JP2015204707A - non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device capable of accurately detecting foreign matter over an entire period of time during power transmission.SOLUTION: A control section 800 intermittently supplies power to a power transmission coil 702 according to a command for a power transmission start. The control section 800 executes metal detection using a detection coil 704 when no power is supplied to the power transmission coil 702, and suspends the metal detection using the detection coil 704 when power is supplied to the power transmission coil 702. The control section 800 monitors a temperature on a housing case 703 by a temperature sensor 705 at least when power is supplied to the power transmission coil 702.

Description

  The present invention relates to a non-contact power transmission device, and more particularly to a technique for detecting a foreign object that has contacted a power transmission device.

  When charging an electric vehicle, a plug-in hybrid vehicle, or the like, the use of a non-contact power transmission system has been studied and a part of it is being put into practical use. However, since it is used outdoors, foreign matter may enter between the power transmission device and the power receiving unit of the vehicle.

  Japanese Patent Laying-Open No. 2013-192411 discloses a technique for detecting a foreign object using a camera and a temperature sensor that image a foreign object detection area in a non-contact power transmission system. In this technique, power transmission is started after confirming that there is no foreign object by the camera. And at the time of electric power transmission, a foreign material is detected by a temperature sensor.

JP 2013-192411 A JP 2013-005682 A JP2013-154815A JP2013-146154A JP2013-146148A JP 2013-110822 A JP 2013-126327 A

  However, it is difficult for a camera to detect small metallic foreign objects. As another detection means, a metal detection coil can be considered. While the metal detection coil has higher foreign object detection accuracy than the camera, there is a problem that the metal foreign object cannot be accurately detected by a magnetic field during power transmission during power transmission. Even if foreign matter is detected before power transmission, a problem arises when a metallic foreign matter enters the power transmission device during power transmission unless foreign matter detection is performed during power transmission.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a non-contact power transmission device that can accurately detect foreign matter over the entire time during power transmission. is there.

  In summary, the present invention is a non-contact power transmission device, a power transmission coil that supplies power to a power receiving coil in a non-contact manner, a housing case that houses the power transmission coil, and a detection that can detect a metal located on the housing case A coil, a temperature sensor that can detect the temperature on the housing case, and a control unit that controls power transmission to the power transmission coil and metal detection using the detection coil. The control unit executes power transmission control so that power is intermittently supplied to the power transmission coil in response to a command to start power transmission. The control unit performs metal detection using the detection coil when power is not supplied to the power transmission coil, and stops metal detection using the detection coil when power is supplied to the power transmission coil. The controller monitors the temperature with a temperature sensor at least when power is supplied to the power transmission coil.

  According to the present invention, power is intermittently supplied to the power transmission coil, and metal foreign matter detection using the detection coil is performed when power is not supplied to the power transmission coil, and the temperature rise is monitored by the temperature sensor. Thereby, the penetration | invasion of a metal foreign material can be accurately monitored by a detection coil from the power transmission start to power transmission completion.

It is a figure for demonstrating the structure of the non-contact electric power transmission system which concerns on this Embodiment. 7 is a diagram illustrating a positional relationship between a power transmission coil 702 and a power reception coil 752. FIG. 2 is a perspective view showing a configuration of a power transmission unit 700. FIG. 6 is a top view showing a more detailed planar arrangement of a power transmission unit 700. FIG. 5 is a flowchart for explaining control of foreign object detection processing executed by a control unit 800.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram for explaining a configuration of a non-contact power transmission system according to the present embodiment.

  Referring to FIG. 1, contactless power transmission system 1 includes a vehicle 10 and a power transmission device 90. In the non-contact power transmission system 1, non-contact power transmission is performed from the power transmission device 90 to the vehicle 10. Non-contact power transmission is performed via a power transmission unit 700 included in the power transmission device 90 and a power reception unit 100 mounted on the vehicle 10.

  First, the vehicle 10 in the non-contact power transmission system 1 will be described. Vehicle 10 includes a power receiving device 120, a relay 210, a battery 300, a system main relay (SMR) 310, a power generation device 400, a vehicle ECU 500, and a notification device 520.

  Power reception device 120 includes power reception unit 100, filter circuit 150, and rectifier 200. Power receiving unit 100 includes a power receiving coil 752 for receiving AC power output from power transmitting unit 700 in a contactless manner. The power received by the power receiving unit 100 is output to the filter circuit 150. The filter circuit 150 suppresses harmonic noise. The filter circuit 150 is configured by an LC filter including an inductor and a capacitor, for example.

  The power receiving unit 100 includes a capacitor in addition to the secondary coil. The secondary coil and the capacitor constitute a resonance circuit. The Q value indicating the strength of resonance is preferably 100 or more.

  The AC power whose harmonic noise is suppressed by the filter circuit 150 is output to the rectifier 200. The rectifier 200 rectifies AC power. The power rectified by the rectifier 200 is output as charging power for the battery 300.

  A relay 210 is provided between the rectifier 200 and the battery 300. Relay 210 is turned on (ON) when battery 300 is charged with power from power transmission device 90.

  Battery 300 is formed of a secondary battery such as a lithium ion battery or a nickel metal hydride battery. The voltage of the battery 300 is about 200V, for example.

  The power generation device 400 uses the electric power stored in the battery 300 to generate the driving force for driving the vehicle 10. Although not particularly illustrated, power generation device 400 includes, for example, an inverter that receives electric power from battery 300, a motor driven by the inverter, a drive wheel driven by the motor, and the like. Power generation device 400 may include a generator for charging battery 300 and an engine capable of driving the generator.

  The vehicle 10 further includes a vehicle ECU (Electronic Control Unit) 500 that is a control unit and a notification device 520. As an example, the vehicle ECU 500 executes traveling control of the vehicle 10 and charging control of the battery 300. The notification device 520 is a user interface, and is used, for example, to notify the vehicle user that there is a foreign object on the power transmission unit 700. The vehicle user can see the image or video output from the notification device 520 to know the presence of a foreign object and remove the foreign object in order to start charging. In addition to or instead of images and videos, sound and sound may be output to the notification device 520.

  Next, the power transmission device 90 in the non-contact power transmission system 1 will be described. Power transmission device 90 includes an external power supply 900, a communication unit 810, a power supply unit 600, a filter circuit 610, and a power transmission unit 700. The power transmission unit 700 is accommodated in the accommodation case 703. The power transmission unit 700 includes a power transmission coil 702, a detection coil 704, and a temperature sensor 705.

  FIG. 2 is a diagram illustrating a positional relationship between the power transmission coil 702 and the power reception coil 752. The power transmission coil 702 is provided, for example, on the ground surface or underground of a parking space where the vehicle 10 is to park. Non-contact charging is a technique for transmitting a large amount of power through a space. For this reason, a strong magnetic field is generated between the power transmission coil 702 and the power reception coil 752. Therefore, when a metal foreign object enters the vicinity of the coil during charging, the foreign object generates heat due to induction heating. In order to prevent such a situation, it is necessary to detect the intrusion of a metal foreign object during charging.

  The mounting location of the sensor for detecting foreign matter is preferably on the power transmission device side than on the vehicle side. The reason for this is that foreign matter can be detected only by the detection coil 704 provided in the power transmission coil 702 before approaching the vehicle even without the power receiving coil 752, and the foreign matter basically exists in a form that rides on the power transmission coil 702. can give.

  Referring to FIG. 1 again, vehicle ECU 500 communicates with communication unit 810 of power transmission device 90 using communication unit 510 when battery 300 is charged by power transmission device 90 to start / stop power reception or receive power of vehicle 10. Information such as the situation is exchanged with a power supply ECU 800 described later.

  The power supply unit 600 receives power from an external power supply 900 such as a commercial power supply and generates AC power having a predetermined transmission frequency. The generated AC power is output to the filter circuit 610.

  Filter circuit 610 suppresses harmonic noise generated from power supply unit 600. The filter circuit 610 is configured by an LC filter including an inductor and a capacitor, for example.

  The AC power whose harmonic noise is suppressed by the filter circuit 610 is output to the power transmission unit 700. The power transmission unit 700 includes a power transmission coil 702 for transmitting power to the power reception unit 100 in a contactless manner. The power transmission unit 700 transmits AC power having a transmission frequency to the power reception unit 100 of the vehicle 10 in a non-contact manner via an electromagnetic field generated around the power transmission unit 700.

  The power transmission unit 700 includes a capacitor in addition to the power transmission coil 702. The power transmission coil 702 and the capacitor constitute a resonance circuit. The Q value indicating the strength of resonance is preferably 100 or more.

  Power supply ECU 800 performs switching control of power supply unit 600 so that power supply unit 600 generates AC power having a transmission frequency.

  The power supply ECU 800 communicates with the communication unit 510 of the vehicle 10 using the communication unit 810 during power transmission to the vehicle 10 and exchanges information such as charging start / stop and the power reception status of the vehicle 10 with the vehicle 10. .

  In the non-contact power transmission system 1 having such a configuration, a configuration for detecting a foreign object will be described in more detail.

  FIG. 3 is a perspective view showing the configuration of the power transmission unit 700. FIG. 4 is a top view showing a more detailed planar arrangement of the power transmission unit 700.

  With reference to FIGS. 1, 3, and 4, a power transmission unit 700 of the non-contact power transmission device includes a power transmission coil 702, a housing case 703, a detection coil 704, and a temperature sensor 705.

  The power transmission coil 702 supplies power to the power reception coil 752 in a contactless manner. The housing case 703 houses the power transmission coil 702. The detection coils 704 are arranged in a matrix on the storage case 703 and can detect a metal located on the storage case 703. For example, the temperature sensor 705 is configured by arranging a plurality of thermistor chains connected in series on a storage case, and can detect the temperature on the storage case 703. The control unit 800 controls power transmission to the power transmission coil 702 and metal detection using the detection coil 704.

  The detection coil 704 includes a coil pair including a primary coil and a secondary coil. The coil pair is disposed on or in the storage case 703, and metal detection can be performed even when the power receiving coil 752 is separated.

