Tuning in a wireless power transmitter
First Claim
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1. An apparatus for tuning in a wireless power transmitter, comprising:
- a transmitter coil configured to generate a magnetic field for wirelessly charging a battery;
a differential amplifier to deliver current to the transmitter coil, wherein the differential amplifier comprises a first output and a second output;
a first set of capacitors arranged in series between the first output and the transmitter coil, and a second set of capacitors arranged in series between the second output and the transmitter coil, the first set of capacitors and the second set of capacitors configured to retune the transmitter coil in response to detuning upon placement of a device over the transmitter coil;
wherein each capacitor in the first set and the second set is coupled to a parallel switch that causes the capacitor to be short circuited to adjust an overall capacitance of the set;
wherein a capacitance value for each of the capacitors in the first set and the second set is a fixed capacitance level that provides a uniform reactance shift each time a new combination of capacitors is activated; and
wherein the first set of capacitors and the second set of capacitors are switched asynchronously with a step difference between the first set of capacitors and the second set of capacitors being less than or equal to one.
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Abstract
Techniques for tuning in a wireless power transmitter in a system, method, and apparatus are described herein. For example, an apparatus may include a transmitter coil configured to generate a magnetic field. The apparatus may also include a set of capacitors in series with the transmitter coil, wherein a capacitance value for each of capacitors in the set is associated with a reactance shift.
12 Citations
22 Claims
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1. An apparatus for tuning in a wireless power transmitter, comprising:
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a transmitter coil configured to generate a magnetic field for wirelessly charging a battery; a differential amplifier to deliver current to the transmitter coil, wherein the differential amplifier comprises a first output and a second output; a first set of capacitors arranged in series between the first output and the transmitter coil, and a second set of capacitors arranged in series between the second output and the transmitter coil, the first set of capacitors and the second set of capacitors configured to retune the transmitter coil in response to detuning upon placement of a device over the transmitter coil; wherein each capacitor in the first set and the second set is coupled to a parallel switch that causes the capacitor to be short circuited to adjust an overall capacitance of the set; wherein a capacitance value for each of the capacitors in the first set and the second set is a fixed capacitance level that provides a uniform reactance shift each time a new combination of capacitors is activated; and wherein the first set of capacitors and the second set of capacitors are switched asynchronously with a step difference between the first set of capacitors and the second set of capacitors being less than or equal to one. - View Dependent Claims (2, 3, 4, 5, 7, 8, 9)
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6. The apparatus of 5, wherein each capacitor in the first set is configured to absorb the parasitic capacitance exhibited by each corresponding solid state relay.
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10. A method for tuning in a wireless power transmitter, comprising:
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generating a magnetic field at a transmitter coil powered by a differential amplifier comprising a first output and a second output; and tuning the transmitter coil by activating one or more of a first set of capacitors arranged in series between the first output and the transmitter coil and a second set of capacitors arranged in series between the second output and the transmitter coil, wherein each capacitor in the first set and the second set is coupled to a parallel switch that causes the capacitor to be short circuited to adjust an overall capacitance of the set; and wherein a capacitance value for each of the capacitors in the set is a fixed capacitance level that provides a uniform reactance shift each time a new combination of capacitors is activated; and wherein the first set of capacitors and the second set of capacitors are switched asynchronously with a step difference between the first set of capacitors and the second set of capacitors being less than or equal to one. - View Dependent Claims (11, 12, 13, 14, 16, 17, 18)
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15. The method of 14, further comprising absorbing the parasitic capacitance exhibited by each corresponding solid state relay by each corresponding capacitor in the first set.
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19. A system for tuning in a wireless power transmitter, comprising:
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a transmitter coil configured to generate a magnetic field for wirelessly charging a battery; a differential amplifier to deliver current to the transmitter coil, wherein the differential amplifier comprises a first output and a second output; a first set of capacitors arranged in series between the first output and the transmitter coil, and a second set of capacitors arranged in series between the second output and the transmitter coil, wherein a capacitance value for each of the capacitors in the first set and the second set is a fixed capacitance level that provides a uniform reactance shift each time a new combination of capacitors is activated; and a first set of solid state relays each configured to activate a corresponding capacitor from among the first set of capacitors to retune the transmitter coil, and a second set of solid state relays each configured to activate a corresponding capacitor from among the second set of capacitors to retune the transmitter coil, wherein each solid state relay in the first set and the second set of solid state relays is in parallel with a corresponding capacitor in the first set and the second set of capacitors and is configured to short circuit the corresponding capacitor to adjust an overall capacitance of the set of capacitors; and wherein the first set of capacitors and the second set of capacitors are switched asynchronously with a step difference between the first set of capacitors and the second set of capacitors being less than or equal to one. - View Dependent Claims (20, 21, 22)
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Specification