AC impedance measuring apparatus and AC impedance measuring method

摘要

PROBLEM TO BE SOLVED: To measure the AC impedance of a battery always with high accuracy.SOLUTION: While calculating a current detection value and a voltage detection value DV in a detection period P while shifting a test AC voltage by a half cycle at a time, an AC impedance measurement device calculates, each time a new voltage detection value DV is calculated, an average value about two sets of voltage detection values (DV, DV), (DV, DV) composed of two consecutive voltage detection values among three latest voltage detection values DV, DV, DV. The AC impedance measurement device also executes a determination process for determining whether or not a difference in absolute value (half value of |DV-DV|) between the two calculated average values falls within a predefined reference range, and, when determined to be within, specifies that a linear change state is in, executes an impedance calculation process on the basis of the latest current detection value and the latest voltage detection value DV, and calculates an AC impedance.