Add thermal model documentation for FS-3 battery accumulator

Data/BatteryThermalModel/BatteryThermal.md

@@ -0,0 +1,64 @@
+## We are modeling and training the thermal model for our accumulator which holds the tractive battery for FS-3
+
+To understand the battery module:       
+There are 5 segments                 
+Each segment has 6 packs of Enpaqa VTC5A Sony/Murata Li-Ion 2x10p                           
+120 cells per segment, 600 cells total            
+
+## Equations
+
+### 1) HEAT GENERATION
+
+$Q = I^2 R$    
+
+Where:              
+Q: Total Heat Generated by the Tractive Battery   
+I: ACC_POWER_CURRENT from the parquet   
+R: 0.8Ω for one pack (2x10) ; 16Ω for the tractive battery 
+
+### 2) CONVECTION/COOLING FROM FANS
+
+$\frac{dT}{dt} = hA_s(\frac{Q}{n}-T_\infty)$    
+
+Where:  
+$\frac{Q}{n}$: Individual packs temprature (2x10) , n is the number of cells   
+$h$: Heat Transfer Coefficient        
+$T_\infty$: Ambient Temprature      
+$A_s$: Surface Area        
+
+### 3) CONDUCTION [Cell to Cell]
+
+$\frac{dT}{dt} = -k \cdot \frac{dT}{dt} \cdot A_c$  
+
+Where:                  
+$\frac{dT}{dt}$:   
+$k$: Thermal Conductivity
+
+### 4) CONDUCTION [Cell to Enclosure]       
+
+$\frac{dT}{dt} = -k \cdot \frac{dT}{dt} \cdot A_c$   
+
+Where:  
+$\frac{dT}{dt}$:   
+$k$: Thermal Conductivity
+
+### 5) CONVECTION (Enclosure to Air)
+
+$\frac{dT}{dt} = hA_s(T_s-T_\infty)$            
+
+Where:      
+$T_s$:   Surface Temprature     
+$h$: Heat Transfer Coeeficient        
+$T_\infty$: Ambient Temprature      
+$A_s$: Surface Area             
+
+### 6) RADIATION (Enclosure to Air)               
+
+$\frac{dT}{dt} = \epsilon \cdot \sigma \cdot A_s(T_s^4 - T_{sur}^4)$                        
+
+Where:      
+$\epsilon$: Emmisivity of Aluminum (Enclosure)      
+$\sigma$: 5.67 $\cdot$ $10^{-8}$        
+$A_s$: Surface Area         
+$T_s^4$: Surface Temprature     
+$T_{sur}^4$: Surrounding/Ambient Temprature

Data/BatteryThermalModel/DataColumns.py

@@ -1,13 +1,13 @@
-"""import matplotlib
+import matplotlib
 matplotlib.use('TkAgg')
 import matplotlib.pyplot as plt
 import polars as pl
 dfa = pl.read_parquet("fs-data/FS-3/08172025/08172025_27autox2&45C_35C_~28Cambient_100fans.parquet")
 dfb = pl.read_parquet("fs-data/FS-3/08172025/08172025_28autox3&4_45C_40C_~29Cambient_0fans.parquet")
 dfc = pl.read_parquet("08172025_20_Endurance1P1.parquet")
-print(dfc.columns)"""
-"""print(dfb.columns)
-print(dfa.columns)"""
+print(dfc.columns)
+print(dfb.columns)
+print(dfa.columns)
 
 import polars as pl
 import matplotlib.pyplot as plt

Data/BatteryThermalModel/DataFrames.py

@@ -0,0 +1,16 @@
+import polars as pl
+import matplotlib.pyplot as plt
+import numpy as np
+from scipy.optimize import curve_fit
+import sys
+sys.path.append(".")
+sys.path.append("..")
+sys.path.append("./Data")
+from Data.FSLib.IntegralsAndDerivatives import *
+dfa = pl.read_parquet("fs-data/FS-3/08172025/08172025_27autox2&45C_35C_~28Cambient_100fans.parquet")
+dfb = pl.read_parquet("fs-data/FS-3/08172025/08172025_28autox3&4_45C_40C_~29Cambient_0fans.parquet")
+print(dfa)
+print(dfb)
+print(dfa.columns)
+print(dfb.columns)
+

