Patent ID: 7515012

Claim:
A tuning system for a magnetic field generator comprising: a tuned circuit comprising a magnetic field generating inductor, a fixed capacitor and an adjustable capacitor, the inductance value of the inductor and the capacitance value of the capacitors establishing the resonant frequency of the tuned circuit; a tuned circuit drive circuit having an output coupled to and adapted to drive the tuned circuit and deliver power thereto; a reference frequency oscillator circuit providing a reference frequency signal, said oscillator circuit coupled to the tuned circuit drive circuit so as to cause said drive circuit to drive the tuned circuit at the reference frequency; and a sense circuit coupled to the reference frequency oscillator circuit and adapted to sense a first parameter related to the reference frequency signal, the sense circuit in electrical communication with the inductor and adapted to sense a second parameter related to the inductor and provide an error signal as a function of the first and second parameters, wherein the power delivered by the tuned circuit drive circuit to the tuned circuit is a function of the resonant frequency of the tuned circuit, and wherein the sense circuit monitors the error signal and causes the adjustable capacitor to be adjusted to a capacitance value that optimizes the error signal to thereby optimize the power delivered by the tuned circuit drive circuit, wherein the reference frequency signal is a voltage signal and the first parameter is the phase angle of such voltage signal and wherein the second parameter is the phase angle of the voltage across the inductor, wherein the sense circuit provides the error signal being the difference of the phase angle between the first and second parameters, each of the phase angles being measured relative to a pre-selected reference.