Wireless power transmission system

A wireless power transmission system which works to supply electric power wirelessly from a power transmitter to a power receiver, comprising:

• a power transmitter which includes a primary resonant circuit and an alternating-current source, the primary resonant circuit including a primary coil and a primary capacitor for use in power transmission, the alternating-current source working to apply ac power at a given operating frequency to the primary resonant circuit;
• a power receiver which includes a secondary resonant circuit, the secondary resonant circuit including a secondary coil and a secondary capacitor for use in a power reception, the secondary coil being to be magnetically coupled with the primary coil;
• and
• a tertiary resonant circuit which includes a tertiary coil and a tertiary capacitor, the tertiary coil being arranged to achieve magnetic coupling with the primary coil and the secondary coil, the tertiary capacitor constituting a short-circuit resonant circuit along with the tertiary coil,
• the primary coil has a self-inductance L1, a capacitance of the primary capacitor is set to a capacitance C1, as given by Eq. (1) below, to cause resonance in the primary capacitor and the primary coil at an angular frequency ω0 that is the operating frequency,
• C
• ⁢
• 1
• =
• 1
• ω
• ⁢
• o
• 2
• ·
• L
• ⁢
• 1
• (
• 1
• )
• the tertiary coil has a self-inductance L3, a capacitance of the tertiary capacitor is set to a capacitance C3, as given by Eq. (2) below, to cause resonance in the tertiary capacitor and the tertiary coil at the operating frequency,
• C
• ⁢
• 3
• =
• 1
• ω
• ⁢
• o
• 2
• ·
• L
• ⁢
• 3
• (
• 2
• )
• a capacitance of the secondary capacitor is determined to decrease a reactive component of the ac power which arises from the self-inductances and mutual inductances of the primary coil, the secondary coil, and the tertiary coil.