JP2014093921A - Contactless charging device and contactless charging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately detect foreign objects in contactless charging.SOLUTION: A contactless charging device includes: a power receiving coil 4 embedded in a battery built-in apparatus 2 mounted on a charging table; a power transmitting coil 3 embedded in the charging table that can be electromagnetically coupled; first temperature detecting means 30 for detecting temperatures, disposed in the vicinity of the power transmitting coil 3; and foreign object detecting means 12 determining whether foreign objects FO are mounted on the charging table on the basis of a time change of temperature information having been detected with a predetermined time interval by means of the first temperature detecting means 30. With the constitution, heat generation in the normal operation of the power transmitting coil 3 and heat generation when the foreign objects FO are inserted can be discriminated not by mere temperature detection but on the basis of a gradient of temperature rising, so that foreign objects can be accurately detected, even specifically in a high-output contactless charging device.

Description

  The present invention relates to a charging device that charges a battery built-in device or a battery pack without contact, and a charging method thereof.

  A contactless charging method has been developed in which a battery built-in device with a built-in power receiving coil is set on a charging stand with a built-in power transmitting coil, power is transferred from the power transmitting coil to the power receiving coil, and the battery of the battery built-in device is charged. (See Patent Document 1).

  In this contactless charging method, the battery built-in device is set on the charging stand so that the power transmission coil of the charging stand and the power receiving coil of the battery built-in device are electromagnetically coupled, and power is transferred from the power transmitting coil to the power receiving coil. The built-in battery of the battery built-in device is charged with the electric power induced in the receiving coil. In this charging method, it is not necessary to connect the battery built-in device to the charging stand via the connector, and the built-in battery can be conveniently charged by a non-contact method.

  In this charging method, as shown in the schematic diagram of FIG. 39, when a metal foreign object FO (Foreign Object) such as a clip is inserted between the power transmission coil 4103 and the power receiving coil 4104, an induced current flows through the metal foreign object. There is a harmful effect of heat generation due to Joule heat. In addition, since the induction current flows through the metal foreign object and consumes power wastefully, the power obtained by the power receiving coil 4104 is reduced and the battery cannot be efficiently charged from the charging stand. In order to eliminate this drawback, the charging base of Patent Document 1 has a large number of temperature sensors arranged vertically and horizontally on the upper surface. The temperature sensor detects that a metal foreign object placed on the charging stand generates heat. In this charging stand, when AC power is supplied to the power transmission coil with a metal foreign object placed on the charging base, an induction current flows through the metal object to generate heat. It is detected by the temperature sensor.

JP 2008-17562 A JP 2008-172874 A JP 2009-273260 A JP 2009-277690 A

  However, since the temperature rise changes depending on the shape and material of the foreign matter, there is a problem that the foreign matter may not always be accurately detected only by simple temperature detection. In particular, in recent years, the capacity of built-in secondary batteries tends to increase in order to improve the performance of battery-embedded devices and increase the operating time. On the other hand, further shortening of the charging time is also demanded, and as a result, a higher output of the charging current is desired. However, in this case, the power transmission current supplied to the power transmission coil also increases, so the amount of heat generated by Joule heat in the power transmission coil itself also increases. For this reason, not only the foreign matter but also the heat generation of the power transmission coil occurs, and it is difficult to determine whether it is caused by the foreign matter or due to an increase in the power transmission current only by detecting the heat generation.

  The present invention has been made for the purpose of solving the conventional problems. A main object of the present invention is to provide a non-contact charging apparatus and a non-contact charging method that enable more accurate foreign object detection during non-contact charging.

Means for Solving the Problems and Effects of the Invention

  According to one non-contact charging apparatus according to the present invention, a power receiving coil built in a charging base electromagnetically coupled to a power receiving coil built in a battery built-in device placed on a charging base, A non-contact charging device provided with a first temperature detecting means arranged in the vicinity for detecting the temperature, and further, with respect to the time change of the temperature information detected at predetermined time intervals by the first temperature detecting means Based on this, it is possible to provide a foreign object detection means for determining whether or not a foreign object is placed on the charging stand. With the above configuration, it is possible to distinguish between heat generation during normal operation of the power transmission coil and heat generation during insertion of a foreign object by not only detecting the temperature but based on the gradient of temperature rise. However, accurate foreign object detection is possible.

  According to another contactless charging apparatus of the present invention, the temperature of the power transmission coil can be detected by the first temperature detecting means.

  Furthermore, according to another contactless charging apparatus of the present invention, the temperature of the foreign matter can be detected by the first temperature detecting means.

  Furthermore, according to another contactless charging apparatus of the present invention, the foreign object detection means detects a threshold value related to a time change of the temperature information detected by the first temperature detection means and a calculation used to calculate the time change. There are a plurality of parameters configured in combination with a time interval, and foreign matter detection can be performed when a condition of any one of the plurality of parameters is met. With the above configuration, various foreign substances can be accurately detected. For example, foreign matters with a fast temperature rise can be detected early, while foreign matters with a slow temperature rise can be determined over time, so even different types of foreign matter can be accurately detected.

  Furthermore, according to another contactless charging apparatus of the present invention, the plurality of parameters can include a set of a plurality of parameters with different detection time intervals while setting the same threshold value.

  Furthermore, according to another contactless charging apparatus of the present invention, the detection time interval can be set to 30 seconds or more. With the above configuration, the difference between the case where foreign matter is present and the case where foreign matter is present can be clarified, and accurate foreign matter detection can be expected.

  Furthermore, according to another contactless charging apparatus of the present invention, the first temperature detection unit is further connected to the first temperature detection unit, and delays information related to the temperature detected by the first temperature detection unit by a first delay time. A delay circuit and a second delay circuit that delays by a second delay time longer than the first delay time, and the foreign object detection means is obtained based on the temperature information delayed by the first delay circuit. The first time change can be compared with the first threshold, and the second time change obtained based on the temperature information delayed by the second delay circuit can be compared with the second threshold.

  Furthermore, according to another contactless charging apparatus of the present invention, the battery pack further includes second temperature detecting means for measuring an ambient environmental temperature, and the foreign object detecting means is detected by the first temperature detecting means. It can be configured to start charging by detecting that the difference between the temperature of the power transmission coil and the environmental temperature detected by the second temperature detecting means is within a predetermined range.

  Furthermore, according to another contactless charging device of the present invention, the first temperature detecting means can be arranged inside the innermost circumference of the power transmission coil. With the above configuration, the temperature of the power transmission coil can be accurately detected without being influenced by the ambient temperature.

  Furthermore, according to another contactless charging apparatus of the present invention, the power transmission coil can be moved. With the above configuration, temperature detection at different positions can be performed by the first temperature detection means.

  Furthermore, according to another contactless charging apparatus of the present invention, the first temperature detecting means can be constituted by an NTC thermistor. With the above configuration, the temperature can be detected with high accuracy.

  Furthermore, according to another contactless charging apparatus of the present invention, an insulating heat conductive sheet can be further coated on the upper surface of the charging stand. With the above configuration, heat dissipation is promoted through the heat conductive sheet, so that temperature rise due to insertion of foreign matter can be suppressed.

  In addition, according to the contactless charging method of the present invention, the power receiving coil built in the battery built-in device placed on the charging stand, the power transmitting coil built in the charging base that can be electromagnetically coupled, and the innermost of the power transmitting coil A non-contact charging method using a non-contact charging device including a first temperature detecting means arranged in an inner part of the circumference, the step of transmitting power from the power transmission coil toward the power receiving coil; and The step of measuring the temperature with the first temperature detection means, and the foreign matter detection means places the foreign matter on the charging stand based on the time change of the temperature information detected at a predetermined time interval by the first temperature detection means. Determining whether it is placed. With the above configuration, it is possible to distinguish between heat generation during normal operation of the power transmission coil and heat generation during insertion of a foreign object by not only detecting the temperature but based on the gradient of temperature rise. However, accurate foreign object detection is possible.

