is less than the threshold value Eth, it is determined that there may be a metal foreign object 90 between the power transmission coil 16 and the power reception coil 31. The charging state control unit 49 causes the power transmission control unit 47 to limit the power transmission Pout(t) transmitted to the power transmission coil 16 to 8.0 W at time t=t2.

[0151] When the transmitted power Pout(t) is limited to 8.0 W at time t=t2, the power reception efficiency calculation unit 45 calculates the efficiency E(t2). The calculated efficiency E(t2) is stored in the calculation result storage unit 22c.

[0152] Then, the power transmission coil position search unit 48 moves the position of the power transmission coil 16 while the power transmission power control unit 47 limits the transmission power Pout(t), and searches for the position of the power transmission coil 16 where the efficiency E(t) calculated by the power reception efficiency calculation unit 45 is the maximum.

[0153] There is no limitation on the movement mode of the power transmission coil 16. Fig.10 In the example, the center position of the power transmission coil 16 at time t=t2 is moved to the outer edge of the power transmission coil 16 in the direction of 12 o'clock at time t=t3. After that, as time t passes, the center position of the power transmission coil 16 is moved counterclockwise along the outer edge position of the power transmission coil 16 at time t=t2. The power receiving efficiency calculation unit 45 calculates the efficiency E(t) that changes with time at any time.

[0154] Since it is known that the efficiency E(t) obtained from time t=t3 to time t=t6 does not exceed the efficiency E(t2) calculated at time t=t2, the charging state control unit 49 determines that the metal foreign matter 90 exists between the power receiving coil 31 and the power transmitting coil 16 from the beginning, and cuts off the power supply to the power transmitting coil 16 at time t=t7.

[0155] At this time, it is desirable that the charging device 10 informs that there is a possibility that the metallic foreign object 90 is present between the power receiving coil 31 and the power transmitting coil 16 .

[0156] In addition, when the efficiency of the power receiving coil 31 of the terminal device 30 is originally poor, the same phenomenon as Fig.10 The same change in efficiency E(t) occurs. That is, in this embodiment, it is not possible to identify the case where the metal foreign matter 90 is initially present between the power receiving coil 31 and the power transmitting coil 16, or the case where the efficiency of the power receiving coil 31 is originally poor. The operation example of the charging device 10 shown below is an example in which charging can be continued even when the efficiency of the power receiving coil 31 is originally poor.

[0157] (Charging device operation example (4))

[0158] use Fig.11 Next, a fourth operation example of the charging device 10 will be described. Figure 7 In the flowchart shown, if the efficiency is not improved even if the power transmission coil 16 is moved, the power is cut off in consideration of the possibility that a metal foreign object exists between the power transmission coil 16 and the power receiving coil 31. However, the power may be not cut off but the power transmission may be further limited and charging may be continued. Figure 7 In the flowchart shown, when it is not determined that the efficiency Q is greater than the threshold value Eth (step S28: No), the charging state control unit 49 may further limit the power transmitted to the power transmission coil 16 and continue charging. Alternatively, charging may be continued at the position of the power transmission coil 16 where the efficiency is the highest. Fig.11 This diagram shows an example of the operation of the charging device in which, when the power efficiency of the power transmission coil 16 and the power reception coil 31 is originally poor, the efficiency E(t1) is not improved and the transmission power is further limited while charging is continued.

[0159] Fig.11 The time t=t1 indicates that the power transmission coil 16 is set to a position without positional deviation from the power reception coil 31 and charging is started when the terminal device 30 is placed on the charging stand 19. At the time t=t1, the efficiency E(t1) calculated by the power reception efficiency calculation unit 45 is a value less than the threshold value Eth (e.g., 70%).

[0160] Since the efficiency E(t1) is less than the threshold value Eth, it is determined that there may be a metal foreign object 90 between the power transmission coil 16 and the power reception coil 31, so that the charging state control unit 49 causes the power transmission control unit 47 to limit the transmission power Pout(t) transmitted by the power transmission coil 16 to 8.0 W at time t=t2.

[0161] Then, the transmission coil position search unit 48 moves the position of the transmission coil 16 while the transmission power control unit 47 limits the transmission power Pout(t), and searches for the position of the transmission coil 16 where the efficiency E(t) calculated by the power receiving efficiency calculation unit 45 is the maximum. The search method is the same as in Fig.10 The method is the same as described in .

[0162] Since it is known that the efficiency E(t) acquired from time t=t3 to time t=t6 is not greater than the efficiency E(t2) calculated at time t=t2, the charging state control unit 49 causes the power transmission control unit 47 to limit the power transmission power Pout(t) transmitted to the power transmission coil 16 to 4.0 W at time t=t7.

[0163] At time t=t8, the power transmission coil position search unit 48 returns the power transmission coil 16 to the position at time t=t2 where the efficiency E(t) is the maximum. Then, the charging state control unit 49 continues charging while limiting the power transmission power Pout(t) to 4.0W. Fig.11 When the position where the efficiency E(t) is maximum is found at a time other than time t=t2, the power transmission coil 16 is returned to the position where the efficiency E(t) is maximum, and charging is continued while limiting the transmission power Pout(t) to 4.0W.

