Foreign object detector, power transmitting device and power receiving device for wireless power transmission, and wireless power transmission system
First Claim
1. A foreign object detector comprising:
- a first resonator;
an oscillator circuit that is connected to the first resonator and oscillates at a first frequency (f1) which is lower than a resonant frequency (fr) of a second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr), the second resonator being electromagnetically coupled to the first resonator and being a parallel resonant circuit including a coil and a capacitor; and
a measurement circuit that measures an inductance value of the first resonator while the first and second resonators are electromagnetically coupled to each other, wherein;
the measurement circuit measures an input inductance value Lin(f1) of the first resonator while the oscillator circuit is oscillating at the first frequency f1 and an input inductance value Lin(f2) of the first resonator while the oscillator circuit is oscillating at the second frequency f2, calculates a coupling coefficient k which is calculated by the equation k2=1−
Lin(f2)/Lin(f1), and detects a metallic foreign object between the first resonator and the second resonator based on the coupling coefficient k;
while the coil is short-circuited, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical; and
while the coil is open, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical.
1 Assignment
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Accused Products
Abstract
A foreign object detector detects a metallic foreign object between a first resonator and a second resonator which is composed of a parallel resonant circuit including a coil and a capacitor. The foreign object detector includes the first resonator; an oscillator circuit capable of oscillating at a first frequency (f1) which is lower than a resonant frequency (fr) of the second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr); and a measurement circuit to measure changes in input impedance of the first resonator. The measurement circuit detects a metallic foreign object between the first resonator and the second resonator based on: changes in input impedance of the first resonator as measured by the measurement circuit while the oscillator circuit is oscillating at the first frequency f1; and changes in input impedance of the first resonator as measured by the measurement circuit while the oscillator circuit is oscillating at the second frequency f2.
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Citations
25 Claims
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1. A foreign object detector comprising:
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a first resonator; an oscillator circuit that is connected to the first resonator and oscillates at a first frequency (f1) which is lower than a resonant frequency (fr) of a second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr), the second resonator being electromagnetically coupled to the first resonator and being a parallel resonant circuit including a coil and a capacitor; and a measurement circuit that measures an inductance value of the first resonator while the first and second resonators are electromagnetically coupled to each other, wherein; the measurement circuit measures an input inductance value Lin(f1) of the first resonator while the oscillator circuit is oscillating at the first frequency f1 and an input inductance value Lin(f2) of the first resonator while the oscillator circuit is oscillating at the second frequency f2, calculates a coupling coefficient k which is calculated by the equation k2=1−
Lin(f2)/Lin(f1), and detects a metallic foreign object between the first resonator and the second resonator based on the coupling coefficient k;while the coil is short-circuited, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical; and while the coil is open, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A foreign object detector comprising:
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a first resonator; an oscillator circuit that is connected to the first resonator and oscillates at a first frequency (f1) which is lower than a resonant frequency (fr) of a second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr), the second resonator being electromagnetically coupled to the first resonator and being a parallel resonant circuit including a coil and a capacitor; and a measurement circuit that measures an inductance value of the first resonator while the first and second resonators are electromagnetically coupled to each other, wherein; the measurement circuit detects a metallic foreign object between the first resonator and the second resonator based on a ratio between an input inductance value Lin(f1) of the first resonator while the oscillator circuit is oscillating at the first frequency f1 and an input inductance value Lin(f2) of the first resonator while the oscillator circuit is oscillating at the second frequency f2; while the coil is short-circuited, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical; and while the coil is open, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A foreign object detector comprising:
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a first resonator; an oscillator circuit that is connected to the first resonator and oscillates at a first frequency (f1) which is lower than a resonant frequency (fr) of a second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr), the second resonator being electromagnetically coupled to the first resonator and being a parallel resonant circuit including a coil and a capacitor; and a measurement circuit that measures an inductance value of the first resonator while the first and second resonators are electromagnetically coupled to each other, wherein; the measurement circuit measures an input inductance value Lin(f1) of the first resonator while the oscillator circuit is oscillating at the first frequency f1 and an input inductance value Lin(f2) of the first resonator while the oscillator circuit is oscillating at the second frequency f2, and detects a metallic foreign object between the first resonator and the second resonator based on a coupling coefficient k which is calculated by k2=1−
Lin(f2)/Lin(f1);while the coil is short-circuited, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical; and while the coil is open, the input inductance value Lin(f1) of the first resonator and the input inductance value Lin(f2) of the first resonator are identical. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification