Interrupted resonance energy transfer system
First Claim
1. A drive circuit for inductively driving a target coil, the target coil connected to a capacitive element to form a target L-C circuit having a first resonant frequency and a corresponding first resonant cycle time, the drive circuit comprising:
- a supply voltage source;
a sending coil inductively coupled to the target coil, the sending coil connected to a capacitive element to form a sending L-C circuit having a second resonant frequency greater than the first resonant frequency, the sending L-C circuit being driven by the supply voltage source; and
control means for periodically connecting the supply voltage source to the sending coil, such that the supply voltage drives the sending coil for inducing cyclical voltage across the sending coil and a cyclical current through the sending coil, and for disconnecting the supply voltage source from the sending coil and connecting the sending coil to a reference potential after a time interval approximately equal to one-half of the first resonant cycle time;
wherein the frequency of the cyclical voltage induced across the sending coil is controlled by the control means to be substantially the same as the first resonant frequency.
2 Assignments
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Accused Products
Abstract
A drive circuit for applying a supply voltage to a sending coil provides resonant coupling of the sending coil with the target coil regardless of changes in the inductance of the sending coil, as long as the resonant frequency of the sending coil is greater than the resonant frequency of the target coil. A controller provides variable delay intervals in the application of the supply voltage, thereby compensating for changes in the sending coil'"'"'s inductance with the passage of time and proximity effects. The controller examines the reflected voltage induced in the sending coil by changing currents in the target coil to examine the degree of resonant coupling between the two coils and correct any mistuning.
107 Citations
26 Claims
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1. A drive circuit for inductively driving a target coil, the target coil connected to a capacitive element to form a target L-C circuit having a first resonant frequency and a corresponding first resonant cycle time, the drive circuit comprising:
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a supply voltage source; a sending coil inductively coupled to the target coil, the sending coil connected to a capacitive element to form a sending L-C circuit having a second resonant frequency greater than the first resonant frequency, the sending L-C circuit being driven by the supply voltage source; and control means for periodically connecting the supply voltage source to the sending coil, such that the supply voltage drives the sending coil for inducing cyclical voltage across the sending coil and a cyclical current through the sending coil, and for disconnecting the supply voltage source from the sending coil and connecting the sending coil to a reference potential after a time interval approximately equal to one-half of the first resonant cycle time; wherein the frequency of the cyclical voltage induced across the sending coil is controlled by the control means to be substantially the same as the first resonant frequency. - View Dependent Claims (2)
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3. A drive circuit for inductively driving a target coil, the target coil connected to a capacitive element to form a target L-C circuit having a first resonant frequency and a corresponding first resonant cycle time, the drive circuit comprising:
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a supply voltage source; a reference source; a pair of complementary MOS field effect transistors coupled in series circuit configuration, the drains of the transistors being coupled together through a pair of series connected diodes, the source of one transistor being connected to the supply voltage source, the source of the other transistor of the pair being connected to the reference source, a first capacitor (C), a sending coil (L) and a resistor (R) connected together to form a series CLR circuit, the series CLR circuit coupled between the series connected diodes and the reference source, the sending coil being inductively coupled to the target coil; and controller means connected to the gate of each transistor, the controller means for producing a cyclical drive voltage having a predetermined frequency for controlling the state of the transistors. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A method for resonantly coupling a sending coil to a target coil L-C circuit for inductive energy transfer comprising the steps of:
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providing a sending coil L-C circuit having a resonant frequency greater than the resonant frequency of the target coil L-C circuit; providing switching means for alternately connecting a supply voltage source and a reference potential to the sending coil L-C circuit; connecting the supply voltage source to the sending coil for a variable time interval that is substantially equal to one-half the cycle time of the target coil L-C circuit resonant frequency; and disconnecting the supply voltage source from the sending coil and connecting the sending coil to the reference potential for a variable time interval that is substantially equal to one-half the cycle time of the target coil circuit.
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11. A method for driving a sending coil with a supply voltage to inductively transfer electrical power to a target coil and capacitor, the sending coil and target coil having respective coil currents, comprising the steps of:
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providing a capacitor in series with the sending coil such that the resonant frequency of the sending coil and capacitor is greater than the resonant frequency of the target coil and capacitor; providing switching means to alternately switch the sending coil and its capacitor between the supply voltage and a reference potential; and connecting the supply voltage to the sending coil and its capacitor for a time interval substantially equal to one-half the cycle time of the resonant frequency of the target coil and its capacitor; and switching the sending coil and its capacitor from the supply voltage to the reference potential for a time interval substantially equal to one-half the cycle time of the resonant frequency of the target coil and its capacitor. - View Dependent Claims (12, 13)
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14. A drive circuit, for inductively driving a target coil connected with a capacitive element to form a target coil L-C circuit having a target coil L-C circuit resonant frequency, comprising:
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a supply voltage source; a sending coil inductively coupled to the target coil; a first pair of transistors coupled together in series circuit fashion, one of the transistors of the first pair being coupled to the supply voltage source, the other transistor of the first pair being coupled to ground; a capacitor (C), the sending coil (L) and a resistor (R) connected together to form a CLR resonant circuit, the CLR resonant circuit coupled between the first pair of transistors and ground; a second pair of transistors coupled to the sending coil and ground; a controller for controlling the conductive state of each transistor, the controller for providing a cyclical drive signal to the first pair of transistors for driving the CLR resonant circuit at a frequency substantially equal to the target coil L-C circuit resonant frequency; and phase detector means for detecting any phase difference between the voltage across the sending coil and the voltage induced in the target coil and providing thereby a phase signal representative of such difference, the controller further controlling the conduction time of the second pair of transistors as a function of the phase signal and correspondingly coupling the sending coil to ground driving conduction of the transistors of the second pair, to thereby inductively drive the target coil L-C resonant circuit at the target coil L-C resonant circuit resonant frequency. - View Dependent Claims (15)
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16. A drive circuit for inductively driving a target coil, the target coil connected to a capacitive element to form a target coil L-C resonant circuit, having a target coil L-C resonant frequency comprising:
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a supply voltage source, a reference source, a sending coil, inductively coupled to the target coil; first transistor means coupled between the supply voltage source and the reference source, the first transistor means having a first input and a first output; a controller, coupled to the first input for controlling the conductive state of the first transistor means; and a capacitor (C) and the sending coil (L) connected together to form a sending coil L-C resonant circuit coupled between the first output and the reference source, wherein the controller cyclically alternates the conductive state of the first transistor means at a predetermined frequency for inducing a cyclical voltage in the target coil having a frequency substantially equal to the target coil L-C circuit resonant frequency. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A drive circuit for inductively driving a target coil connected to a capacitor to form a target coil L-C circuit having a target coil L-C circuit resonant frequency comprising:
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a voltage source; a reference potential; a sending coil (L) inductively coupled to the target coil; first switch means having an output controllably switchable between the voltage source and the reference potential; a capacitor (C), the sending coil (L) and a resistor (R) together connected to form a CLR resonant circuit, the resonant circuit coupled to the first switch means output; and a controller for controlling the first switch means output, wherein the controller alternates the first switch means output between the voltage source and the reference potential at a frequency substantially equal to the target coil L-C circuit resonant frequency. - View Dependent Claims (23, 24, 25, 26)
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Specification