  Furthermore, according to another contactless charging method of the present invention, as the current control means, the charging current is limited to a value lower than a predetermined value until it can be confirmed by the foreign matter detection means that there is no foreign matter whose temperature rises quickly. The battery can be charged with a current and charged with a predetermined charging current after a predetermined time has elapsed. With the above configuration, when charging is performed with a normal charging current from the beginning, it is possible to avoid a situation in which a rapid temperature increase occurs due to the presence of a foreign object whose temperature increases quickly.

It is a block diagram which shows the state which mounted the battery built-in apparatus in the non-contact charging device which concerns on Embodiment 1 of this invention. It is a block diagram which shows the state by which a foreign material is interposed between a non-contact charging device and a battery built-in apparatus in the state of FIG. It is a schematic diagram which shows an example of the moving mechanism of a power transmission coil. It is a perspective view which shows a mode that the mobile telephone which incorporated the receiving coil is mounted in the charging stand which made the power transmission coil movable. It is a block diagram which shows an example of the foreign material detection circuit which comprises a foreign material detection means. It is a graph which shows a mode that the temperature of the power transmission coil detected by the 1st temperature detection means changes with the presence or absence of a foreign material. It is a graph which shows the temperature change of the foreign material in the example of FIG. It is a graph which shows the result of having measured change time dependence of temperature change. It is the graph which confirmed that the false detection of a foreign material did not arise with a threshold value of 1.26 degreeC with respect to six thermistors. It is the graph which confirmed that the false detection of a foreign material did not arise at the threshold value of 1.26 degreeC in the state which separated the power transmission coil and the power receiving coil by 0 mm-3 mm. In FIG. 6, the vertical axis is a graph representing a voltage value obtained by a thermistor instead of a temperature change as a digital value obtained by AD conversion for processing by a microcomputer. It is a graph which shows the result of having arrange | positioned the foreign material in the center of a power transmission coil, and measuring the temperature change and temperature for every time. It is a graph which shows the result of having measured the temperature change and temperature for every time, arranging a foreign substance apart from a power transmission coil. 14 is a table showing temperatures at which charging is stopped in FIGS. 12 and 13. It is a block diagram which shows a mode that a battery pack is mounted in the charging stand which fixed the power transmission coil. It is a schematic cross section which shows the state in which a foreign material exists between a power transmission coil and a receiving coil. It is a schematic plan view which shows the example which has arrange | positioned the 1st temperature detection means in the center of the power transmission coil. It is a schematic plan view which shows a mode that the 2nd thermistor was provided in the stage. It is a flowchart which shows the flow of the operation | movement in which a foreign material detection circuit detects the presence or absence of a foreign material. 10 is a flowchart illustrating an operation for performing foreign object determination according to the second embodiment. It is a flowchart which shows the operation | movement which performs the foreign material determination which concerns on a modification. It is a schematic cross section which shows the state by which the metal foreign material was placed in the position away from the thermistor. 6 is a schematic diagram showing a state in which a foreign object is placed on a contactless charging apparatus according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view showing a state where a battery built-in device is placed on a contactless charging apparatus according to Embodiment 3. It is a graph which shows the temperature change of the power transmission coil detected with the thermistor with respect to time by the presence or absence of a heat conductive sheet, and the temperature of a foreign material. It is a graph which shows the time variation | change_quantity of a 1st temperature detection means when ambient temperature raises by 0.5 degreeC / min. It is a graph which shows the time variation | change_quantity of a 1st temperature detection means when ambient temperature falls by 0.5 degreeC / min. It is a graph which shows the time variation | change_quantity of the 1st temperature detection means at the time of correct | amending with ambient temperature. It is a block diagram which shows an example of the foreign material detection circuit which comprises the foreign material detection means which concerns on Embodiment 4. It is a top view which shows the example of arrangement | positioning of a 2nd temperature detection means. It is a top view which shows the other example of arrangement | positioning of a 2nd temperature detection means. It is a graph which shows the result of having measured the time change of the temperature of a power transmission coil, and a foreign material temperature, changing the temperature difference of ambient temperature and power transmission coil temperature. It is a flowchart which shows the operation | movement which performs charging, detecting a foreign material in consideration of the change of ambient temperature. FIG. 10 is a block diagram illustrating a contactless charging apparatus according to a sixth embodiment. It is a graph which shows the result of having measured the temperature change and the time change of a foreign material temperature in the state which has arrange | positioned the foreign material. 18 is a flowchart illustrating a procedure for performing foreign object detection based on temperature change and charging efficiency according to the seventh embodiment. 19 is a flowchart illustrating a procedure for performing foreign object detection based on a plurality of threshold temperature changes and charging efficiency according to an eighth embodiment. It is a graph which shows the temperature change which concerns on Embodiment 9, and a comparative example, and the time change of a foreign material temperature. It is a schematic diagram which shows the case where a foreign material exists between a power transmission coil and a receiving coil.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a contactless charging apparatus and a contactless charging method for embodying the technical idea of the present invention, and the present invention is a contactless charging apparatus and a contactless charging method. Is not specified as below. In addition, the member shown by the claim is not what specifies the member of embodiment. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in the embodiments are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. In addition, the contents described in some examples and embodiments may be used in other examples and embodiments.
(Embodiment 1)

  1 to 2 show a state of charging a battery built-in device 2 with a contactless charging stand 1 as a contactless charging apparatus according to Embodiment 1 of the present invention. In these drawings, FIG. 1 is a block diagram showing a state in which a battery built-in device 2 is placed on the contactless charging apparatus according to Embodiment 1, and FIG. 2 is a state of FIG. The block diagram which shows the state in which a foreign material is interposed between each is shown. The non-contact charging stand 1 shown in these drawings shows a state in which the battery built-in device 2 is placed on the charging stand 1 and the battery 6 of the battery built-in device 2 is charged.

  In the contactless charging stand 1, an upper surface plate 7 on which the battery built-in device 2 is placed is provided on the upper surface of the case, and the power transmission coil 3 is disposed inside the upper surface plate 7. The power transmission coil 3 is connected to an AC power supply 8 and controls the AC power supply 8 using a control circuit 9. The control circuit 9 detects the detection signal transmitted from the transmission circuit 10 of the battery built-in device 2 by the receiving circuit 11, and controls the power supplied to the power transmission coil 3 with the detection signal to be detected. To carry power.

  On the other hand, the battery built-in device 2 includes a battery 6, a power receiving coil 4, a charge control circuit 15 that converts the alternating current induced in the power receiving coil 4 into direct current and charges the battery, and detects the full charge of the battery, A transmission circuit 10 in which the battery built-in device 2 is set on the contactless charging stand 1, stores a change amount (ΔH) that increases the inductance of the power transmission coil 3 as a threshold value, and transmits the threshold value to the contactless charging stand 1; Is provided. The battery built-in device 2 can also be detachably built in with a battery to be charged as a battery pack.

  In this example, an example of charging a mobile phone or a battery pack for a mobile phone with a contactless charging stand will be described, but the contactless charging device of the present invention is not limited to a mobile phone or its battery pack, Needless to say, the present invention can be appropriately used for other battery-equipped devices.

  The contactless charging stand 1 detects the amount of change (ΔH) in the inductance of the detection coil K, and detects the amount of change in inductance (ΔH) to be detected. A foreign object detection circuit 12 is provided for determining whether 5 is set. The contactless charging stand 1 of FIG. 1 determines that the metal foreign object 5 is set on the upper surface plate 7 in the vicinity of the battery built-in device 2 by using the power transmission coil 3 together with the detection coil K. However, in the contactless charging method of the present invention, as shown in FIG. 2, the metal detecting coil 14 dedicated to foreign matter detection is provided without using the power transmission coil 3 together with the detection coil K, and the vicinity of the battery built-in device 2 is provided. It is also possible to detect that a metal foreign object has been set on the surface.

