US 12,135,358 B2
Non steady state energy cell impedance measurement
Matheus Johannus Gerardus Lammers, Nederweert (NL); Henri Verhoeven, Someren (NL); Oswald Moonen, Eindhoven (NL); and Edwin Schapendonk, Oss (NL)
Assigned to NXP B.V., Eindhoven (NL)
Filed by NXP B.V., Eindhoven (NL)
Filed on Dec. 15, 2022, as Appl. No. 18/066,525.
Prior Publication US 2024/0201273 A1, Jun. 20, 2024
Int. Cl. G01R 31/389 (2019.01); G01R 31/3842 (2019.01); G01R 31/396 (2019.01)
CPC G01R 31/389 (2019.01) [G01R 31/3842 (2019.01); G01R 31/396 (2019.01)] 20 Claims
OG exemplary drawing
 
1. A method for measuring energy cell impedance, the method comprising:
generating a plurality of time sequences comprising:
a time sequence representing a repetitive signal at a characterizing frequency;
a time sequence representing an orthogonal-phase-repetitive signal at the characterizing frequency that is ninety degrees out of phase with the repetitive signal; and
at least one time sequence corresponding to a respective term of a power series polynomial, each respective term of the power series polynomial having at least one respective exponential value;
applying, to an energy cell, one of an electrical current or an electrical voltage corresponding to the time sequence representing the repetitive signal;
measuring, contemporaneously with the applying, a time sequence of measured values of a response waveform corresponding to another of the electrical current or the electrical voltage across the energy cell;
determining a set of correlation values comprising a respective correlation value between the time sequence of measured values and each of:
the time sequence representing the repetitive signal;
the time sequence representing the orthogonal-phase-repetitive signal; and
the at least one time sequence corresponding to a respective term of a power series polynomial; and
transforming the set of correlation values into a set of fitted coefficients comprising:
a fitted repetitive coefficient corresponding to a magnitude of a repetitive signal component within the time sequence of measured values at the characterizing frequency; and
a fitted orthogonal-phase-repetitive coefficient corresponding to a magnitude of an orthogonal-phase-repetitive signal component within the time sequence of measured values at the characterizing frequency that is ninety degrees out of phase with the repetitive signal component; and
determining an impedance of the energy cell at the characterizing frequency based on a ratio of the fitted orthogonal-phase-repetitive coefficient to the fitted repetitive coefficient.