NON-CONTACT POWER FEEDING SYSTEM
First Claim
1. A non-contact power feeding system comprising a power transmission device and a power reception device, transmission and reception of electric power being possible therebetween by magnetic field resonance, whereinthe power transmission device includes:
- a transmission-side resonance circuit including a transmission-side coil for transmitting the electric power;
a power transmission circuit which feeds an alternating-current voltage to the transmission-side resonance circuit to generate a magnetic field in the transmission-side coil;
a sensing circuit which senses an amplitude of a current passing in the transmission-side coil; and
a transmission-side control circuit which operates in, as an operation mode thereof, one of a plurality of modes including a first mode and a second mode;
the power reception device includes;
a reception-side resonance circuit including a reception-side coil for receiving the electric power;
a changing/short-circuiting circuit which canchange a resonance frequency of the reception-side resonance circuit from a resonance frequency during the power reception orshort-circuit the reception-side coil; and
a reception-side control circuit which operates in, as an operation mode thereof, one of a plurality of modes including the first mode and the second mode,whereinin the first mode,the reception-side control circuit, according to a signal from the power transmission device by communication and by using the changing/short-circuiting circuit, changes the resonance frequency of the reception-side resonance circuit, or short-circuits the reception-side coil, for a predetermined time, and then cancels the change or the short-circuiting, andthe transmission-side control circuit, during a period in which the resonance frequency of the reception-side resonance circuit is changed or the reception-side coil is short-circuited and prior to the power transmission, controls the power transmission circuit such that a predetermined test magnetic field is generated in the transmission-side coil, then, based on first evaluation data representing a sensed amplitude value obtained from the sensing circuit while the test magnetic field is being generated in the first mode, judges whether or not execution of the power transmission is permissible, and, after judging that execution of the power transmission is permissible, controls the power transmission circuit such that a power transmission magnetic field stronger than the test magnetic field is generated in the transmission-side coil to carry out the power transmission, andin the second mode,the reception-side control circuit, by using the changing/short-circuiting circuit, maintains the change of the resonance frequency of the reception-side resonance circuit or the short-circuiting of the reception-side coil, andthe transmission-side control circuit controls the power transmission circuit such that the test magnetic field is generated continuously in the transmission-side coil, and acquires second evaluation data representing a sensed amplitude value obtained from the sensing circuit while the test magnetic field is being generated in the second mode.
1 Assignment
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Accused Products
Abstract
In a normal mode, a power receiving device changes the resonant frequency of a power receiving side resonant circuit from a reference frequency or short-circuits a power receiving side coil for a predetermined time and then eliminates the changed or short-circuited state. Meanwhile, in the normal mode, a power transmitting device generates a test magnetic field in a power transmitting side coil during the above changed or short-circuited period and then determines, on the basis of a current amplitude detection value of the power transmitting side coil, whether a foreign object is present or not, thereby determining and controlling whether power transmission is executed or not. In a test mode, the power receiving device maintains the above changed or short-circuited state, and the power transmitting device continuously generates the test magnetic field and continuously obtains the current amplitude detection value of the power transmitting side coil.
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Citations
12 Claims
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1. A non-contact power feeding system comprising a power transmission device and a power reception device, transmission and reception of electric power being possible therebetween by magnetic field resonance, wherein
the power transmission device includes: -
a transmission-side resonance circuit including a transmission-side coil for transmitting the electric power; a power transmission circuit which feeds an alternating-current voltage to the transmission-side resonance circuit to generate a magnetic field in the transmission-side coil; a sensing circuit which senses an amplitude of a current passing in the transmission-side coil; and a transmission-side control circuit which operates in, as an operation mode thereof, one of a plurality of modes including a first mode and a second mode; the power reception device includes; a reception-side resonance circuit including a reception-side coil for receiving the electric power; a changing/short-circuiting circuit which can change a resonance frequency of the reception-side resonance circuit from a resonance frequency during the power reception or short-circuit the reception-side coil; and a reception-side control circuit which operates in, as an operation mode thereof, one of a plurality of modes including the first mode and the second mode, wherein in the first mode, the reception-side control circuit, according to a signal from the power transmission device by communication and by using the changing/short-circuiting circuit, changes the resonance frequency of the reception-side resonance circuit, or short-circuits the reception-side coil, for a predetermined time, and then cancels the change or the short-circuiting, and the transmission-side control circuit, during a period in which the resonance frequency of the reception-side resonance circuit is changed or the reception-side coil is short-circuited and prior to the power transmission, controls the power transmission circuit such that a predetermined test magnetic field is generated in the transmission-side coil, then, based on first evaluation data representing a sensed amplitude value obtained from the sensing circuit while the test magnetic field is being generated in the first mode, judges whether or not execution of the power transmission is permissible, and, after judging that execution of the power transmission is permissible, controls the power transmission circuit such that a power transmission magnetic field stronger than the test magnetic field is generated in the transmission-side coil to carry out the power transmission, and in the second mode, the reception-side control circuit, by using the changing/short-circuiting circuit, maintains the change of the resonance frequency of the reception-side resonance circuit or the short-circuiting of the reception-side coil, and the transmission-side control circuit controls the power transmission circuit such that the test magnetic field is generated continuously in the transmission-side coil, and acquires second evaluation data representing a sensed amplitude value obtained from the sensing circuit while the test magnetic field is being generated in the second mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12-24. -24. (canceled)
Specification