  The non-contact charging stand 1 electromagnetically couples the power transmission coil 3 to the power receiving coil 4 and carries power from the power transmitting coil 3 to the power receiving coil 4. The contactless charging stand 1 for charging the battery 6 by setting the battery built-in device 2 at a free position on the top plate 7 so that the power transmission coil 3 approaches the power reception coil 4 as shown in FIGS. A moving mechanism can also be incorporated. In the contactless charging stand 1, the power transmission coil 3 is disposed below the upper surface plate 7 of the case, and is moved along the upper surface plate 7 to approach the power receiving coil 4. However, the charging base does not necessarily have a built-in mechanism for moving the power transmission coil so that the power transmission coil approaches the power reception coil. The battery built-in device is arranged at a fixed position of the charging base, and the power transmission coil is used as the power reception coil. An approaching structure can also be used.

  The power transmission coil 3 is a flat coil wound in a spiral shape on a surface parallel to the upper surface plate 7, and radiates an alternating magnetic flux above the upper surface plate 7. The power transmission coil 3 radiates an alternating magnetic flux substantially orthogonal to the upper surface plate 7 above the upper surface plate 7. The power transmission coil 3 is supplied with AC power from the AC power source 8 and radiates AC magnetic flux above the top plate 7. The power transmission coil 3 is substantially equal to the outer diameter of the power reception coil 4 and efficiently conveys power to the power reception coil 4.

  The AC power supply 8 supplies, for example, high frequency power of 20 kHz to 1 MHz to the power transmission coil 3. The contactless charging stand 1 that moves the power transmission coil 3 so as to approach the power receiving coil 4 connects an AC power supply 8 to the power transmission coil 3 via a flexible lead wire. The AC power supply 8 includes an oscillation circuit and a power amplifier that amplifies the AC output from the oscillation circuit.

The contactless charging stand 1 is a state in which the power transmission coil 3 is brought close to the power reception coil 4 and the metallic foreign object 5 is not set. In the state where the metal foreign object 5 is set in the vicinity of the coil 4, electric power is not conveyed. The AC power of the power transmission coil 3 is conveyed to the power receiving coil 4 and charges the battery 6. When the battery 6 is fully charged, the non-contact charging stand 1 stops the power supply to the power transmission coil 3 by the full charge signal transmitted from the battery built-in device 2 and stops the charging of the battery 6.
(Foreign matter detection circuit 12)

  Further, the charging stand includes a foreign matter detection circuit 12 as foreign matter detection means for detecting whether or not a foreign matter is placed on a charging surface provided for charging on the charging surface. A configuration example of such a foreign matter detection circuit 12 is shown in FIG. The foreign object detection circuit 12 shown in this figure is connected to the power transmission coil 3 and first temperature detection means 30 that is disposed in the vicinity of the power transmission coil 3 and detects temperature. The foreign object detection circuit 12 includes a first A / D converter, a delay circuit, and a control unit. The foreign matter detection circuit 12 measures the temperature of the power transmission coil 3 and the foreign matter with the first temperature detection means 30, and determines the presence or absence of the foreign matter based on the degree of the temperature rise. The determination of the presence or absence of a foreign object can be performed based on, for example, the absolute value of the temperature or the efficiency of power sent from the power transmission coil to the power reception coil. However, this method is effective when the rated output is relatively low, such as 5 W, but when the power is high, such as 10 W or more, the power transmission current flowing through the power transmission coil also increases, so the heat generation amount of the power transmission coil also increases. Thus, even when the object is normal without foreign matter, it generates a certain amount of heat, and it is difficult to distinguish the cause of the heat generation only by the absolute value of the temperature. Moreover, since the power transmission current becomes large, the efficiency determination based on the same standard as 5 W may cause a rapid and large temperature rise of foreign matter.

On the other hand, when there is a foreign substance, not only the absolute value of the temperature changes, but also the rate of temperature rise in a certain time changes. Therefore, the presence / absence of foreign matter is determined by examining the gradient of temperature rise (hereinafter referred to as “temperature change”). With this method, it is possible to more accurately detect the presence or absence of foreign matter even when the absolute value of the temperature is high during normal operation with high output.
(Threshold)

Here, the temperature change of the power transmission coil detected by the first temperature detection means and the time change from the start of charging the foreign object temperature are shown in FIGS. 6 and 7, respectively. In this example, a 15 mm square piece of aluminum is used as a foreign object, placed at a position (0 mm, 5 mm, 10 mm, 15 mm) away from the center of the power transmission coil, and power transmission is started to perform charging. Next, the temperature change measured by the thermistor arranged at the center of the power transmission coil was measured. The temperature change is T ₀ ° C at a certain time t ₀ and the temperature at time t ₁ = t ₀ + Δt after a lapse of Δt seconds is T ₁ = T ₀ + ΔT, where T ₁ = T ₀ + ΔT. Is represented by (T ₁ −T ₀ ) / (t ₁ −t ₀ ) = ΔT / Δt. As shown in FIG. 6, the absolute value of the temperature change is lower and the time change is smaller as the foreign object is not present or the installation position of the foreign object is farther from the center of the power transmission coil. On the other hand, it can be seen that when the foreign object is placed at a position close to the center of the power transmission coil, the absolute value of the temperature change is high and the time change is also large. Thus, it can be seen that the absolute value of the temperature differs depending on the position where the foreign object is placed, and that it is effective to determine the foreign object based on the temperature change. The example in FIG. 6 suggests that the presence / absence determination of foreign matter can be performed by setting the threshold value for determining the presence / absence of foreign matter to about 1 ° C. In this example, 1.26 ° C. was set as the threshold value.

The method is not limited to the method of immediately determining that there is a foreign object once the threshold value is exceeded, but may be configured to determine that there is a foreign material when the threshold value is exceeded a certain number of times. As a result, it is possible to avoid a situation in which it is erroneously detected due to a disturbance such as noise. In this example, it is determined that the foreign object detection circuit 12 has detected a foreign object when the threshold value is exceeded five times or more cumulatively.
(Detection time interval)

  On the other hand, the result of measuring the change time dependency of the temperature change is shown in FIG. Here, as in FIG. 6, when a 15 mm square aluminum piece is used as a foreign object and placed at a position 15 mm away from the center of the power transmission coil and charged, the change time of the temperature change of the power transmission coil for 6 minutes from the start of charging. Dependency was measured. In the figure, the case where there is a foreign object is indicated by a solid line, and the case where there is no foreign object is indicated by a broken line. The solid lines in the figure indicate the maximum and minimum values of temperature change, and ◇ and Δ indicate average values, respectively. As shown in this figure, the amount of change increases as the change time, that is, the time interval for detecting the temperature by the thermistor is longer. In addition, in 30 seconds or less, the temperature change partially overlaps with or without foreign matter, and erroneous detection occurs. For this reason, it is necessary to secure the detection time interval for at least 30 seconds. Preferably, it can be said that determination with a detection time interval of 60 seconds at which the range in which the temperature change can be taken is sufficiently separated depending on the presence or absence of foreign matter is preferable in terms of improving the accuracy of foreign matter detection.

  In addition to the detection time interval described above, the threshold value for determining the presence / absence of a foreign object is not limited to the individual difference of the thermistor constituting the first temperature detection means, the distance between the power transmission coil and the power reception coil in the charging stand, etc. Dependent. In particular, when the object to be charged is covered with a protective cover, or when the charging stand is covered with a heat conductive sheet 20 described later, the distance between the power transmission coil and the power reception coil is increased in the height direction (Z direction). Therefore, an appropriate threshold value that does not cause erroneous detection of foreign matters is set while considering these variations. According to the test conducted by the present inventor, by setting 1.26 ° C. set as the threshold value as described above, it is possible to detect a foreign object in a plurality of randomly extracted samples, and to mistakenly indicate that there is no foreign object. It was confirmed that there was no false detection that there was a foreign object (FIG. 9). In addition, the same experiment was performed by changing the distance between the power transmission coil and the power reception coil by 1 mm in the range of 0 mm to 3 mm in the height direction of the charging stand. It was confirmed that there was no false detection that there was a foreign object (FIG. 10).

