Resonance tuning
First Claim
1. A wireless power transfer device, comprising:
- power transfer terminals for coupling to a power transfer resonator external to the device, the resonator including;
a resonator power transfer coil, anda resonator tuning capacitor with an adjustable tuning capacitance C_A,the power transfer resonator having a self-resonant frequency controllable based on adjusting C_A;
a variable converter circuit to generate a variable alternating current voltage Vac and adjustable tuning signals to adjust adjustable tuning capacitance C_A, output through the power transfer terminals, corresponding to the controllable self-resonant frequency of the power transfer resonator;
the variable converter circuit operable, when the power transfer device is magnetically coupled through the power transfer resonator to a power receiver device with a power receiver resonator, to;
output through the power transfer terminals an initial Vac corresponding to an initial self-resonant frequency fA for the power transfer resonator, based on an initial capacitance value C_A for the adjustable tuning capacitor;
iteratively adjust Vac to control the self-resonant frequency fA for the power transfer resonator, including iteratively adjusting capacitance C_A for the resonator tuning capacitor, based on iteratively estimating a self-resonant frequency fB of the power receiver device, by;
sweeping the frequency of Vac in discrete frequency steps, and in each frequency step, monitoring a circuit parameter of the variable converter circuit,identifying a first local maximum and a second local maximum for the values of the circuit parameter corresponding to two resonant modes of the power transfer resonator and the power receiver resonator,ascertaining a first frequency and a second frequency corresponding to the first and second local maxima, respectively, andestimating a self-resonant frequency fB_est of the power receiver device based on the first and second frequencies;
the variable converter circuit operable, when (fA−
fB_est) is different than a threshold value, to;
adjust the tuning capacitance C_A so that fA is substantially equal to fB_est; and
iteratively perform a next estimation for a next estimated self-resonant frequency fB_est.
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Accused Products
Abstract
One heuristic for tuning a wireless power transfer device includes monitoring a circuit parameter while sweeping a power source frequency; identifying two frequencies related to local maxima of the circuit parameter values; estimating self-resonant frequency of an electromagnetically coupled device based on the two frequencies; determining a value for a tuning component of the wireless power transfer device such that the device self-resonant frequency equals the estimated coupled device self-resonant frequency; and adjusting the tuning component to the determined value.
Another tuning heuristic includes monitoring a circuit parameter while sweeping the power source frequency; identifying two frequencies related to two local maximum for the values of the circuit parameter; determining a desired resonance frequency for the wireless power transfer device based on stored information; and adjusting the tuning component to a value that causes the wireless power transfer device when uncoupled to operate at or near the desired resonance frequency.
9 Citations
10 Claims
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1. A wireless power transfer device, comprising:
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power transfer terminals for coupling to a power transfer resonator external to the device, the resonator including; a resonator power transfer coil, and a resonator tuning capacitor with an adjustable tuning capacitance C_A, the power transfer resonator having a self-resonant frequency controllable based on adjusting C_A; a variable converter circuit to generate a variable alternating current voltage Vac and adjustable tuning signals to adjust adjustable tuning capacitance C_A, output through the power transfer terminals, corresponding to the controllable self-resonant frequency of the power transfer resonator; the variable converter circuit operable, when the power transfer device is magnetically coupled through the power transfer resonator to a power receiver device with a power receiver resonator, to; output through the power transfer terminals an initial Vac corresponding to an initial self-resonant frequency fA for the power transfer resonator, based on an initial capacitance value C_A for the adjustable tuning capacitor; iteratively adjust Vac to control the self-resonant frequency fA for the power transfer resonator, including iteratively adjusting capacitance C_A for the resonator tuning capacitor, based on iteratively estimating a self-resonant frequency fB of the power receiver device, by; sweeping the frequency of Vac in discrete frequency steps, and in each frequency step, monitoring a circuit parameter of the variable converter circuit, identifying a first local maximum and a second local maximum for the values of the circuit parameter corresponding to two resonant modes of the power transfer resonator and the power receiver resonator, ascertaining a first frequency and a second frequency corresponding to the first and second local maxima, respectively, and estimating a self-resonant frequency fB_est of the power receiver device based on the first and second frequencies; the variable converter circuit operable, when (fA−
fB_est) is different than a threshold value, to;adjust the tuning capacitance C_A so that fA is substantially equal to fB_est; and iteratively perform a next estimation for a next estimated self-resonant frequency fB_est. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification