JP2015023595A - Foreign matter detection device and method for non-contact power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foreign matter detection device and method for a non-contact power supply device capable of reducing an induction voltage generated in a coil for foreign matter detection, and therefore achieving the increase of the sensitivity of foreign matter detection for detecting the presence/absence of a conductive foreign matter and the reduction of erroneous detection.SOLUTION: The foreign matter detection device includes: a detection coil 12 positioned between a power transmission coil 3 and a power reception coil 4; and a detection unit 14 for detecting an induction voltage V generated in the detection coil 12, and for detecting the presence/absence of a conductive foreign matter positioned between the power transmission coil 3 and the power reception coil 4 from this. The detection coil 12 is configured of a consecutive conductive wire 13 in which two loop parts 12a are wound mutually in reverse directions. The area and the number of windings of each loop part 12a or a direction connecting the centroids of the two loop parts 12a are set such that the induction voltage V(that is, a reference voltage V0) generated in the detection coil 12 when there does not exist any conductive foreign matter becomes 0 or minimum.

Description

  The present invention relates to a foreign object detection apparatus and method for a non-contact power supply apparatus.

  In recent years, a hybrid electric vehicle (HEV) including an electric motor and an internal combustion engine has been put into practical use. An electric vehicle (EV) having only an electric motor has also been put into practical use.

A non-contact power supply apparatus that performs non-contact power supply to an electric vehicle or the like is a device that magnetically couples a primary coil on a power supply side and a secondary coil on a power reception side to transmit power from the power supply side to the power reception side in a contactless manner. .
For example, Patent Documents 1 and 2 disclose such non-contact power feeding devices.

In the non-contact power feeding device of Patent Document 1, the axes of the primary coil and the secondary coil are vertical and have the same axis. This type of non-contact power feeding device is called a “circular type”.
Moreover, the non-contact electric power feeder of patent document 2 has the axis line of a primary coil and a secondary coil located in parallel with each other. This type of non-contact power feeding device is called a “solenoid type”.

The non-contact power supply is roughly classified into three methods: an electromagnetic induction method, a radio wave method, and a magnetic field resonance method.
The electromagnetic induction method uses electromagnetic induction in which an electromotive force is generated in the other coil using a magnetic flux generated when a current is passed through one of two adjacent coils as a medium.
In the radio wave system, current is converted into electromagnetic waves and transmitted / received via an antenna.
The magnetic field resonance method uses magnetic flux as a medium in the same manner as the electromagnetic induction method, but amplifies the induced current flowing in the coil by actively utilizing the resonance phenomenon of the electric circuit.

In the non-contact power supply apparatus described above, when a metal foreign object is mixed between the primary coil and the secondary coil, an eddy current may be generated in the metal foreign object and heat may be generated due to Joule heat.
For this reason, for example, Patent Document 3 discloses a non-contact power feeding device that detects such a foreign object.

  The non-contact power feeding device of Patent Document 3 is the above-described electromagnetic induction type non-contact power feeding device, in which a third coil is provided between the first coil and the second coil, and induction generated in the third coil. A foreign object between the first coil and the second coil is detected based on the voltage.

JP 2010-226889 A JP 2013-90392 A JP 2012-249401 A

When a third coil is provided between the first coil and the second coil and an induced voltage generated in the third coil is detected, no foreign matter exists between the first coil and the second coil. An induced voltage is generated even in the state.
For this reason, the presence of an induced voltage when there is no foreign object may make it difficult or erroneous to detect the foreign object using the third coil.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to reduce the induced voltage generated in the coil for detecting foreign matter when there is no conductive foreign matter, thereby increasing the sensitivity of foreign matter detection for detecting the presence or absence of conductive foreign matter. It is an object of the present invention to provide a foreign object detection device and method for a non-contact power supply device that can reduce detection.

According to the present invention, a detection coil located between the power transmission coil and the power reception coil;
A detection unit that detects an induced voltage generated in the detection coil and detects the presence or absence of a conductive foreign substance positioned between the power transmission coil and the power reception coil.
The detection coil is composed of continuous conductive wires in which two loop portions are wound in opposite directions,
The area of each loop part, the number of turns, or the direction connecting the centroids of the two loop parts is set so that the induced voltage generated in the detection coil when the conductive foreign matter does not exist is 0 or minimum There is provided a foreign object detection device for a non-contact power feeding device.