[0164] In this way, by further limiting the transmission power Pout(t), even if the efficiency of the power receiving coil 31 is originally poor, charging can be continued with the limited transmission power Pout(t). In addition, even if there is a metal foreign object 90 between the power receiving coil 31 and the power transmitting coil 16 from the beginning, since the transmission power Pout(t) is limited to 4.0W, excessive heating of the metal foreign object 90 (for example, above 60°C) can be suppressed. In addition, the transmission power control unit 47 can limit the transmission power Pout(t) or the power difference ΔW between the transmission power Pout(t) and the receiving power Rp(t).

[0165] In addition, at this time, it is desirable that the charging device 10 notify that charging is being performed in a state where the transmitted power Pout(t) is limited.

[0166] (Charging device operation example (5))

[0167] use Fig.12 A fifth operation example of the charging device 10 will be described. Fig.12 is a diagram showing an example of the operation of the charging device when the user moves the terminal device during charging. Fig.14 The flowchart shown corresponds to the following.

[0168] The action from time t = t1 to time t = t7 is Figure 5 The same, therefore the description is omitted.

[0169] After time t=t8, charging is continued with the transmitted power Pout(t) being limited.

[0170] Assume that the user moves the position of the terminal device 30 from time t=t10 to time t=t11. At this time, the efficiency E(t10) and the efficiency E(t11) are improved and exceed the threshold value Eth (=70%).

[0171] At time t=t12, the charging state control unit 49 releases the limitation on the transmitted power Pout(t) by the transmitted power control unit 47, that is, returns the transmitted power Pout(t) to the original state, and continues charging.

[0172] In this way, when the efficiency E(t) is improved by the user's position correction of the terminal device 30, the charging state control unit 49 can cancel the restriction of the transmission power Pout(t) by the transmission power control unit 47 and continue charging. In particular, when the placement position of the terminal device 30 is shifted to the outside of the movable range of the power transmission coil 16, or when the power transmission coil 16 has a plurality of fixed coils, the placement position of the terminal device 30 is shifted to the outside of the fixed coils, the position correction operation performed by the user can be effectively used.

[0173] Furthermore, when the efficiency E(t) has not improved, the charging device 10 may issue a notification urging the user to confirm the placement position of the terminal device 30 .

[0174] (Variation Example (1) of Implementation Method)

[0175] use Fig.13 A first modified example of the charging device 10 will be described. Fig.13 This is a flowchart showing an example of the operation of the first modified example of the charging device according to the embodiment.

[0176] The charging device 10 of this modified example temporarily stops charging when the efficiency E(t) does not reach the threshold value Eth, and during the temporary stop of charging, detects the position of the terminal device 30 and detects whether there is a metal foreign object 90 between the power transmission coil 16 and the power reception coil 31. Figure 7 The description of the same processing as in the flowchart is omitted.

[0177] When the terminal device 30 is placed on the charging stand 19 , the power transmission coil position setting unit 41 detects the position of the terminal device 30 (step S41 ).

[0178] The foreign object detector 50 detects whether or not there is a metallic foreign object 90 between the power transmission coil 16 and the power reception coil 31 when charging is not being performed (step S42 ).

[0179] The foreign object detector 50 determines whether a foreign object is detected (step S43). If it is determined that a foreign object is detected (step S43: Yes), the process proceeds to step S56. On the other hand, if it is determined that a foreign object is not detected (step S43: No), the process proceeds to step S44.

[0180] If it is determined in step S43 that a foreign object has been detected, the charging state control unit 49 starts charging in the power-limited state (step S56 ), and then proceeds to step S57 .

[0181] On the other hand, when it is determined in step S43 that a foreign object is not detected, the charging state control unit 49 causes the power transmission instruction unit 42 to start charging the terminal device 30 (step S44 ).

[0182] Following step S44 , the power receiving efficiency calculation unit 45 calculates the efficiency E(t) (step S45 ).

[0183] The power receiving efficiency comparison unit 46 determines whether the efficiency E(t) calculated in step S45 is greater than or equal to the threshold value Eth (step S46). If it is determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S46: Yes), the process proceeds to step S47. On the other hand, if it is not determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S46: No), the process proceeds to step S48.

[0184] If it is determined in step S46 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging state control unit 49 determines whether the terminal device 30 is fully charged (step S47). If it is determined that the terminal device 30 is fully charged (step S47: Yes), the charging device 10 ends the charging process. Fig.13 On the other hand, when it is not determined that the terminal device 30 has reached the fully charged state (step S47: No), the process returns to step S45.

[0185] On the other hand, when it is not determined in step S46 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging device 10 notifies the terminal device 30 of the intention to interrupt charging (step S48). When the terminal device 30 receives the notification, it operates in the same manner as when receiving charging from the charging device 10 while maintaining the communication state with the charging device. Next, the charging state control unit 49 cuts off the power supply to the power transmission coil 16 (step S49).

[0186] The control unit 22 makes Fig.13 The processing of is stopped for a predetermined time (step S50). Fig.13 The processing of the charging process is stopped for a predetermined time, and the temperature of the metal foreign matter 90 can be reduced when the metal foreign matter 90 exists between the power transmission coil 16 and the power receiving coil 31. As the predetermined time, it is desirable to stop for more than 5 seconds. In addition, for example, the same time can be ensured by delaying the notification of the restart of charging to the terminal device 30 in step S53.

