The nominal voltage of the battery cell was changed without changing the other parameters. The effect of the nominal voltage of the battery cell on the output voltage of the power battery was obtained. The initial SOC, battery capacity, number of batteries in series and number of parallel connections remained unchanged.
The resulting voltage deviation Δ V depends on all three parameters discussed in Section 5.1. (8) Δ V = O C V (SoC) − O C V (SoC ¯) + Δ R abs ⋅ I Together, Eqs. (7) and (8) formalize the relation between parameter distributions and resulting voltage distributions.
For measuring the total module voltage and current, a Scienlab SL/80/100/8BT6C battery tester was used. The individual cell voltages were measured via a Scienlab SL/U/MCM16C, with the measurement tabs being located on the respective cell connectors interconnecting the parallel cell groups.
The DV standard deviation of cell i can be calculated by: (14) s i = ∑ t = t 0 t e (D V i t - DV ¯) l where l denotes the number of sampling points, and DV ¯ denotes the average value of DV for cell i from the time t0 to te. The DV standard deviation is a measure of the amount of variation or dispersion of DV.
Obtain the battery cell voltage matrix Um × n from the fault data, where m is the time point and n is the cell number. The voltage matrix U k × n ′ to be calculated every time is taken from the voltage matrix according to a certain time window, where k is the size of the time window.
In-situ determination of capacity and resistance distributions for battery systems. Cell voltage distributions are simulated using battery system modeling approach. Statistical methods are used to reduce computational complexity of system models.