WO2014156655A1

WO2014156655A1 - Contactless power transmission device

Info

Publication number: WO2014156655A1
Application number: PCT/JP2014/056515
Authority: WO
Inventors: 木下　拓哉; 研吾毎川
Original assignee: 日産自動車株式会社
Priority date: 2013-03-29
Filing date: 2014-03-12
Publication date: 2014-10-02
Also published as: JPWO2014156655A1

Abstract

A contactless power transmission device according to the present invention and equipped with a search coil (19) in which a sensor coil is positioned so as to be flat and cover a ground coil (14), wherein the voltage generated by the sensor coil is stored as a reference voltage table when foreign matter is not present near the search coil (19). Furthermore, the contactless power transmission device determines whether or not foreign matter is present near the search coil (19) by comparing the voltage generated by the sensor coil and the reference voltage table.

Description

Non-contact power transmission device

The present invention relates to a non-contact power transmission device that transmits or receives power in a non-contact manner via a power transmission coil.

Conventionally, a power supply system described in International Publication No. 2011/142419 (Patent Document 1) is known as a non-contact power transmission device that charges a battery of an electric vehicle in a non-contact manner without requiring a plug connection. ing. In the power supply system described in Patent Document 1, a coil provided on the vehicle and a coil provided on the power supply device side are arranged to face each other, and in this state, a current is passed through the coil on the power supply side, thereby Electric power is transmitted to the coil. And by such a structure, the electric power feeding system described in patent document 1 can charge electric power to the battery of a vehicle easily, without requiring operation, such as plug connection.

In such a conventional power feeding system, since a strong magnetic field is generated between the power transmission coil on the power feeding device side and the power transmission coil on the charging side, a metallic material such as iron, aluminum, and stainless steel is formed in the vicinity of the coil. When a foreign object is placed, the magnetic field may be disturbed by the foreign object. As a result, the foreign matter may generate heat and become high temperature. For example, when an iron foreign object (bolt or nail) has fallen on the power transmission coil on the power feeding device side, a problem arises in that the temperature of the foreign object increases due to the eddy current heating.

International Publication 2011/142419

As described above, the conventional example disclosed in Patent Document 1 has a problem that, when a metal foreign object exists in the vicinity of the power transmission coil, the foreign object generates heat and becomes a high temperature state. It was.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a non-contact power transmission device capable of detecting a foreign object existing in the vicinity of a power transmission coil. It is to provide.

In order to achieve the above object, a non-contact power transmission device according to an aspect of the present invention includes a search coil in which a plurality of sensor coils are arranged in a plane so as to cover a power transmission coil, and the plurality of sensor coils. Detects the voltage generated at. In addition, the non-contact power transmission device stores, as a reference voltage table, voltages generated in the plurality of sensor coils when there is no foreign object in the vicinity of the search coil. Then, the non-contact power transmission apparatus compares the voltage generated in the plurality of sensor coils with the reference voltage table, and determines whether there is a foreign object near the search coil based on the comparison result.

FIG. 1 is a block diagram illustrating a configuration of a contactless charging system in which a contactless power transmission apparatus according to an embodiment of the present invention is employed. FIG. 2 is an explanatory diagram showing a detailed configuration of a search coil used in the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 3 is an explanatory diagram showing the positional relationship between the ground coil and the vehicle-side coil used in the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 4 is an explanatory diagram showing directions of magnetic fluxes generated in the ground coil and the vehicle side coil used in the contactless power transmission device according to the embodiment of the present invention. FIG. 5 is a block diagram illustrating a detailed configuration of the voltage detection control unit provided in the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory diagram showing a configuration of a solenoid type coil used as a ground coil and a vehicle side coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 7 is an explanatory diagram showing magnetic flux generated in a solenoid type coil used as a ground coil and a vehicle side coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 8 is an explanatory diagram showing a magnetic flux distribution generated in a solenoid type coil used as a ground coil and a vehicle side coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 9 is an explanatory diagram showing a configuration of a disk-type coil used as a ground coil and a vehicle-side coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 10 is an explanatory diagram showing magnetic flux generated in a disk-type coil used as a ground coil and a vehicle-side coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 11 is a characteristic diagram showing a voltage distribution of a reference voltage table used in the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 12 is a characteristic diagram showing a comparison between a reference voltage table used in the non-contact power transmission apparatus according to one embodiment of the present invention and an actually measured voltage. FIG. 13 is an explanatory diagram showing a change in voltage distribution when iron is placed on the search coil of the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 14 is an explanatory diagram showing a change in voltage distribution when aluminum is placed on the search coil of the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 15 is an explanatory diagram showing a magnetic flux when a rod-shaped iron is placed in the center portion of the search coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 16 is an explanatory diagram showing the magnetic flux when iron is placed at the end of the search coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 17 is a diagram illustrating a change in voltage generated in each sensor coil when iron is placed in the vicinity of the search coil of the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 18 is an explanatory diagram showing magnetic flux when sheet-like aluminum is placed at the center of the search coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 19 is an explanatory diagram showing magnetic flux when sheet-like aluminum is placed at the end of the search coil of the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 20 is a diagram illustrating a change in voltage generated in each sensor coil when aluminum is placed in the vicinity of the search coil of the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 21 is a diagram for explaining a temperature increase due to the direction of the bar-shaped iron and the direction of the magnetic flux in the non-contact power transmission apparatus according to one embodiment of the present invention. FIG. 22 is a flowchart showing a processing procedure of reference voltage table creation processing by the non-contact power transmission apparatus according to the embodiment of the present invention. FIG. 23 is a flowchart showing a foreign matter detection processing procedure performed by the non-contact power transmission apparatus according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a contactless charging system in which a contactless power transmission apparatus according to an embodiment of the present invention is employed. As shown in FIG. 1, this non-contact charging system 100 includes a vehicle side device 101 mounted on an electric vehicle (hereinafter referred to as “vehicle”) and a power supply device 102 that is installed on the ground side and supplies power to the vehicle. It consists of and. And electric power is transmitted from the electric power feeder 102, the vehicle side apparatus 101 receives this electric power non-contactingly, and the received electric power is charged to the battery mounted in the electric vehicle.

