Coil unit and noncontact power transmission apparatus
First Claim
Patent Images
1. A coil unit configured to transmit or receive electric power by electromagnetic induction in a noncontact manner, comprising:
- a coil into or from both terminals of which a high-frequency voltage is input or output;
a metal conductor placed near the coil; and
a first capacitor and a second capacitor respectively connected to the terminals of the coil, whereinthe ratio of the capacitance between the first capacitor and the second capacitor is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced, andthe ratio between capacitances C1 and C2 (C1/C2) where C1 is the capacitance of the first capacitor and C2 is the capacitance of the second capacitor is set to satisfy conditions (1) and (2) below when a high-frequency voltage is input into or output from the coil;
(1) a combined capacitance [C1×
C2/(C1+C2)] of the first capacitor and the second capacitor serially connected to the coil is constant; and
(2) the current induced into the metal conductor due to capacitance coupling is smaller than that observed when C1=C2.
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Abstract
A coil unit configured to transmit or receive electric power by electromagnetic induction in a noncontact manner, including: a coil into or from both terminals of which a high-frequency voltage is input or output; a metal conductor placed near the coil; and a first capacitor and a second capacitor connected to the terminals of the coil, wherein the ratio of the capacitance between the first capacitor and the second capacitor is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced.
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Citations
11 Claims
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1. A coil unit configured to transmit or receive electric power by electromagnetic induction in a noncontact manner, comprising:
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a coil into or from both terminals of which a high-frequency voltage is input or output; a metal conductor placed near the coil; and a first capacitor and a second capacitor respectively connected to the terminals of the coil, wherein the ratio of the capacitance between the first capacitor and the second capacitor is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced, and the ratio between capacitances C1 and C2 (C1/C2) where C1 is the capacitance of the first capacitor and C2 is the capacitance of the second capacitor is set to satisfy conditions (1) and (2) below when a high-frequency voltage is input into or output from the coil; (1) a combined capacitance [C1×
C2/(C1+C2)] of the first capacitor and the second capacitor serially connected to the coil is constant; and(2) the current induced into the metal conductor due to capacitance coupling is smaller than that observed when C1=C2. - View Dependent Claims (2, 3, 4)
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5. A noncontact power transmission apparatus configured to transmit electric power from a power-transmitting coil to a power-receiving coil by electromagnetic induction in a noncontact manner, wherein
at least one of the power-transmitting coil and the power-receiving coil includes: -
a coil into or from both terminals of which a high-frequency voltage is input or output, a metal conductor placed near the coil, and a first capacitor and a second capacitor respectively connected to the terminals of the coil, and the ratio of the capacitance between the first capacitor and the second capacitor is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced, and the ratio between capacitances C1 and C2 (C1/C2) where C1 is the capacitance of the first capacitor and C2 is the capacitance of the second capacitor is set to satisfy conditions (1) and (2) below when a high-frequency voltage is input into or output from the coil; (1) a combined capacitance [C1×
C2/(C1+C2)] of the first capacitor and the second capacitor serially connected to the coil is constant; and(2) the current induced into the metal conductor due to capacitance coupling is smaller than that observed when C1=C2. - View Dependent Claims (6, 7)
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8. A coil unit configured to transmit or receive electric power by electromagnetic induction in a noncontact manner, comprising:
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a coil into or from both terminals of which a high-frequency voltage is input or output; a metal conductor placed near the coil; and a capacitor inserted in the coil, wherein the coil is separated by the capacitor into a first coil and a second coil different in the magnitude of inductance, and the ratio of the inductance between the first coil and the second coil is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced. - View Dependent Claims (9)
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10. A coil unit configured to transmit or receive electric power by electromagnetic induction in a noncontact manner, comprising:
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a coil into or from both terminals of which a high-frequency voltage is input or output; a metal conductor placed near the coil; and a ground site at which the coil is grounded, wherein the coil is separated by the ground site into a first coil and a second coil different in the magnitude of inductance, and the ratio of the inductance between the first coil and the second coil is set to a value at which a current induced into the metal conductor due to capacitance coupling when a high-frequency voltage is input into or output from the coil is reduced. - View Dependent Claims (11)
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Specification