Semiconductor Energy Laboratory Co., Ltd.

Misako Miwa

Shuhei Maeda

Koichiro Kamata

Yutaka Shionoiri

Kei Takahashi

A power receiving device and a power feeding system which are capable of performing communication and power feeding at the same time are provided. Further, a power receiving device and a power feeding system which are capable of stably performing communication during power feeding are provided. One embodiment of the present invention relates to a power receiving device which includes an antenna for communication and power feeding that receives AC power, a rectifier circuit that rectifies the received AC power including the modulation signal into DC power, a smoothing circuit that smoothes the resulting DC power, a power storage device that stores the smoothed DC power, a communication control unit that analyzes the modulation signal included in the AC power, and a transformer that is positioned between the antenna and the rectifier circuit and changes a reference potential of the AC power, and a power feeding device.

Power receiving device and power feeding system

A circuit capable of keeping input impedance constant is provided. Further, a circuit which can contribute to improvement in power feeding efficiency in power feeding by a magnetic resonance method is provided. A voltage (a former voltage) proportional to a direct-current voltage input to a DC-DC converter from the outside and a voltage (a latter voltage) proportional to a current input from the outside are detected, and the ratio of the former voltage and the latter voltage are held constant. Accordingly, input impedance can be kept constant. Further, impedance conversion is performed in the DC-DC converter. Thus, even when the battery in which power feeding is performed exists on an output side of the DC-DC converter, input impedance can be kept constant. Consequently, power can be supplied to a power receiving device including the DC-DC converter and the battery with high power feeding efficiency by a magnetic resonance method.

DC-DC converter, power receiving device, and power feeding system

Provided is a power transmitting device, a power feeding system, and a power feeding method in which power loss is cut by increasing power use efficiency and power can be supplied to a power feeding user (a power receiving device) with high power transmission efficiency. Depending on a power feeding state (e.g., resonant frequency of a power transmitting resonance coil is not the same as that of a power receiving resonance coil, or the influence of their positional relation), power transmitted from a power source portion of the power transmitting device is reflected to the power transmitting coil side by the power transmitting resonance coil. Further, a power recovering function (circulation function) for power reflected to the power transmitting device is provided to recover the power reflected to the power transmitting coil side and to reuse it for power transmission.

Power transmitting device, power feeding system, and power feeding method

The invented power feeding system includes power transmitting and power receiving devices. The power transmitting device includes an AC power source, a first electromagnetic induction coil, a first resonant coil, and a first capacitor. The power receiving device includes an antenna unit including a second resonant coil, a second capacitor, and a second electromagnetic induction coil; a charging circuit unit including a rectifier circuit, a power storage device, a current detection circuit for detecting a current value supplied to the power storage device, and a voltage detection circuit for detecting a voltage value applied to the power storage device; and a communication control unit including a control circuit for generating a selection signal based on the detected current value and the detected current voltage, a plurality of switches to be turned on or off by the selection signal, and passive elements electrically connected to the plurality of switches.

Provided is a power reception device in which power consumption at the time of wireless power supply is reduced. A power reception device is provided with a power reception control device capable of temporarily stopping supply of power supply voltage to a communication control unit for controlling communication in a break period of communication intermittently performed between a power transmission device and a power reception device. In the structure, a clock signal is generated on the basis of a power receiving signal transmitted from the power transmission device, and a period of communication intermittently performed can be measured using the clock signal. Further, a structure may be employed in which supply of power supply voltage to the communication unit in the power reception control device can be stopped in the break period of the communication.

Power reception control device, power reception device, power transmission and reception system, and electronic device

There is provided a power transmission device which includes an antenna receiving a reflected power from a power receiving device, a power detection unit detecting a value of the reflected power received by the antenna, a control circuit determining a power adjustment value in accordance with the value of the reflected power, a power adjustment unit to which the reflected power whose value is detected is input and which adjusts impedance in accordance with the power adjustment value determined by the control circuit, and a demodulation circuit to which the reflected power having the power adjustment value determined by the control circuit is input via the power adjustment unit having the adjusted impedance, and relates to a power feeding system including the power transmission device.

Power transmission device and power feeding system

To provide a power feeding system and the like with which charging can be performed without a decrease in the power supply efficiency. To provide a power feeding system and the like with which can offer a power feeding service which is efficient to both a power feeding user and a power feeding provider. The power transmission state in each of power transmitting portions is monitored, the power transmitting portion having the highest power transmission efficiency is selected based on positional advantage, and the power transmitting resonance coil included in the selected power transmitting portion is kept at a first resonance frequency, whereby power transmission continues. The resonance frequency of the power transmitting resonance coil included in the non-selected power transmitting portion (the number of the non-selected power transmitting portions may be plural) is set to a second resonance frequency, whereby power transmission is stopped.

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Miyagi, Japan

Misako Miwa