Here, the “non-contact power transmission device” according to the present embodiment indicates both the vehicle-side device 101 and the power feeding device 102. That is, the power supply apparatus 102 is a non-contact power transmission apparatus that transmits power in a non-contact manner via a power transmission coil (a ground coil 14 described later). The vehicle-side device 101 is a non-contact power transmission device that receives power in a non-contact manner via a power transmission coil (a vehicle coil 35 described later). Hereinafter, the configuration of the non-contact charging system 100 will be described.

A power supply apparatus 102 shown in FIG. 1 rectifies AC power from a commercial power supply 10 (for example, 100 V, 50 Hz) and outputs DC power, and DC power output from the DC power supply 11 is desired. An inverter 12 that converts AC power of a frequency, a ground coil 14 for power supply provided on a road surface of a parking space where the vehicle is parked, and a resonance capacitor 13 that resonates power between the ground coil 14. ing. In addition, the power supply apparatus 102 includes a voltage / current / temperature sensor 16 that detects the voltage, current, and temperature of the DC power supply 11 and the inverter 12, a ground side control unit 15, and reference voltage data (described later) used for foreign object determination. A calibration switch 18 that is operated when acquiring, a reference voltage storage unit 21 (reference voltage table storage unit) that stores a reference voltage table, a wireless LAN 17 that performs short-range communication with the vehicle-side device 101, and various types And a display unit 22 for displaying information (particularly, information related to the presence of foreign matter).

Furthermore, the power feeding device 102 is installed on the upper surface side (power transmission side) of the ground coil 14, and has a planar search coil 19 disposed substantially parallel to the ground coil 14, and a voltage generated in the search coil 19. A voltage detection control unit 20 (voltage detection unit) for measurement.

For example, a solenoid type coil or a disk type coil can be used as the ground coil 14. Details of these coils will be described later. As shown in the plan view of FIG. 2, the search coil 19 includes a plurality of sensor coils 19 L (54 × 9 × 6 are shown as an example) on the upper surface side of the ground coil 14 (power transmission side). Is arranged in a plane so as to cover. A voltage due to the magnetic flux output from the ground coil 14 is generated in each sensor coil 19L.

The voltage detection controller 20 shown in FIG. 1 measures the voltage generated in the search coil 19. More specifically, the voltage detection control unit 20 individually detects the voltage generated in each sensor coil 19 L constituting the search coil 19, and transmits each detected voltage data to the ground side control unit 15. Details will be described later.

The ground side control unit 15 comprehensively controls the power supply apparatus 102. In particular, the ground side control unit 15 performs various controls including operations of the inverter 12 and the DC power supply 11. Specifically, when transmitting power to the vehicle-side device 101, the ground-side control unit 15 supplies AC power output from the inverter 12 to the ground coil 14 and performs control for exciting the ground coil 14. Do. When the operator operates the calibration switch 18 after confirming that no foreign matter (eg, nails, bolts, empty cans, etc.) exists around the search coil 19, the ground side control unit 15 excites the ground coil 14. At this time, the voltage generated in each sensor coil 19L is measured as a reference voltage, and the reference voltage is stored in the reference voltage storage unit 21 as a reference voltage table. Further, the ground-side control unit 15 compares the voltage data detected by the voltage detection control unit 20 with the reference voltage table described above, and determines whether there is a foreign object near the ground coil 14. In addition, when there is a foreign object, the ground-side control unit 15 determines the position where the foreign object exists and the material of the foreign object, and notifies the operator of the power supply apparatus 102 and the driver of the vehicle, Alarm output, control to forcibly cut off power, etc. are performed.

That is, the ground side control unit 15 compares the voltage detected by the voltage detection control unit 20 (voltage detection unit) with the reference voltage table, and based on the comparison result, there is a foreign object in the vicinity of the search coil 19. It has a function as a foreign matter detection unit that determines whether or not to do so.

On the other hand, the vehicle-side device 101 includes a vehicle coil 35 provided on the bottom surface of the vehicle, a resonance capacitor 34 that resonates power between the vehicle coil 35, and AC power received via the vehicle coil 35. Are rectified and converted to DC power, a battery 31 that charges DC power, and a relay box 32 that switches between charging and discharging of the battery 31.