Data/BatteryThermalModel/FS4_FanTherm.py

@@ -3,11 +3,10 @@
 import numpy as np
 from scipy.optimize import curve_fit
 import sys
-from pathlib import Path
-
-sys.path.append(str(Path(__file__).resolve().parent.parent))
-
-from FSLib.IntegralsAndDerivatives import *
+sys.path.append(".")
+sys.path.append("..")
+sys.path.append("./Data")
+from Data.FSLib.IntegralsAndDerivatives import *
 # from Data.integralsAndDerivatives import in_place_derive
 
 def simpleTimeCol (dfa, dt=60/5035):

Data/BatteryThermalModel/FanBatteryThermalModeling.py

@@ -0,0 +1,91 @@
+#Fan&BatteryThermalModeling
+# Understanding the Tractive Battrey Accumulator Model
+## We have 5 segments, with each segment having six 2x10 packs/(cells according to the parquet). 120 cells per segment, 600 cells total. 
+# There are 3 holes in each segment which are cooling the batteries and the cells/packs are arranged 2x3 2 in the front and 3 wide, distance of the holes is 3 times the width/length
+import polars as pl
+import matplotlib.pyplot as plt
+import numpy as np
+import argparse
+from scipy.optimize import curve_fit
+import sys
+sys.path.append(".")
+sys.path.append("..")
+sys.path.append("./Data")
+from Data.FSLib.IntegralsAndDerivatives import *
+from Data.FSLib.AnalysisFunctions import *
+parser = argparse.ArgumentParser()
+parser.add_argument(
+    "parquet_path",
+    type=str,
+    help="Path to the Parquet file"
+)
+
+args = parser.parse_args()
+df = pl.read_parquet(args.parquet_path)
+
+#df1= pl.read_parquet("fs-data/FS-3/08172025/08172025_27autox2&45C_35C_~28Cambient_100fans.parquet")
+#df2= pl.read_parquet("fs-data/FS-3/08172025/08172025_28autox3&4_45C_40C_~29Cambient_0fans.parquet")
+#df3= pl.read_parquet("fs-data/FS-3/08102025/08102025Endurance1_FirstHalf.parquet")
+#time starts from 0
+
+#df1 = df1.with_columns(simpleTimeCol(df1))[6788:]
+#df2 = df2.with_columns(simpleTimeCol(df2))[69330+370+6788:]
+#df3 = df3.with_columns(simpleTimeCol(df3))[69330+370+6788:]
+ambientTemp = 28
+df = df.with_columns(simpleTimeCol(df))[6788:]
+df = df.with_columns((pl.col("Time") - df["Time"][ambientTemp]).alias("Time"))
+
+#time starts from 0
+#df1 = df1.with_columns((pl.col("Time") - df1["Time"][0]).alias("Time"))
+#df2 = df2.with_columns((pl.col("Time") - df2["Time"][0]).alias("Time"))
+#df3 = df3.with_columns((pl.col("Time") - df3["Time"][0]).alias("Time"))
+
+#constants
+mc = 1026 # J/K 1.14*900=1026
+Area = 0.02620083033 # m^2 A=n*l*c => n=20, l=0.0695, c=0.01884951822
+Ac=0.00691908680696
+sigma=5.67*(10**-8) # Stefan-Boltzmann constant
+#AsACC=
+e= 0.1 # Emissivity of Aluminium [TRAININGPARAMETER]
+h = 50# W/m^2K (convection coefficient) [TRAININGPARAMETER] [-184.90636861]
+k=0.205 #(Thermal conductivity of the cell) [calculate physically]
+k1=0.205
+
+I = df["SME_TEMP_BusCurrent"] ## Accordingly change the 'df1' to any data frame choosen] 
+Temprature=(((I**2)*(16*(10**-3)))/mc) 
+IntegratedTemp=in_place_integrate(Temprature, dt=60/5035) #integrating the temperature change to get the total temperature generated by the battery over time
+q1=h*Area*(IntegratedTemp-ambientTemp) #Cooling
+q1=q1/mc 
+q2=-k*IntegratedTemp*Ac #Pack to Pack conduction; k: Thermal conductivity, Ac: Cross-section area of the Pack [TRAININGPARAMETER]
+q2=q2/mc
+q3=k1*surfaceTemp*Ac2 #Cell to enclosure conduction; k1: Thermal conductivity, Ac2: Cross-section area of the Accumulator wall [TRAININGPARAMETER]
+#q4=h*AsACC*(ACCst-ambientTemp) #enclosure to air convection; AsACC: Surface area of the accumulator [TRAININGPARAMETER]
+#q5=e*sigma*AsACC*(ACCst^4-ambientTemp^4) #Radiation; e: emissivity of aluminium, sigma: Stefan-Boltzmann constant [TRAININGPARAMETER]
+IntegratedTemp=in_place_integrate(Temprature, dt=60/5035) #integrating the temperature change to get the total temperature generated by the battery over time
+# dT/dt = (I^2*R - h*A*(T-T_ambient)) / (m*c))
+temp_cols = [f"ACC_SEG{s}_TEMPS_CELL{c}" for s in range(5) for c in range(6)] #We are not using this anymore since out Ts is now measured by T/mc instead 
+#Q=(q2+q3)-(q1+q5+q4)
+
+temps = np.array((30, 19))
+
+for i in range(len(Temprature)):
+
+
+
+df = df.with_columns(
+df.select([pl.col(col).cast(pl.Float32) for col in temp_cols])
+.mean_horizontal()
+.alias("TempMean")
+)
+
+#plt.ylim(bottom=ambientTemp)
+plt.plot(df["Time"], IntegratedTemp)
+plt.xlabel("Time (s)")
+plt.ylabel("Temperature (°C)")
+plt.legend()
+plt.show()  
+
+#python Data/BatteryThermalModel/FanBatteryThermalModeling.py fs-data/FS-3/08102025/08102025Endurance1_FirstHalf.parquet
+#python Data/BatteryThermalModel/FanBatteryThermalModeling.py fs-data/FS-3/08172025/08172025_27autox2&45C_35C_~28Cambient_100fans.parquet
+#python Data/BatteryThermalModel/FanBatteryThermalModeling.py fs-data/FS-3/08102025/08102025Endurance1_SecondHalf.parquet
+#python Data/BatteryThermalModel/FanBatteryThermalModeling.py fs-data/FS-3/08102025/08102025RollingResistanceTestP1.parquet

