Inductev, Inc.

Momentum Dynamics Corporation

Daniel S Hackman

Andrew William Daga

Bruce Richard Long

John M Wolgemuth

Benjamin H Cohen

Andrew S Daga

A current sensing method measures a fractional current through a coil having a plurality of coil windings by using a current sensing resistor to measure a current through a subset of the plurality of coil windings and using a voltage sensor to measure a voltage drop across the current sensing resistor. The measured current and voltage values are provided to a processor to determine the fractional current and phase of the coil. For example, the fractional current and phase of the coil may be determined by calculating a total current of the coil as I=n(V/Rx), where n is the number of coil windings of the coil, V is the measured voltage, and Rx is the impedance of the current sensing resistor. The coil may be a secondary winding used in a wireless power transfer system.

Current sensing in a wireless power transfer system

A method for adjusting reactance includes an adjustable reactance generator including a comparator receiving an input sinusoidal waveform and outputting a square wave that retains the frequency and phase of the applied sinusoidal waveform. The reactance adjustment is generated using a power switching circuit that receives the square wave from the comparator as a control signal and outputs a square wave that retains the frequency and phase of the applied sinusoidal voltage waveform, an adjustable power supply that adjusts the amplitude of the square wave output by the power switching circuit, and an amplitude detector that controls the output level of the adjustable power supply. The power switching circuit output, when converted to a sinusoid, provides the effect of an adjustable reactance.

Method of and apparatus for generating an adjustable reactance

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Reading, PA, United States of America

Daniel S Hackman