In measuring the temperature change, it is not always necessary to convert to temperature, and information representing temperature can be used. For example, when a thermistor is used as the first temperature detecting means, a digital value obtained by A / D converting the voltage value obtained from the thermistor may be used as it is for the calculation of the threshold value. For example, in FIG. 6, a graph in which the vertical axis represents digital values instead of temperature changes is shown in FIG. In this case, the same result as described above can be obtained by setting a digital value of 10 instead of 1.26 ° C. indicating the time change of temperature as the threshold value.
(Multiple thresholds)

  Furthermore, a plurality of parameters composed of combinations of threshold values and detection time intervals can be set. In particular, the degree of the temperature rise of the foreign matter varies depending on the position where the foreign matter is placed, the size and material of the foreign matter, and the like. The result of measuring the temperature rise when the position where the foreign object is placed is changed is shown in FIGS. In these figures, the 15 mm square aluminum piece described above is used as a foreign substance, and this is located at the center of the power transmission coil in FIG. 12 and at a position 15 mm away from the center of the power transmission coil in FIG. The time interval is changed from 20 seconds to 60 seconds in increments of 10 seconds, and the temperature change detected by the thermistor and the absolute value of the temperature (foreign object temperature) are measured. FIG. 14 shows the temperature when the foreign object detection circuit 12 detects a foreign object and stops power transmission. As shown in these figures, the temperature change differs depending on the position of the foreign object and the detection time interval. When installed at a position of 15 mm, it can be seen that foreign matter cannot be detected unless the detection time interval is set to 50 seconds or more.

  On the other hand, when it is installed at a position of 0 mm, charging is stopped at the lowest temperature (64.3 ° C.) in the example in which the detection time interval is set to 30 seconds. Compared with the case where the detection time interval is 60 seconds, the temperature is reduced by about 11%. For these reasons, as a parameter, in addition to the threshold value of 1.26 ° C. and the detection time interval of 60 seconds, the foreign matter determination is performed even at the threshold value of 1.26 ° C. and the detection time interval of 30 seconds. Can be reliably detected over time, while a foreign substance whose temperature rises quickly can be detected in a shorter time, and reliability can be improved. Further, such a change in the detection time interval is sufficient only by changing the sampling period, and there is an advantage that it can be easily implemented without requiring hardware change or addition.

In addition, if a plurality of parameters are set in this way and a foreign object is detected if any of the parameters, that is, the conditions are met, an appropriate value is set according to different conditions such as a plurality of different foreign objects, positions, and materials. Since the conditions can be set, the foreign object detection accuracy can be improved. Also, in this example, a set of parameters with different detection time intervals while setting the threshold value constant is set, but conversely, a set of parameters with different threshold values while setting the detection time interval constant, Alternatively, a set of parameters in which both the threshold value and the detection time interval are different can be set. Further, the number of parameters can be set to two sets, or three or more sets.
(Delay circuit)

Returning to FIG. 5, the configuration of the contactless charging apparatus will be described. The delay circuit is provided to acquire a temperature value (delay temperature) before a predetermined time from the current temperature value in order to calculate a temperature change. Here, a delay circuit is provided on the output side of the first A / D converter, and the temperature information output from the first A / D converter is held for a predetermined time and output to the control circuit. By providing a plurality of such delay circuits, a plurality of time parameters can be set (details will be described later). In the example of FIG. 5, the output output from the first delay circuit is delayed by a first time. The output of the second delay circuit connected in parallel with the first delay circuit is output after being delayed by a second delay time longer than the first delay time.
(Control part)

The control unit acquires an output from the first A / D converter, that is, real-time temperature information, and an output from the first delay circuit, that is, temperature information after the first delay time has elapsed. Further, when the second delay circuit is provided, temperature information after the second delay time has elapsed is acquired. Based on this, the first temperature change (and second temperature change) in the first delay time (and second delay time) can be acquired. Furthermore, the control unit compares the first temperature change with a first threshold value set in advance as a reference value for determining the presence or absence of foreign matter. When the first temperature change is larger than the first threshold, it is determined that the temperature change is large and there is a foreign object, and when it is small, it is determined that there is no foreign object. In addition, as a process when a control part determines with there being a foreign material, predetermined processes, such as charge stop and reduction of a charging current, are performed. In addition, the control unit includes a nonvolatile memory that holds a predetermined value such as a preset first threshold value.
(Coil moving mechanism 16)

  The power transmission coil 3 is moved by the coil moving mechanism 16 so as to approach the power receiving coil 4. An example of the moving mechanism of the power transmission coil is shown in FIGS. The coil moving mechanism 16 shown in this figure moves the power transmission coil 3 along the upper surface plate 7 in the X-axis direction and the Y-axis direction to approach the power receiving coil 4. The coil moving mechanism 16 shown in the figure rotates the screw rod 18 by the servo motor 17 controlled by the position detection controller, moves the nut member 41 screwed into the screw rod 18, and moves the power transmission coil 3 to the power receiving coil 4. To approach. The servo motor 17 includes an X-axis servo motor 17A that moves the power transmission coil 3 in the X-axis direction, and a Y-axis servo motor 17B that moves the Y-axis direction. The screw rod 18 includes a pair of X-axis screw rods 18A that move the power transmission coil 3 in the X-axis direction, and a Y-axis screw rod 18B that moves the power transmission coil 3 in the Y-axis direction. The pair of X-axis screw rods 18A are arranged in parallel to each other, driven by the belt 19, and rotated together by the X-axis servomotor 17A. The nut material 41 includes a pair of X-axis nut materials screwed into the respective X-axis screw rods 18A and a Y-axis nut material screwed into the Y-axis screw rods 18B. Both ends of the Y-axis screw rod 18B are coupled to a pair of X-axis nut members so that they can rotate. The power transmission coil 3 is connected to the Y-axis nut material.

  Furthermore, the coil moving mechanism 16 shown in the figure has a guide rod 42 disposed in parallel with the Y-axis screw rod 18B in order to move the power transmission coil 3 in the Y-axis direction in a horizontal posture. Both ends of the guide rod 42 are connected to a pair of X-axis nut members and move together with the pair of X-axis nut members. The guide rod 42 passes through a guide portion connected to the power transmission coil 3 so that the power transmission coil 3 can be moved along the guide rod 42 in the Y-axis direction. That is, the power transmission coil 3 moves in the Y-axis direction in a horizontal posture via the Y-axis screw rod 18 </ b> B and the Y-axis nut member that moves along the guide rod 42 and the guide portion arranged in parallel to each other.

  In the coil moving mechanism 16, when the X-axis servomotor 17A rotates the X-axis screw rod 18A, the pair of X-axis nut members move along the X-axis screw rod 18A, and the Y-axis screw rod 18B and the guide rod 42 is moved in the X-axis direction. When the Y-axis servomotor 17B rotates the Y-axis screw rod 18B, the Y-axis nut material moves along the Y-axis screw rod 18B, and moves the power transmission coil 3 in the Y-axis direction. At this time, the guide part connected to the power transmission coil 3 moves along the guide rod 42 to move the power transmission coil 3 in the Y-axis direction in a horizontal posture. Therefore, the power transmission coil 3 can be moved in the X-axis direction and the Y-axis direction by controlling the rotation of the X-axis servomotor 17A and the Y-axis servomotor 17B by the position detection controller. However, the charging stand of the present invention does not specify the coil moving mechanism as described above, and any mechanism that can move the power transmission coil in the X-axis direction and the Y-axis direction can be used as the coil moving mechanism.

In the above example, the power transmission coil 3 is moved on the back surface side of the top plate 7 along the XY direction of the charging surface. However, the present invention is not limited to the movement of the power transmission coil in the XY direction, and may be a moving mechanism only in the X direction or only in the Y direction. Further, the present invention is not limited to the example in which the power transmission coil is movable, but may be fixed. In this case, it is preferable to provide a guide mechanism that can position the power receiving coil of the battery built-in device at the position of the power transmitting coil. For example, in the example shown in FIG. 15, a guide wall 1501 is provided around the charging surface, and the battery built-in device 2 is housed and positioned inside the guide wall 1501.
(First temperature detection means 30)

  The first temperature detection means 30 shown in FIG. 5 detects the temperature of the power transmission coil 3, A / D converts it into a digital value by the first A / D converter 21, and then sends it to the control unit 24. The control unit 24 determines the presence or absence of foreign matter based on the temperature change and temperature rise of the power transmission coil 3. As shown in FIG. 16, when a foreign object FO such as a metal object is interposed between the power transmission coil 3 of the non-contact charging base and the power reception coil 4 of the battery built-in device, this is detected and charged as necessary. Can be interrupted or a warning message can be issued to the user to notify the presence of a foreign object and prompt the user to remove it. As the first temperature detecting means 30, for example, an NTC thermistor can be suitably used. Alternatively, a sensor capable of detecting a known temperature, such as a PTC thermistor or a thermocouple, can be used as appropriate. In this example, an NTC thermistor is used. NTC thermistors are preferred because they are more accurate than PTC thermistors.

The first temperature detection means 30 is preferably arranged inside the innermost circumference of the power transmission coil 3. FIG. 17 shows an example in which a thermistor is arranged in the central portion of the power transmission coil 3, that is, the core portion as the first temperature detection means 30. This makes it possible to effectively use the dead space of the power transmission coil and accurately detect the environmental temperature and the temperature of the isolated power transmission coil. Further, even if the power transmission coil is movable, the thermistor is moved together with the power transmission coil, so that the temperature of the power transmission coil can be reliably detected with one thermistor. Further, depending on the position where the foreign object is placed, it can also be used for detecting the temperature of the foreign object. In particular, since it is not possible to specify where the foreign object is placed, if it is attempted to detect the temperature, it is necessary to dispose a thermistor over the entire charging surface, complicating the circuit and increasing the cost. On the other hand, if the thermistor is moved together with the power transmission coil, it is possible to deal with a case where a foreign object is placed at a different position. In particular, when a foreign object is placed at a position sufficiently away from the power transmission coil, the amount of heat generated by eddy current loss is reduced, and there are many cases where there is no practical problem. In other words, a foreign substance placed at a position where the temperature of the foreign substance cannot be detected by a thermistor provided in the vicinity of the power transmission coil can be ignored.
(Second thermistor)

On the other hand, since it becomes difficult to detect the temperature of the foreign matter only with the first temperature detection means placed at the center of the power transmission coil, for example, a thermistor for detecting the temperature of the foreign matter may be disposed outside the power transmission coil. Even in this case, for example, by arranging the second thermistor as the second temperature detecting means 432 on the stage for moving the power transmission coil as shown in FIG. 18, the second thermistor is also moved together with the power transmission coil. The second thermistor can cope with temperature detection of foreign matters placed at various positions.
(Foreign matter detection flowchart)

  Next, the flow of the operation of charging while detecting the presence / absence of a foreign substance by the foreign substance detection circuit 12 will be described based on the flowchart of FIG. Here, a first threshold value is set in advance as a reference value for determining the presence or absence of foreign matter.

  First, in step S1901, power transmission from the power transmission coil to the power reception coil is started to start charging. Next, in step S1902, the temperature rise after a certain time has elapsed is measured. Here, the first difference value between the A / D conversion value of the thermistor shown in FIG. 5 and the value after the first time elapses by the first delay circuit, that is, the temperature change before the first time from the present is calculated.

In step S1903, the first difference value is compared with the first threshold value. Thereby, the foreign object detection circuit 12 determines the presence or absence of a foreign object. That is, when the first difference value is larger than the first threshold value, it is determined that there is a foreign object, and when the first difference value is smaller than the first threshold value, it is determined that there is no foreign object. Here, if the first difference value is larger than the first threshold value in step S1903, the process proceeds to step S1904, and charging is stopped and terminated. On the other hand, if the first difference value is not greater than the first threshold value, the process returns to step S1902 to repeat the above processing. In this way, the foreign object detection circuit 12 can determine the presence or absence of a foreign object based on the temperature change of the power transmission coil.
(Embodiment 2)

  In the above method, the presence or absence of a foreign object is determined based on the temperature change of the power transmission coil. However, the temperature rise of the power transmission coil also varies depending on the type of material constituting the foreign matter, the position where the foreign matter is placed, and the like. Therefore, by providing the foreign object detection circuit with a plurality of threshold values for detecting the presence or absence of foreign objects, more accurate foreign object detection can be achieved. Such an example will be described based on the flowchart of FIG.

  First, in step S2001, charging is started. Next, in step S2002, a temperature increase after a lapse of a fixed time, here, the first time is measured. Here, the first difference value between the A / D conversion value of the thermistor shown in FIG. 5 and the value after the first time has elapsed by the first delay circuit is calculated. In step S2003, the first difference value is compared with the first threshold value. As a result, when the first difference value is larger than the first threshold value, it is determined that there is a foreign object, the process proceeds to step S2004, charging is stopped, and the process ends. The operations so far are the same as those in FIG.

  Next, when the first difference value is not larger than the first threshold value, the process proceeds to step S2005, and the temperature rise after the elapse of the second time longer than the first time is measured. Here, the second difference value between the A / D conversion value of the thermistor shown in FIG. 5 and the value after the second time has elapsed by the second delay circuit is calculated. In step S2006, the second difference value is compared with the second threshold value. As a result, when the second difference value is larger than the second threshold value, it is determined that there is a foreign object, the process proceeds to step S2007, charging is stopped, and the process ends. On the other hand, if the second difference value is not greater than the second threshold value, the process returns to step S2002 and the above process is repeated. In this way, the foreign object detection circuit can detect the foreign object that could not be detected with the first threshold value with the second threshold value, so that the detection accuracy of the foreign object can be increased by two-stage detection.

Moreover, although the example which sets two threshold values was demonstrated in the above example, it cannot be overemphasized that three or more threshold values can also be set.
(Modification)

  Further, in the above example, the case where charging is stopped when a foreign object is detected has been described. However, the present invention is not limited to this method, and charging can be continued by reducing transmitted power. As a result, it is possible to avoid a situation in which the battery built-in device cannot be charged, and to charge over time even if there is a foreign object. Such an example will be described as a modification based on the flowchart of FIG. Here, the power transmitted from the power transmission coil in step S2101 is set to the first power value, and charging is started. Next, in step S2102, the temperature rise after the elapse of the first time is measured, and the first difference value is calculated. Further, in step S2103, the first difference value is compared with the first threshold value. If it is larger, it is determined that there is a foreign object, and the process proceeds to step S2104 to reduce the transmitted power of the power transmission coil by a certain amount. Here, it switches to the 2nd electric power value lower than the 1st electric power value. Then, the process returns to step S2102, and the above operation is repeated.

  On the other hand, if the first difference value is not larger than the first threshold value, the process proceeds to step S2105, the temperature rise after the second time has elapsed is measured, and the second difference value is calculated. In step S2106, the second difference value is compared with the second threshold value. If the second difference value is larger, it is determined that there is a foreign object, and the process proceeds to step S2107. Here, similarly to step S2104, the transmission power is reduced by a certain amount to continue the power transmission, and the process returns to step S2102 to repeat the above operation. Note that the amount of transmission power reduction is not limited to the same amount as in step S2104, and may be a different value according to the second threshold.

  On the other hand, if the second difference value is not greater than the second threshold value, the process returns to step S2102 and the above process is repeated. In this way, it is possible to safely continue the charging by suppressing the temperature rise due to the foreign matter by reducing the electric energy without stopping the charging.

