# US 12,000,903 B2 · Impedance determination with phase determination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,000,903 B2 - Document ID: US12000903B2 - Status: Granted - Kind: B2 - Application number: 17/770,771 - Filed: 2020-10-23 - Published: 2022-11-17 - Granted: 2024-06-04 - Earliest claimed: 2019-10-31 - Assignees: Bayerische Motoren Werke Aktiengesellschaft - Applicants: Bayerische Motoren Werke Aktiengesellschaft - Inventors: Jan Philipp Schmidt - Web page: https://patentgrep.com/patent/US12000903B2 ## CPC - G01R 31/389: Measuring internal impedance, internal conductance or related variables - G01R 19/2509: {Details concerning sampling, digitizing or waveform capturing} - G01R 27/28: Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response (in line transmission systems H04B3/46) - G01R 31/367: Software therefor, e.g. for battery testing using modelling or look-up tables - G01R 35/005: {Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence)} - G01R 25/00: Arrangements for measuring phase angle between a voltage and a current or between voltages or currents - G01R 27/14: Measuring resistance by measuring current or voltage obtained from a reference source (G01R27/16, G01R27/20, G01R27/22 take precedence) - Y02E 60/10: Energy storage using batteries - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method for the correction of synchronization errors Δt in the measurement of the impedance of an electrical or electrochemical component, more particularly a lithium ion cell is provided. In general, synchronization errors in an impedance measurement can arise between the excitation and response signals, which can misrepresent the phase of the impedance value obtained. According to the method, the synchronization error can be determined by measuring the impedance at two different frequencies and solving an optimization problem in respect of the deviation of the phases from an equivalent circuit diagram, which comprises at least one resistance and an inductance. The phase of the impedance value obtained can be corrected in this way. ## Claims ### Claim 1 A method for determining an impedance of an electrical or electrochemical component with correction of a synchronization error, the method comprising: choosing an impedance model for the component, which has a resistance and an inductance; applying an excitation signal with a first frequency and a second frequency; measuring a response signal, which is beset by the synchronization error relative to the excitation signal; determining a first impedance at the first frequency and a second impedance at the second frequency from the excitation signal and the response signal; determining the synchronization error as a value for which a deviation between a difference between the second impedance and the first impedance and a corresponding value of an impedance difference that is calculated for an equivalent circuit diagram falls below a predetermined threshold value in respect of at least one impedance component; and correcting values of the first impedance and the second impedance using the synchronization error. ### Claim 2 (depends on 1) The method of claim 1, wherein the component is a lithium ion cell. ### Claim 3 (depends on 1) The method according to claim 1, wherein: determining the synchronization error is carried out iteratively, in each iteration the difference is calculated, from a phase of the difference a differential is calculated and accumulated, and from an accumulated value a phase of the first impedance and the second impedance is corrected. ### Claim 4 (depends on 1) The method according to claim 1, wherein the first frequency and the second frequency are between 1 kHz and 20 kHz. ### Claim 5 (depends on 1) The method according to claim 1, further comprising determining an impedance at one or more further frequencies that are lower than the first and the second frequency. ### Claim 6 (depends on 5) The method according to claim 5, wherein the one or more further frequencies are between 10 and 300 Hz. ### Claim 7 (depends on 5) The method according to claim 5, wherein the excitation signal comprises a superposition of the first frequency, the second frequency, and the one or more further frequencies. ### Claim 8 (depends on 1) The method according to claim 1, wherein the excitation signal comprises a superposition of the first frequency and the second frequency. ### Claim 9 (depends on 1) A battery system comprising: a plurality of lithium ion cells, wherein individual cells or blocks composed of a plurality of cells connected in parallel are connected in series; one or more signal generators that are configured to apply the excitation signal; one or more cell monitoring units that are configured to monitor a cell voltage of the lithium ion cells and to record the response signal; and one or more computing units that are configured to carry out the method according to claim 1. ### Claim 10 (depends on 9) The battery system according to claim 9, wherein the one or more signal generators comprise a single signal generator, which impresses the excitation signal globally on a total current. ### Claim 11 (depends on 9) The battery system according to claim 9, wherein the one or more computing units are integrated into the one or more cell monitoring units.