US-12625193-B2 - Droop compensation for device under test spectroscopy

US12625193B2US 12625193 B2US12625193 B2US 12625193B2US-12625193-B2

Abstract

A method includes transforming a signal from a first domain representation to a second domain representation, the signal representing a parameter of a device and having multiple cycles. The method further comprises determining the second domain representation of a droop component of the parameter based on the signal, in which the droop component represents a rate of change of the parameter across one or more cycles of the multiple cycles. The method further comprises generating an adjusted parameter of the device based on combining the respective second domain representations of the parameter and the droop component.

Inventors

Charles Kasimer Sestok, IV
David Patrick Magee

Assignees

TEXAS INSTRUMENTS INCORPORATED

Dates

Publication Date: 20260512
Application Date: 20230922

Claims (20)

1 . A method, comprising: transforming a signal from a first domain representation to a second domain representation, the signal representing a parameter of a device and having multiple cycles; determining the second domain representation of a droop component of the parameter, in which the droop component represents a rate of change of the parameter across one or more cycles of the multiple cycles; and generating an adjusted parameter of the device responsive to combining the respective second domain representations of the parameter and the droop component.
2 . The method of claim 1 , wherein the signal is a first signal, and the method further comprises: determining the second domain representation of an excitation signal, in which the parameter represents a response of the device to the excitation signal; responsive to determining the second domain representation of the excitation signal, determining a first component of the parameter and a second component of the droop component, and wherein generating the adjusted parameter of the device responsive to combining the respective second domain representations of the parameter and the droop component includes generating a third component of the adjusted parameter responsive to combining the first and second components.
3 . The method of claim 2 , wherein responsive to determining the second domain representation of the excitation signal, determining the first component of the parameter and the second component of the droop component includes: determining, from the second domain representation of the excitation signal, a particular second domain bin; and determining, from the second domain representation of the parameter, the first component associated with the particular second domain bin; and determining, from the second domain representation of the droop component, the second component associated with the particular second domain bin.
4 . The method of claim 2 , wherein determining the second domain representation of a droop component of the parameter includes: determining, from the first domain representation of the parameter, a first value associated with a first time; determining, from the first domain representation of the parameter, a second value associated with a second time; and determining the second domain representation of the droop component responsive to determining the first and second values.
5 . The method of claim 4 , wherein determining the second domain representation of the droop component includes determining a slope responsive to determining the first value and the second value, and wherein an amount of time between the first time and the second time is equal to an integer multiple of a period of the excitation signal.
6 . The method of claim 5 , wherein the slope is determined responsive to a least-square line fitting computation.
7 . The method of claim 1 , wherein the device includes a battery cell or a group of battery cells.
8 . The method of claim 2 , wherein the excitation signal includes at least one of a current signal or a voltage signal, and wherein the parameter includes at least one of: a current conducted by the device, a voltage across the device, or an impedance of the device.
9 . The method of claim 2 , further comprising: receiving samples of a current through the device or a voltage across the device; and identifying subsets of the samples in different windows; and determining the parameter responsive to averaging the subsets of the samples.
10 . The method of claim 1 , wherein the first domain representation is a time domain representation, and the second domain representation is a frequency domain representation.
11 . A system, comprising: a parameter determination circuit having a device input and a parameter output, the device input coupled to a device, and the parameter determination circuit configurable to transform a signal from a first domain representation to a second domain representation, and provide the second domain representation of the signal at the parameter output, the signal representing a parameter of a device and having multiple cycles; a droop determination circuit having a first parameter input and a droop output, the first parameter input coupled to the parameter output, and the droop determination circuit configurable to provide the second domain representation of a droop component of the parameter at the droop output, in which the droop component represents a rate of change of the parameter across one or more cycles of the multiple cycles; and a parameter adjustment circuit having a second parameter input, a droop input, and an adjusted parameter output, the second parameter input coupled to the parameter output, the droop input coupled to the droop output, and the parameter adjust circuit configurable to provide an adjusted parameter of the device at the adjusted parameter output responsive to combining the respective second domain representations of the parameter and the droop component.
12 . The system of claim 11 , wherein: the signal is a first signal; the parameter determination circuit has a second domain bin output and configurable to: determine the second domain representation of an excitation signal, in which the parameter represents a response of the device to the excitation signal; responsive to determining the second domain representation of the excitation signal, provide a first component of the parameter associated with a particular second domain bin at the parameter output and a second signal representing the particular second domain bin at the second domain bin output; and the droop determination circuit has a second domain bin input coupled to the second domain bin output and configurable to provide a second component of the droop component associated with the particular second domain bin responsive to the second signal; and the parameter adjustment circuit is configurable to provide the adjusted parameter based generating a third component of the adjusted parameter associated with the particular second domain bin responsive to combining the first and second components.
13 . The system of claim 12 , wherein the first domain representation is a time domain representation, and the droop determination circuit is configurable to: determine, from the time domain representation of the parameter, a first value associated with a first time; determine, from the time domain representation of the parameter, a second value associated with a second time; and determine the second domain representation of the droop component responsive to determining the first and second values.