Moreover, it is also possible to adjust the transmission current, the charging current, the charging voltage, etc., instead of increasing or decreasing the transmission power value.
(Embodiment 3)

As described above, the presence of foreign matter can be detected by the first temperature detecting means such as a thermistor. However, depending on the size and position of the foreign matter, when the foreign matter is detected by the thermistor, for example, the temperature of the foreign matter may become as high as 80 ° C. or higher, which is not preferable. Therefore, as shown in the schematic cross-sectional view of FIG. 23, an insulating heat conductive sheet 20 may be disposed between the power transmission coil and the power reception coil. Such an example is shown in FIG.
(Thermal conductive sheet 20)

  The contactless charging stand shown in FIG. 24 has a heat conductive sheet 20 disposed on the upper surface of the charging surface. As a result, as shown in the schematic cross-sectional view of FIG. 23, the entire surface of the heat conductive sheet 20 can be used as a heat radiating surface, and the temperature rise and rapid temperature change of foreign matter can be suppressed. For such a heat conductive sheet 20, a resin or the like having an insulating property and an excellent heat conductivity can be used. For example, a polycarbonate resin in which a heat conductive filler is dispersed, a silicone resin, or the like can be used. Moreover, it is preferable that the heat conductive sheet 20 raises heat conductivity, for example, shall be 1.0 W / m * K or more. Furthermore, it is preferable to reduce the thickness of the heat conductive sheet 20. Thereby, the space | interval of a charging surface and the battery built-in apparatus mounted on it becomes wide, and the situation where charging efficiency falls can be suppressed.

FIG. 25 shows a graph showing the temperature change with time depending on the presence or absence of the heat conductive sheet and the temperature of the foreign matter. In this graph, the thin line indicates the temperature change, and the left vertical axis corresponds. The thick line indicates the temperature of the foreign matter, and the right vertical axis corresponds to it. As shown in FIG. 25, it was confirmed that by arranging the heat conductive sheet 20, the temperature change is small, the gradient of the temperature rise becomes gentle, and further the temperature rise of the foreign matter can be suppressed. In addition, by using the heat conductive sheet 20, charging can be stopped at a lower temperature. In this example, when the heat conductive sheet 20 was present, charging was stopped at 58.1 ° C., which was reduced by about 20% compared to 72.1 ° C. without the heat conductive sheet.
(Embodiment 4)

In the above example, the temperature of the power transmission coil or the foreign object is detected by the first temperature detecting means, and the foreign object is detected based on the temperature change. However, in addition to this, the present invention can also detect the ambient temperature, thereby changing the threshold for determining the presence or absence of foreign matter, suitability for charging, and the like according to the ambient temperature. In order to detect the presence or absence of a foreign object, a method for measuring the temperature of the foreign object by installing a temperature sensor on the power transmission stand is known (Patent Documents 2 to 4). Since the temperature is detected only by the temperature sensor, if the ambient temperature changes during charging, or if the initial value of the temperature sensor differs from normal due to continuous charging, it may be falsely detected or undetectable. there were. According to the test conducted by the inventors of the present application, when the ambient temperature rose by 0.5 ° C./min, foreign matter could not be detected by the determination based on the temperature change (FIG. 26). In FIG. 26, under the condition that a 15 mm square aluminum piece is placed at a position of 15 mm, it is determined that there is no foreign matter because there is a foreign matter but the threshold value (10) or less. On the other hand, when the ambient temperature is reduced by 0.5 ° C./min, there may be a case where, even if there is no foreign matter, the threshold value (10) is exceeded as shown in FIG. Therefore, by detecting the ambient temperature and correcting the temperature detected by the first temperature detection means, it is possible to detect foreign matter similar to the case where there is no change in the ambient temperature (FIG. 28). In this example, accurate foreign object detection can be performed without changing the threshold value from the example in FIG. In this way, it is possible to prevent foreign objects from being erroneously detected due to changes in ambient temperature.
(Second temperature detection means 432)

An example having an ambient temperature detection function is shown in a block diagram of FIG. 29 as a fourth embodiment. The contactless charging apparatus shown in FIG. 29 includes first temperature detection means 430, a foreign object detection circuit 412, a power transmission coil 403, and the like. The foreign object detection circuit 412 includes a first A / D converter 421, a first delay circuit 422, a second delay circuit 423, a control unit 424, and the like. These members can be the same as those shown in FIG. 5 and will not be described in detail. The contactless charging apparatus includes a second temperature detection unit 432 and is connected to the control unit 424 via the second A / D converter 425.
(Second temperature detection means 432)

  In this configuration, it is desirable to accurately measure the ambient temperature without being affected by the temperature of the power transmission coil or the like. For this reason, as shown in FIG. 29, the contactless charging stand includes second temperature detection means 432 for measuring the ambient temperature separately from the first temperature detection means. For example, as shown in the plan view of FIG. 18, the second temperature detection unit 432 is provided at a position separated from the power transmission coil 403. As a result, the ambient temperature can be accurately detected without being affected by the temperature of the power transmission coil 403. The thermistor, thermocouple, etc. can be used for the second temperature detection means 432 as well as the first temperature detection means 430. The second temperature detection means 432 functions as an ambient temperature sensor that detects the ambient temperature.

  Furthermore, a plurality of second temperature detecting means can be provided at a fixed position, not on the stage that moves with the power transmission coil by the coil moving mechanism. In this case, the second temperature sensor is most unlikely to be affected by the heat generation of the power transmission coil or the power transmission circuit in the casing of the charging stand. In other words, the second temperature sensor is installed at a position away from the heat generation source. And according to the position of the power transmission coil that moves by the coil moving mechanism, the value of the second temperature detection means installed at the position farthest from the power transmission coil among the plurality of second temperature detection means is set to the ambient temperature. Used for detection. By selecting the ambient temperature detected by the second temperature detection means as a reference value and correcting the power transmission coil temperature detected by the first temperature detection means on the power transmission coil side, more accurate foreign object detection is possible. Become.

  It is preferable to arrange | position a 2nd temperature detection means in the site | part which remove | deviated from the movement area | region of the power transmission coil. An example of the arrangement of such second temperature detection means is shown in the plan view of FIG. Here, two NTC thermistors are provided as the second temperature detecting means 432B at the corner opposite to the power transmission circuit 403B serving as a heat source in the contactless charging base 1B. In addition, the second temperature detecting means 432C can be provided at the corner in the short direction as in the contactless charging stand 1C shown in the plan view of FIG. Each second temperature detecting means is preferably provided separately. Thereby, according to the position of a power transmission coil, it can be easy to select the suitable 2nd temperature detection means in a position far from this power transmission coil. Also, which second temperature detection means is used is determined by the control unit of the foreign object detection circuit 412 or the like.

  The foreign object detection circuit detects that the difference between the temperature of the power transmission coil detected by the first temperature detection means and the ambient temperature detected by the second temperature detection means is within a predetermined range, and performs charging. Allow to start. In other words, charging is not started until the difference between the ambient temperature and the power transmission coil temperature falls within a predetermined range. By doing in this way, exact charge control is realizable based on exact detection of temperature.

When the temperature difference between the ambient temperature and the power transmission coil is large, the power transmission coil, ambient temperature, and foreign material when a 15 mm square iron piece is installed at the 0 mm position and charged to confirm that foreign matter detection is not performed correctly. The graph of FIG. 32 shows the results of measuring the change in temperature over time. In this figure, the ambient temperature is 40 ° C., and when the temperature difference between the ambient temperature and the power transmission coil is 1.5 ° C. and 2.2 ° C., the temperature change is plotted on the left vertical axis, The temperature is shown on the right vertical axis. As shown in this figure, when charging started when the temperature difference between the ambient temperature and the power transmission coil was 2.2 ° C., the amount of change in the thermistor did not reach the threshold value, and charging did not stop. On the other hand, when charging started when the temperature difference between the ambient temperature and the power transmission coil was 1.5 ° C., the temperature change reached the threshold of 1.26 ° C., and it was determined that there was a foreign object, and charging was stopped. Therefore, the temperature difference between the ambient temperature and the power transmission coil temperature is set to less than 2.2 ° C., preferably 2 ° C. or less, and the foreign object detection circuit 412 controls not to start charging until this condition is reached.
(Embodiment 5)

  FIG. 33 shows a flowchart of the operation of performing charging while detecting foreign matter in consideration of such a change in ambient temperature. First, in step S3501, it is determined whether or not the difference between the coil temperature detected by the first temperature detection means and the ambient temperature detected by the second temperature detection means is equal to or less than a predetermined threshold temperature. It is determined whether or not the temperature is equal to or lower than a predetermined threshold temperature. If not, the flow returns to step S3501 to repeat the operation.