Data/BatteryThermalModel/Simultaneous_Plot_Viewer.py

@@ -19,7 +19,7 @@ def load_avg_temp_from_parquet(path: str) -> NDArray[np.float64]:
 
     Returns
     -------
-    NDArray[np.float64]
+    NDArray[np.float64] 
         Array of average temperatures across all cells.
     """
     columns_list = [
@@ -44,7 +44,7 @@ def run_thermal_model_from_parquet(
     path: str,
     current_column: str = "SME_TEMP_BusCurrent",
     t_span: Tuple[float, float] = (0, 10),
-    initial_temp: float = 30,
+    initial_temp: float = 33.5,
     t_eval: NDArray[np.float64] | None = None,
 ):
     """
@@ -72,7 +72,7 @@ def run_thermal_model_from_parquet(
     current_draw = df[current_column].to_numpy()
 
     if t_eval is None:
-        t_eval = np.linspace(t_span[0], t_span[1], 100, dtype=np.float64)
+        t_eval = np.linspace(t_span[0], t_span[1], 1000, dtype=np.float64)
 
     return thermal_ode_solve_ivp(current_draw, t_span, initial_temp, t_eval)
 
@@ -152,3 +152,5 @@ def main() -> None:
 # run the main function: python Simultaneous_Plot_Viewer.py "/Users/gautham/Documents/fs-data/FS-3/08102025/08102025Endurance1_FirstHalf.parquet"
 if __name__ == "__main__":
     main()
+
+#python Data/BatteryThermalModel/Simultaneous_Plot_Viewer.py fs-data/FS-3/08102025/08102025Endurance1_FirstHalf.parquet

Data/BatteryThermalModel/fs4BatteryThermalModelingEx.py

@@ -5,6 +5,7 @@
 
 
 THERMAL_COEFFICIENT: float = 12.6316 / (49.9 * 1000.0)
+ambient_temp: float = 32.0
 """
 Effective thermal coefficient relating I² to temperature rate of change.
 
@@ -50,10 +51,14 @@ def thermal_ode(
         Instantaneous temperature time derivative ``dT/dt`` in
         degrees Celsius per second.
     """
+    mc = 967.6 # J/K
+    Area = 0.71 # m^2
     idx = int(t * len(current_draw) / total_time)
     idx = min(max(idx, 0), len(current_draw) - 1)
     I_t = current_draw[idx]
-    return float(THERMAL_COEFFICIENT * (I_t ** 2))
+    heatingCoeff = 5.0
+    coolingCoeff = 20.0
+    return float(THERMAL_COEFFICIENT * (I_t ** 2) * heatingCoeff + (T-ambient_temp) * -184.90636861 * Area/mc * coolingCoeff)
 
 
 def thermal_ode_solve_ivp(

Data/BatteryThermalModel/pyproject.toml

@@ -0,0 +1,2 @@
+[project]
+name = "BatteryThermalModel"