# US 11,112,814 B2 · Impedance adjustment in wireless power transmission systems and methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,814 B2 - Document ID: US11112814B2 - Status: Granted - Kind: B2 - Application number: 15/837,904 - Filed: 2017-12-11 - Published: 2018-04-12 - Granted: 2021-09-07 - Earliest claimed: 2013-08-14 - Assignees: WiTricity Corporation - Applicants: WiTricity Corporation - Inventors: Andre B. Kurs; Morris P. Kesler; Noam Katz; Matthew Dillon; Herbert Toby Lou - Web page: https://patentgrep.com/patent/US11112814B2 ## CPC - G05F 1/625: wherein it is irrelevant whether the variable actually regulated is AC or DC - B60L 53/122: Circuits or methods for driving the primary coil, e.g. supplying electric power to the coil - G05F 1/66: Regulating electric power - H02J 50/12: of the resonant type - H02J 50/80: involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices - H02J 7/933: {the cycle being controlled or terminated in response to electric parameters} - H02J 2105/37: exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] - 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 - G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES - 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 - 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 The disclosure features wireless power transfer systems that include a power transmitting apparatus configured to wirelessly transmit power, a power receiving apparatus connected to an electrical load and configured to receive power from the power transmitting apparatus, and a controller connected to the power transmitting apparatus and configured to receive information about a phase difference between output voltage and current waveforms in a power source of the power transmitting apparatus, and to adjust a frequency of the transmitted power based on the measured phase difference. ## Claims ### Claim 1 A power transmitting apparatus configured to wirelessly transmit power to a power receiving apparatus connected to an electrical load, the power transmitting apparatus comprising: a circuit comprising an inductive element formed by at least one loop of conductive material, wherein the inductive element forms a resonator with at least a portion of the circuit; and a controller configured to: receive information about a phase difference between a voltage waveform and a current waveform associated with impedance matching circuitry of a power source of the power transmitting apparatus; determine whether the phase difference is within an allowable range of phase differences; adjust an impedance of the circuit if the phase difference is outside the allowable range of phase differences; and adjust at least one of a phase, a duty cycle, and a bus voltage of an amplifier of the power source if the phase difference is within the allowable range of phase differences to drive the power transmitting apparatus toward a target output power. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the controller is further configured to receive information about a phase difference between a voltage waveform and a current waveform associated with an amplifier of the power source of the power transmitting apparatus. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the voltage and current waveforms correspond to one member selected from the group consisting of voltage and current waveforms within the impedance matching circuitry, voltage and current waveforms at an output of the impedance matching circuitry, and voltage and current waveforms at an input of the impedance matching circuitry. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the controller is configured to adjust the impedance of the circuit to reduce the phase difference. ### Claim 5 (depends on 4) The apparatus of claim 4, further comprising: a detector coupled to the power source and to the controller, and comprising: a first input terminal configured to receive a first waveform corresponding to the voltage waveform; a second input terminal configured to receive a second waveform corresponding to the current waveform; and at least one logic unit, wherein the at least one logic unit is configured to generate an output waveform that corresponds to the phase difference between the first and second waveforms; and wherein the controller is configured to receive the output waveform from the detector. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the at least one logic unit comprises: a first logic unit connected to the first and second input terminals and configured to produce a third waveform based on the first and second waveforms; and a second logic unit configured to receive the third waveform and configured to produce the output waveform based on the third waveform. ### Claim 7 (depends on 5) The apparatus of claim 5, wherein the output waveform comprises a pulse having a width that corresponds to a temporal offset between the first and second electrical signals. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein the first logic unit is configured to perform an AND logical operation, and the second logic unit is configured to perform an XOR logical operation. ### Claim 9 (depends on 4) The apparatus of claim 4, wherein the controller is configured to reduce the impedance of the circuit to reduce the phase difference. ### Claim 10 (depends on 4) The apparatus of claim 4, wherein the controller is configured to increase the impedance of the circuit to increase the phase difference. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the controller is configured to adjust a frequency of the power source based on the target output power of the power transmitting apparatus. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the power transmitting apparatus is configured to transmit power to the power receiving apparatus when the power receiving apparatus is mounted to an electric vehicle. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the power transmitting apparatus is configured to transmit power to the power receiving apparatus when the electrical load comprises one or more batteries of an electric vehicle. ### Claim 14 A method comprising: wirelessly transferring power from a power transmitting apparatus to a power receiving apparatus connected to an electrical load; receiving a first electrical signal comprising information about a voltage waveform associated with impedance matching circuitry of a power source of the power transmitting apparatus; receiving a second electrical signal comprising information about a current waveform associated with the impedance matching circuitry of the power source; determining a phase difference between the first and second electrical signals; determining whether the phase difference is within an allowable range of phase differences; adjusting an impedance of a circuit of the power transmitting apparatus if the phase difference is outside the allowable range of phase differences; and adjusting at least one of a phase, a duty cycle, and a bus voltage of an amplifier of the power source if the phase difference is within the allowable range of phase differences to drive the power transmitting apparatus toward a target output power. ### Claim 15 (depends on 14) The method of claim 14, further comprising adjusting a frequency of a component of the power source based on the target output power of the power transmitting apparatus. ### Claim 16 (depends on 14) The method of claim 14, further comprising adjusting at least one of an inductor and a capacitor of the circuit based on the phase difference to adjust the impedance of the circuit. ### Claim 17 (depends on 14) The method of claim 14, comprising adjusting the impedance of the circuit to minimize the phase difference.