The vehicle-side device 101 also includes a voltage / current / temperature sensor 38 for detecting the input / output voltage and current of the battery 31 and the temperature of the relay box 32, a vehicle-side control unit 39, and a reference voltage table used for foreign object determination. A calibration switch 44 that is operated when acquiring the reference voltage, a reference voltage storage unit 43 (reference voltage table storage unit) that stores a reference voltage table, a wireless LAN 41 that performs short-range communication with the power supply apparatus 102, And a display unit 42 for displaying information (particularly information relating to the presence of foreign matter).

The vehicle-side control unit 39 is connected to the vehicle network 40, and can transmit and receive data to and from in-vehicle devices such as an ECU in the vehicle.

Further, the vehicle-side device 101 is installed so as to cover the lower surface side (electric power receiving side) of the vehicle coil 35, the planar search coil 36 disposed substantially parallel to the vehicle coil 35, and the search And a voltage detection control unit 37 that measures a voltage generated in the coil 36.

The vehicle coil 35 may be a solenoid type coil or a disk type coil, similar to the ground coil 14 described above. Similar to the search coil 19 on the power supply apparatus 102 side, the search coil 36 has a configuration in which a plurality of sensor coils are arranged in a plane so as to cover the lower surface side (power reception side) of the vehicle coil 35. is doing.

The voltage detection control unit 37 measures the voltage generated in the search coil 36. More specifically, the voltage detection control unit 37 individually detects the voltage generated in each sensor coil constituting the search coil 36 and transmits each detected voltage data to the vehicle side control unit 39.

The vehicle-side control unit 39 controls the vehicle-side device 101 as a whole. In particular, the vehicle-side controller 39 excites the vehicle coil 35 after confirming that no foreign matter exists around the search coil 36, measures the voltage generated in each sensor coil at this time, and uses this voltage. The reference voltage is stored in the reference voltage storage unit 43 as a reference voltage table. Further, the vehicle-side control unit 39 determines whether there is a foreign object near the search coil 36 based on the detection signal from the voltage detection control unit 37. Further, when the vehicle-side control unit 39 determines that there is a foreign object, the vehicle-side control unit 39 determines the position where the foreign object exists and the material of the foreign object, and notifies the operator of the power supply apparatus 102 and the driver of the vehicle. In addition, an alarm is output, and control for forcibly cutting off the charging of the battery 31 is performed. That is, the vehicle side control unit 39 compares the voltage detected by the voltage detection control unit 37 (voltage detection unit) with the reference voltage table, and based on the comparison result, there is a foreign object near the search coil 36. It has a function as a foreign matter detection unit for determining whether or not.

Here, the vehicle-side control unit 39 and the above-described ground-side control unit 15 can be configured as, for example, an integrated computer including a central processing unit (CPU) and storage means such as a RAM, a ROM, and a hard disk. .

Next, the positional relationship between the ground coil 14 and the vehicle coil 35 when non-contact charging is performed will be described with reference to FIG. FIG. 3 is a side view schematically showing a state when the ground coil 14 and the vehicle coil 35 face each other.

As shown in FIG. 3, the search coil 19 is provided so as to cover the upper surface side of the ground coil 14 provided on the road surface of the parking space, and the lower surface side of the vehicle coil 35 provided on the vehicle bottom surface is covered. A search coil 36 is provided. When the vehicle stops at a predetermined position in the parking space, the ground coil 14 and the vehicle coil 35 face each other. And if electric power is supplied to the ground coil 14, this electric power will be transmitted to the coil 35 for vehicles, and the battery 31 shown in FIG. 1 can be charged.

FIG. 4 is an explanatory diagram showing the direction of magnetic flux generated around the ground coil 14, FIG. 4 (a) is a plan view, and FIG. 4 (b) is a side view. As can be understood from FIG. 4, when electric power is supplied to the ground coil 14, a magnetic flux is generated in a direction from one end side to the other end side of the ground coil 14, and this magnetic flux passes through the vehicle coil 35 shown in FIG. Therefore, electric power is generated in the vehicle coil 35. Accordingly, non-contact power transmission is possible.

Further, as shown in FIG. 2 described above, the search coil 19 includes a plurality of sensor coils 19L. That is, the search coil 19 is formed by arranging a plurality of sensor coils 19L in a planar shape. Moreover, the voltage detection control part 20 is provided in the side part of each sensor coil 19L. Each sensor coil 19 L is connected to a voltage detection control unit 20.

FIG. 5 is a block diagram showing a detailed configuration of the voltage detection control unit 20. As shown in FIG. 5, the voltage detection control unit 20 is connected to each sensor coil 19 L (in FIG. 5, each sensor coil 19 L is expressed as channel 1, channel 2,..., Channel n). A multiplexer 51 that sequentially switches and outputs the voltage signal detected by 19L, a differential amplifier 52 that amplifies the voltage signal output from the multiplexer 51, and a rectifier that rectifies the voltage signal output from the differential amplifier 52 53, a filter 54 for removing AC components, and a CPU 55 for A / D converting the voltage signal.

