A wireless power transmitter configured to transfer power to a wireless power receiver including primary coils comprising first and second bottom coils placed adjacent to each other in a line and each consisting of a single layer of 11 turns and a top coil stacked on the first and second bottom coils and consisting of a single layer of 12 turns; a shielding; and a full-bridge inverter, wherein the first and second bottom coils and the top coil have a substantially rectangular frame structure with a through hole in the center, wherein the top coil lies on a plane surface in the middle between the first and second bottom coils, wherein a distance from the center of the first and second bottom coils to the center of the top coil is set to a range of 21 mm to 25 mm, wherein the first and second bottom coils have a height of 48 mm to 50 mm and a width of 43 mm to 45 mm, and the through hole in the first and second bottom coils has a height of 25 mm to 27 mm and a width of 21 mm to 23 mm, wherein the top coil has a height of 45 mm to 47 mm and a width of 48.5 mm to 50.5 mm, and the through hole in the top coil has a height of 20 mm to 22 mm and a width of 24.5 mm to 26.5 mm, wherein the first and second bottom coils and the top coil have a thickness of 0.9 mm to 1.3 mm, wherein an amount of power which is transferred is controlled based on an input voltage of the full-bridge inverter, wherein the input voltage has a range of 1 V to 18 V, wherein an operating frequency to control the amount of the power is within a range of 140 kHz to 150 kHz, wherein an assembly of the primary coils and the shielding has a self-inductance value of 11.3 .Math.H, wherein the full-bridge invertor drives a series capacitance, and wherein a value of the series capacitance is 139 nF.

A wireless power transmitter configured to transfer power to a wireless power receiver including primary coils comprising first and second bottom coils placed adjacent to each other in a line and each consisting of a single layer of 11 turns and a top coil stacked on the first and second bottom coils and consisting of a single layer of 12 turns; a shielding; and a full-bridge inverter, wherein the first and second bottom coils and the top coil have a substantially rectangular frame structure with a through hole in the center, wherein the top coil lies on a plane surface in the middle between the first and second bottom coils, wherein a distance from the center of the first and second bottom coils to the center of the top coil is set to a range of 21 mm to 25 mm, wherein the first and second bottom coils have a height of 48 mm to 50 mm and a width of 43 mm to 45 mm, and the through hole in the first and second bottom coils has a height of 25 mm to 27 mm and a width of 21 mm to 23 mm, wherein the top coil has a height of 45 mm to 47 mm and a width of 48.5 mm to 50.5 mm, and the through hole in the top coil has a height of 20 mm to 22 mm and a width of 24.5 mm to 26.5 mm, wherein the first and second bottom coils and the top coil have a thickness of 0.9 mm to 1.3 mm, wherein an amount of power which is transferred is controlled based on an input voltage of the full-bridge inverter, wherein the input voltage has a range of 1 V to 18 V, wherein an operating frequency to control the amount of the power is within a range of 140 kHz to 150 kHz, wherein an assembly of the primary coils and the shielding has a self-inductance value of 11.3 .Math.H, wherein the full-bridge invertor drives a series capacitance, and wherein a value of the series capacitance is 139 nF.

A chargeability determining method, including before start of transmitting first electric power to a mobile object, wirelessly supplying second electric power to a charging space, detecting whether temperature in the charging space increases after the second electric power is transmitted, and before start of transmitting the first electric power, determining chargeability of the mobile object based on presence information and foreign object information. The presence information indicating whether a charging object is present in the charging space, and the foreign object information indicating whether the temperature in the charging space increases.

A chargeability determining method, including before start of transmitting first electric power to a mobile object, wirelessly supplying second electric power to a charging space, detecting whether temperature in the charging space increases after the second electric power is transmitted, and before start of transmitting the first electric power, determining chargeability of the mobile object based on presence information and foreign object information. The presence information indicating whether a charging object is present in the charging space, and the foreign object information indicating whether the temperature in the charging space increases.

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

In an embodiment, an apparatus for charging an electric vehicle, can include a receptacle mountable to a structure above the electric vehicle. The receptacle can maintain a charge transmitting device, which can be automatically moveable and directable from the receptacle toward a target area on the electric vehicle associated with a receiving coil mounted on the electric vehicle for the charging of an electric vehicle when the one receiving coil engages with the charge transmitting device when the electric vehicle is located below the receptacle. One or more optical sensors can be utilized to direct the charge transmitting device toward the target.

Systems and methods are described for an extended-range positioning system based on foreign-object detection (FOD). In particular, a power-transfer apparatus is disclosed that includes a coil and a foreign-object-detection (FOD) system. The coil is configured to generate a magnetic field based on an electric current running through the coil for transferring power to a receiver device. the FOD system includes a plurality of FOD sense loops, FOD circuitry, and active-beacon receive circuitry. The FOD sense loops detect metal objects within the magnetic field based on changes to an electrical characteristic(s) of one or more of the FOD sense loops. The FOD circuitry processes a modulation pattern of the electrical characteristic(s) of the one or more FOD sense loops and provides first positioning information. The active-beacon receive circuitry processes induced voltage in at least two sense loops to provide second positioning information.

Systems and methods are described for an extended-range positioning system based on foreign-object detection (FOD). In particular, a power-transfer apparatus is disclosed that includes a coil and a foreign-object-detection (FOD) system. The coil is configured to generate a magnetic field based on an electric current running through the coil for transferring power to a receiver device. the FOD system includes a plurality of FOD sense loops, FOD circuitry, and active-beacon receive circuitry. The FOD sense loops detect metal objects within the magnetic field based on changes to an electrical characteristic(s) of one or more of the FOD sense loops. The FOD circuitry processes a modulation pattern of the electrical characteristic(s) of the one or more FOD sense loops and provides first positioning information. The active-beacon receive circuitry processes induced voltage in at least two sense loops to provide second positioning information.

A power feed system includes a power feed mat. The power feed mat includes a plurality of power transmission coils. The power feed mat is configured to feed power to at least one movable body on the power feed mat by using at least one of the plurality of power transmission coils. The power feed system further includes a computer. When the computer restricts power feed to at least one movable body among a plurality of movable bodies on the power feed mat, the computer selects the at least one movable body power feed to which is to be restricted, based on a priority of each of the plurality of movable bodies.