14 . The system of claim 13 , wherein the droop determination circuit is configurable to determine a slope responsive to determining the first value and the second value, and wherein an amount of time between the first time and the second time is equal to an integer multiple of a period of the excitation signal.
15 . The system of claim 14 , wherein the droop determination circuit is configurable to determine the slope responsive to a least-square line fitting computation.
16 . The system of claim 11 , wherein the device includes a battery cell or a group of battery cells.
17 . The system of claim 12 , wherein the excitation signal includes at least one of a current signal or a voltage signal, and wherein the parameter includes at least one of: a current conducted by the device, a voltage across the device, or an impedance of the device.
18 . The system of claim 11 , wherein the first domain representation is a time domain representation, and the second domain representation is a frequency domain representation.
19 . A non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to: transform a signal from a first domain representation to a second domain representation, the signal representing a parameter of a device and having multiple cycles; determine the second domain representation of a droop component of the parameter, in which the droop component represents a rate of change of the parameter across one or more cycles of the multiple cycles; and generate an adjusted parameter of the device responsive to combining the respective second domain representations of the parameter and the droop component.
20 . The non-transitory computer-readable medium of claim 19 , further comprising instructions that, when executed by the processor, cause the processor to: determining the second domain representation of an excitation signal, in which the parameter represents a response of the device to the excitation signal; responsive to determining the second domain representation of the excitation signal, determine a first component of the parameter and a second component of the droop component, and generate a third component of the adjusted parameter responsive to combining the first and second components.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of U.S. patent application Ser. No. 17/463,186, filed Aug. 31, 2021, titled “Droop Compensation For Device Under Test Spectroscopy”, and claims priority to U.S. Provisional Patent Application No. 63/148,638, filed Feb. 12, 2021, titled “Voltage Droop Compensation For Battery Electrochemical Impedance Spectroscopy,” both of which are incorporated herein by reference in their entireties. BACKGROUND Spectroscopy measures device under test (DUT) response spectra to characterize behavior of the DUT as a function of frequency. One type of spectroscopy is electrochemical impedance spectroscopy (EIS), in which the DUT is a battery cell or a group of battery cells, and the measured response is battery impedance. SUMMARY In an example of this description, a method includes determining a droop component of a measured parameter of a device under test (DUT). The measured parameter is responsive to an excitation signal having a frequency component, and the droop component is determined responsive to a first value of the parameter at a first time and a second value of the parameter at a second time. The parameter at the first time has a first phase value, and the parameter at the second time has a second phase value. The first phase value is equal to the second phase value. The method also includes correcting a frequency domain representation of the parameter by applying the droop component at a frequency of the representation of the parameter corresponding to the frequency component of the excitation signal. In another example of this description, a system includes a droop estimation circuit configured to determine a droop component of a parameter. The parameter is responsive to an excitation signal provided to a device under test (DUT), and the excitation signal includes a frequency component. The droop component is determined responsive to a first value of the parameter at a first time and a second value of the parameter at a second time. The parameter at the first time has a first phase value, and the parameter at the second time has a second phase value. The first phase value is equal to the second phase value. The system also includes a droop correction circuit coupled to the droop estimation circuit. The droop correction circuit is configured to correct a frequency domain representation of the parameter by applying the droop component at a frequency of the representation of the parameter corresponding to the frequency component of the excitation signal. In yet another example of this description, a non-transitory, computer-readable medium contains instructions that, when executed by a processor, cause the processor to be configured to determine a droop component of a measured parameter of a device under test (DUT). The measured parameter is responsive to an excitation signal that includes a frequency component, and the droop component is determined responsive to a first value of the parameter at a first time a second value of the parameter at a second time. The parameter at the first time has a first phase value, and the parameter at the second time has a second phase value. The first phase value is equal to the second phase value. The instructions, when executed by the processor, also cause the processor to be configured to correct a frequency domain representation of the parameter by applying the droop component at a frequency of the representation of the parameter corresponding to the frequency component of the excitation signal. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a model circuit diagram of a device under test, such as a battery, in an example. FIG. 2 is a circuit diagram of a battery monitoring system coupled to battery logical cells in an example. FIG. 3 is a graph of a waveform of a measured parameter of a device under test, which demonstrates estimating a droop component in an example. FIG. 4 is a block diagram of a system to compensate for a droop component in a measured parameter of a device under test in an example. FIG. 5 is a block diagram of a system to compensate for a droop component in a measured parameter of a device under test, and in an excitation signal provided to the device under test, in an example. FIG. 6 is a graph of a waveform of a measured parameter of a device under test, which demonstrates estimations of a droop component using multiple sample lines in an example. FIG. 7 is a flow chart of a method of compensating for a droop component in a measured parameter of a device under test in an example. FIG. 8 is a graph of the power spectra for measured parameter waveforms demonstrating a reduction in interference that results from using droop compensation systems and methods in an example. FIG. 9 is a graph comparing impedance spectrum estimates of a device under test with and without using droop compensation systems and/or methods in an example DETAILED DESCRIPTION In some cases, circuit models appro