  The two loop portions are located on the same plane located between the power transmission coil and the power reception coil, and the direction connecting the centroids is perpendicular to the magnetic gradient direction at the detection coil installation position. Is arranged.

  The loop portions are circular, rectangular, triangular, or rhombus loops that are located on the same plane without overlapping each other.

  The detection unit includes a detection unit that detects an induced voltage generated in the detection coil, a determination unit that compares the detected induced voltage with a reference voltage when no conductive foreign matter is present, and determines the presence or absence of the conductive foreign matter. Have

According to the present invention, the detection coil located between the power transmission coil and the power reception coil is constituted by continuous conductive wires in which two loop portions are wound in opposite directions,
The induced voltage generated in the detection coil when the area of each loop part, the number of turns, or the direction connecting the centroids of the two loop parts does not exist between the power transmission coil and the power reception coil is 0. Or set it to the minimum,
There is provided a foreign matter detection method for a non-contact power feeding device, characterized in that an induced voltage generated in the detection coil is detected, and then the presence or absence of a conductive foreign matter located between the power transmission coil and the power reception coil is detected. The

  The induced voltage generated in the detecting coil is measured while the detecting coil is moved back and forth or left and right, or rotated around the vertical axis, and the measured value of the induced voltage is zero or minimized and positioned at the rotation angle. .

According to the apparatus and method of the present invention, since the detection coil is composed of continuous conductive wires in which two loop portions are wound in opposite directions, induced currents caused by magnetic fields are reversed in the two loop portions and are mutually opposite. Negate each other.
Further, the area of each loop part, the number of turns, or the direction connecting the centroids of the two loop parts is set so that the induced voltage generated in the detection coil is 0 or minimum when there is no conductive foreign matter. Therefore, even in a place with a magnetic gradient, the induced voltage generated in the detection coil when there is no conductive foreign matter is 0 or minimum.
Accordingly, it is possible to reduce the induced voltage generated in the foreign object detection coil when there is no conductive foreign object, thereby increasing the sensitivity of foreign object detection and reducing false detection.

It is a block diagram of the non-contact electric power feeder provided with the foreign material detection apparatus of this invention. It is a figure which shows the installation position of a detection coil. It is a block diagram of a detection unit. It is a figure which shows the specific example of the detection coil located between a power transmission coil and a receiving coil. It is a figure which shows another structural example of a loop part. It is principle explanatory drawing of the foreign material detection in the detection coil of FIG.5 (C). It is a figure which shows the example of arrangement | positioning of a some detection coil. It is a flowchart of the foreign material detection method of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is a configuration diagram of a non-contact power feeding device 2 including a foreign object detection device 10 of the present invention, where (A) is a use state diagram and (B) is a block circuit diagram. The foreign object detection device 10 of the present invention is a foreign object detection device 10 for a non-contact power supply device.
In this figure, a non-contact power feeding device 2 feeds power from a power transmission coil 3 to a power receiving coil 4 in a non-contact manner by electromagnetic induction.

In FIG. 1, 1 is a parking space, 3 is a power transmission coil, 4 is a power reception coil, 5 is a power reception side rectifier, and 6 is an in-vehicle battery.
The non-contact power feeding device 2 includes an AC power source 2a, a power transmission side rectifier 2b, an inverter 2c, and a power transmission coil 3, and supplies the power transmission coil 3 with electric power converted into a high frequency.
The power transmission coil 3 generates a high-frequency magnetic field with this electric power. This magnetic field generates high-frequency power in the receiving coil 4. This electric power is converted into direct current by the power receiving side rectifier 5 and charged to the in-vehicle battery 6.

  In FIG. 1, a foreign object detection device 10 of the present invention includes a detection coil 12 and a detection unit 14.

The detection coil 12 is located between the power transmission coil 3 and the power reception coil 4.
FIG. 2 is a diagram showing the installation position of the detection coil 12. In this figure, (A) is an example in which the detection coil 12 is installed close to the power transmission coil 3, (B) is an example in which the detection coil 12 is installed close to the power receiving coil 4, and (C) is two detection coils. This is an example in which 12 is installed close to the power transmission coil 3 and the power reception coil 4.
As shown in this figure, as long as the detection coil 12 is between the power transmission coil 3 and the power reception coil 4, the detection coil 12 may be close to either, or may be installed at an intermediate position between the two.

