JP-7854853-B2 - Power transmission equipment, power transmission system, and power transmission method

Inventors

• 木下 岳
• 東 純史
• 内野 直孝

Assignees

• 古河電気工業株式会社

Dates

Publication Date

20260507

Application Date

20220520

Priority Date

20210521

Claims (17)

1. A power supply unit that supplies first power to the power transmission unit, The power transmission unit wirelessly transmits the power supplied from the power supply unit to the power receiving device, A power transmission device comprising: a processing unit that determines that a charger operating with power received by the power receiving device is performing constant voltage charging when the slope of a graph showing the time change of a second power, which is reflected by a circuit downstream of the power supply unit from the first power, is positive and the graph is convex upwards; and
2. The power transmission device according to claim 1, wherein the processing unit determines that the charger is performing constant voltage charging when the slope of the graph is positive and the graph remains convex upward for a predetermined period of time or longer.
3. The power transmission device according to claim 1, wherein the processing unit determines that the charger is performing constant voltage charging, calculates the estimated time until charging by the charger is completed, and stops transmitting power by the power transmission unit once the estimated time has elapsed.
4. The power transmission device according to claim 1, wherein the processing unit causes the power supply unit to supply a third power less than the first power, and when the ratio of the third power to the fourth power (which is the third power reflected by the circuit downstream of the power supply unit) falls below a predetermined threshold, the processing unit causes the power supply unit to start supplying the first power.
5. The power transmission device according to claim 4, wherein the processing unit, upon receiving a signal from a sensor that detects the power receiving device being in a predetermined position, initiates the supply of the third power to the power supply unit.
6. The power transmission device according to claim 1, wherein the processing unit, upon receiving a signal from a sensor that detects the power receiving device being in a predetermined position, initiates the supply of the first power to the power supply unit.
7. The power transmission device according to claim 1, further comprising a sensor for detecting when the power receiving device is in a predetermined position and when the power receiving device has moved away from the predetermined position.
8. The power transmission device according to any one of claims 5 to 7, wherein the sensor has a shape or structure corresponding to the shape of the power receiving device.
9. The power transmission device according to claim 1, wherein the processing unit stops transmitting power by the power transmission unit when the ratio of the second power to the first power falls outside a predetermined range.
10. The power transmission device according to claim 1, wherein the processing unit stops the transmission of power by the power transmission unit when the first power is at an abnormal value.
11. The power transmission device according to claim 1, wherein the processing unit stops the transmission of power by the power transmission unit when the second power is at an abnormal value.
12. Including power transmission equipment and power receiving equipment, The aforementioned power transmission device is A power supply unit that supplies first power to the power transmission unit, The power transmission unit wirelessly transmits the power supplied from the power supply unit to the power receiving device, The power receiving device comprises a processing unit which determines that a charger operating with power received by the power receiving device is performing constant voltage charging when the slope of a graph showing the time change of a second power, which is reflected by the circuit downstream of the power supply unit from the first power, is positive and the graph is convex upwards, and the power receiving device A power receiving unit that receives power from the aforementioned power transmission unit, A power transmission system comprising: a supply unit that supplies power received by the power receiving unit to the charger.
13. The aforementioned processing unit, The power supply unit is instructed to supply a third power less than the first power, and when the ratio of the third power to the fourth power reflected by the circuit downstream of the power supply unit falls below a predetermined threshold, the power supply unit is instructed to start supplying the first power. The power transmission system according to claim 12, wherein if it is determined that the charger is performing constant voltage charging, the estimated time until charging by the charger is completed is determined, and if the estimated time has elapsed, the power transmission unit stops transmitting power.
14. The power transmission system according to claim 12 or 13, wherein the processing unit, upon receiving a signal from a sensor that detects the power receiving device being in a predetermined position, causes the power supply unit to begin supplying the first power or a third power less than the first power.
15. The first power is supplied to the power transmission section. The power supplied to the power transmission unit is transmitted wirelessly from the power transmission unit to the power receiving device. A power transmission method in which, if the slope of a graph showing the time change of a second power, which is reflected by a circuit downstream of the power supply unit from the first power, is positive and the graph is convex upward, it is determined that a charger operating with power received by the power receiving device is performing constant voltage charging.
16. A third power less than the first power is supplied to the power transmission unit, and when the ratio of the fourth power, which is the third power reflected by the circuit downstream of the power supply unit, to the third power falls below a predetermined threshold, the supply of the first power is started. The power transmission method according to claim 15, wherein if it is determined that the charger is performing constant voltage charging, the estimated time until charging by the charger is completed is determined, and if the estimated time has elapsed, the power transmission is stopped.
17. The power transmission method according to claim 15 or claim 16, wherein when the power receiving device detects that it is in a predetermined position, the supply of the first power or a third power less than the first power is started.

