Wireless power transmission apparatus and relative position detection method

摘要

PROBLEM TO BE SOLVED: To reduce standby electric power without spoiling convenience of a wireless power transmission system.SOLUTION: A wireless power transmission system includes: a primary coil 15 which supplies electric power to a secondary coil 31 by electromagnetic induction; an excitation coil 18 which excites the secondary coil 31; a plurality of detection coils 21-24 which detect an AC magnetic field generated by the excited secondary coil 31; and a detection circuit 25 which selectively outputs all or any of detection signals Vs1-Vs4 excited by the plurality of detection coils 21-24. A period at which the secondary coil 31 is excited when the detection circuit 25 outputs all the detection signals Vs1-Vs4 to the control circuit 16 is set to be longer than a period at which the secondary coil 31 is excited when the detection circuit 25 outputs any of the detection signals Vs1-Vs4 to the control circuit 16 one after another.