Wireless power transmission system with foreign-substance detection
First Claim
1. A wireless power transmission system comprising:
- a power transmission apparatus having a power transmission coil to wirelessly transmit electric power;
a power receiving apparatus having a power receiving coil to wirelessly receive electric power from the power transmission apparatus; and
a foreign-substance detector to detect a foreign substance which is present between the power transmission coil and the power receiving coil,whereinthe power transmission apparatus includes;
a voltage supply to be frequency-variable and capable of outputting a first AC signal;
a power supply controller that varies a frequency of the first AC signal in a frequency range from a first frequency to a second frequency;
the power transmission coil to resonate at a first resonance frequency and to generate a magnetic field by receiving the first AC signal; and
a first measurement unit to measure a first reflectance between the voltage supply and the power transmission coil in the frequency range two or more times, the first reflectance being at least one of a voltage reflectance of the first AC signal, an AC reflectance of the first AC signal, and a power reflectance of the first AC signal;
whereinthe power receiving apparatus includes;
the power receiving coil to resonate at a second resonance frequency and to generate a second AC signal by receiving the magnetic field, the second AC signal being passed through a load; and
a second measurement unit to measure a second reflectance between the power receiving coil and the load in the frequency range two or more times, the second reflectance being at least one of a voltage reflectance of the second AC signal, an AC reflectance of the second AC signal, and a power reflectance of the second AC signal; and
whereinthe foreign-substance detector acquires a first peaking frequency from the first measurement unit and a second peaking frequency from the second measurement unit, and detects the foreign substance by the use of shift amounts of the first peaking frequency and the second peaking frequency, the first peaking frequency being a frequency at which the first reflectance reaches a local minimum, the second peaking frequency being a frequency at which the second reflectance reaches a local minimum.
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Accused Products
Abstract
A power transmission system includes a power transmission apparatus, a power receiving apparatus, and a foreign-substance detecting unit. The power transmission apparatus has a power transmission coil to wirelessly transmit electric power. The power receiving apparatus has a power receiving coil to wirelessly receive electric power from the power transmission apparatus. The foreign-substance detecting unit detects a foreign substance which is present between the power transmission coil and the power receiving coil. In addition, the power transmission apparatus includes a voltage supply, a power supply controller, the power transmission coil, and a first measurement unit. The power receiving apparatus includes the power receiving coil and a second measurement unit.
21 Citations
19 Claims
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1. A wireless power transmission system comprising:
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a power transmission apparatus having a power transmission coil to wirelessly transmit electric power; a power receiving apparatus having a power receiving coil to wirelessly receive electric power from the power transmission apparatus; and a foreign-substance detector to detect a foreign substance which is present between the power transmission coil and the power receiving coil, wherein the power transmission apparatus includes; a voltage supply to be frequency-variable and capable of outputting a first AC signal; a power supply controller that varies a frequency of the first AC signal in a frequency range from a first frequency to a second frequency; the power transmission coil to resonate at a first resonance frequency and to generate a magnetic field by receiving the first AC signal; and a first measurement unit to measure a first reflectance between the voltage supply and the power transmission coil in the frequency range two or more times, the first reflectance being at least one of a voltage reflectance of the first AC signal, an AC reflectance of the first AC signal, and a power reflectance of the first AC signal; wherein the power receiving apparatus includes; the power receiving coil to resonate at a second resonance frequency and to generate a second AC signal by receiving the magnetic field, the second AC signal being passed through a load; and a second measurement unit to measure a second reflectance between the power receiving coil and the load in the frequency range two or more times, the second reflectance being at least one of a voltage reflectance of the second AC signal, an AC reflectance of the second AC signal, and a power reflectance of the second AC signal; and wherein the foreign-substance detector acquires a first peaking frequency from the first measurement unit and a second peaking frequency from the second measurement unit, and detects the foreign substance by the use of shift amounts of the first peaking frequency and the second peaking frequency, the first peaking frequency being a frequency at which the first reflectance reaches a local minimum, the second peaking frequency being a frequency at which the second reflectance reaches a local minimum. - View Dependent Claims (2, 3, 4, 5)
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6. A wireless power transmission system comprising:
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a power transmission apparatus having a power transmission coil to wirelessly transmit electric power; a power receiving apparatus having a power receiving coil to wirelessly receive electric power from the power transmission apparatus; and a foreign-substance detector to detect a foreign substance which is present between the power transmission coil and the power receiving coil, wherein the power transmission apparatus includes; a voltage supply to be frequency-variable and capable of outputting a first AC signal; a power supply controller that varies a frequency of the first AC signal in a frequency range from a first frequency to a second frequency; the power transmission coil to resonate at a first resonance frequency and to generate a magnetic field by receiving the first AC signal; a first measurement unit to measure a first reflectance between the voltage supply and the power transmission coil and first electric power in the frequency range two or more times, the first reflectance being at least one of a voltage reflectance of the first AC signal, an AC reflectance of the first AC signal, and a power reflectance of the first AC signal, the first electric power being transmitted by the power transmission coil; wherein the power receiving apparatus includes; the power receiving coil to resonate at a second resonance frequency and to generate a second AC signal in response to the magnetic field; a second measurement unit to measure second electric power in the frequency range two or more times, the second electric power being supplied to a load; and wherein the foreign-substance detector identifies a first peaking frequency and a third peaking frequency, and detects the foreign substance by the use of shift amounts of the first peaking frequency and the third peaking frequency, the first peaking frequency being a frequency at which the first reflectance reaches a local minimum, the third peaking frequency being a frequency at which a power transmission efficiency reaches a local maximum, the power transmission efficiency being determined by the first electric power and the second electric power. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A wireless power transmission apparatus using a power transmission coil to wirelessly transmit electric power to a power receiving apparatus having a power receiving coil, comprising:
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a voltage supply to be frequency-variable and capable of outputting a first AC signal; a power supply controller that varies a frequency of the first AC signal in a frequency range from a first frequency to a second frequency; the power transmission coil to resonate at a first resonance frequency and to generate a magnetic field by receiving the first AC signal; a first measurement unit to measure a first reflectance between the voltage supply and the power transmission coil in the frequency range two or more times, the first reflectance being at least one of a voltage reflectance of the first AC signal, an AC reflectance of the first AC signal, and a power reflectance of the first AC signal, wherein a foreign substance between the power transmission coil and the power receiving coil is detected by the use of a first peaking frequency at which the first reflectance reaches a local minimum. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification