JP2012210034A - Power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power transmission system capable of controlling power transmission with the safety secured even if a foreign material exists between a power transmission device and a power reception device.SOLUTION: Reception power value acquisition means 12 for acquiring a reception power value is provided on a power reception device 8 side, while on a power transmission device 1 side, the following are provided: injection power value acquisition means 5 for acquiring an injection power value; reflection power value acquisition means 6 for acquiring a reflection power value; and power transmission control means 7 for performing control of stopping power transmission if a loss-power value exceeds a pre-set threshold, where the loss-power value is calculated based on the reception power value acquired by the reception power value acquisition means 12, the injection power value acquired by the injection power value acquisition means 5, and the reflection power value acquired by the reflection power value acquisition means 6.

Description

  The present invention relates to a power transmission system that transmits power through an electromagnetic field generated in space.

  In recent years, a wireless power transmission system using electromagnetic resonance has been proposed and put into practical use, which has a much higher degree of freedom in position than the electromagnetic induction method. Such a wireless power transmission system includes a power transmission device including a primary antenna that generates an electromagnetic field in a space based on an energy waveform obtained from a power transmission circuit, and two components that extract energy by receiving an action from an electromagnetic field existing in the space. Since the power receiving device including the secondary antenna is included and the power transmitting device and the power receiving device are not always in close contact with each other, there is a possibility that foreign matter is caught in the gap.

  Further, even in a conventional non-contact power feeding system configured to include a charging base (power transmission device) with a built-in primary coil and a power receiving device that performs non-contact power feeding by electromagnetic induction, between the charging base and the power receiving device. It is known that there is a possibility that foreign matter may be mixed in, and it is assumed that this foreign matter is mixed and the oscillation circuit of the charging unit is intermittently stopped to prevent the foreign matter from becoming high temperature. It is known (see, for example, Patent Document 1).

JP-A-9-233706

  However, even in the above-described conventional wireless power transmission system, if foreign matter exists in the transmission space between the power transmitting device and the power receiving device, depending on the material of the foreign matter, an induced current or a resonant current is generated in the foreign matter, which causes safety. The problem may occur. Therefore, unlike the conventional non-contact power supply system, it is desirable to perform control so as to stop the power transmission by determining the presence of foreign matter that causes heating.

  An object of the present invention is to provide a power transmission system capable of controlling power transmission while ensuring safety even when a foreign object exists between a power transmission device and a power reception device.

  In order to achieve the above object, the present invention provides a power transmission system including a power transmitting device and a power receiving device that perform non-contact power transmission using an antenna, wherein the power receiving device acquires a received power value. Means and a received power value transmission means for transmitting the received power value acquired by the received power value acquisition means to the power transmission device, the power transmission device including an incident power value acquisition means for acquiring an incident power value; The received power value receiving means for receiving the received power value transmitted from the received power value transmitting means, and the loss power is calculated based on the received power value, the incident power value, and the reflected power value acquired by each means, and the value And control means for performing control to stop power transmission when the value exceeds a certain value.

  According to the power transmission system of the present invention, when there is a foreign substance that causes heating in the transmission space between the power transmission device and the power receiving device, the power loss value when energy loss such as heating due to the inclusion of such a foreign substance occurs. From this, it is possible to detect it separately from other situations, so that it is possible to perform control to stop power transmission in an undesirable situation. Although it is conceivable to provide a temperature sensor to detect the entry of foreign matter that causes heating, if this type of foreign matter is present at a position insulated from the temperature sensor, energy loss due to the inclusion of foreign matter has occurred. However, the above-described configuration can reliably detect such a situation, and a safe and highly efficient power transmission system can be realized.

1 is a block diagram illustrating a power transmission system according to an embodiment of the present invention. It is the flowchart which showed the energy loss factor detection processing operation | movement of the electric power transmission system shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a power transmission system according to an embodiment of the present invention. The power transmission device 1 includes a power transmission circuit 2 that converts electrical energy into a waveform suitable for power transmission in space, a primary antenna 3 that generates an electromagnetic field in space based on the energy waveform obtained from the power transmission circuit 2, and a later-described antenna. The received power value receiving means 4 for receiving the received power value from the power receiving device, the incident power value acquiring means 5 for acquiring the incident power value transmitted from the power transmission circuit 2, and reflected to the power transmitting device 1 without being transmitted to the power receiving device The reflected power value acquisition means 6 for calculating the reflected power value, the received power value notified through the received power value reception means 4, the incident power value acquired by the incident power value acquisition means 5, and the reflected power value acquisition means 6 A power transmission control means 7 for providing a power transmission circuit 2 with a power transmission stop signal for stopping power transmission when the power loss calculated based on the reflected power value from the power source exceeds a predetermined constant value; It has.

