The present invention suppresses leakage magnetic field. A power transfer coil configured to transmit or receive power includes: an inner coil; a first outer coil formed so as to surround the inner coil such that a magnetic flux opposite in phase to a magnetic flux outside the inner coil is generated outside the first outer coil, the first outer coil having one end connected to a first terminal and the other end connected to one end of the inner coil; and a second outer coil formed so as to surround the inner coil such that a magnetic flux opposite in phase to the magnetic flux outside the inner coil is generated outside the second outer coil, the second outer coil having one end connected to a second terminal and the other end connected to the other end of the inner coil.

A vehicle is provided that comprises two or more radio frequency (RF) antennas and two or more RF transceivers to communicate wirelessly sensitive information associated with a user of the vehicle (the two or more RF antennas being at different physical locations on an exterior of the vehicle). The vehicle determines which one of the two or more RF antennas is receiving a strongest signal from a common signal source, selects a first RF transceiver associated with the RF antenna with the strongest signal to send the sensitive information associated with the user to the common signal source, and sends the sensitive information associated with the user to the first RF transceiver for transmission to the common signal source.

A system for ground power supply of aircraft includes at least one mobile transformer unit having a first vehicle chassis and a voltage transformer mounted on the first vehicle chassis; at least two energy stores which can be alternately connected to an input of the voltage transformer in order to supply the voltage transformer with electric energy; and a supply cable for ground power supply of one of the aircraft. The supply cable is configured to be connected to an output of the voltage transformer. Each of the at least two energy stores is part of one of at least two mobile storage units each including a second vehicle chassis. The first vehicle chassis of the transformer unit and each of the second vehicle chassis of the at least two mobile storage units are moveable on the ground independently on each other.

A power transmitting device includes a power transmitting coil for providing output power to a power receiving coil, a thermal sensor that detects a temperature around the power transmitting coil, and a power transmission control circuit that controls the power transmitting device. The power transmission control circuit causes the power transmitting coil to provide first output power, the power transmitting coil to provide second output power to the power receiving coil for charging a battery connected to the power receiving coil, the thermal sensor to detect the temperature around the power transmitting coil, and, if the detected temperature is equal to or higher than a threshold because of existing a metal foreign object, the power transmitting coil to reduce a level of the output power or stop the output power. The level of the first output power is lower than the level of the second output power

A power transmitting device includes a power transmitting coil for providing output power to a power receiving coil, a thermal sensor that detects a temperature around the power transmitting coil, and a power transmission control circuit that controls the power transmitting device. The power transmission control circuit causes the power transmitting coil to provide first output power, the power transmitting coil to provide second output power to the power receiving coil for charging a battery connected to the power receiving coil, the thermal sensor to detect the temperature around the power transmitting coil, and, if the detected temperature is equal to or higher than a threshold because of existing a metal foreign object, the power transmitting coil to reduce a level of the output power or stop the output power. The level of the first output power is lower than the level of the second output power

A non-contact power supply device includes an inverter to convert power supplied from a power supply into a predetermined AC power, feeders provided on a track rail to transmit the AC power to a ceiling conveyor, a filter circuit including a reactor and a capacitor, and a controller configured or programmed to perform power control of the AC power that is to be supplied to the feeders. The controller is configured or programmed to obtain a current value output from the inverter while changing a switching frequency of switches of the inverter in a state in which a current having a predetermined value flows through the feeders, and to set and output a reactor value of the reactor and a capacitance value of the capacitor based on the switching frequency at which the current value is minimum.

A non-contact power supply device includes an inverter to convert power supplied from a power supply into a predetermined AC power, feeders provided on a track rail to transmit the AC power to a ceiling conveyor, a filter circuit including a reactor and a capacitor, and a controller configured or programmed to perform power control of the AC power that is to be supplied to the feeders. The controller is configured or programmed to obtain a current value output from the inverter while changing a switching frequency of switches of the inverter in a state in which a current having a predetermined value flows through the feeders, and to set and output a reactor value of the reactor and a capacitance value of the capacitor based on the switching frequency at which the current value is minimum.

Provided is an electric work machine powerable by an external power supply through a power supply cable. The electric work machine includes a machine body including an electric motor, a power receiving device supplied with power through the power feed cable, connection wires extending from the power receiving device, a power feed cable connected to the machine body and a connection unit. The connection unit is disposed outside the power receiving device and connects the power feed cable and the connection wires to each other.

Provided is an electric work machine powerable by an external power supply through a power supply cable. The electric work machine includes a machine body including an electric motor, a power receiving device supplied with power through the power feed cable, connection wires extending from the power receiving device, a power feed cable connected to the machine body and a connection unit. The connection unit is disposed outside the power receiving device and connects the power feed cable and the connection wires to each other.

A wireless power transfer system 1 includes a power transmission device 2 and a power reception device 3. The power transmission device 2 is a power transmission device 2 installed in a road 4, is provided with a power transmission coil 21 that transmits power wirelessly, and is configured such that when installed in the road 4, the normal line of a coil plane of the power transmission coil 21 is inclined with respect to the normal line of the road surface of the road 4 in a lateral cross section of the road 4. The power reception device 3 is provided with a power reception coil 31 that receives power wirelessly, and at least a portion of the power reception coil 31 is housed in the wheel 6 of the moving body 5.