The CPU 55 has a function of transmitting a channel designation signal to the multiplexer 51. Therefore, the voltage signal detected by each sensor coil 19L is input to the CPU 55 as an analog signal, further digitized by the CPU 55, and transmitted to the ground side control unit 15 shown in FIG. Note that the voltage detection control unit 37 provided in the vehicle-side device 101 also has the same configuration as in FIG.

Next, a solenoid type coil and a disk type coil used as the ground coil 14 and the vehicle coil 35 will be described with reference to FIGS. 6A and 6B are explanatory views showing the configuration of the solenoid type coil 61, wherein FIG. 6A is a plan view and FIG. 6B is a side view. As shown in the figure, the solenoid type coil 61 is configured by covering the periphery of a planar ferrite 62 with an insulating material 63 and winding an electric wire 64 around the periphery. In addition, a terminal 65 for connection is provided at each end of the electric wire 64. A magnetic flux can be generated around the solenoid coil 61 by connecting the terminal 65 to the inverter 12 (see FIG. 1) and passing an alternating current through the electric wire 64. Since this magnetic flux is transmitted to the vehicle coil 35 side, electric power can be transmitted to the vehicle coil 35.

FIG. 7 is an explanatory view showing the magnetic flux generated around the solenoid type coil 61, and the magnetic flux when the solenoid type coil 61 is viewed from the side surface direction is indicated by arrows. As shown in a region R1 in FIG. 7, a magnetic flux is generated from one end of the solenoid coil 61 to the other end (from the right side to the left side in the drawing).

FIG. 8 is an explanatory diagram schematically showing the relationship between the plurality of sensor coils 19L1 to 19L9 provided on the upper surface side of the ground coil 14 (in this case, the solenoid type coil 61) and the magnetic flux. In FIG. 8, in order to distinguish the sensor coils 19L arranged in a line, a numerical value is added to the end. That is, the sensor coils 19L arranged in a line are indicated as 19L1 to 19L9.

And as shown in FIG. 8, it turns out that the magnetic flux which arises in the solenoid type | mold coil 61 concentrates and passes the sensor coils 19L1, 19L2, 19L8, and 19L9 which become an edge part side. Moreover, the magnitude | size of magnetic flux changes according to the electric power output from the ground coil 14. FIG.

Therefore, if the output power is determined, the magnetic flux passing through each sensor coil 19L1 to 19Ln (n is the number of sensor coils) is determined to be a substantially constant value, so that the voltage generated in each sensor coil 19L1 to 19Ln is determined. For this reason, when there is a foreign object (for example, metal) that disturbs the magnetic flux in the vicinity of the ground coil 14, the voltage generated in each of the sensor coils 19L1 to 19Ln is acquired in advance when the reference voltage (the foreign object is not present). For each sensor coil 19L1 to 19Ln). Therefore, by detecting this voltage change, it is possible to detect whether there is a foreign object in the vicinity of the ground coil 14. Furthermore, it is possible to detect a position where a foreign substance exists.

In FIG. 8, only four magnetic fluxes are shown in the figure to avoid complexity, but in reality, magnetic fluxes are generated more complicatedly.

Next, the disk type coil will be described. 9A and 9B are explanatory views showing the configuration of the disk-type coil 71, wherein FIG. 9A is a plan view and FIG. 9B is a side view. As shown in the figure, the disk-shaped coil 71 is provided with an insulating material 73 so as to cover the upper surface of the flat plate-shaped ferrite 72, and further, the electric wire 74 is spirally formed on the upper surface side of the insulating material 73 and has a donut shape. It is wound around (a shape with a hole in the center). Furthermore, a terminal 75 is provided at each end of the electric wire 74. Then, by connecting the terminal 75 to the inverter 12 (see FIG. 1) and passing an alternating current through the electric wire 74, a magnetic flux can be generated around the disk type coil 71. Since this magnetic flux is transmitted to the vehicle coil 35 side, electric power can be transmitted to the vehicle coil 35.

FIG. 10 is an explanatory diagram showing the magnetic flux generated around the disk-type coil 71, and the magnetic flux when the disk-type coil 71 is viewed from the side is indicated by arrows. As shown in a region R2 (right half region) in FIG. 10, a magnetic flux is generated from one end of the disk-type coil 71 toward the other end. Therefore, also in this region R2, as shown in FIG. 8 described above, the magnetic flux is detected by each sensor coil 19L (19L1 to 19L9). However, since this shows the right half region, a magnetic flux having a symmetrical shape with the magnetic flux shown in FIG. 10 is also generated in the left half region.

Therefore, since the voltage generated in each sensor coil 19L is known in advance, the presence of a foreign object can be detected by using this voltage as a reference voltage.

Next, a foreign object detection method executed by the ground control unit 15 will be described. In the present embodiment, as an initial operation, when there is no foreign object in the vicinity of the search coil 19, the ground side control unit 15 supplies power to the ground coil 14 to excite the ground coil 14, and the search coil A voltage generated in each of the 19 sensor coils 19L is detected. The detected voltage data is stored in the reference voltage storage unit 21 as a reference voltage table.