  When power is transmitted from the primary coil of the detection coil 704, an induced current (or voltage) is generated in the secondary coil of the detection coil 704. When a metal foreign object exists, the L value of the detection coil in the vicinity of the metal foreign object decreases, and the induced current (or voltage) also decreases.

  The detection circuit 701 detects a decrease in induced current (or voltage), and the control unit 800 determines the presence or absence of foreign matter.

  Based on the determination result of the presence or absence of a foreign object, control unit 800 pauses or stops power transmission from power supply unit 600.

  The control unit 800 in FIG. 1 intermittently supplies power to the power transmission coil 702 in response to a power supply command (charge start command) to the power receiving coil 752. During intermittent power transmission, the control unit 800 performs metal detection using the detection coil 704 when power is not supplied to the power transmission coil 702, while the detection coil 704 is detected when power is supplied to the power transmission coil 702. Stop the metal detection used. The control unit 800 may perform the operation at all times, but monitors the temperature of the housing case 703 by the temperature sensor 705 at least when power is supplied to the power transmission coil 702.

  Thus, in the configuration in which the detection coil 704 and the temperature sensor 705 such as the thermistor are arranged, a detection method (for example, thermistor) that is not affected by the magnetic field is used during charging, and the detection coil 704 is used when charging is interrupted. Perform foreign object detection. Thereby, the low detection accuracy of the thermistor can be covered by the detection coil 704.

  FIG. 5 is a flowchart for explaining the control of the foreign object detection process executed by the control unit 800. The processing of this flowchart is called from the main routine and executed at regular time intervals or whenever a specific condition is satisfied.

  Referring to FIG. 5, when the process is started, a charging operation is started in step S101. At this time, the transmission power is still 0 W.

  Subsequently, in step S102, foreign object detection is started by the detection coil 704 and a temperature sensor 705 such as a thermistor. In step S103, the presence or absence of foreign matter is determined. If it is determined in step S103 that there is a foreign object, the process proceeds to step S104, charging is stopped and the user is notified that there was a foreign object. Thereafter, the process is returned to the main routine.

  On the other hand, if it is determined in step S103 that there is no foreign object, the process proceeds to step S105. In step S105, the detection operation by the detection coil 704 is stopped. In step S106, power supply ECU 800 increases the charging power.

  Thereafter, charging is performed until a predetermined time elapses. In step S107, it is determined whether or not charging has been interrupted after a predetermined time has passed (output 0W). If charging is interrupted in step S107, the process proceeds to step S108.

  In step S108, a foreign object detection operation using the detection coil 704 is performed. In step S109, the presence / absence of a foreign object is determined. If it is determined in step S109 that there is a foreign object, the process proceeds to step S110, charging is stopped and the user is notified that there was a foreign object. Thereafter, the process is returned to the main routine.

  On the other hand, if it is determined in step S109 that there is no foreign object, the process proceeds to step S111. In step S111, after the entire upper surface of the coil housing case of the power transmission coil (primary coil) is searched with the detection coil 704 and it is confirmed that there is no foreign matter, release of the charge interruption is permitted. Thereafter, in step S112, charging using the power transmission coil is resumed, and the processes in and after step S106 are repeated.

  A feature of this process is that foreign matter detection using the detection coil 704 is performed only when charging is interrupted (when the transmission power is 0 W) in step S107. By doing so, since it is not affected by the magnetic field of the charging system, the detection coil 704 does not need to have a special and complicated winding method (for example, the shape of the number “8”) for canceling the magnetic field. The restriction on the shape of the coil 704 is also eliminated. In addition, it is not necessary to learn and correct the influence of the magnetic field. In addition, unlike a temperature sensor, it is possible to detect the metal foreign object in the air without being in close contact with the housing case.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiment but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  DESCRIPTION OF SYMBOLS 1 Non-contact electric power transmission system, 10 Vehicle, 90 Power transmission apparatus, 100 Power receiving part, 120 Power receiving apparatus, 150,610 Filter circuit, 200 Rectifier, 210 Relay, 300 Battery, 400 Power generation apparatus, 500 Control part (vehicle ECU), 510,810 communication unit, 520 notification device, 600 power supply unit, 700 power transmission unit, 701 detection circuit, 702 power transmission coil, 703 housing case, 704 detection coil, 705 temperature sensor, 752 power reception coil, 800 control unit (power supply ECU), 900 External power supply.

Claims (1)

A power transmission coil that supplies power to the power receiving coil in a contactless manner;
A housing case for housing the power transmission coil;
A detection coil capable of detecting metal located on the housing case;
A temperature sensor capable of detecting the temperature on the housing case;
A control unit that controls power transmission to the power transmission coil and metal detection using the detection coil;
The control unit executes power transmission control so that power is intermittently supplied to the power transmission coil in response to a power transmission start command.
The control unit performs metal detection using the detection coil when power is not supplied to the power transmission coil, and performs metal detection using the detection coil when power is supplied to the power transmission coil. Stop,
The said control part is a non-contact power transmission apparatus which monitors temperature by the said temperature sensor, when electric power is supplied to the said power transmission coil at least.

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