[0187] The power transmission coil position setting unit 41 detects the position of the terminal device 30 (step S51). The power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position where there is no positional deviation from the power receiving coil 31. In the case where the charging device 10 is a structure having a power transmission coil 16 (movable coil) whose position is variable, the power transmission coil position setting unit 41 sets the position of the power transmission coil 16 to a position facing the power receiving coil 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 to the position set by the power transmission coil position setting unit 41 by the moving mechanism 17. On the other hand, in the case where the charging device 10 is a structure having a plurality of fixed coils as the power transmission coil 16, the power transmission coil position setting unit 41 sequentially energizes each fixed coil and sets the position of the fixed coil with the best power receiving efficiency as the position of the power transmission coil 16. In addition, in step S41, various authentications are performed between the charging device 10 and the terminal device 30 before charging starts, but various authentications are not performed in this step S51.

[0188] Next, the control unit 22 causes the power transmission coil 16 to transmit a small amount of power to the terminal device 30 in order to determine whether the terminal device 30 is placed on the charging stand 19 (step S52). More specifically, the control unit 22 causes the power transmission coil 16 to transmit a small amount of power for communication to the terminal device 30. The terminal device 30 determines that it has been placed on the charging stand 19 by receiving the small amount of power. Next, the charging device 10 notifies the terminal device 30 that charging has been restarted (step S53).

[0189] The foreign object detection unit 50 detects the metal foreign object 90 between the power transmission coil 16 and the power reception coil 31 when charging is not in progress (step S54). Next, the foreign object detection unit 50 determines whether a foreign object is detected (step S55). When it is determined that a foreign object is detected (step S55: "Yes"), the process proceeds to step S56. On the other hand, when it is determined that a foreign object is not detected (step S55: "No"), the process returns to step S44 and charging is started again.

[0190] When it is determined in step S55 that a foreign object is detected, the charging state control unit 49 starts charging in the power limited state (step S56 ).

[0191] The charging state control unit 49 determines whether the terminal device 30 is fully charged (step S57). If it is determined that the terminal device 30 is fully charged (step S57: Yes), the charging device 10 ends the charging process. Fig.13 On the other hand, when it is not determined that the terminal device 30 has reached the fully charged state (step S57: No), step S57 is repeated.

[0192] In addition, Fig.13During the operation, the charging device 10 monitors whether the communication with the terminal device 30 is continuing. If the communication with the terminal device 30 is disconnected, the process proceeds to step S41 and the operation is repeated. Fig.13 processing.

[0193] In addition, Fig.13 In the flowchart of Figure 7 As described in the flowchart of FIG. 1 , the power transmission coil position search unit 48 moves the power transmission coil 16 to search for a position where the positional deviation between the power transmission coil 16 and the power reception coil 31 is eliminated.

[0194] (Variation Example (2) of Implementation Method)

[0195] use Fig.14 A second modification of the charging device 10 will be described. Fig.14 This is a flowchart showing an example of the operation of the second modified example of the charging device according to the embodiment.

[0196] The charging device 10 of this modification example limits the power to be transmitted when the efficiency E(t) does not reach the threshold value Eth, and then releases the limitation on the power to be transmitted when the value of the efficiency E(t) improves. Fig.12 That is, when the position of the terminal device 30 is offset during charging, for example, when the user moves the terminal device 30 to the correct position to eliminate the position offset of the terminal device 30, the restriction on the transmitted power can be lifted and the terminal device 30 can be charged. Figure 7 The same processing as in the flowchart is appropriately omitted.

[0197] When the terminal device 30 is placed on the charging stand 19 , the power transmission coil position setting unit 41 detects the position of the terminal device 30 (step S61 ).

[0198] The foreign object detector 50 detects whether or not there is a metallic foreign object 90 between the power transmission coil 16 and the power reception coil 31 when charging is not being performed (step S62 ).

[0199] The foreign object detector 50 determines whether a foreign object is detected (step S63). If it is determined that a foreign object is detected (step S63: Yes), the process proceeds to step S64. On the other hand, if it is determined that a foreign object is not detected (step S63: No), the process proceeds to step S65.

[0200] If it is determined in step S63 that a foreign object has been detected, the charging state control unit 49 cuts off the power supply to the power transmission coil 16 (step S64). Fig.14 processing.

[0201] On the other hand, when it is determined in step S63 that a foreign object is not detected, the charging state control unit 49 causes the power transmission instruction unit 42 to start charging the terminal device 30 (step S65 ).

[0202] Next, the power receiving efficiency calculation unit 45 calculates the efficiency E(t) (step S68 ).

[0203] The power receiving efficiency comparison unit 46 determines whether the efficiency E(t) calculated in step S68 is greater than or equal to the threshold value Eth (step S69). If it is determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S69: Yes), the process proceeds to step S70. On the other hand, if it is not determined that the efficiency E(t) is greater than or equal to the threshold value Eth (step S69: No), the process proceeds to step S71.

[0204] If it is determined in step S69 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging state control unit 49 determines whether the terminal device 30 is fully charged (step S70). If it is determined that the terminal device 30 is fully charged (step S70: Yes), the charging device 10 ends the charging process. Fig.14 On the other hand, when it is not determined that the terminal device 30 has reached the fully charged state (step S70: No), the process returns to step S68.

[0205] When it is not determined in step S69 that the efficiency E(t) is equal to or greater than the threshold value Eth, the charging state control unit 49 causes the transmission power control unit 47 to limit the transmission power Pout(t) to be transmitted to the transmission coil 16 (step S71 ).

