06172483 is referenced by 128 patents and cites 151 patents.

A periodic time-varying current with smallest period 1/f

1

excites a cell/battery and provides a timing reference. Linear circuitry produces two signals, one proportional to the excitation current, the other proportional to the responding time-varying voltage. These signals are processed with identical frequency-limiting filters to attenuate higher-order harmonics and noise. Using the timing reference for synchronization, a microprocessor/microcontroller commands analog to digital converters to sample the frequency-limited current and voltage signals at equally-spaced times over a period and accepts the digitized samples as inputs. The digital samples are averaged over multiple periods and employed to calculate averaged Fourier coefficients of in-phase and quadrature components of frequency-limited current and voltage at frequency f

1

. By numerically combining these Fourier coefficients, the microprocessor/microcontroller determines real and imaginary parts of the cell/battery's complex impedance at frequency f

1

.

Title
Method and apparatus for measuring complex impedance of cells and batteries
Application Number
9/454629
Publication Number
6172483 (B2)
Application Date
December 3, 1999
Publication Date
January 9, 2001
Inventor
Keith S Champlin
5437 Elliot Ave. South, Minneapolis
MN, US
Agent
Westman Champlin & Kelly P A
US
IPC
H02J 7/00
View Original Source