FIG. 11 is a characteristic diagram showing an example of a reference voltage table set for each output power. In FIG. 11, a curve s1 indicates a reference voltage detected by each sensor coil 19L when the output power of the ground coil 14 is 1 KW. The horizontal axis in FIG. 11 arranges “channels” in ascending order of generated voltage. That is, the left end of the curve s1 indicates the channel with the lowest generated voltage, and the right end indicates the channel with the highest generated voltage. Similarly, the curve s2 indicates the reference voltage when the output power is 2 KW, and the curve s3 indicates the reference voltage when the output power is 3 KW.

Then, when detecting foreign matter existing in the vicinity of the search coil 19 during actual power transmission, the difference between the voltage of each sensor coil 19L detected by the voltage detection control unit 20 and the reference voltage table is calculated. As a result, for example, as shown in FIG. 12, the difference between the measured voltage data (curve s12) and the reference voltage (curve s11) stored in the reference voltage table is obtained, and based on this difference, the foreign object Detect presence.

That is, the ground-side control unit 15 compares the voltage detected by each sensor coil 19L with the reference voltage, and if there is a large difference, the ground-side control unit 15 places a metal near the search coil 19, that is, near the ground coil 14. It is determined that there is a manufactured foreign object.

Here, with respect to the search coil 36 provided on the lower surface side of the vehicle coil 35 shown in FIG. 1, the presence of a foreign object can be detected by the same method as described above. Detailed description is omitted. Thereby, even when a foreign object exists in the vicinity of the vehicle coil 35 due to a metal foreign object tangled in the vehicle coil 35, the foreign object can be detected by using the search coil 36.

Note that the search coil need not be provided in both the vehicle side device 101 and the power feeding device 102, and may be provided in either one. That is, when detecting only the foreign matter existing in the vicinity of the ground coil 14, the search coil 36 and the voltage detection control unit 37 shown in FIG. 1 are not necessary. Further, in the case of detecting only foreign matter existing in the vicinity of the vehicle coil 35, the search coil 19 and the voltage detection control unit 20 shown in FIG.

Next, the magnetic flux disturbance when a foreign substance actually exists in the vicinity of the ground coil 14 will be described. First, the case where a foreign matter having a high magnetic permeability such as iron is placed in the vicinity of the search coil 19 will be described with reference to FIG. FIG. 13A shows a case where a rod-like foreign matter (for example, iron) having a high magnetic permeability is placed in the substantially central portion of the search coil 19, and FIG. 13B is slightly shifted from the center of the search coil 19. It is explanatory drawing which shows a voltage change when the foreign material (for example, iron) with the block shape and high magnetic permeability is put in the position.

As shown in FIG. 13A, when a rod-like foreign material x1 is placed, the voltage generated in the central region r1 of the foreign material x1 decreases with respect to the reference voltage, and both end regions r2, The voltage generated at r3 increases. On the other hand, as shown in FIG. 13B, when a lump-like foreign material x2 is placed, the voltage generated in the region r4 where the foreign material x2 is present rises with respect to the reference voltage, and the regions r5 and r5 at both ends are located. The voltage generated at r6 decreases. Therefore, based on such a voltage change pattern, it is possible to recognize the position and material where the foreign matter exists.

Next, a case where a foreign matter having a low magnetic permeability such as aluminum or copper is placed in the vicinity of the search coil 19 will be described. FIG. 14A shows a case where a rod-like foreign material (for example, aluminum) having a low magnetic permeability is placed at the substantially central portion of the search coil 19, and FIG. 14B is slightly shifted from the center of the search coil 19. It is explanatory drawing which shows a voltage change when the block-shaped foreign material with low magnetic permeability is put in the position.

As shown in FIG. 14A, when a rod-shaped foreign material x3 is placed in the direction of the magnetic flux on the search coil 19, the foreign material x3 hardly affects the change of the magnetic flux. Accordingly, the voltage detected by the search coil 19 does not change. Further, as shown in FIG. 14B, when a lump-like foreign matter x4 is placed, the voltage generated in the region r7 where the foreign matter x4 is present decreases. Therefore, based on such a voltage change pattern, it is possible to recognize the position and material where the foreign matter exists.

Next, a change in voltage generated in each sensor coil 19L will be described in more detail. FIG. 15 is an explanatory diagram showing changes in magnetic flux when a rod-shaped iron 81 (for example, an iron nail or bolt) is placed in the lateral direction at the approximate center of the upper surface of the search coil 19. Since the iron 81 has a high magnetic permeability, when iron is placed in the center of the search coil 19, the magnetic flux changes so as to pass through the iron 81. As a result, the magnetic flux passing through each sensor coil 19L changes, thereby changing the voltage generated in each sensor coil 19L. As a specific example, for example, the voltage changes as shown in FIG. The “channel number” shown in FIG. 17 indicates the number of the sensor coil 19L, the upward arrow “↑” indicates that the voltage rises with respect to the reference voltage, and the downward arrow “↓” indicates the reference voltage. On the other hand, the voltage decreases. In addition, “−” indicates that there is no change.

As shown in FIG. 15, when the rod-shaped iron 81 is placed at the center of the search coil 19, as shown in FIG. 17A, the sensor coils 19L1 to 19L3 and 19L7 to 19L9 at both ends are provided. Is increased, and the voltage generated in the central sensor coils 19L4 to 19L6 is decreased. Therefore, when such a voltage change is detected, it can be determined that a metal foreign matter having a high magnetic permeability such as iron exists in the approximate center of the search coil 19 (ground coil 14).