[0206] The power receiving efficiency calculation unit 45 calculates the efficiency E(t) when the transmission power Pout(t) is limited, and stores it in the calculation result storage unit 22c. In addition, the efficiency E(t) stored at this time is set as the efficiency Q (step S72). In addition, at this time, the position of the power transmission coil 16 is also stored in the calculation result storage unit 22c.

[0207] The charging state control unit 49 determines whether the terminal device 30 is fully charged (step S73). If it is determined that the terminal device 30 is fully charged (step S73: Yes), the charging device 10 ends the charging process. Fig.14 On the other hand, when it is not determined that the terminal device 30 has reached the fully charged state (step S73: No), the process proceeds to step S74.

[0208] If it is not determined in step S73 that the terminal device 30 is fully charged, the power receiving efficiency calculation unit 45 calculates the efficiency E(t) (step S74). If the user moves the terminal device 30 during charging, the value of the efficiency E(t) calculated in step S74 changes.

[0209] The power receiving efficiency comparison unit 46 determines whether the efficiency E(t) calculated in step S74 is greater than the efficiency Q (step S75). If it is determined that the efficiency E(t) is greater than the efficiency Q (step S75: Yes), the process proceeds to step S76. On the other hand, if it is not determined that the efficiency E(t) is greater than the efficiency Q (step S75: No), the process returns to step S73.

[0210] When it is determined in step S75 that the efficiency E(t) is greater than the efficiency Q, the power receiving efficiency comparison unit 46 replaces the efficiency Q with the efficiency E(t) calculated in step S74 (step S76). The replaced efficiency Q value is stored in the calculation result storage unit 22c together with the position of the power transmission coil 16 at that time.

[0211] The power receiving efficiency comparison unit 46 determines whether the efficiency Q is greater than or equal to the threshold value Eth (step S77). If it is determined that the efficiency Q is greater than or equal to the threshold value Eth (step S77: Yes), the process proceeds to step S78. On the other hand, if it is not determined that the efficiency Q is greater than or equal to the threshold value Eth (step S77: No), the process returns to step S73.

[0212] When it is determined in step S77 that the efficiency Q is equal to or greater than the threshold value Eth, the charging state control unit 49 cancels the limitation on the transmitted electric power performed in step S71 (step S78 ), and then returns to step S68 .

[0213] In addition, Fig.14 During the operation, the charging device 10 monitors whether the communication with the terminal device 30 is continuing. If the communication with the terminal device 30 is disconnected, the process proceeds to step S61 and the operation is repeated. Fig.14 processing.

[0214] (Variation Example (3) of Implementation Method)

[0215] use Fig.15 A third modified example of the charging device 10 will be described. Fig.15 This is a flowchart showing an example of the operation of the third modified example of the charging device according to the embodiment. Fig.15 The processing of steps S81 to S91 of the flowchart shown in FIG. Figure 7 The flow chart shown is different.

[0216] In the charging device 10 of this modified example, when the efficiency E(t) is not improved even by moving the power transmission coil 16, there is a high possibility that a metal foreign object 90 is present between the power transmission coil 16 and the power receiving coil 31, so charging is temporarily stopped, and the presence of the metal foreign object 90 is detected during the temporary stop of charging. Then, when the metal foreign object 90 is detected, charging is resumed in a state where the power transmission electric power is further limited. Figure 7 and Fig.13 Description of the same processing as in the flowchart is omitted.

[0217] When the charging device 10 of this modification does not determine that the efficiency Q is greater than or equal to the threshold value Eth in step S28 (step S28: No), it notifies the terminal device 30 of the intention to interrupt charging (step S81). When the terminal device 30 receives the notification, it operates in the same manner as the state of receiving charging from the charging device 10 while maintaining the communication state with the charging device. Next, the charging state control unit 49 cuts off the power supply to the power transmission coil 16 (step S82).

[0218] The foreign object detector 50 detects the metal foreign object 90 between the power transmission coil 16 and the power reception coil 31 (step S83). Next, when the foreign object detector 50 determines that a foreign object is detected (step S84: "Yes"), the process proceeds to step S86. On the other hand, when it is determined that a foreign object is not detected (step S84: "No"), the charging state control unit 49 restarts charging with the transmission power limited in step S21 (step S85), and proceeds to step S91.

[0219] In step S86, the control unit 22 makes Fig.13 The processing is stopped for a predetermined time. Fig.13 The processing of the charging device 30 is stopped for a predetermined time, so that the temperature of the metal foreign matter 90 can be reduced between the power transmission coil 16 and the power reception coil 31. As the predetermined time, it is desirable to stop for more than 5 seconds. In addition, for example, the same time can be ensured by delaying the notification of the restart of charging to the terminal device 30 in step S89.

[0220] In step S87 , the power transmission coil position search unit 48 moves the power transmission coil 16 to a position where the efficiency Q is maximized.

[0221] In step S88, the control unit 22 causes the power transmission coil 16 to transmit small power to the terminal device 30 in order to determine whether the terminal device 30 is placed on the charging stand 19. Next, in step S89, the charging device 10 notifies the terminal device 30 that charging has been resumed.

[0222] In step S90 , the charging state control unit 49 further limits the transmitted electric power compared with the transmitted electric power in step S21 and restarts charging.

[0223] In step S91 , the charging state control unit 49 determines whether the terminal device 30 has reached a fully charged state, and repeats the process of step S91 until it is determined that the terminal device 30 has reached a fully charged state.

