Energy receiving device, energy transmitting device, detection device, and detection method

The invention provides an energy receiving device, an energy transmitting device, a detection device, and a detection method. The energy receiving device comprises a power receiving coil for receiving power from the energy transmitting device, an energy storage element for storing the power received from the energy transmitting device after receiving a command about foreign matter detection, a storage for storing a Q-value threshold value which will compare with a calculated Q value, and a control unit for supplying the received power to a load connected with the energy receiving device when receiving a charge command from the energy transmitting device, wherein the charge command is released after a result of the foreign matter detection shows that there is no foreign matter.