Wireless power transmitting device and wireless power transmission system using the same

A wireless power transmission system comprising:

• a wireless power transmitting device;
• and
• a wireless power receiving device that receives power from the wireless power transmitting device by wireless,
• wherein the wireless power transmitting device comprising:
• a boost converter that boosts an input DC voltage;
• an inverter that converts an output voltage of the boost converter into an AC voltage;
• a power transmitting coil that is supplied with the AC voltage to generate an AC magnetic field;
• a receiving circuit that receives a power transmission command signal from the wireless power receiving device;
• a boost control circuit that controls a boost level of the boost converter according to the power transmission command signal;
• an operation detection circuit that detects whether or not the boost converter is operated;
• and
• an inverter control circuit that controls the inverter,
• wherein the operation detection circuit activates a stop signal when detecting that the boost converter does not perform operation after an elapse of a predetermined time period from a start of power transmission,
• wherein the inverter control circuit stops an operation of the inverter in response to the stop signal,
• wherein the wireless power receiving device includes:
• a power receiving coil that takes in AC power through the AC magnetic field;
• a rectifying circuit that converts the AC power received by the power receiving coil into DC power;
• an output detection circuit that generates the power transmission command signal based on a comparison result between an output characteristic value of the rectifying circuit and a target value;
• a transmitting circuit that transmits the power transmission command signal;
• and
• a start-up circuit that permits transmission of the power transmission command signal to the receiving circuit when the output characteristic value of the rectifying circuit is equal to or larger than a threshold value.