Inductive link coil de-tuning compensation and control
First Claim
1. A wireless coupling system comprising:
- a first coil, wherein an alternating current is present on the first coil;
a second coil, the second coil being directly inductively coupled to the first coil;
an electrostatic shield for the first coil, wherein the electrostatic shield is inductively coupled to the first coil, the electrostatic shield having a gap extending an axial length of the electrostatic shield;
a variable impedance element coupled across the gap of the electrostatic shield; and
a control loop, wherein the control loop controls an impedance of the variable impedance element based on the alternating current on the first coil to maximize an amplitude of the alternating current on the first coil.
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Accused Products
Abstract
An inductive wireless power transfer and communication system includes an electrostatic shield for one of the coils. The electrostatic shield is inductively coupled with the coil and is configured as an open circuit. A signal processing element or elements, especially a modulator or a demodulator, are connected across the electrical discontinuity in the electrostatic shield. Because the electrostatic shield is inductively coupled to the coil, the modulator or demodulator can operate on the signal on the coil. A variable impedance element is connected across the electrical discontinuity in the electrostatic shield. Because the electrostatic shield is inductively coupled to the coil, the variable impedance element can tune the impedance of the system.
38 Citations
39 Claims
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1. A wireless coupling system comprising:
- a first coil, wherein an alternating current is present on the first coil;
a second coil, the second coil being directly inductively coupled to the first coil;
an electrostatic shield for the first coil, wherein the electrostatic shield is inductively coupled to the first coil, the electrostatic shield having a gap extending an axial length of the electrostatic shield;
a variable impedance element coupled across the gap of the electrostatic shield; anda control loop, wherein the control loop controls an impedance of the variable impedance element based on the alternating current on the first coil to maximize an amplitude of the alternating current on the first coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- a first coil, wherein an alternating current is present on the first coil;
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23. A wireless coupling system comprising:
- a first coil, wherein an alternating current is present on the first coil;
a second coil, the second coil being inductively coupled to the first coil;
an electrostatic shield for the first coil, wherein the electrostatic shield is inductively coupled to the first coil, the electrostatic shield having a gap extending an axial length of the electrostatic shield;
a variable impedance element coupled across the gap of the electrostatic shield; anda control loop, wherein the control loop controls an impedance of the variable impedance element based on the alternating current on the first coil to maximize an amplitude of the alternating current on the first coil, wherein the control loop is configured to generate a control voltage;
apply a dither signal to the control voltage;
apply the dithered control voltage to the variable impedance element;
detect a variation signal in the amplitude of the alternating current on the first coil; and
increase the control voltage when the detected variation signal is in phase with the dither signal, or decrease the control voltage when the detected variation signal is out of phase with the dither signal.
- a first coil, wherein an alternating current is present on the first coil;
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24. A wireless coupling system comprising:
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a first coil, wherein an alternating current is present on the first coil; a second coil, the second coil being directly inductively coupled to the first coil;
an electrostatic shield for the first coil, wherein the electrostatic shield is inductively coupled to the first coil, the electrostatic shield having a gap extending an axial length of the electrostatic shield;
a variable impedance element coupled across the gap of the electrostatic shield, wherein the variable impedance element comprises a plurality of varactor diodes arranged in a back-to-back configuration across the gap; and
a control voltage source which supplies a control voltage to the varactor diodes;wherein the control voltage can be varied based on the alternating current present on the first coil, and wherein the control voltage is varied to maximize an amplitude of the alternating current present on the first coil.
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25. A method of tuning a wireless coupling system comprising a first coil and a second coil, wherein an alternating current is present on the first coil and wherein an electrostatic shield for the first coil is inductively coupled to the first coil and has a gap extending an axial length of the electrostatic shield, the method comprising:
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providing a variable impedance element across the gap of the electrostatic shield; and controlling an impedance of the variable impedance element comprising;
monitoring the alternating current of the first coil; andadjusting the impedance of the variable impedance element based on the alternating current on the first coil to maximize an amplitude of the alternating current on the first coil. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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32. A method of tuning a wireless coupling system comprising a first coil and a second coil, wherein an alternating current is present on the first coil and wherein an electrostatic shield for the first coil is inductively coupled to the first coil and has a gap extending an axial length of the electrostatic shield, the method comprising:
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providing a variable impedance element across the gap of the electrostatic shield; and controlling an impedance of the variable impedance element, comprising;
generating a control voltage;
applying a dither signal to the control voltage;applying the dithered control voltage to the variable impedance element;
detecting a variation signal in an amplitude of the alternating current on the first coil; andsetting the control voltage based on the detected variation signal, wherein setting the control voltage based on the detected variation signal comprises; increasing the control voltage when the detected variation signal is in phase with the dither signal; and decreasing the control voltage when the detected variation signal is out of phase with the dither signal.
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33. A method of tuning a wireless coupling system comprising a first coil and a second coil, wherein an alternating current is present on the first coil and wherein an electrostatic shield for the first coil is inductively coupled to the first coil and has a gap extending an axial length of the electrostatic shield, the method comprising:
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providing a variable impedance element across the gap of the electrostatic shield; and controlling an impedance of the variable impedance element, wherein controlling the impedance of the variable impedance element comprises;
applying a control voltage to control the variable impedance element;
setting the control voltage to a first voltage VC−
;taking a first measurement corresponding to an amplitude of the alternating current on the first coil; setting the control voltage to a second voltage VC+;
taking a second measurement corresponding to the amplitude of the alternating current on the first coil;increasing VC+ and VC−
if the second measurement is greater than the first measurement; anddecreasing VC+ and VC−
if the second measurement is not greater than the first measurement.
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34. A wireless power transfer and communication system comprising:
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a first coil; an electrostatic shield for the first coil, the electrostatic shield having a gap extending an axial length of the electrostatic shield, wherein the electrostatic shield is inductively coupled to the first coil;
a first signal processor coupled across the gap of the electrostatic shield;
a second coil, the second coil being inductively coupled to the first coil;
a second signal processor coupled to the second coil;a variable impedance element coupled across the gap of the electrostatic shield; a coil driver coupled to the first coil and configured to generate a carrier signal on the first coil; and a control loop, wherein the control loop controls an impedance of the variable impedance element based on a current on the first coil to maximize an amplitude of the current on the first coil. - View Dependent Claims (35, 36, 37, 38, 39)
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Specification