Added Thermal Runaway Event

sphinx_config/models.rst

@@ -11,9 +11,9 @@ Models Summary
 +----------------------+----------------------------+-----------------------------------+---------------------------------+---------------------------------+
 |                      | Battery Model - Circuit    | Battery Model - Electro Chemistry | Centrifugal Pump                | Pneumatic Valve                 |
 +======================+============================+===================================+=================================+=================================+
-| Events               | End of Discharge (EOD)     | * End of Discharge (EOD)          | * Impeller Wear Failure         | * Leak-Bottom                   |
-|                      |                            | * InsufficientCapacity            | * Pump Oil Overheating          | * Leak-Top                      |
-|                      |                            |                                   | * Radial Bering Overheat        | * Leak-Internal                 |
+| Events               | * End of Discharge (EOD)   | * End of Discharge (EOD)          | * Impeller Wear Failure         | * Leak-Bottom                   |
+|                      | * ThermalRunaway           | * InsufficientCapacity            | * Pump Oil Overheating          | * Leak-Top                      |
+|                      |                            | * ThermalRunaway                  | * Radial Bering Overheat        | * Leak-Internal                 |
 |                      |                            |                                   | * Thrust Beiring Overheat       | * Spring Failure                |
 |                      |                            |                                   |                                 | * Friction Failure              |
 +----------------------+----------------------------+-----------------------------------+---------------------------------+---------------------------------+

src/prog_models/models/battery_circuit.py

@@ -13,8 +13,9 @@ class BatteryCircuit(prognostics_model.PrognosticsModel):
     This class implements an equivilant circuit model as described in the following paper:
     `M. Daigle and S. Sankararaman, "Advanced Methods for Determining Prediction Uncertainty in Model-Based Prognostics with Application to Planetary Rovers," Annual Conference of the Prognostics and Health Management Society 2013, pp. 262-274, New Orleans, LA, October 2013. https://papers.phmsociety.org/index.php/phmconf/article/view/2253`
 
-    Events: (1)
+    Events: (2)
         EOD: End of Discharge
+        ThermalRunaway: Thermal runaway has begun
 
     Inputs/Loading: (1)
         i: Current draw on the battery
@@ -63,7 +64,7 @@ class BatteryCircuit(prognostics_model.PrognosticsModel):
 
     Note: This is much quicker but also less accurate as the electrochemistry model
     """
-    events = ['EOD']
+    events = ['EOD', 'ThermalRunaway']
     inputs = ['i']
     states = ['tb', 'qb', 'qcp', 'qcs']
     outputs = ['t',  'v']
@@ -104,8 +105,12 @@ class BatteryCircuit(prognostics_model.PrognosticsModel):
         # current ratings
         'nomCapacity': 2.2,  # nominal capacity, Ah
         'CRateMin': 0.7,  # current necessary for cruise,
-        'CRateMax': 2.5   # current necessary for hover
+        'CRateMax': 2.5,   # current necessary for hover
         # CRateMin, CRateMax based on values determined in `C. Silva and W. Johnson, "VTOL Urban Air Mobility Concept Vehicles for Technology Development" Aviation and Aeronautics Forum (Aviation 2018),June 2018. https://arc.aiaa.org/doi/abs/10.2514/6.2018-3847`
+
+        # ThermalRunaway
+        'ApproachingRunaway': 30,  # Temperature (C) before RunawayTemp at which the battery is said to be approaching runaway
+        'RunawayTemp': 130  # Temperature (C) at which thermal runaway is said to begin
     }
 
     state_limits = {
@@ -152,6 +157,7 @@ def event_state(self, x):
         voltage_EOD = (z['v'] - self.parameters['VEOD']) / \
             self.parameters['VDropoff']
         return {
+            'ThermalRunaway': min((self.parameters['RunawayTemp'] - x['tb'])/self.parameters['ApproachingRunaway'], 1), 
             'EOD': min(charge_EOD, voltage_EOD)
         }
 
@@ -179,5 +185,6 @@ def threshold_met(self, x):
 
         # Return true if voltage is less than the voltage threshold
         return {
+             'ThermalRunaway': x['tb'] >= parameters['RunawayTemp'],
              'EOD': V < parameters['VEOD']
         }

src/prog_models/models/battery_electrochem.py

@@ -108,8 +108,9 @@ class BatteryElectroChemEOD(PrognosticsModel):
 
     The default model parameters included are for Li-ion batteries, specifically 18650-type cells. Experimental discharge curves for these cells can be downloaded from the `Prognostics Center of Excellence Data Repository https://ti.arc.nasa.gov/tech/dash/groups/pcoe/prognostic-data-repository/`.
 
-    Events: (1)
+    Events: (2)
         EOD: End of Discharge
+        ThermalRunaway: Thermal runaway has begun
 
     Inputs/Loading: (1)
         i: Current draw on the battery
@@ -161,7 +162,7 @@ class BatteryElectroChemEOD(PrognosticsModel):
         | VEOD : End of Discharge Voltage Threshold
         | x0 : Initial state
     """
-    events = ['EOD']
+    events = ['EOD', 'ThermalRunaway']
     inputs = ['i']
     states = ['tb', 'Vo', 'Vsn', 'Vsp', 'qnB', 'qnS', 'qpB', 'qpS']
     outputs = ['t', 'v']
@@ -208,7 +209,11 @@ class BatteryElectroChemEOD(PrognosticsModel):
 
         # End of discharge voltage threshold
         'VEOD': 3.0, 
-        'VDropoff': 0.1 # Voltage above EOD after which voltage will be considered in SOC calculation
+        'VDropoff': 0.1, # Voltage above EOD after which voltage will be considered in SOC calculation
+
+        # ThermalRunaway
+        'ApproachingRunaway': 30,  # Temperature (K) before runaway temp at which the battery is said to be approaching runaway
+        'RunawayTemp': 400.15  # Temperature (K) at which thermal runaway is said to begin
     }
 
     state_limits = {
@@ -295,6 +300,7 @@ def event_state(self, x):
         charge_EOD = (x['qnS'] + x['qnB'])/self.parameters['qnMax']
         voltage_EOD = (z['v'] - self.parameters['VEOD'])/self.parameters['VDropoff'] 
         return {
+            'ThermalRunaway': min((self.parameters['RunawayTemp'] - x['tb'])/self.parameters['ApproachingRunaway'], 1), 
             'EOD': min(charge_EOD, voltage_EOD)
         }
 
@@ -354,6 +360,7 @@ def threshold_met(self, x):
 
         # Return true if voltage is less than the voltage threshold
         return {
+            'ThermalRunaway': x['tb'] >= self.parameters['RunawayTemp'],
              'EOD': z['v'] < self.parameters['VEOD']
         }