# RCAIDE/Library/Components/Powertrain/Energy/Sources/Battery_Modules/Lithium_Ion_LFP.py
#
#
# Created: Nov 2024, S. Shekar
# ----------------------------------------------------------------------------------------------------------------------
# IMPORT
# ----------------------------------------------------------------------------------------------------------------------
# RCAIDE imports
import RCAIDE
from RCAIDE.Framework.Core import Units,Data
from .Generic_Battery_Module import Generic_Battery_Module
from RCAIDE.Library.Methods.Powertrain.Sources.Batteries.Lithium_Ion_LFP import *
# package imports
import numpy as np
import os
from scipy.interpolate import NearestNDInterpolator
# ----------------------------------------------------------------------------------------------------------------------
# Lithium_Ion_LFP
# ----------------------------------------------------------------------------------------------------------------------
[docs]
class Lithium_Ion_LFP(Generic_Battery_Module):
"""
Class for modeling A123 26650 lithium iron phosphate battery characteristics
Attributes
----------
tag : str
Identifier for the battery module (default: 'lithium_ion_lfp')
power_split_ratio : float, optional
Power distribution ratio for multiple battery systems
number_of_cells : int
Number of cells in the module (default: 1)
maximum_energy : float
Maximum energy storage capacity [J] (default: 0.0)
maximum_power : float
Maximum power output [W] (default: 0.0)
maximum_voltage : float
Maximum voltage output [V] (default: 0.0)
cell : Data
Cell-specific properties
- chemistry : str
Battery chemistry type (default: 'LiFePO4')
- diameter : float
Cell diameter [m] (default: 0.0185)
- height : float
Cell height [m] (default: 0.0653)
- mass : float
Cell mass [kg] (default: 0.03)
- surface_area : float
Total cell surface area [m^2]
- volume : float
Cell volume [m^3]
- density : float
Cell density [kg/m^3]
- electrode_area : float
Active electrode area [m^2] (default: 0.0342)
- maximum_voltage : float
Maximum cell voltage [V] (default: 3.6)
- nominal_capacity : float
Rated capacity [Ah] (default: 2.6)
- nominal_voltage : float
Nominal operating voltage [V] (default: 3.6)
- resistance : float
Internal resistance [Ohms] (default: 0.022)
- specific_heat_capacity : float
Cell specific heat [J/kgK] (default: 1115)
- radial_thermal_conductivity : float
Radial thermal conductivity [W/mK] (default: 0.475)
- axial_thermal_conductivity : float
Axial thermal conductivity [W/mK] (default: 37.6)
- discharge_performance_map : NearestNDInterpolator
Interpolator for voltage vs discharge characteristics
Notes
-----
The LFP cell model includes detailed thermal and electrical characteristics
based on the A123 26650 cell. Performance data is interpolated from
experimental measurements.
References
----------
[1] LithiumWerks (2019).A123 26650 Datasheet
https://a123batteries.com/product_images/uploaded_images/26650.pdf
[2] Arora, S., & Kapoor, A. (2019). Experimental Study of Heat Generation
Rate during Discharge of LiFePO4 Pouch Cells. Batteries, 5(4), 70.
https://doi.org/10.3390/batteries5040070
See Also
--------
RCAIDE.Library.Components.Powertrain.Sources.Battery_Modules.Generic_Battery_Module
Base battery module class
"""
def __defaults__(self):
# ----------------------------------------------------------------------------------------------------------------------
# Module Level Properties
# ----------------------------------------------------------------------------------------------------------------------
self.tag = 'lithium_ion_lfp'
self.power_split_ratio = None
self.number_of_cells = 1
self.maximum_energy = 0.0
self.maximum_power = 0.0
self.maximum_voltage = 0.0
# ----------------------------------------------------------------------------------------------------------------------
# Cell Level Properties
# ----------------------------------------------------------------------------------------------------------------------
self.cell.chemistry = 'LiFePO4'
self.cell.diameter = 0.0185 # [m]
self.cell.height = 0.0653 # [m]
self.cell.mass = 0.03 * Units.kg # [kg]
self.cell.surface_area = (np.pi*self.cell.height*self.cell.diameter) \
+ (0.5*np.pi*self.cell.diameter**2) # [m^2]
self.cell.volume = np.pi*(0.5*self.cell.diameter)**2*self.cell.height # [m^3]
self.cell.density = self.cell.mass/self.cell.volume # [kg/m^3]
self.cell.electrode_area = 0.0342 # [m^2] # estimated
self.cell.maximum_voltage = 3.6 # [V]
self.cell.nominal_capacity = 2.6 # [Amp-Hrs]
self.cell.nominal_voltage = 3.6 # [V]
self.cell.watt_hour_rating = self.cell.nominal_capacity * self.cell.nominal_voltage # [Watt-hours]
self.cell.specific_energy = self.cell.watt_hour_rating*Units.Wh/self.cell.mass # [J/kg]
self.cell.specific_power = self.cell.specific_energy/self.cell.nominal_capacity # [W/kg]
self.cell.resistance = 0.022 # [Ohms]
self.cell.specific_heat_capacity = 1115 # [J/kgK]
self.cell.radial_thermal_conductivity = 0.475 # [J/kgK]
self.cell.axial_thermal_conductivity = 37.6 # [J/kgK]
battery_raw_data = load_battery_results()
self.cell.discharge_performance_map = create_discharge_performance_map(battery_raw_data)
return
[docs]
def energy_calc(self,state,bus,coolant_lines, t_idx, delta_t):
"""
Computes the state of the LFP battery cell
Parameters
----------
state : Data
Current system state
bus : Component
Connected electrical bus
coolant_lines : Component
Connected cooling system
t_idx : int
Time index
delta_t : float
Time step [s]
Returns
-------
stored_results_flag : bool
Flag indicating if results were stored
stored_battery_tag : str
Identifier for stored results
"""
stored_results_flag, stored_battery_tag = compute_lfp_cell_performance(self,state,bus,coolant_lines, t_idx,delta_t)
return stored_results_flag, stored_battery_tag
[docs]
def reuse_stored_data(self,state,bus,stored_results_flag, stored_battery_tag):
"""
Reuses previously stored battery performance data
Parameters
----------
state : Data
Current system state
bus : Component
Connected electrical bus
coolant_lines : Component
Connected cooling system
t_idx : int
Time index
delta_t : float
Time step [s]
stored_results_flag : bool
Flag indicating stored results exist
stored_battery_tag : str
Identifier for stored results
"""
reuse_stored_lfp_cell_data(self,state,bus,stored_results_flag, stored_battery_tag)
return
[docs]
def update_battery_age(self,segment, battery_conditions,increment_battery_age_by_one_day):
"""
Updates battery age and degradation parameters
Parameters
----------
segment : Segment
Flight segment data
battery_conditions : Data
Battery operating conditions
increment_battery_age_by_one_day : bool
Flag to increment battery age
"""
update_lfp_cell_age(self,segment, battery_conditions,increment_battery_age_by_one_day)
return
[docs]
def load_battery_results():
'''Load experimental raw data of LFP cells
Assumptions:
Source:
Args:
None
Returns:
battery_data: raw data from battery [unitless]
'''
current_dir = os.path.dirname(os.path.abspath(__file__))
full_path = os.path.join(current_dir, 'lfp_raw_data.res')
# Load the raw_data using RCAIDE.load()
raw_data = RCAIDE.load(full_path)
return raw_data
