US 11,719,847 B2
Systems, methods, and apparatus for detecting ferromagnetic foreign objects in a predetermined space
Hans Peter Widmer, Wohlenschwil (CH); Lukas Sieber, Olten (CH); and Andreas Daetwyler, Unterentfelden (CH)
Assigned to WiTricity Corporation, Watertown, MA (US)
Filed by WiTricity Corporation, Watertown, MA (US)
Filed on Jun. 9, 2022, as Appl. No. 17/836,841.
Application 17/836,841 is a continuation of application No. 16/438,104, filed on Jun. 11, 2019, granted, now 11,378,711.
Application 16/438,104 is a continuation of application No. 14/720,539, filed on May 22, 2015, granted, now 10,324,215, issued on Jun. 18, 2019.
Claims priority of provisional application 62/098,273, filed on Dec. 30, 2014.
Prior Publication US 2022/0326406 A1, Oct. 13, 2022
Int. Cl. B60L 53/12 (2019.01); G01V 3/10 (2006.01); B60L 3/00 (2019.01); B60L 3/04 (2006.01); B60L 53/36 (2019.01); B60L 55/00 (2019.01); B60L 53/65 (2019.01); B60L 53/66 (2019.01); B60L 50/60 (2019.01); B60L 53/124 (2019.01); B60L 53/68 (2019.01); B60L 53/122 (2019.01); B60L 53/126 (2019.01); B60L 53/30 (2019.01); H02J 50/10 (2016.01); H02J 50/12 (2016.01); H02J 50/90 (2016.01); H02J 7/00 (2006.01)
CPC G01V 3/10 (2013.01) [B60L 3/0069 (2013.01); B60L 3/04 (2013.01); B60L 50/66 (2019.02); B60L 53/12 (2019.02); B60L 53/122 (2019.02); B60L 53/124 (2019.02); B60L 53/126 (2019.02); B60L 53/30 (2019.02); B60L 53/305 (2019.02); B60L 53/36 (2019.02); B60L 53/65 (2019.02); B60L 53/665 (2019.02); B60L 53/68 (2019.02); B60L 55/00 (2019.02); H02J 7/00034 (2020.01); H02J 50/10 (2016.02); H02J 50/12 (2016.02); H02J 50/90 (2016.02); B60L 2200/12 (2013.01); B60L 2200/22 (2013.01); B60L 2200/26 (2013.01); B60L 2210/10 (2013.01); B60L 2210/30 (2013.01); B60L 2210/40 (2013.01); B60L 2240/36 (2013.01); B60L 2270/147 (2013.01); Y02E 60/00 (2013.01); Y02T 10/70 (2013.01); Y02T 10/7072 (2013.01); Y02T 10/72 (2013.01); Y02T 90/12 (2013.01); Y02T 90/14 (2013.01); Y02T 90/16 (2013.01); Y02T 90/167 (2013.01); Y04S 10/126 (2013.01); Y04S 30/14 (2013.01)] 17 Claims
OG exemplary drawing
 
1. An apparatus for detecting a presence of an object in a predetermined space of a wireless power transfer system, the apparatus comprising:
an inductive sense circuit comprising an electrically conductive structure configured to generate a magnetic field at a sense frequency when driven with a sense signal to thereby inductively sense the presence of the object, a capacitor electrically connected to the electrically conductive structure and having a capacitance configured to tune the inductive sense circuit for a resonance substantially at the sense frequency, and a measurement port configured for measuring an impedance of the inductive sense circuit;
a signal source coupled to the inductive sense circuit and configured to generate the sense signal at the sense frequency;
a sensor electrically connected to the measurement port and configured to sense an electrical characteristic at the measurement port and to provide a sensor output signal indicative of the electrical characteristic;
a detector circuit electrically connected to the sensor and configured to perform narrowband filtering and detection of the sensor output signal at the sense frequency, and to provide a detector output signal indicative of the electrical characteristic; and
a controller electrically connected to the signal source and to the detector circuit, the controller configured to:
control the signal source and the detector circuit including the sense frequency,
receive the detector output signal,
measure an impedance indicative of the impedance of the inductive sense circuit based on the received detector output signal when the electrically conductive structure is driven by the sense signal at the sense frequency,
tune the sense frequency to a frequency providing an extremum of a magnitude of the measured impedance,
determine a phase error as a phase angle of the impedance as measured at the frequency of the extremum,
correct the measured impedance for the phase error by shifting the phase angle of the measured impedance by an amount of the determined phase error to produce a corrected impedance value,
detect a potential interference signal coupled into the electrically conductive structure based on a level of the received detector output signal in absence of the sense signal,
determine that the level exceeds a threshold,
shift at least one of the sense frequency or an operating frequency of the wireless power transfer system in a manner to reduce the potential interference signal while substantially remaining at the resonance of the sense circuit, and
determine the presence of the object based on a change in the corrected impedance value.