  On the other hand, the power receiving device 8 disposed in the vicinity of the power transmitting device 1 receives the secondary side antenna 9 that receives an action from the electromagnetic field existing in the space and extracts the energy, and the electromagnetic energy picked up by the secondary side antenna 9. Power receiving circuit 10 for converting to a format suitable for use, functional circuit 11 using the received power in power receiving circuit 10, received power value acquiring means 12 for acquiring the received power value received by power receiving circuit 10, and the received power And a received power value transmitting unit 13 for transmitting the received power value acquired by the power value acquiring unit 12 to the received power value receiving unit 4 of the power transmission device 1.

Next, an energy loss factor detection processing operation in the case where an energy loss factor such as heating due to foreign object pinching occurs will be described using the flowchart shown in FIG.
A power receiving device 8 that receives power supply in the vicinity of the power transmitting device 1 is disposed opposite to the power transmitting device 1, and antennas 14 and 15 indicate between the received power value receiving unit 4 of the power transmitting device 1 and the received power value transmitting unit 13 of the power receiving device 8. When the power transmission request signal is transmitted from the received power value transmission unit 13 of the power receiving device 8 to the power transmission device 1 by wireless communication, the power transmission control unit 7 of the power transmission device 1 passes through the received power value reception unit 4 in step S1. This is received, and power transmission from the power transmission circuit 2 of the power transmission device 1 to the power reception device 8 through the primary antenna 3 is started in step S2.

  Then, the power receiving circuit 10 of the power receiving device 8 receives this through the secondary antenna 9 in step S3. At this time, the received power value acquisition unit 12 that monitors the power reception circuit 10 acquires the received power value through the power reception circuit 10 in step S4, and transmits the acquired received power value to the power transmission device 1 through the received power value transmission unit 13. Notice.

  In the power transmission device 1, the power transmission control unit 7 receives the received power value notified from the received power value transmission unit 13 through the received power value reception unit 4 in step S5. In response to this, or in step S6 before and after that, the incident power value acquisition means 5 of the power transmission device 1 acquires the incident power value of the transmission power through the power transmission circuit 2, and the reflected power value acquisition means 6 receives the power reception device 8. The reflected power value reflected to the power transmission device 1 without being transmitted is acquired. The power transmission control unit 7 receives the received power value received from the power receiving device 8 through the received power value receiving unit 4, the reflected power value acquired from the reflected power value acquisition unit 6, and the incident power value acquired from the incident power value acquisition unit 5. Is used to calculate the total loss power α shown in the following Equation 1.

[Equation 1]
Total power loss α = incident power value-(reflected power value + received power value)

  Further, the sum of the inherent known loss power determined by the internal circuits of the power transmitting device 1 and the power receiving device 8 is set as the in-system loss power β, and the outside power loss γ is calculated by the following formula 2.

[Equation 2]
γ = α-β

  Here, when the power loss γ outside the system does not become zero, it can be determined that some energy loss factor, for example, heating due to the inclusion of foreign matter, etc. has occurred outside the system, but a measurement error is included. Since there is a possibility, the power transmission control means 7 performs the determination process using the threshold value in step S7. For example, the time integral value (energy value consumed outside) γt of the power loss γ outside the system is compared with a preset value, and if the time integral value γt is equal to or less than that value, power is received from the power transmitting device 1 in step S8. Although it is determined that power transmission to the device 8 is continued, if the time integration value γt exceeds a certain value, it is determined in step S9 that power transmission needs to be stopped due to the occurrence of an energy loss factor, and a power transmission stop signal is transmitted. 2 to stop power transmission. The determination using the constant value in the power transmission control means 7 here is not limited to the method described above, and other methods may be used.

