Electronic tuning system
AssigneeWilliam Redman-White
InventorWILLIAM REDMAN-WHITE
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Abstract
A system is described for maintaining an inductive-capacitive (LC) network at resonance while the excitation frequency may be varied between a number of discrete frequencies at desired instants controlled by a modulation input, while taking into account component parameter errors due environmental and ageing as well as manufacturing tolerances. Control of the resonance while the excitation frequency changes permits the transmission of frequency modulation (FM) or frequency shift keying (FSK) information through an inductively coupled power transfer system.
Claims20
A circuit configured to maintain resonance of a tuned circuit selecting between at least two discrete excitation frequencies, the tuned circuit comprising at least one switch connected in combination with one of at least two capacitors, a duty cycle of the at least one switch configured to vary an apparent resonant frequency of the tuned circuit;
- and a source providing an excitation signal, the source comprising means for selecting between the at least two discrete excitation frequencies, the circuit configured to maintain resonance comprising:
- a voltage sensor configured to sense a voltage across the at least one switch when the at least one switch is in an open state;
- tuning control circuitry configured to derive a tuning control signal from the sensed voltage, comprising:
- correction signal circuitry configured to derive a correction signal from the said sensed voltage wherein the correction signal is configured to alter the apparent resonant frequency to correspond with a selected one of the discrete excitation frequencies;
- and
- tuning signal circuitry configured to generate at least two tuning control signals configured to selectively receive the correction signal, each tuning control signal associated with a respective one of the discrete excitation frequencies;
- and
- switch timing control circuitry configured to control the timing of the opening and closing of the at least one switch in a manner based on the derived tuning control signal associated with each of the at least two discrete excitation frequencies such that the voltage across the at least one switch when the at least one switch is in an open state immediately prior to closing is substantially zero;
- and
- frequency selection control circuitry configured to select between the at least two discrete excitation frequencies, and further configured to connect the tuning control signal associated with the selected discrete excitation frequency with which the tuned circuit is being driven to the switch timing control circuitry controlling the timing of the opening and closing of the at least one switch and said frequency selection control circuitry is further configured to control the timing of the opening and closing of the at least one switch in a manner based on the selected derived tuning control signal at each of the at least two discrete excitation frequencies.
A method for maintaining resonance of a tuned circuit selecting between two or more discrete excitation frequencies, the tuned circuit comprising at least one switch connected in combination with one of at least two capacitors, a duty cycle of the at least one switch configured to vary an apparent resonant frequency of the tuned circuit;
- and a source providing a excitation signal, the method comprising selecting between the two or more discrete excitation frequencies, the method comprising:
- sensing a voltage across the at least one switch when the at least one switch is in an open state;
- deriving a tuning control signal from the sensed voltage, wherein deriving a tuning control signal comprises:
- deriving a correction signal from the sensed voltage wherein the correction signal is configured to alter the apparent resonant frequency to correspond with a selected one of the discrete excitation frequencies;
- and
- generating at least two tuning control signals from the correction signal, each tuning control signal associated with a respective one of the discrete excitation frequencies;
- and
- controlling the timing of the opening and closing of the at least one switch in a manner based on the derived tuning control signal at each of the two or more discrete excitation frequencies such that the voltage across the at least one switch when the at least one switch is in an open state immediately prior to closing is substantially zero;
- controlling the selecting between the two or more discrete excitation frequencies, wherein controlling the selecting between the two or more discrete excitation frequencies comprises selecting the tuning control signal associated with a respective one of the discrete excitation frequencies with which the tuned circuit is being driven to enable controlling of the timing of the opening and closing of the at least one switch in a manner based on the derived tuning control signals at each of the two or more discrete excitation frequencies.
Dependencies are inferred from the claim text.