# US 2022/0037933 A1 · Low power object detection in multi-coil wireless charging systems and related systems, methods, and devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0037933 A1 - Document ID: US20220037933A1 - Status: Published application - Kind: A1 - Application number: 17/451,673 - Filed: 2021-10-21 - Published: 2022-02-03 - Earliest claimed: 2020-03-03 - Assignees: Microchip Technology Incorporated - Applicants: Microchip Technology Incorporated - Inventors: Santosh Bhandarkar; Alex Dumais - Web page: https://patentgrep.com/patent/US20220037933A1 ## CPC - H02J 50/60: responsive to the presence of foreign objects, e.g. detection of living beings - G01R 27/2611: {Measuring inductance} - 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} - H04B 5/263: {Multiple coils at either side} - H04B 5/48: Transceivers - H04B 5/79: for data transfer in combination with power transfer - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H04B: TRANSMISSION ## Abstract Object detection for wireless power transmitters and related systems, methods, and devices are disclosed. A controller for a wireless power transmitter is configured to receive a measurement voltage potential responsive to a tank circuit signal at a tank circuit, provide an alternating current (AC) signal to each of the plurality of transmit coils one at a time, and determine at least one of a resonant frequency and a quality factor (Q-factor) of the tank circuit responsive to each selected transmit coil of the plurality of transmit coils. The controller is also configured to select a transmit coil to use to transmit wireless power to a receive coil of a wireless power receiver responsive to the determined at least one of the resonant frequency and the Q-factor for each transmit coil of the plurality of transmit coils. ## Claims ### Claim 1 An apparatus, comprising: a measurement voltage potential input terminal to receive a measurement voltage potential responsive to a tank circuit signal at a tank circuit of a wireless power transmitter, the tank circuit including a plurality of transmit coils; and a processing core to: control one or more coil select signals to provide an alternating current (AC) signal to charge each of the plurality of transmit coils one at a time; determine at least one of a resonant frequency and a quality factor (Q-factor) of the tank circuit responsive to discharge of each selected transmit coil of the plurality of transmit coils in absence of the AC signal after completion of provision of the AC signal to the tank circuit; and select a transmit coil from the plurality of transmit coils to use to transmit wireless power to a receive coil of a wireless power receiver responsive to the determined at least one of the resonant frequency and the Q-factor for each transmit coil of the plurality of transmit coils. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the processing core is to determine both the resonant frequency and the Q-factor of the tank circuit responsive to the discharge of each selected transmit coil of the plurality of transmit coils in the absence of the AC signal after the completion of the provision of the AC signal to the tank circuit. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the processing core is to identify a lowest Q-factor transmit coil of the plurality of transmit coils associated with a lowest determined Q-factor value; and identify a lowest resonant frequency transmit coil associated with a lowest determined resonant frequency value. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the processing core is to determine that a foreign object is located proximate to the one or more transmit coils responsive to: a determination that the lowest determined Q-factor value is less than a threshold minimum Q-factor value; and a determination that the lowest determined resonant frequency value is greater than an expected uncoupled resonant frequency. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the processing core is to enter a sleep mode responsive to a determination that the foreign object is located proximate to the one or more transmit coils. ### Claim 6 (depends on 3) The apparatus of claim 3, wherein the processing core is to determine that a proximity of the one or more transmit coils is free of foreign objects and receive coils responsive to: a determination that the lowest determined Q-factor value is not less than a threshold minimum Q-factor value; and a determination that the lowest determined resonant frequency value is not less than a threshold minimum resonant frequency value. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the processing core is to enter a sleep mode responsive to a determination that the proximity of the one or more transmit coils is free of foreign objects and receive coils. ### Claim 8 (depends on 3) The apparatus of claim 3, wherein the processing core is to select the lowest Q-factor transmit coil to transmit the wireless power to the receive coil responsive to: a determination that the lowest determined Q-factor value is less than a threshold minimum Q-factor value; and a determination that the lowest determined resonant frequency value is not greater than an expected uncoupled resonant frequency. ### Claim 9 (depends on 3) The apparatus of claim 3, wherein the processing core is to select the lowest resonant frequency transmit coil to transmit the wireless power to the receive coil responsive to: a determination that the lowest determined Q-factor value is not less than a threshold minimum Q-factor value; and a determination that the lowest determined resonant frequency value is less than a threshold minimum resonant frequency value. ### Claim 10 (depends on 3) The apparatus of claim 3, wherein the processing core is to determine that the receive coil is proximate to the plurality of transmit coils responsive to each one of: determinations that both the lowest determined Q-factor value is less than a threshold minimum Q-factor value and the lowest determined resonant frequency value is not greater than an expected uncoupled resonant frequency; and determinations that both the lowest determined Q-factor value is not less than a threshold minimum Q-factor value and the lowest determined resonant frequency value is less than a threshold minimum resonant frequency value. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein a selected transmit coil is to transmit the wireless power to the receive coil responsive to a selection, by the processing core, of the selected transmit coil. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the processing core is to determine the at least one of the resonant frequency and the Q-factor of the tank circuit based, at least in part, on identified peaks of the measurement voltage potential responsive to the discharge of each selected transmit coil of the plurality of transmit coils in the absence of the AC signal after the completion of the provision of the AC signal to the tank circuit. ### Claim 13 A method of operating a controller for a wireless power transmitter, the method comprising: sampling a measurement voltage potential responsive to a tank circuit signal at a tank circuit of the wireless power transmitter, the tank circuit including a plurality of transmit coils; providing an alternating current (AC) signal to charge each of the plurality of transmit coils one at a time; determining at least one of a resonant frequency and a quality factor (Q-factor) of the tank circuit responsive to discharge of each selected transmit coil of the plurality of transmit coils in absence of the AC signal after completion of provision of the AC signal to the tank circuit; and selecting a transmit coil from the plurality of transmit coils to use to transmit wireless power to a receive coil of the wireless power receiver responsive to the determined at least one of the resonant frequency and the Q-factor for each transmit coil of the plurality of transmit coils. ### Claim 14 (depends on 13) The method of claim 13, wherein determining the at least one of the resonant frequency and the Q-factor of the tank circuit comprises determining both the resonant frequency and the Q-factor of the tank circuit responsive to the discharge of each selected transmit coil of the plurality of transmit coils in the absence of the AC signal after the completion of the provision of the AC signal to the tank circuit. ### Claim 15 (depends on 13) The method of claim 13, comprising entering a sleep mode responsive to a determination that a foreign object is located proximate to the one or more transmit coils. ### Claim 16 (depends on 13) The method of claim 13, comprising entering a sleep mode responsive to a determination that a proximity of the one or more transmit coils is free of foreign objects and receive coils. ### Claim 17 (depends on 13) The method of claim 13, comprising controlling a selected transmit coil to transmit the wireless power to the receive coil responsive to the selecting of the selected transmit coil. ### Claim 18 (depends on 13) The method of claim 13, comprising determining the at least one of the resonant frequency and the Q-factor of the tank circuit based, at least in part, on identified peaks of the measurement voltage potential responsive to the discharge of each selected transmit coil of the plurality of transmit coils in the absence of the AC signal after the completion of the provision of the AC signal to the tank circuit. ### Claim 19 (depends on 18) The method of claim 18, comprising identifying the identified peaks of the measurement voltage potential. ### Claim 20 (depends on 13) The method of claim 13, wherein providing the AC signal to charge each of the plurality of transmit coils one at a time comprises controlling one or more coil select signals to select the plurality of transmit coils one at a time.