  The detection unit 14 detects the induced voltage V generated in the detection coil 12, and detects the presence or absence of a conductive foreign substance (not shown) located between the power transmission coil 3 and the power reception coil 4.

FIG. 3 is a configuration diagram of the detection unit 14.
The detection unit 14 is preferably a computer (PC) including a storage device and an arithmetic device, and includes a detection unit 14a and a determination unit 14b.
The detection unit 14 a detects the induced voltage V generated in the detection coil 12.
The determination unit 14b compares the detected induced voltage V with the reference voltage V0 when no conductive foreign matter is present, and determines the presence or absence of the conductive foreign matter.
The reference voltage V0 when there is no conductive foreign matter is preferably stored in advance in the storage device.

  FIG. 4 is a diagram illustrating a specific example of the detection coil 12 positioned between the power transmission coil 3 and the power reception coil 4, (A) is a side view, and (B) is a cross-sectional view in the BB plane. FIG. 4 also shows an outline of a magnetic field generated around the power transmission coil 3 and the power reception coil 4 when power converted into a high frequency is supplied to the power transmission coil 3.

In FIG. 4A, the axes of the power transmission coil 3 and the power reception coil 4 are positioned in parallel to each other. That is, this figure shows the “solenoid type” non-contact power feeding device 2 described above. In FIG. 4A, each broken line indicates a magnetic field line.
In addition, in this figure, although the power transmission coil 3 and the receiving coil 4 are shown by the cylindrical shape, it is not limited to this, A rectangular cross section or another shape may be sufficient. Further, although the power transmission coil 3 and the power reception coil 4 are shown as empty cores inside, ferrite or the like may be included inside.
Further, the present invention is not limited to the “solenoid type”, and may be the above-described “circular type” non-contact power feeding device 2 in which the axes of the power transmission coil 3 and the power reception coil 4 are vertical and on the same axis. .

In FIG. 4A, the BB plane is a symmetrical plane of the power transmission coil 3 and the power reception coil 4, but the present invention is not limited to this, and is located between the power transmission coil 3 and the power reception coil 4. Any plane may be used.
The detection coil 12 is located at an arbitrary place on the BB plane.

FIG. 4B shows the distribution of the magnetic field on the BB plane, and each broken line shows isomagnetic field lines (lines having the same magnetic field strength).
In this figure, the detection coil 12 comprises a continuous conductive wire 13 in which two loop portions 12a are wound in opposite directions. Both end portions 13a and 13b of the continuous conductive wire 13 are connected to the detection unit 14 via signal lines (not shown). This signal line is arranged so as not to be affected by the magnetic field.

The area of each loop portion 12a, the number of windings, or the direction connecting the centroids of the two loop portions 12a (line segment CC) is an induced voltage V generated in the detection unit 14 when there is no conductive foreign matter (ie, The reference voltage V0) is set to 0 or minimum.
In addition, the induced voltage V (that is, the reference voltage V0) generated in the detection coil 12 when there is no conductive foreign matter is stored in advance in the storage device of the detection unit 14.

In this example, the area and the number of turns of the two loop portions 12a are the same, and the direction connecting the centroids of the loop portion 12a (line segment CC) is the magnetic gradient direction at the installation position of the detection coil 12 (in the figure). It is arranged so as to be perpendicular to (indicated by a broken arrow).
With this configuration, the two loop portions 12a are composed of continuous conductive wires 13 wound in opposite directions, and the area and the number of turns of the two loop portions 12a are the same. Induced currents i1 and i2 are substantially the same, and the two induced currents i1 and i2 are reversed in the two loop portions 12a and cancel each other.
Accordingly, the reference voltage V0 generated in the detection coil 12 when there is no conductive foreign matter is substantially zero even in a place with a magnetic gradient.

FIG. 5 is a diagram illustrating another configuration example of the loop unit 12a. In this figure, (A) is an example in which the area is changed, (B) is an example in which the area and the number of turns are changed, and (C) is an example in which the shape is rectangular.
As shown in FIG. 5, the area and the number of turns of each loop portion 12a may be changed. The loop portion 12a may be a circular, rectangular, triangular, or rhombus loop that is positioned on the same plane without overlapping each other.