  If the temperature is equal to or lower than the threshold temperature, the process proceeds to step S3502 and after, and a normal charging operation is performed. That is, in step S3502, charging at the first power value is started from the power transmission coil to the power reception coil. Next, the time change of the temperature detected by the first temperature detecting means is calculated in step S3503, and this is compared with the first threshold value in step S3504. If the first threshold is not exceeded, the process returns to step S3503 and the above operation is repeated. That is, charging is continued in a range where the temperature rise does not exceed the threshold value.

On the other hand, when the time change of temperature exceeds the first threshold, it is determined that there is a foreign substance, and the process proceeds to step S3505 to perform a predetermined operation. For example, after reducing the transmission power of the power transmission coil to a second power value, the process returns to step S3501, and charging is continued. Alternatively, power transmission from the power transmission coil can be stopped in step S3505. In this way, erroneous detection can be prevented by starting charging after waiting for the temperature difference between the ambient temperature and the temperature of the power transmission coil to decrease.
(Embodiment 6)

  Furthermore, the heat generation current supplied to the power transmission coil is limited at the initial stage of charging, and a rapid heat generation of foreign matter can be suppressed by returning to a normal power transmission current after a predetermined time has elapsed. An example of such a non-contact charging apparatus will be described as a sixth embodiment based on the block diagram of FIG. This contactless charging apparatus includes first temperature detection means 630, a foreign object detection circuit 612, a power transmission coil 603, and the like. The foreign object detection circuit 612 includes a first A / D converter 621, a first delay circuit 622, a control unit 624, and the like. This contactless charging apparatus has substantially the same configuration as that of FIG. 5 and the like described above, and detailed description of members having the same names is omitted. Here, the first current setting means 626 that sets the charging current to a first current value lower than the normal charging current at the start of power transmission, the first temperature detection means 630 configured with a thermistor, and the first temperature A foreign matter detection circuit 612 (first A / D converter 621, first delay circuit 622, and the like) constituting foreign matter detection means for detecting foreign matter based on a temperature rise detected by the detection means 630, a decrease in power transfer efficiency, or the like. Controller 624), timer means 628 for measuring the passage of time from the start of power transmission, and detecting that a time preset in the timer means 628 (first charging time) has passed, Second current setting means 627 for setting a second current value larger than the one current value. The first current setting unit 626 defines an initial value of the charging current, and the second current setting unit 627 defines a normal charging current. As such current setting means 626 and 627, a nonvolatile memory or the like can be suitably used.

  The timer means 628 sets a first charging time for charging with the first current value. This time is adjusted according to the type of foreign matter and required specifications, and is 180 seconds in this example.

Moreover, the graph of FIG. 35 shows the result of measuring the temperature change and the time change of the foreign object temperature in a state where the foreign object is arranged using this contactless charging apparatus. Here, similarly to the above, using a 15 mm square aluminum piece as a foreign object, charging is started in a state where it is positioned at the center of the power transmission coil, and the charging current is made constant at 2 A, and the initial charging current is used. In the case where a certain first current value is 500 mA and the second current value is 2 A, the temperature change (left vertical axis) and the foreign substance temperature (right vertical axis) are measured. In this example, when charging was performed at a constant 2A, after 61 seconds had elapsed from the start of charging, foreign matter was detected by a 60 second change in the thermistor, and charging was stopped at a foreign matter temperature of 68.1 ° C. On the other hand, when charging at 500 mA for the first 180 seconds and then charging at 2 A, after 61 seconds from the start of charging, the thermistor detects a foreign object by a 60-second change and stops charging at a foreign material temperature of 49.2 ° C. In addition, it was confirmed that the safety could be improved because the charging could be stopped at a lower temperature than in the case of 2A constant.
(Embodiment 7)

  Further, when determining the presence or absence of foreign matter, charging efficiency can be referred to in addition to temperature change. That is, when there is a foreign object, it is considered that the charging efficiency is lowered because a part of the transmitted power is changed to heat, so that the foreign object can be detected by monitoring the decrease in the charging efficiency. The accuracy can be improved by combining the foreign object detection based on the charging efficiency with the foreign object detection based on the temperature change. Such an example will be described as Embodiment 7 based on the flowchart of FIG.

  First, in step S3801, power transmission is started, and in step S3802, the charging current is set to the first current value. In this example, the charging current is 500 mA.

  Next, a temperature change is measured and compared with a predetermined threshold A in step S3803. If the threshold value A is exceeded, it is determined that there is a foreign object, and the process advances to step S3809 to perform necessary processing such as reducing the charging current or stopping charging.

  On the other hand, if the threshold value A is not reached, the process proceeds to step S3804 to check the charging efficiency. Here, it is determined whether or not the charging efficiency is equal to or less than the threshold value B. In the following case, it is determined that there is a foreign object, and the process proceeds to step S3809.

  Next, in step S3805, it is determined whether the first charging time has elapsed from the start of charging. Here, 180 seconds is set as the first charging time. If the first charging time has not been reached, the process returns to step S3803 and the above procedure is repeated. On the other hand, if the first charging time has elapsed, the process proceeds to step S3806, where the charging current is switched to the second current value. Here, 2 A is set as the second current value.

Next, in step S3807, the temperature change is checked in the same manner as in step S3803. If the predetermined threshold A is exceeded, it is determined that there is a foreign substance, and the flow advances to step S3809 to perform predetermined processing. On the other hand, if the threshold value A is not reached, the process proceeds to step S3808, and the charging efficiency is examined in the same manner as in step S3804. Here, it is determined whether or not it is equal to or less than the threshold value B. In the following case, it is determined that there is a foreign object, and the process proceeds to step S3809. When the threshold value B is exceeded, the process returns to step S3807 and the above processing is repeated. In this way, foreign object detection can be performed accurately based on temperature change and charging efficiency. In particular, in the initial stage of charging, by reducing the charging current, it is possible to suppress the rapid temperature rise of foreign matter and improve safety.
(Embodiment 8)

  Furthermore, in the above example, as in the example shown in FIG. 5 and the like, a plurality of threshold values are prepared, and when any of the threshold values is met, it is determined that there is a foreign object, thereby handling foreign substances of various different conditions. Can be made. Such an example is shown in the flowchart of FIG. 37 as an eighth embodiment.

  First, in step S3901, power transmission is started, and in step S3902, the charging current is set to the first current value (here, 500 mA). Next, in step S3903, the temperature change is measured and compared with a threshold value A 'that is a first threshold value. If the threshold value A 'is exceeded, it is determined that there is a foreign substance, and the process advances to step S3909 to perform processing such as stopping charging.

  On the other hand, if the threshold value A 'is not reached, the process proceeds to step S3904, and the temperature change is compared with a threshold value B' that is the second threshold value. Here, if the threshold value B 'is exceeded, it is determined that there is a foreign substance, and the process proceeds to step S3909. If the threshold value B' is not satisfied, the process proceeds to step S3905, and the charging efficiency is examined. Here, it is determined whether or not the charging efficiency is equal to or less than the threshold value C ′. In the following case, it is determined that there is a foreign object, and the process proceeds to step S3909.

  Next, in step S3906, it is determined whether or not the first charging time (here, 180 seconds) has elapsed since the start of charging. If not, the process returns to step S3903 and the above procedure is repeated. On the other hand, if the first charging time has elapsed, the process proceeds to step S3907, and the charging current is switched to the second current value (here 2A).