[0224] In addition, Fig.15 During the operation, the charging device 10 monitors whether the communication with the terminal device 30 is continuing. If the communication with the terminal device 30 is disconnected, the process proceeds to step S11 and the operation is repeated. Fig.15 processing.

[0225] (Other Modifications of Embodiments)

[0226] exist Figure 7 In step S28 of the flowchart, when it is not determined that the efficiency Q is greater than the threshold value Eth (step S28: No), the charging state control unit 49 does not cut off the power supply to the power transmission coil 16, but further limits the transmission power and continues charging.

[0227] exist Fig.13 In the flowchart, it is set to wait for a specified time (step S50) before the position detection of the terminal device 30 (step S51), but the timing of executing the processing of step S50 is not limited to this, and it can also be executed at any time between steps S49 to step S56.

[0228] exist Fig.13 In the flowchart, the timing of executing the processing of sending a small amount of power to the terminal device 30 (step S52) and notifying the terminal device 30 to restart charging (step S53) is not limited to this, for example, it can also be executed after the foreign object determination in step S55.

[0229] (Note)

[0230] The following techniques are disclosed through the description of the above embodiments and modifications.

[0231] (Technology 1) A charging device that performs contactless charging of a terminal device having a power receiving coil by placing the terminal device on a charging stand, wherein the power receiving coil receives power that is wirelessly transmitted, and the charging device comprises: a power transmitting coil that transmits power to the terminal device; a power transmission instruction unit that causes the power transmitting coil to transmit power; a power transmission power acquisition unit that acquires the size of the power transmission power that the power transmission instruction unit causes to be transmitted; a power receiving power acquisition unit that acquires the size of the power receiving power received by the power receiving coil; a calculation unit that calculates the ratio of the power receiving power to the power transmitting power; and a charging state control unit that limits the power transmitting power when the ratio is less than a threshold value.

[0232] With this structure, when the ratio of the receiving power to the transmitting power is less than a threshold, the transmitting power can be limited and charging can be continued. By limiting the transmitting power, even if a metal foreign object enters between the transmitting coil and the receiving coil during charging, the heating of the metal foreign object can be suppressed and charging can be continued.

[0233] (Technique 2) The charging device according to Technique 1, wherein the charging state control unit releases the limitation on the transmitted power and continues charging when the ratio becomes greater than the threshold value while the transmitted power is limited when the ratio is less than the threshold value.

[0234] With this configuration, when the ratio is improved to a threshold value or more, the restriction on the transmitted power can be lifted and charging can be continued, thereby shortening the charging time.

[0235] (Technique 3) A charging device according to Technique 2, further comprising a power transmission position search unit (power transmission coil position search unit), wherein, when the power transmission power is limited when the ratio is less than a threshold value, the power transmission position search unit searches for the position of the power transmission coil that maximizes the ratio, and when the ratio at the position of the power transmission coil searched by the power transmission position search unit is greater than the threshold value, the charging state control unit releases the restriction on the power transmission power at the position of the power transmission coil searched by the power transmission position search unit and continues charging.

[0236] With this structure, the position of the power transmission coil can be corrected to the position of the power transmission coil where the ratio is improved to above the threshold, in other words, the position of the power transmission coil where there is no positional offset between the power transmission coil and the power receiving coil, without stopping charging, and charging can be continued. Therefore, the extension of charging time and power loss caused by the positional offset between the power transmission coil and the power receiving coil can be reduced.

[0237] (Technique 4) The charging device according to Technique 3, wherein when the ratio at the position of the power transmission coil searched by the power transmission position search unit is smaller than the threshold value, the charging state control unit stops charging or further limits the transmission power.

[0238] With this structure, if the ratio is not improved to above the threshold value and there is a high possibility that a metal foreign object has entered between the power transmission coil and the power reception coil, charging can be stopped or the power transmission power can be further limited. Thus, the heating of the metal foreign object can be suppressed, device failure can be avoided, and the device can be operated more safely.

[0239] (Technology 5) A charging device according to Technology 4, wherein, when the ratio at the position of the power transmission coil searched by the power transmission position search unit is less than the threshold value, the charging state control unit further limits the power transmission at the position of the power transmission coil that maximizes the ratio searched by the power transmission position search unit and continues charging.

[0240] This structure can suppress the heat generated by the metal foreign matter, avoid device failure, and enable the device to operate more safely.

[0241] (Technique 6) A charging device according to Technique 4, further comprising a foreign object detection unit, wherein the foreign object detection unit detects whether there is a metal foreign object between the power transmitting coil and the power receiving coil, and when the ratio at the position of the power transmitting coil searched by the power transmitting position search unit is less than the threshold value and the foreign object detection unit detects a metal foreign object, the charging state control unit stops charging or further limits the transmission power.

[0242] This structure can suppress the heat generated by the metal foreign matter, avoid device failure, and enable the device to operate more safely.

[0243] (Technique 7) The charging device according to Technique 6, wherein the foreign object detection unit detects whether or not a metallic foreign object is present between the power transmission coil and the power reception coil when the charging device is not charging.

[0244] This configuration allows detection of metallic foreign matter with high accuracy, and since charging is not performed during foreign matter detection, the temperature of metallic foreign matter can be lowered when there is metallic foreign matter.

