# US 10,371,848 B2 · Foreign object detection in wireless energy transfer systems

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- Number: US 10,371,848 B2
- Document ID: US10371848B2
- Status: Granted
- Kind: B2
- Application number: 16/026,123
- Filed: 2018-07-03
- Published: 2018-11-15
- Granted: 2019-08-06
- Earliest claimed: 2014-05-07
- Assignees: WiTricity Corporation
- Applicants: WiTricity Corporation
- Inventors: Arunanshu Mohan Roy; Noam Katz; Nathaniel Endale Atnafu
- Web page: https://patentgrep.com/patent/US10371848B2

## CPC

- B60L 53/124: Detection or removal of foreign bodies
- G01V 3/081: {the magnetic field is produced by the objects or geological structures (characterised by the method of magnetic field measurement G01R33/00)}
- G01V 3/104: {using several coupled or uncoupled coils (G01V3/101 takes precedence)}
- H02J 50/12: of the resonant type
- H02J 50/402: {the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas}
- H02J 50/60: responsive to the presence of foreign objects, e.g. detection of living beings
- H02J 50/70: involving the reduction of electric, magnetic or electromagnetic leakage fields
- H02J 50/80: involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
- H02J 50/90: involving detection or optimisation of position, e.g. alignment
- B60L 2270/147: electro magnetic [EMI]
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
- Y02T 90/12: Electric charging stations
- Y02T 90/14: Plug-in electric vehicles
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Systems and methods for detecting foreign object debris around a wireless power transfer system include a plurality of detectors, each detector featuring one or more loops of conducting material, and a controller configured to measure at least one of a voltage and a current in each detector and to determine, based on the measurements, whether foreign object debris is present around the wireless power transfer system, where at least some of the plurality of detectors include a first number of loops of the conducting material, and at least some of the plurality of detectors include a second number of loops of the conducting material larger than the first number.

## Claims

### Claim 1

An apparatus for detecting foreign object debris around a wireless power transfer system, the apparatus comprising:
a plurality of detectors, each detector comprising one or more loops of conducting material and positioned so that each detector receives at least a portion of a common oscillating magnetic field generated by the wireless power transfer system; and
a controller configured to measure at least one of a voltage and a current in each detector and to determine, based on the measurements, whether foreign object debris is present around the wireless power transfer system,
wherein at least some of the plurality of detectors comprise a first number of loops of the conducting material, and at least some of the plurality of detectors comprise a second number of loops of the conducting material larger than the first number.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein at least some of the plurality of detectors comprise one loop and wherein at least some of the plurality of detectors comprise two loops.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein at least some of the plurality of detectors comprise three loops.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein, the common oscillating magnetic field is generated by a wireless power transfer source of the wireless power transfer system, and wherein the at least some of the plurality of detectors comprising the first number of loops are positioned in regions where the magnetic field is larger than in regions in which the at least some of the plurality of detectors comprising the second number of loops are positioned.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the plurality of detectors form an array.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein spacings between at least some adjacent detectors in the array are different.

### Claim 7 (depends on 5)

The apparatus of claim 5, wherein cross-sectional areas of at least some detectors in the array are different from cross-sectional areas of at least some other detectors in the array.

### Claim 8

A method for detecting foreign object debris around a wireless power transfer system, the method comprising:
measuring at least one of a voltage and a current in each one of a plurality of detectors, wherein the plurality of detectors are positioned so that each detector receives at least a portion of a common oscillating magnetic field generated by the wireless power transfer system; and
determining, based on the measurements, whether foreign object debris is present around the wireless power transfer system,
wherein each of the detectors comprises one or more loops of conducting material; and
wherein at least some of the plurality of detectors comprise a first number of loops of the conducting material, and at least some of the plurality of detectors comprise a second number of loops of the conducting material larger than the first number.

### Claim 9 (depends on 1)

The apparatus of claim 1, wherein the common oscillating magnetic field is generated by a source resonator of the wireless power transfer system.

### Claim 10 (depends on 1)

The apparatus of claim 1, wherein the common oscillating magnetic field is generated by an auxiliary coil that is different from a source resonator of the wireless power transfer system.

### Claim 11 (depends on 1)

The apparatus of claim 1, wherein at least some of the detectors comprising the second number of loops are positioned in regions where a maximum amplitude of the common oscillating magnetic field is smaller than in regions where at least some of the detectors comprising the first number of loops are positioned.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein each of the detectors comprising the second number of loops is positioned in a region where a maximum amplitude of the common oscillating magnetic field is smaller than in each of the regions where the detectors comprising the first number of loops is positioned.

### Claim 13 (depends on 8)

The method of claim 8, wherein at least some of the plurality of detectors comprise one loop, and wherein at least some of the plurality of detectors comprise two loops.

### Claim 14 (depends on 13)

The method of claim 13, wherein at least some of the plurality of detectors comprise three loops.

### Claim 15 (depends on 8)

The method of claim 8, further comprising generating the common oscillating magnetic field using a source resonator of the wireless power transfer system.

### Claim 16 (depends on 8)

The method of claim 8, further comprising generating the common oscillating magnetic field using an auxiliary coil that is different from a source resonator of the wireless power transfer system.

### Claim 17 (depends on 8)

The method of claim 8, wherein at least some of the detectors comprising the second number of loops are positioned in regions where a maximum amplitude of the common oscillating magnetic field is smaller than in regions where at least some of the detectors comprising the first number of loops are positioned.

### Claim 18 (depends on 17)

The method of claim 17, wherein each of the detectors comprising the second number of loops is positioned in a region where a maximum amplitude of the common oscillating magnetic field is smaller than in each of the regions where the detectors comprising the first number of loops is positioned.