WIRELESS CHARGING SYSTEM AND WIRELESS POWER TRANSMITTING DEVICE

A wireless power transmitting device comprises a first coil structure and a control circuit. The first coil structure comprises a first circuit board and a plurality of turns of a coil conductor arranged on the first circuit board. The coil conductor comprises at least one first capacitor structure. Linear distance between the first capacitor structure and an output terminal of the coil conductor is shorter than the linear distance between the first capacitor structure and an input terminal of the coil conductor. Position of the first capacitor structure does not overlap with position of the output terminal. The control circuit measures the first coil structure to determine a power transfer value and determine whether a foreign object has entered a power transmission range between the wireless power transmitting device and the receiving device according to the power transfer value.