Furthermore, as shown in FIG. 16, when the iron 82 is placed at the end of the search coil 19 in the vertical direction, the magnetic flux changes so as to pass through the iron 82. Magnetic flux concentrates on the second sensor coil 19L2. Accordingly, as shown in FIG. 17B, the voltage generated in the sensor coils 19L1, 19L3 to 19L5 decreases, and the voltage generated in the sensor coil 19L2 increases. Therefore, when such a voltage change is detected, it can be determined that a metallic foreign matter having a high magnetic permeability such as iron exists at the end of the search coil 19. That is, by referring to the voltage change pattern shown in FIG. 17, it is possible to determine the position and material (whether the material has a high magnetic permeability or a low material) of the foreign matter existing above the search coil 19. .

Also, as shown in FIG. 21 (a), when a rod-shaped iron is placed in parallel with the direction of the magnetic flux, the magnetic flux concentrates on the iron, so heat is generated and the temperature rises. And since the voltage detected by each sensor coil 19L changes, presence of a foreign material can be detected. On the other hand, as shown in FIG. 21B, when the rod-shaped iron is placed so as to be orthogonal to the direction of the magnetic flux, the magnetic flux does not concentrate on this iron (or the degree of concentration is low). This iron does not generate heat and the temperature does not increase (or the heat generation is very small). At this time, the voltage detected by each sensor coil 19L does not change greatly, and the presence of foreign matter cannot be detected.

That is, the foreign matter that does not affect the magnetic flux does not cause the problem of heat generation in the first place, so it is not necessary to detect this foreign matter. In other words, since foreign matter that does not cause heat generation is not detected, generation of an unnecessary alarm signal or circuit interruption can be avoided.

Next, a case where a metal foreign matter (for example, copper or aluminum) having low permeability exists in the vicinity of the search coil 19 will be described. FIG. 18 is an explanatory diagram showing a change in magnetic flux when a sheet-like aluminum 83 is placed in the upper central portion of the search coil 19. Since aluminum has a low magnetic permeability, magnetic flux passes through it to avoid it. However, in the example shown in FIG. 18, the sheet-like aluminum 83 is placed substantially at the center of the search coil 19 and is substantially parallel to the surface of the search coil 19, so that the magnetic flux is not affected. Therefore, as shown in FIG. 20A, the voltages generated in the sensor coils 19L1 to 19L9 do not change. Further, since the magnetic flux does not change, the problem that the sheet-like aluminum 83 generates heat does not occur.

On the other hand, as shown in FIG. 19, when a sheet-like aluminum 84 is placed on the end of the upper surface of the search coil 19, the magnetic flux changes so as to pass through the aluminum 84. Therefore, as shown in FIG. 20B, the voltage generated in the sensor coil 19L8 increases and the voltage generated in the sensor coil 19L9 decreases. Accordingly, when such a voltage change is detected, it can be determined that there is a metallic foreign matter having a low magnetic permeability such as aluminum near the end of the search coil 19. That is, based on the voltage change shown in FIG. 20, it is possible to determine the position and material of the foreign matter existing on the search coil 19 (whether the material has a high magnetic permeability or a low material).

Next, the operation when detecting the presence of a foreign object in the non-contact charging system 100 according to the present embodiment configured as described above will be described with reference to the flowcharts shown in FIGS. The contactless charging system 100 according to the present embodiment acquires in advance voltage data detected by each sensor coil 19L when no foreign matter exists in the vicinity of the search coils 19 and 36. The non-contact charging system 100 stores and saves the voltage data in the reference voltage storage units 21 and 43 (see FIG. 1) as a reference voltage table.

Hereinafter, a processing procedure for creating a reference voltage table stored in the reference voltage storage unit 21 will be described with reference to a flowchart shown in FIG. First, in step S31, the ground-side control unit 15 shown in FIG. 1 supplies power to the ground coil 14 so that the output becomes 0.5 KW. In step S32, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores and stores it in the reference voltage storage unit 21 as a reference voltage table for 0.5 kW.

In step S33, the ground-side control unit 15 supplies power to the ground coil 14 so that the output becomes 1 KW. In step S34, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores it in the reference voltage storage unit 21 as a reference voltage table for 1 kW.

Furthermore, in step S35, the ground side control part 15 supplies electric power to the ground coil 14 so that an output may be set to 1.5 kW. In step S36, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores and stores it in the reference voltage storage unit 21 as a 1.5 kW reference voltage table.

In step S37, the ground-side control unit 15 supplies power to the ground coil 14 so that the output becomes 2 KW. In step S38, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores and stores it in the reference voltage storage unit 21 as a reference voltage table for 2 kW.

In step S39, the ground-side control unit 15 supplies power to the ground coil 14 so that the output becomes 2.5 KW. In step S40, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores and stores it in the reference voltage storage unit 21 as a 2.5 kW reference voltage table.

In step S41, the ground-side control unit 15 supplies power to the ground coil 14 so that the output becomes 3 KW. In step S42, the ground-side control unit 15 acquires the voltage distribution in each sensor coil 19L of the search coil 19 at this time, and stores and stores it in the reference voltage storage unit 21 as a reference voltage table for 3 kW.

