Multispectral impedance measurements across strings of interconnected cells
An in-line rapid impedance measurement device and methods of performing in-line rapid impedance spectroscopy including a switch network operable under a switching algorithm useful to rapidly perform targeted impedance measurements to assess state of health, defect or failure of battery packs or modules having a plurality of electrochemical cells interconnected in series or parallel and to isolate individual cells within a pack or module to distinguish between non-repeatable anomalous impedance measurements from repeatable deviant impedance measurements and identify the source of deviant impedance measurements.
1. A device, comprising:
a processor communicatively coupled to a non-transitory computer readable media containing a program code including:
a high-fidelity cell impedance spectrum algorithm, a mid-fidelity cell impedance spectrum algorithm, and a low fidelity cell impedance spectrum algorithm; and
a switching algorithm;
a switching circuit controlled by said switching algorithm under control of said processor to connect a plurality of cells to said impedance measurement device, said switching circuit switchable to electrically connect said plurality of cells (C 1 , C 2 , . . . C n ) in a series string of cells (C 1 s , C 2 s , . . . C ns ), or electrically connect said plurality of cells (C 1 , C 2 , C n ) in a parallel string of cells (C 1 p , C 2 p , . . . C np ) or electrically connect all of said plurality of cells (C 1 , C 2 , . . . C n ) interconnected in a series string of cells (s) and/or in a parallel string of cells (p); and
an impedance measurement device controlled by said program code to:
apply one or more of a high-fidelity stimulus signal, a mid-fidelity stimulus signal, or a low fidelity cell stimulus signal to said plurality of cells;
detect a response signal to said one or more of said high-fidelity stimulus signal, said mid-fidelity stimulus signal or said low fidelity stimulus signal applied to said plurality of cells;
process said response signal to said one or more of said high-fidelity stimulus signal, said mid-fidelity stimulus signal, or said low fidelity stimulus signal applied to said plurality of cells; and
correspondingly generate a high-fidelity impedance measurement spectrum, a mid-fidelity impedance measurement spectrum, or a low-fidelity impedance measurement spectrum.
2. The device of claim 1 , wherein said plurality of cells can comprise a pack, a module, sub-module, or individual cells within a pack, a module or a sub-module.
3. The device of claim 1 , said program code further executable to assess a controlled in-use cell condition or a controlled rest cell condition of said plurality of cells.
4. The device of claim 3 , wherein said program code executable to:
perform a high-fidelity impedance measurement of said plurality of cells;
detect an anomalous condition in said plurality of cells based on a deviation of said high-fidelity impedance measurement to a preselected impedance measurement threshold; and
repeatedly perform a low-fidelity impedance measurement of said plurality of cells within a pack or module to identify a cell string or a cell within said plurality of cells associated said deviation of said high-fidelity impedance measurement to said preselected impedance measurement threshold.
5. The device of claim 4 , wherein said high-fidelity impedance measurement includes a greater number of stimulus signal frequencies than said low-fidelity stimulus signal.
6. The device of claim 5 , wherein said high-fidelity impedance measurement includes a longer measurement duration than said low-fidelity impedance measurement.
7. The device of claim 1 , wherein said program code further executable to:
analyze said one or more of said high-fidelity impedance measurement spectrum, said mid-fidelity impedance measurement spectrum, or said low-fidelity impedance measurement spectrum; and
update a stability of said plurality of cells.