[0245] (Technique 8) A charging device according to Technique 4, further comprising a foreign object detection unit, wherein the foreign object detection unit detects whether there is a metal foreign object between the power transmission coil and the power receiving coil, and when the ratio at the position of the power transmission coil searched by the power transmission position search unit is less than the threshold value, the charging state control unit stops charging, and when the charging is stopped by the charging state control unit, the foreign object detection unit detects whether there is the metal foreign object, and when the metal foreign object is detected by the foreign object detection unit, the charging state control unit further limits the transmission power after a specified time and restarts charging.

[0246] This configuration allows detection of metallic foreign matter with high accuracy, and since charging is not performed during foreign matter detection, the temperature of metallic foreign matter can be lowered when there is metallic foreign matter.

[0247] (Technique 9) The charging device according to Technique 8, wherein the charging state control unit resumes the charging at the position of the power transmission coil that maximizes the ratio, which is searched for by the power transmission position search unit.

[0248] With this structure, the charging time can be shortened.

[0249] (Technique 10) The charging device according to any one of Techniques 1 to 9, wherein the power transmission coil has a plurality of fixed coils, and the fixed coils have coil surfaces parallel to the coil surfaces of the power receiving coils of the terminal device placed on the charging stand.

[0250] With this configuration, the position of the fixed coil that provides the best ratio of received power to transmitted power (efficiency E(t)) can be set as the position of the power transmission coil, and the fixed coil can transmit power to the terminal device to continue charging.

[0251] (Technique 11) A charging device according to any one of Techniques 1 to 9, wherein the power transmission coil is a movable coil whose coil surface position is variable on a plane parallel to the coil surface of the power receiving coil of the terminal device placed on the charging base.

[0252] With this configuration, the power transmission coil can be moved to a position where there is no positional deviation from the power reception coil, and charging can be continued.

[0253] (Technology 12) A charging device that performs contactless charging of a terminal device having a power receiving coil by placing the terminal device on a charging stand, wherein the power receiving coil receives power transmitted wirelessly, and the charging device comprises: a power transmitting coil that transmits power to the terminal device; a power transmitting indication unit that causes the power transmitting coil to transmit power; a power transmitting power acquisition unit that acquires the size of the power transmitted by the power transmitting indication unit; a power receiving power acquisition unit that acquires the size of the power receiving power received by the power receiving coil; a calculation unit that calculates the ratio of the power receiving power to the power transmitting power; and a charging state control unit that stops charging when the ratio is less than a threshold value and restarts charging after a specified time has passed.

[0254] With this structure, when the ratio of the received power to the transmitted power is less than a threshold value, charging is temporarily stopped, and charging is resumed after a predetermined time has passed. Therefore, when a metal foreign object 90 enters between the power transmission coil and the power reception coil, the temperature of the metal foreign object can be lowered, and charging can be continued. Therefore, the heat generation of the metal foreign object can be suppressed, and charging can be continued.

[0255] (Technology 13) A charging device according to Technology 12, further comprising a foreign object detection unit, wherein the foreign object detection unit detects whether there is a metal foreign object between the power transmission coil and the power receiving coil, and when the power transmission to the terminal device is stopped when the ratio is less than the threshold, the foreign object detection unit detects whether there is a metal foreign object between the power transmission coil and the power receiving coil, and the charging state control unit stops charging when the ratio is less than the threshold, and when the metal foreign object is detected by the foreign object detection unit, the transmission power is limited and charging is restarted.

[0256] With this structure, when a metal foreign object is detected, the power transmission is limited and charging is restarted, so that the heating of the metal foreign object can be further suppressed and charging can be continued. Since the heating of the metal foreign object is further suppressed, the device can be prevented from malfunctioning and the device can be operated safely.

[0257] (Technology 14) A charging device according to Technology 12, further comprising a power transmission coil position setting unit, wherein the power transmission coil position setting unit sets the position of the power transmission coil according to the loading position of the terminal device, the power transmission coil transmits electric power to the terminal device at the position set by the power transmission coil position setting unit, and when charging is stopped when the ratio is less than the threshold, the power transmission coil position setting unit sets the position of the power transmission coil, and the charging state control unit stops charging when the ratio is less than the threshold, and restarts charging at the position of the power transmission coil set by the power transmission coil position setting unit.

[0258] This configuration allows the position of the power transmission coil to be corrected to a position where there is no positional misalignment between the power transmission coil and the power reception coil, thereby allowing charging to continue. This reduces the extension of charging time and power loss caused by the positional misalignment between the power transmission coil and the power reception coil.

[0259] (Technique 15) A charging device according to Technique 14, further comprising a foreign object detection unit, wherein the foreign object detection unit detects whether there is a metal foreign object between the power transmitting coil and the power receiving coil, and when charging is stopped when the ratio is less than the threshold, the foreign object detection unit detects whether there is a metal foreign object between the power transmitting coil and the power receiving coil, and the charging state control unit stops charging when the ratio is less than the threshold, and when a metal foreign object is detected by the foreign object detection unit, the transmission power is limited and charging is restarted.

[0260] With this structure, when a metal foreign object is detected, the power transmission is limited and charging is restarted, so that the heating of the metal foreign object can be further suppressed and charging can be continued. Since the heating of the metal foreign object is further suppressed, the device can be prevented from malfunctioning and the device can be operated safely.