Thus, the non-contact charging system 100 according to the present embodiment can acquire the reference voltage table indicating the voltage distribution of the search coil 19 at each output. In the flowchart of FIG. 22, the case where the reference voltage table is acquired for the search coil 19 is shown, but the search coil 36 provided in the vehicle-side device 101 is also processed for each output power by the same process. The reference voltage table can be created.

Next, with reference to the flowchart shown in FIG. 23, a specific processing procedure for detecting a foreign object existing in the vicinity of the search coil 19 will be described. This process is executed under the control of the ground side control unit 15 shown in FIG.

First, in step S11, when the ground side control unit 15 performs an initial diagnosis and starts foreign object detection processing, in step S12, the ground side control unit 15 determines whether or not to perform calibration processing of the reference voltage table. This process can be determined by whether or not the operator has pressed the calibration switch 18. When the calibration switch 18 is pressed (ON in step S12), in step S13, the ground side control unit 15 executes the process shown in FIG. 22 and creates a new reference voltage table. .

On the other hand, when the calibration switch 18 is not pressed (OFF in step S12), the ground side control unit 15 acquires voltage data detected by each sensor coil 19L included in the search coil 19 in step S14. . That is, voltage data for each sensor coil 19L detected by the voltage detection control unit 20 shown in FIG. 1 is acquired.

Next, in step S 15, the ground-side control unit 15 reads a reference voltage table stored and saved in advance in the reference voltage storage unit 21. At this time, a reference voltage table corresponding to the output power of the ground coil 14 is used. For example, when the output power of the ground coil 14 is 2 KW, the reference voltage table corresponding to 2 KW is read.

In step S16, the ground control unit 15 compares the reference voltage table read in step S15 with the voltage data acquired in step S14, and obtains a differential voltage.

In step S17, the ground-side control unit 15 determines a voltage change pattern in an area where the differential voltage is equal to or higher than a preset threshold voltage (an installation position of the sensor coil 19L). Then, based on the voltage change pattern, the ground side control unit 15 specifies the position where the foreign matter exists on the search coil 19. Further, it is determined whether the foreign material is a foreign matter having a high magnetic permeability such as iron or a foreign matter having a low magnetic permeability such as copper or aluminum.

Specifically, the position and material of the foreign matter are specified with reference to the data described in FIGS.

For example, in the region where the magnetic flux is generated in the vertical direction (the region where the magnetic flux is generated in the direction orthogonal to the search coil 19), the central voltage is high and the surrounding voltage is low (FIGS. 16 and 17B). In the example shown, the ground-side control unit 15 determines that a foreign material made of a material having a high magnetic permeability such as iron exists at a position that is an end of the search coil 19.

Further, in the region where the magnetic flux is generated in the vertical direction, when the central voltage is low and the surrounding voltage is high (examples shown in FIGS. 19 and 20B), the ground side control unit 15 performs the search. It is determined that a foreign material having a low magnetic permeability such as aluminum or copper is present at the end of the coil 19. That is, as shown in FIG. 19, when a foreign object (sheet-like aluminum 84) is placed at the end of the search coil 19, magnetic flux passes so as to avoid the aluminum 84. In this case, the voltage of the sensor coil 19L9) is decreased, and the voltage of the surrounding portion (in this case, the sensor coil 19L8) is increased. Therefore, it can be estimated that the aluminum 84 with low magnetic permeability exists at the end.

Further, in the region where the magnetic flux is generated in the horizontal direction (the region where the magnetic flux is generated in the direction parallel to the search coil 19), the central voltage is low and the surrounding voltage is high (see FIGS. 15 and 17A). In the example shown), the ground-side control unit 15 determines that there is a foreign material made of a material having a high magnetic permeability such as iron at the center of the search coil 19.

On the other hand, in the region where the magnetic flux is generated in the horizontal direction, when the central voltage is high and the surrounding voltage is not changed, the ground side control unit 15 places the aluminum or the like at the center of the search coil 19. It is determined that foreign matter having a low magnetic permeability such as copper is present in a standing state.

Then, by displaying these pieces of information on the display unit 22, the ground side control unit 15 can notify the operator of the power supply apparatus 102 that there is a foreign object in the vicinity of the search coil 19. Further, foreign object detection information can be notified to the vehicle-side device 101 by communication between the wireless LAN 17 of the power supply device 102 and the wireless LAN 41 of the vehicle-side device 101. Therefore, by displaying this detection information on the display unit 42 of the vehicle-side device 101, it is possible to notify the driver of the vehicle that there is a foreign object. As a result, when a foreign object exists in the vicinity of the search coil 19, an operator or the like who has recognized the presence of the foreign object can remove the foreign object in advance, so that the metal made in the vicinity of the search coil 19 can be removed. It is possible to avoid the occurrence of a problem that the foreign matter generates heat.

In the flowchart shown in FIG. 23, the foreign object detection procedure by the search coil 19 installed on the upper surface side of the ground coil 14 has been described. However, the search coil 36 installed on the lower surface side of the vehicle coil 35 is similar in procedure. Foreign matter can be detected.