  FIG. 6 is a diagram for explaining the principle of foreign matter detection in the detection coil 12 of FIG. 5C. FIG. 6A shows a case where no conductive foreign matter exists between the power transmission coil 3 and the power receiving coil 4, and FIG. It shows when conductive foreign matter is present.

When there is no conductive foreign matter, as shown in FIG. 6 (A), the two loop portions 12a are composed of continuous conductive wires 13 wound in opposite directions, and the area and winding of the two loop portions 12a. When the numbers are the same, the magnetic fluxes of the two loop portions 12a are equal. Therefore, in this case, the generated induced currents i1 and i2 are the same, and the induced currents i1 and i2 are reversed in the two loop portions 12a and cancel each other, so that the induced voltage V generated in the detection coil 12 (ie, the reference voltage) The voltage V0) is substantially zero.
Even in a place where there is a magnetic gradient, as shown in FIG. 4B, the direction connecting the centroids of the loop portion 12a (line segment CC) is the magnetic gradient direction at the installation position of the detection coil 12 (indicated by the broken line in the figure). Similarly, the induced voltage V (that is, the reference voltage V0) generated in the detection coil 12 when there is no conductive foreign matter is 0 or minimum.

When conductive foreign matter exists, as shown in FIG. 6B, the magnetic flux of the loop portion 12a on which conductive foreign matter is present becomes stronger, so that one induced current i1 becomes larger than the other induced current i2. The induced voltage V generated in the detection coil 12 increases.
Therefore, the presence or absence of conductive foreign matter can be determined by comparing the detected induced voltage V with the reference voltage V0 when no conductive foreign matter is present.

FIG. 7 is a diagram illustrating an arrangement example of the plurality of detection coils 12. In this figure, the isomagnetic field lines are the same as in FIG. The detection coil 12 uses rectangular and triangular loop portions 12a.
As shown in this figure, a plurality of detection coils 12 are used, and the induction voltage V (that is, the reference voltage V0) generated in each detection coil 12 when there is no conductive foreign matter is set to 0 or minimum. Thus, when a conductive foreign substance exists, the position can be detected.

  FIG. 8 is a flowchart of the foreign object detection method of the present invention. The foreign matter detection method of the present invention includes steps (steps) S1 to S4. The detection coil 12 is composed of continuous conductive wires 13 in which two loop portions 12a are wound in opposite directions. Before performing step S1, the area, the number of turns, or two of the loop portions 12a The direction connecting the centroids of the loop portion 12a is such that the induction voltage V (that is, the reference voltage V0) generated in the detection coil 12 when the conductive foreign matter is not present between the power transmission coil 3 and the power reception coil 4 is 0 or minimized. It is set to be.

In step S <b> 1, the detection coil 12 is positioned between the power transmission coil 3 and the power reception coil 4. More specifically, the induction voltage V generated in the detection coil 12 is measured while the detection coil 12 is moved by a small amount of parallel movement from front to back or from side to side, or slightly rotated around the vertical axis, and the measured value of the induction voltage V is 0. Or, position at the minimum position and rotation angle. Thereafter, the position and rotation angle of the detection coil 12 are fixed.
Note that the induced voltage V (that is, the reference voltage V0) generated in the detection coil 12 at the positioned position and rotation angle is measured and stored.

  The induction voltage V (that is, the reference voltage V0) generated in the detection coil 12 is 0 or minimized in the area connecting the loop portions 12a of the detection coil 12, the number of turns, or the direction connecting the centroids of the two loop portions 12a. Is set to However, if the magnetic field generated in the non-contact power supply device 2 changes minutely due to the influence of substances present in the surroundings, for example, the induced voltage V (that is, the reference voltage V0) generated in the detection coil 12 is strictly deviated from 0 or the minimum. End up. By performing step S1, even if there is a minute change in the magnetic field, there is an effect that the detection coil 12 can be installed at a position and rotation angle at which the induced voltage V (that is, the reference voltage V0) is strictly zero or minimum.

  In step S2, the induced voltage V generated in the detection coil 12 is detected.