[0261] (Technique 16) A charging device according to any one of Techniques 12 to 15, wherein when the ratio is less than the threshold, the terminal device is notified to stop charging, and when the ratio is less than the threshold, after the terminal device is notified, the charging state control unit stops charging, and before power supply to the terminal device is restarted, the terminal device is notified to restart charging, and charging is restarted after the terminal device is notified.

[0262] (Technique 17) A charging device according to any one of Techniques 12 to 16, wherein the communication state with the terminal device is maintained in the state where the charging is stopped.

[0263] With this structure, the charging device and the terminal device maintain a communication state, so there is no need to perform various authentication processes between the charging device and the terminal device before charging is restarted. For example, during the period when charging is stopped, the terminal device can operate in the same state as when receiving charging from the charging device. In addition, since there is no need to perform various authentication processes, charging can be restarted quickly after deciding to restart charging using the charging device.

[0264] (Technique 18) The charging device according to any one of Techniques 12 to 17, wherein the power transmission coil transmits power for determining whether the terminal device is placed on the charging stand after the power transmission to the terminal device is stopped.

[0265] With this structure, the terminal device can determine that the device is placed on the charging station by receiving the power. Moreover, the terminal device continues to perform the same action as when receiving charge from the charging device, and can quickly restart charging after deciding to restart charging using the charging device.

[0266] (Technique 19) A charging device according to any one of Techniques 12 to 18, wherein the power transmission coil has a plurality of fixed coils, and the fixed coils have coil surfaces parallel to the coil surfaces of the power receiving coils of the terminal device placed on the charging stand.

[0267] With this configuration, the fixed coil having the best ratio of received power to transmitted power (efficiency E(t)) is set as the position of the power transmission coil, and the fixed coil can be made to transmit power to the terminal device for charging.

[0268] (Technique 20) A charging device according to any one of Techniques 12 to 18, wherein the power transmission coil is a movable coil whose coil surface position is variable on a plane parallel to the coil surface of the power receiving coil of the terminal device placed on the charging stand.

[0269] With this configuration, charging can be performed while the power transmission coil is moved to a position where there is no positional deviation between the power transmission coil and the power reception coil.

[0270] The embodiments of the present invention are described above, but the above embodiments are presented as examples and are not intended to limit the scope of the present invention. The new embodiments can be implemented in various other ways. In addition, various omissions, substitutions, and changes can be made within the scope of the main purpose of the invention. In addition, the embodiments are included in the scope and main purpose of the invention, and are included in the scope equivalent to the invention described in the claims.

[0271] Description of Reference Numerals

[0272] 10: Charging device; 11: DC power supply; 12: DC-DC converter; 13: Bridge circuit; 14: Voltage detection circuit; 15: Current detection circuit; 16: Transmitting coil (movable coil); 17: Moving mechanism; 18: Position detection controller; 19: Charging stand; 20: Receiving coil position detection circuit; 21: Foreign matter detection circuit; 22: Control unit; 22a: Calculation unit; 22b: Calculation result comparison unit; 22c: Calculation result storage unit; 22d: Transmitting coil position control unit; 30: Terminal device; 31: Receiving coil; 32: Servo motor; 32a: X-axis servo motor; 32b: Y-axis servo motor; 33a: X-axis screw; 33b: Y-axis screw; 34a: X-axis nut Component; 34b: Y-axis nut component; 35: belt; 36: guide rod; 37: core; 38: position control circuit; 39: power supply circuit; 40: shell; 41: power transmission coil position setting unit; 42: power transmission indication unit; 43: power transmission power acquisition unit; 44: power receiving power acquisition unit; 45: power receiving efficiency calculation unit (calculation unit); 46: power receiving efficiency comparison unit; 47: power transmission power control unit; 48: power transmission coil position search unit (power transmission position search unit); 49: charging state control unit; 50: foreign matter detection unit; 90: metal foreign matter; C: capacitor; E(t), Q: efficiency; Eth: threshold value; Pout(t): power transmission power; Rp(t): receiving power; t: time; ΔW: power difference.

Claims

1. A charging device, wherein a terminal device having a power receiving coil is placed on a charging stand to perform contactless charging on the terminal device, wherein: The power receiving coil receives the wirelessly transmitted power, and the charging device comprises: a power transmission coil for transmitting power to the terminal device; a power transmission instruction unit configured to cause the power transmission coil to transmit power; a transmission power acquisition unit configured to acquire the magnitude of the transmission power to be transmitted by the transmission instruction unit; a received power acquisition unit that acquires the magnitude of the received power received by the received power coil; a calculation unit that calculates a ratio of the received power to the transmitted power; and A charging state control unit is configured to limit the transmitted electric power when the ratio is smaller than a threshold value.

2. The charging device according to claim 1, wherein: The charging state control unit releases the limitation on the transmitted power and continues charging when the ratio becomes equal to or greater than the threshold value while the transmitted power is limited when the ratio is less than the threshold value.

3. The charging device according to claim 2, wherein: The invention further comprises a power transmission position search unit, which searches for a position of the power transmission coil that maximizes the ratio when the ratio is less than a threshold value and the power transmission electric power is limited. When the ratio at the position of the power transmission coil searched by the power transmission position search unit is equal to or greater than the threshold, the charging state control unit releases the restriction on the transmission power at the position of the power transmission coil searched by the power transmission position search unit and continues charging.