Thus, in the non-contact power transmission apparatus according to the present embodiment, the search coil 19 including the plurality of sensor coils 19L is provided on the upper surface side of the ground coil 14, and the voltage generated in each sensor coil 19L is detected. Furthermore, the detected voltage data is compared with the reference voltage set in the reference voltage table acquired in advance, and the presence position of the foreign matter and the material of the foreign matter are detected based on the voltage increase / decrease pattern.

Therefore, it is possible to reliably detect the position and material of the metallic foreign object existing in the vicinity of the search coil 19 and notify the operator of the power supply apparatus 102 and the driver of the vehicle.

That is, when the vehicle is stopped in the charging parking space, it is difficult to visually recognize the situation on the search coil 19 provided on the road surface from the surroundings. Therefore, by using the search coil 19 of the present embodiment, it is possible to surely confirm the presence and position of the foreign matter and the material, and the foreign matter can be removed immediately.

Similarly, by providing the search coil 36 on the lower surface side of the vehicle coil 35, the position and material of the metallic foreign object existing in the vicinity of the vehicle coil 35 are detected, and the vehicle driver And the operator of the power supply apparatus 102 can be notified.

Further, the presence position and material of the foreign matter can be detected based on the voltage change pattern in the plurality of sensor coils 19L. That is, based on the voltage change pattern in the sensor coil 19L shown in FIG. 17 and FIG. 20, it is possible to recognize where the foreign substance exists on the search coil 19 and to recognize the material of the foreign substance. Accordingly, the driver or operator of the vehicle can recognize the position and material where the foreign matter exists in the vicinity of the search coil 19 and can immediately perform the work of removing the foreign matter. The same effect as described above can be achieved for the search coil 36 of the vehicle-side device 101.

As mentioned above, although the non-contact electric power transmission apparatus of this invention was demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part is set to the thing of the arbitrary structures which have the same function. Can be replaced.

For example, in the above-described embodiment, an example in which a solenoid type coil is used as the ground coil 14 has been described. That is, as shown in FIG. 10 described above, in the disk-type coil 71, the right half magnetic flux generation pattern substantially coincides with that of the solenoid-type coil 61 shown in FIG. If the same method is adopted for the left half, the presence position and material of the foreign substance can be detected by the same method as in the above embodiment.

In the above-described embodiment, the example in which the search coil 36 is provided on the lower surface side of the vehicle coil 35 and the search coil 19 is provided on the upper surface side of the ground coil 14 has been described, but the present invention is not limited to this. Alternatively, the search coil may be provided on at least one side. For example, if the search coil 19 is provided only on the upper surface side of the ground coil 14, it is possible to detect foreign matter existing in the vicinity of the ground coil 14. Further, if the search coil 36 is provided only on the lower surface of the vehicle coil 35, foreign matter existing in the vicinity of the vehicle coil 35 can be detected.

This application claims priority based on Japanese Patent Application No. 2013-071268 filed on Mar. 29, 2013, and the contents of this application are incorporated into the specification of the present invention by reference.

DESCRIPTION OF SYMBOLS 10 Commercial power supply 11 DC power supply 12

Inverter

13, 34 Resonance capacitor 14 Ground coil 15 Ground

side control part

16, 38 Voltage / current /

temperature sensor

17, 41 Wireless LAN
18, 44

Calibration switch

19, 36 Search coil

19L Sensor coil

20, 37 Voltage

detection control unit

21, 43 Reference

voltage storage unit

22, 42 Display unit 31 Battery 32 Relay box 33 Rectifier circuit 35 Vehicle coil 39 Vehicle side control unit 40 Vehicle network 51 Multiplexer 52 Differential amplifier 53 Rectifier 54 Filter 55 CPU
61

Solenoid type coil

62, 72

Ferrite

63, 73 Insulating

material

64, 74

Electric wire

65, 75 Terminal 71

Disc type coil

81, 82

Iron

83, 84 Aluminum 100 Non-contact charging system 101 Vehicle side device 102 Power feeding device

Claims

A non-contact power transmission device that transmits or receives power in a non-contact manner via a power transmission coil,
A search coil in which a plurality of sensor coils are arranged in a plane so as to cover a surface to be a transmission side or a reception side of the power transmission coil;
A voltage detection unit that detects voltages generated in the plurality of sensor coils when power is transmitted or received by the power transmission coil; and
A reference voltage table storage unit that stores, as a reference voltage table, voltages generated in the plurality of sensor coils when there is no foreign object in the vicinity of the search coil;
A foreign object detection unit that compares the voltage detected by the voltage detection unit with the reference voltage table and determines whether there is a foreign object in the vicinity of the search coil based on the comparison result;
A non-contact power transmission device comprising:
The foreign matter detection unit obtains a differential voltage between a voltage detected by two or more sensor coils among the plurality of sensor coils and a voltage generated in each sensor coil stored in the reference voltage table, and The non-contact power transmission apparatus according to claim 1, wherein the presence position of the foreign object is determined based on an ascending / descending pattern.
The foreign matter detection unit obtains a differential voltage between a voltage detected by two or more sensor coils among the plurality of sensor coils and a voltage generated in each sensor coil stored in the reference voltage table, and The non-contact power transmission apparatus according to claim 1, wherein the material of the foreign matter is determined based on an ascending / descending pattern.