Wireless power transfer system and wireless power transfer method

A wireless power transfer method comprising:

• setting a first transmitter coil, a second transmitter coil, and a third transmitter coil such that normal directions to planes of the first, the second and the third transmitter coils are orthogonal to each other in a three-dimensional space;
• placing a power receiver in the three-dimensional space formed by the first transmitter coil, the second transmitter coil, and the third transmitter coil;
• and
• controlling electric currents supplied to the first transmitter coil, the second transmitter coil and the third transmitter coil such that a synthetic magnetic field vector produced by the first transmitter coil, the second transmitter coil and the third transmitter coil rotates in a plane of rotation at a first angular frequency “ω”, and that a normal vector to the plane of rotation rotates about an axis of rotation perpendicular to the normal vector at a second angular frequency “a” equal to or smaller than the first angular frequency,
• wherein the controller controls a first power source connected to the first transmitter coil to modulate a non-oscillating magnitude (H0) of a magnetic field vector with −sin(at)*cos(ωt), controls a second power source connected to the second transmitter coil to modulate the non-oscillating magnitude (H0) of the magnetic field vector with cos(at)*cos(ωt), and controls a third power source connected to the third transmitter coil to modulate the non-oscillating magnitude (H0) of the magnetic field vector with α*sin(ωt), and wherein a point of the synthetic magnetic field vector continuously moves on a sphere or a spheroid.