4. The charging device according to claim 3, wherein: When the ratio at the position of the power transmission coil searched by the power transmission position search unit is smaller than the threshold value, the charging state control unit stops charging or further limits the transmission power.

5. The charging device according to claim 4, wherein: When the ratio at the position of the power transmission coil searched by the power transmission position search unit is smaller than the threshold value, the charging state control unit further limits the transmission power and continues charging at the position of the power transmission coil searched by the power transmission position search unit where the ratio is maximized.

6. The charging device according to claim 4, wherein: The device further comprises a foreign object detector for detecting whether a metallic foreign object exists between the power transmission coil and the power reception coil. When the ratio at the position of the power transmission coil searched by the power transmission position search unit is smaller than the threshold value and a metal foreign object is detected by the foreign object detector, the charging state control unit stops charging or further limits the transmission power.

7. The charging device according to claim 6, wherein: The foreign object detection unit detects whether a metallic foreign object is present between the power transmission coil and the power reception coil when the charging device is not charging.

8. The charging device according to claim 4, wherein: The device further comprises a foreign object detector for detecting whether a metallic foreign object exists between the power transmission coil and the power reception coil. The charging state control unit stops charging when the ratio at the position of the power transmission coil searched by the power transmission position search unit is smaller than the threshold value. The foreign object detection unit detects whether the metal foreign object exists in a state where the charging is stopped by the charging state control unit. When the foreign object detector detects the metal foreign object, the charging state control unit further limits the transmitted power and restarts charging after a predetermined time has passed.

9. The charging device according to claim 8, wherein: The charging state control unit resumes the charging at the position of the power transmission coil that maximizes the ratio, which is searched for by the power transmission position search unit.

10. The charging device according to any one of claims 1 to 9, wherein: The power transmission coil includes a plurality of fixed coils, and the fixed coils have coil surfaces parallel to the coil surfaces of the power reception coils of the terminal device placed on the charging station.

11. The charging device according to any one of claims 1 to 9, wherein: The power transmission coil is a movable coil whose coil surface position is variable on a plane parallel to the coil surface of the power reception coil of the terminal device placed on the charging stand.

12. A charging device, which performs contactless charging on a terminal device having a power receiving coil by placing the terminal device on a charging stand, wherein: The power receiving coil receives the wirelessly transmitted power, and the charging device comprises: a power transmission coil for transmitting power to the terminal device; a power transmission instruction unit configured to cause the power transmission coil to transmit power; a transmission power acquisition unit configured to acquire the magnitude of the transmission power to be transmitted by the transmission instruction unit; a received power acquisition unit that acquires the magnitude of the received power received by the received power coil; a calculation unit that calculates a ratio of the received power to the transmitted power; and The charging state control unit stops charging when the ratio is smaller than a threshold value, and restarts charging after a predetermined time has passed.

13. The charging device according to claim 12, wherein: The device further comprises a foreign object detector for detecting whether a metallic foreign object exists between the power transmission coil and the power reception coil. When the power transmission to the terminal device is stopped when the ratio is less than the threshold value, the foreign object detection unit detects whether there is a metallic foreign object between the power transmission coil and the power reception coil. The charging state control unit stops charging when the ratio is smaller than the threshold value, and limits the transmitted power and restarts charging when a metallic foreign object is detected by the foreign object detection unit.

14. The charging device according to claim 12, wherein: The device further comprises a power transmission coil position setting unit, the power transmission coil position setting unit setting the position of the power transmission coil according to the placement position of the terminal device, The power transmission coil transmits electric power to the terminal device at a position set by the power transmission coil position setting unit. When charging is stopped when the ratio is smaller than the threshold value, the power transmission coil position setting unit sets the position of the power transmission coil. The charging state control unit stops charging when the ratio is smaller than the threshold value, and restarts charging at the position of the power transmission coil set by the power transmission coil position setting unit.

15. The charging device according to claim 14, wherein: The device further comprises a foreign object detector for detecting whether a metallic foreign object exists between the power transmission coil and the power reception coil. When charging is stopped when the ratio is less than the threshold value, the foreign object detection unit detects whether there is a metallic foreign object between the power transmission coil and the power reception coil. The charging state control unit stops charging when the ratio is smaller than the threshold value, and limits the transmitted power and restarts charging when a metallic foreign object is detected by the foreign object detection unit.

16. The charging device according to any one of claims 12 to 15, wherein: When the ratio is less than the threshold, notifying the terminal device to stop charging, When the ratio is smaller than the threshold, the charging state control unit stops charging after notifying the terminal device of the ratio. Before the power transmission to the terminal device is resumed, the terminal device is notified of the resumption of charging, and after the terminal device is notified, charging is resumed.

17. The charging device according to any one of claims 12 to 15, wherein: In the charging stopped state, the communication state with the terminal device is maintained.

18. The charging device according to any one of claims 12 to 15, wherein: The power transmission coil transmits power for determining whether the terminal device is placed on the charging stand after the power transmission to the terminal device is stopped.

19. The charging device according to any one of claims 12 to 15, wherein: The power transmission coil includes a plurality of fixed coils, and the fixed coils have coil surfaces parallel to the coil surfaces of the power reception coils of the terminal device placed on the charging station.

20. The charging device according to any one of claims 12 to 15, wherein: The power transmission coil is a movable coil whose coil surface position is variable on a plane parallel to the coil surface of the power reception coil of the terminal device placed on the charging stand.

Images