Next, in step S3908, the temperature change is checked in the same manner as in step S3903. If the predetermined threshold A ′ is exceeded, it is determined that there is a foreign substance, and the process proceeds to step S3909. The comparison with the second threshold value B ′ is performed in the same manner. That is, when the threshold value B ′ is exceeded, it is determined that there is a foreign object, and the process proceeds to step S3909. When the threshold value B ′ is not satisfied, the process proceeds to step S3910, and the charging efficiency is examined as in step S3905. Here, it is determined whether or not the charging efficiency is equal to or less than the threshold value C ′. If the charging efficiency is equal to or less than the threshold value C ′, the process proceeds to step S3909. If the charge efficiency exceeds the threshold value C ′, the process returns to step S3908 and the above processing is repeated. In this way, more accurate foreign object detection can be expected based on the two threshold values related to temperature change, and the accuracy of foreign object detection can be improved together with detection based on charging efficiency.
(Embodiment 9)

  In addition to the method of automatically switching the charging current from the first current value to the second current value after a certain period of time has passed, the charging current is switched when it is confirmed by the foreign matter determination circuit that no foreign matter is present. It may be. In this case, as the first charging time set in advance by the timer means, it is desirable to specify a time longer than the delay time required for foreign object determination due to a temperature change using the first temperature detecting means. Thus, after the foreign object detection is performed by the foreign object detection circuit, it is possible to smoothly switch to the second charging time. Such an example is shown as a ninth embodiment in the graph of FIG. In this graph, the temperature change (on the left side) is shown for each of the ninth embodiment in which the first charging time is longer than the delay time and the comparative example in which the first charging time is shorter than the delay time under the same conditions as FIG. The results of measuring the vertical axis) and the foreign object temperature (right vertical axis) are shown. As shown in this figure, in the comparative example, since the charging current was increased earlier than the delay time elapsed, the temperature rise is large. On the other hand, in Embodiment 9, since the charging current is increased after the delay time has elapsed, charging control based on the foreign object detection result is possible, and stable charging with reduced temperature rise is realized.

  In this example, by adjusting the charging current of the battery built-in device, the power transmission current flowing through the power transmission coil that is feedback controlled is adjusted. However, the present invention is not limited to this configuration, and the power transmission current can be directly adjusted. Needless to say.

  Since the contactless charging device and the contactless charging method of the present invention detect that a metal foreign object has been set on a charging base for charging the built-in battery of the battery built-in device, preventing adverse effects such as heat generation of the metal foreign object, It is most suitable for a power stand for safely charging battery-equipped devices.

DESCRIPTION OF SYMBOLS 1, 1B, 1C ... Non-contact charging stand 2 ... Battery built-in apparatus 3 ... Power transmission coil 4 ... Power reception coil 5 ... Metal foreign material 6 ... Battery 7 ... Top plate 8 ... AC power supply 9 ... Control circuit 10 ... Transmission circuit 11 ... Reception circuit DESCRIPTION OF SYMBOLS 12 ... Foreign object detection circuit 13 ... Magnetic shield 14 ... Metal detection coil 15 ... Charge control circuit 16 ... Coil moving mechanism 17 ... Servo motor; 17A ... X-axis servo motor; 17B ... Y-axis servo motor 18 ... Screw rod; X-axis screw rod; 18B ... Y-axis screw rod 19 ... belt 20 ... heat conduction sheet 21 ... first A / D converter 22 ... first delay circuit 23 ... second delay circuit 24 ... control unit 30 ... first temperature detection Means 41 ... nut material 42 ... guide rod 403 ... power transmission coil 403B ... power transmission circuit 412 ... foreign matter detection circuit 421 ... first A / D converter 422 ... first delay circuit 423 ... second delay circuit 424 Control unit 425 ... second A / D converter 430 ... first temperature detection means 432 ... second temperature detection means 432B ... second temperature detection means 432C ... second temperature detection means 603 ... power transmission coil 612 ... foreign matter detection circuit 621 ... 1st A / D converter 622 ... 1st delay circuit 624 ... control part 626 ... 1st current setting means 627 ... 2nd current setting means 628 ... timer means 630 ... 1st temperature detection means 1501 ... guide wall 4103 ... power transmission coil 4104 ... Power receiving coil FO ... Foreign matter K ... Detection coil

Claims (14)

  A power receiving coil built in a battery built-in device mounted on a charging base, a power transmission coil built in a charging base that can be electromagnetically coupled, and a first temperature that is arranged in the vicinity of the power transmission coil and detects a temperature A non-contact charging device comprising a detecting means, and whether or not a foreign object is placed on the charging base based on a temporal change in temperature information detected at a predetermined time interval by the first temperature detecting means A contactless charging apparatus comprising a foreign matter detecting means for determining The contactless charging device according to claim 1,
The contactless charging apparatus, wherein the first temperature detecting means detects a temperature of the power transmission coil. The contactless charging device according to claim 1 or 2,
The contactless charging apparatus, wherein the first temperature detecting means detects the temperature of a foreign object. It is a non-contact charging device according to any one of claims 1 to 3,
The foreign object detection means has a plurality of parameters composed of a combination of a threshold value related to a time change of temperature information detected by the first temperature detection means and a detection time interval used for calculation of the time change. ,
A contactless charging apparatus, wherein foreign matter detection is performed when a condition of any one of the plurality of parameters is met. The contactless charging device according to claim 4,
The contactless charging apparatus, wherein the plurality of parameters include a set of a plurality of parameters having different detection time intervals while setting the threshold values to be the same. The contactless charging device according to claim 4 or 5,
A contactless charging apparatus, wherein a detection time interval is 30 seconds or more. The contactless charging device according to any one of claims 4 to 6, further comprising:
A first delay circuit connected to the first temperature detection means and delaying information about the temperature detected by the first temperature detection means by a first delay time;
A second delay circuit for delaying by a second delay time longer than the first delay time;
The foreign matter detecting means compares a first time change obtained based on the temperature information delayed by the first delay circuit with a first threshold, and based on the temperature information delayed by the second delay circuit. A contactless charging apparatus, wherein the obtained second time change is compared with a second threshold value. The contactless charging apparatus according to any one of claims 1 to 7, further comprising:
A second temperature detecting means for measuring the ambient temperature is provided;
The foreign object detection means detects that the difference between the temperature of the power transmission coil detected by the first temperature detection means and the environmental temperature detected by the second temperature detection means is within a predetermined range. Then, the non-contact charging device is configured to start charging. A contactless charging apparatus according to any one of claims 1 to 8,
The contactless charging apparatus, wherein the first temperature detecting means is arranged inside the innermost circumference of the power transmission coil. A contactless charging device according to any one of claims 1 to 9,
A contactless charging apparatus, wherein the power transmission coil is movable. It is a non-contact charging device according to any one of claims 1 to 10,
The contactless charging apparatus, wherein the first temperature detecting means is an NTC thermistor. The contactless charging device according to any one of claims 1 to 11, further comprising:
A contactless charging apparatus, wherein an upper surface of the charging base is covered with an insulating heat conductive sheet. A power receiving coil built in the battery built-in device mounted on the charging base, a power transmitting coil built in the charging base that can be electromagnetically coupled, and a first temperature detecting means arranged on the innermost inner periphery of the power transmitting coil A contactless charging method using a contactless charging device comprising:
Power transmission from the power transmission coil toward the power reception coil;
Measuring the temperature of the power transmission coil with a first temperature detection means;
The step of determining whether or not the foreign object is placed on the charging base based on the time change of the temperature information detected at predetermined time intervals by the first temperature detection means;
A contactless charging method comprising: The contactless charging method according to claim 13,
The current control means charges the charging current with a limit current lower than a predetermined value until it can be confirmed by the foreign substance detection means that there is no foreign substance whose temperature rises quickly, and after a predetermined time has elapsed, A contactless charging device configured to perform charging.

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