Description

This invention relates to a power transmission device, a power transmission system, and a power transmission method. There is a technology called wireless power transmission that transmits power wirelessly from a power transmission device to a power reception device. The power reception device may have a charging function to charge a secondary battery. In this case, once charging is complete, the power transmission device should stop supplying power to the power reception device to prevent overcharging and reduce power consumption. Therefore, conventional power reception devices are equipped with communication means to notify the power transmission device that charging is complete. Similarly, conventional power transmission devices are equipped with communication means to receive notifications from the power reception device. However, incorporating communication means into both the power reception and power transmission devices leads to increased costs and larger device sizes. The power reception side includes the power reception device and devices that operate on the power supplied by the power reception device. Patent Document 1 discloses a method for a power transmission device to detect the completion of charging without communicating with a power receiving device. Japanese Patent Publication No. 2013-70581 A diagram showing an overview of the power transmission system according to the first embodiment.Figure 1 shows a power transmission system and a block diagram illustrating an example of the main circuit configuration of the components included in the power transmission system.A flowchart showing an example of processing by the processor of the power transmission device in Figure 2 according to the first embodiment.A diagram showing an example of the waveform of the output power (forward wave) of the power supply according to the first embodiment.A diagram showing various waveforms when a charger is charging a battery.A diagram showing various waveforms when a charger is charging a battery.A diagram showing an overview of the power transmission system according to the third embodiment.Figure 7 is a block diagram showing an example of the circuit configuration of the main components of the power transmission system and its constituent elements.A flowchart showing an example of processing by the processor of the power transmission device in Figure 8 according to the first embodiment.A diagram showing various waveforms when a misalignment occurs in the power receiving coupler. The following describes several embodiments of power transmission systems with reference to the drawings. Note that the scale of the parts in the drawings used in the following descriptions of embodiments may be appropriately changed. Also, for illustrative purposes, some components may be omitted in the drawings used in the following descriptions of embodiments. Furthermore, in the drawings and this specification, the same reference numerals indicate the same elements. [First Embodiment] The configuration of the power transmission system 1 according to the first embodiment will be described using Figures 1 and 2. Figure 1 is a diagram showing an overview of the power transmission system 1 according to the first embodiment. Figure 2 is a block diagram showing an example of the main circuit configuration of the power transmission system 1 and the components included in the power transmission system 1 according to the first embodiment. The power transmission system 1 is a system that wirelessly transmits power from a power transmission device 100 to a power receiving device 210. The power transmission system 1 includes, as an example, a power transmission device 100 and a cart 200. The power transmission device 100 is a device that wirelessly transmits power to the power receiving device 210 of the cart 200. The power transmission device 100 is fixed to the ground G, for example, the floor. Alternatively, the power transmission device 100 may be embedded beneath the ground G. The power transmission device 100 may also be located above the ground G. As an example, the power transmission device 100 includes a power transmission coupler 110, a power supply 120, a control unit 130, and a power detection unit 140. The power transmission coupler 110 wirelessly transmits power to the power receiving coupler 211 of the power receiving device 210. The method of power transmission from the power transmission coupler 110 to the power receiving coupler 211 may be, for example, electric field coupling, magnetic field coupling, or other power transmission methods. Alternatively, the power transmission method from the power transmission coupler 110 to the power receiving coupler 211 may be electric field resonance, a type of electric field coupling. Furthermore, the power transmission method from the power transmission coupler 110 to the power receiving coupler 211 may be magnetic field resonance, a type of magnetic field coupling. The power trans