  In the process of continuing power transmission in step S8, the processes of steps S4 to S7 are executed at a predetermined cycle. Then, although not shown in the flowchart of FIG. 2, when the power receiving device 8 transmits a power transmission end notification from the received power value transmitting unit 13 and the power receiving power value receiving unit 4 of the power transmitting device 1 receives the power transmission end notification, The power transmission control unit 7 stops power transmission to the power receiving device 8. However, in the present invention, while the power receiving device 8 transmits the power transmission request signal from the received power value transmission unit 13 at regular intervals, and the power transmission device 1 receives the power transmission signal from the power reception value receiving unit 4 at regular intervals. May be configured to transmit power. In this case, the power transmission control unit 7 stops power transmission to the power receiving device 8 if the power transmission request signal cannot be received for a predetermined interval or more during the process of step S8.

  According to the power transmission system described above, based on the received power value acquired by the received power value acquisition unit 12, the incident power value acquired by the incident power value acquisition unit 5, and the reflected power value acquired by the reflected power value acquisition unit 6. The power transmission control means 7 that performs control to stop power transmission when the calculated power loss value exceeds a preset threshold value causes the transmission space between the power transmission device 1 and the power reception device 8 to be heated. When there is a foreign object, it can be detected by distinguishing it from other situations based on the power loss when energy loss such as heating occurs due to the inclusion of that type of foreign object. It is possible to perform control. In addition, it is conceivable to provide a temperature sensor to detect the entry of foreign matter that causes heating. However, if this type of foreign matter is present at a position insulated from the temperature sensor, energy loss due to the inclusion of the foreign matter has occurred. However, it cannot be detected. However, with the above-described configuration, even in such a situation can be reliably detected, and a safe and highly efficient power transmission system can be realized.

  In order to obtain such an effect, in a power transmission system according to a more specific embodiment, a power transmission circuit 2 that converts electric energy into a waveform suitable for power transmission in space, and an energy waveform obtained from the power transmission circuit 2 Based on the power transmission device 3 including the primary antenna 3 that generates an electromagnetic field in the space, the secondary antenna 9 that extracts the energy by receiving the action from the electromagnetic field existing in the space, and the secondary antenna 9 picks up the energy. In a power transmission system including a power receiving device 8 including a power receiving circuit 10 that converts electromagnetic energy into a format suitable for use, and means for communicating information between the power transmitting device 1 and the power receiving device 8. The received power value acquisition means 12 for acquiring the received power value on the power receiving device 8 side and the incident power value on the power transmission device 1 side are acquired. Incident power value acquisition means 5, reflected power value acquisition means 6 for acquiring the reflected power value on the power transmission device 1 side, received power value acquired by the received power value acquisition means 12, and incident power value acquisition means 5 Loss power is calculated based on the acquired incident power value and the reflected power value acquired by the reflected power value acquisition unit 6, and transmission is performed when the calculated loss power value exceeds a preset value. A power transmission control means 7 that performs control to stop is preferably provided.

  The power transmission system of the present invention is not limited to the configuration shown in FIG. 1 and can be applied to other configurations. For example, since the above-described power transmission system is intended for non-contact power transmission, the received power value receiving means 4 of the power transmitting device 1 and the received power value transmitting means 13 of the power receiving device 8 are connected by wireless communication. However, it does not hinder the wired connection between the received power value receiving means 4 and the received power value transmitting means 13.

DESCRIPTION OF SYMBOLS 1 Power transmission device 2 Power transmission circuit 3 Primary side antenna 4 Received power value reception means 5 Incident power value acquisition means 6 Reflected power value acquisition means 7 Power transmission control means 8 Power reception device 9 Secondary side antenna 10 Power reception circuit 11 Functional circuit 12 Received power acquisition Means 13 Received power value transmission means 14, 15 Antenna

Claims (1)

  In a power transmission system including a power transmitting device and a power receiving device that perform non-contact power transmission using an antenna, the power receiving device is acquired by a received power value acquiring unit that acquires a received power value, and the received power value acquiring unit Receiving power value transmitting means for transmitting the received power value to the power transmitting device, the power transmitting device receiving incident power value acquiring means for acquiring an incident power value, and receiving power transmitted from the received power value transmitting means. Received power value receiving means for receiving the value, and calculating the loss power based on the received power value, the incident power value, and the reflected power value acquired by each means, and transmitting the power if the value exceeds a certain value And a control means for performing control to stop the power transmission system.

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