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Signal Pre-Processing
This section describes how slow and fast filters are applied to current, cell voltage, and temperature for different BMS functions
Calibration Parameters
\[
N_{\text{slo}} = 10, \quad N_{\text{fast}} = 5
\]
Slow Inputs (SOC Function, 200 ms)
The State of Charge (SOC) function requires slow filtering.
- Current filter:
\[
I_{\text{filt-slo}}(k) =
\frac{1}{N_{\text{slo}}}
\sum_{i=0}^{N_{\text{slo}}-1} I(k-i)
\]
- Cell Voltage filter:
\[
V_{\text{cell, filt-slo}}(k) =
\frac{1}{N_{\text{slo}}}
\sum_{i=0}^{N_{\text{slo}}-1} V_{\text{cell}}(k-i)
\]
- Temperature filter:
\[
T_{\text{filt-slo}}(k) =
\frac{1}{N_{\text{slo}}}
\sum_{i=0}^{N_{\text{slo}}-1} T(k-i)
\]
Fast Inputs (SOP Function, 100 ms)
The State of Power (SOP) function requires fast filtering.
- Current filter:
\[
I_{\text{filt-fast}}(k) =
\frac{1}{N_{\text{fast}}}
\sum_{i=0}^{N_{\text{fast}}-1} I(k-i)
\]
- Cell Voltage filter:
\[
V_{\text{cell, filt-fast}}(k) =
\frac{1}{N_{\text{fast}}}
\sum_{i=0}^{N_{\text{fast}}-1} V_{\text{cell}}(k-i)
\]
- Temperature filter:
\[
T_{\text{filt-fast}}(k) =
\frac{1}{N_{\text{fast}}}
\sum_{i=0}^{N_{\text{fast}}-1} T(k-i)
\]
Synchronization Rule
Important
Whenever a function uses current and voltage together,
it must consistently use either slow-filtered or fast-filtered signals,
but never mix them.
This ensures synchronization of current & voltage measurements.