Patent ID: 6172483
Filing Date: 2001-01-09
Classification: G01R,Y10S

Abstract:
Apparatus for evaluating a component of the complex impedance of an electrochemical cell or battery at a discrete frequency comprising:current excitation circuitry coupled to said cell or battery and adapted to pass a periodic excitation current through said cell or battery, said periodic excitation current characterized by a smallest period equal to the reciprocal of said discrete frequency;current sensing and processing circuitry coupled to said current excitation circuitry and adapted to provide a current signal in response to said periodic excitation current;voltage sensing and processing circuitry coupled to said cell or battery and adapted to provide a voltage signal in response to a periodic voltage across said cell or battery;current-signal sampling circuitry coupled to said current sensing and processing circuitry and adapted to provide sampled values of said current signal, said sampled values acquired at discrete current-signal sampling times synchronized with said periodic excitation current and uniformly distributed in time over half-period or full-period intervals of said smallest period of said periodic excitation current;voltage-signal sampling circuitry coupled to said voltage sensing and processing circuitry and adapted to provide sampled values of said voltage signal, said sampled values acquired at discrete voltage-signal sampling times synchronized with said periodic excitation current and uniformly distributed in time over half-period or full-period intervals of said smallest period of said periodic excitation current; and,computation and control circuitry coupled to said current-signal sampling circuitry and to said voltage-signal sampling circuitry and adapted to combine said sampled values of said current signal and said sampled values of said voltage signal to evaluate said component of said complex impedance at said discrete frequency.