In step S <b> 3, the induced voltage V generated in the detection coil 12 is detected, and from this, the presence or absence of a conductive foreign substance located between the power transmission coil 3 and the power reception coil 4 is detected.
Specifically, for example, when the difference between the induced voltage V measured in step S2 and the reference voltage V0 measured in step S1 exceeds a predetermined threshold, between the power transmission coil 3 and the power reception coil 4 Judge that conductive foreign matter exists.

  If it is determined in step S3 that conductive foreign matter is present, power supply is stopped (step S4).

According to the apparatus and method of the present invention, the detection coil 12 is composed of the continuous conductive wires 13 in which the two loop portions 12a are wound in opposite directions, so that the induced currents i1 and i2 due to the magnetic field are generated by the two loop portions. At 12a, the directions are reversed and cancel each other.
Further, the induction voltage V (that is, the reference voltage V0) generated in the detection coil 12 when the area of each loop portion 12a, the number of turns, or the direction connecting the centroids of the two loop portions 12a is not present in the conductive foreign matter. Since it is set to be 0 or the minimum, the induced voltage V generated in the detection coil 12 when there is no conductive foreign matter is 0 or the minimum even in a place with a magnetic gradient.
Accordingly, the induced voltage V generated in the foreign object detection coil when there is no conductive foreign object can be reduced, thereby increasing the sensitivity of foreign object detection and reducing false detection.

  In addition, this invention is not limited to embodiment mentioned above, is shown by description of a claim, and also includes all the changes within the meaning and range equivalent to description of a claim. Of course, not only the magnetic field resonance method but also other methods such as an electromagnetic induction method are included.

i1 induced current, i2 induced current, V induced voltage, V0 reference voltage,
1 parking space, 2 contactless power supply device,
2a AC power supply, 2b Power transmission side rectifier, 2c Inverter,
3 power transmission coil, 4 power reception coil, 5 power reception side rectifier, 6 vehicle-mounted battery,
10 foreign object detection device, 12 detection coil, 12a loop part,
13 conductive wire, 13a end, 13b end,
14 detection unit (computer), 14a detection unit, 14b determination unit

Claims (6)

A detection coil positioned between the power transmission coil and the power reception coil;
A detection unit that detects an induced voltage generated in the detection coil and detects the presence or absence of a conductive foreign substance positioned between the power transmission coil and the power reception coil.
The detection coil is composed of continuous conductive wires in which two loop portions are wound in opposite directions,
The area of each loop part, the number of turns, or the direction connecting the centroids of the two loop parts is set so that the induced voltage generated in the detection coil when the conductive foreign matter does not exist is 0 or minimum A foreign matter detection device for a non-contact power feeding device.   The two loop portions are located on the same plane located between the power transmission coil and the power reception coil, and the direction connecting the centroids is perpendicular to the magnetic gradient direction at the detection coil installation position. The foreign matter detection device for a non-contact power feeding device according to claim 1, wherein   The foreign object detection device for a non-contact power feeding device according to claim 2, wherein the loop portions are circular, rectangular, triangular, or rhombus loops that are located on the same plane without overlapping each other.   The detection unit includes a detection unit that detects an induced voltage generated in the detection coil, a determination unit that compares the detected induced voltage with a reference voltage when no conductive foreign matter is present, and determines the presence or absence of the conductive foreign matter. The foreign object detection device for a non-contact power feeding device according to claim 1, wherein The detection coil located between the power transmission coil and the power reception coil is composed of continuous conductive wires in which two loop portions are wound in opposite directions,
The induced voltage generated in the detection coil when the area of each loop part, the number of turns, or the direction connecting the centroids of the two loop parts does not exist between the power transmission coil and the power reception coil is 0. Or set it to the minimum,
A foreign object detection method for a non-contact power supply device, comprising: detecting an induced voltage generated in the detection coil; and detecting presence or absence of a conductive foreign object positioned between the power transmission coil and the power reception coil. The induced voltage generated in the detecting coil is measured while the detecting coil is moved back and forth or left and right, or rotated around the vertical axis, and the measured value of the induced voltage is zero or minimized and positioned at the rotation angle. The foreign object detection method for a non-contact power feeding device according to claim 5.

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