Wireless power transmission system, power transmission device and power reception device

A power transmission device that wirelessly transmits power to a power reception device that supplies received power to a battery, comprising:

• an AC power source configured to generate an AC voltage;
• a power transmission resonator configured to generate a magnetic field that couples with the power reception device according to the AC voltage;
• and
• a first circuit disposed between the AC voltage source and the power transmission resonator;
• the first circuit comprising at least one passive element,
• wherein a parameter value of the at least one passive element in the first circuit are set so that an absolute value of an inverse transfer function between an input voltage and an output voltage of a target system at a frequency of the AC voltage is equal to or less than a divided value of the AC voltage by a battery voltage during a period of time when the AC voltage is increased from a first voltage value to a second voltage value, the target system comprising the first circuit, the power transmission resonator and the power reception device.

A power reception device that wirelessly receives power from a power transmission device, comprising:

• a power reception resonator configured to receive AC power from a power transmission resonator of the power transmission device via magnetic field coupling;
• an AC/DC converter configured to convert the AC power to DC power and supply the DC power to a battery;
• and
• a first circuit disposed between the power reception resonator and the AC/DC converter, the first circuit comprising at least one passive element,
• wherein a parameter value of the passive element in the first circuit is set so that an absolute value of an inverse transfer function between an input voltage and an output voltage of a target system at a frequency of the AC voltage is equal to or less than a divided value of the AC voltage by a battery voltage during a period of time when the AC voltage is increased from a first voltage value to a second voltage value, the target system comprising the power transmission resonator, the power reception resonator and the AC/DC converter,