To provide a power transmission system that can inform a conversion in a battery charging mode from a power-receiving side system to a power-transmitting side system.
A power transmission system in which electric energy is transmitted via an electromagnetic field comprises: an inverter part 130 for converting a DC voltage to an AC voltage in a prescribed frequency to output the AC voltage; a power-transmitting side control part 150 for controlling electric power; a power transmission antenna 140 to which the AC voltage from the inverter part 130 is input; a power-receiving side rectification part 220 for rectifying output from the power receiving antenna 210 into a DC voltage to output the DC voltage; a power-receiving side voltage step-up/step-down part 230; a battery 240; a power-receiving side control part 250; and a voltage detection part for detecting the voltage of the battery 240. When the voltage detection part exceeds a prescribed voltage, the power-receiving side control part 250 increases input resistance of the power-receiving side voltage step-up/step-down part 230, the input resistance being the resistance viewed from the power-receiving side rectification part 220.
YAMAKAWA HIROYUKI
ITO YASUO
Takashi Koyama
Yoshiaki Minami
Hideo Sugai
Kenji Aoki
Hiroshi Nagisawa
Akira Yonezawa
Takehiko Katayose