Project 2 Thermal modeling of battery pack
For a 10 cell series lithium-ion battery model, simulate the thermal effects and compare life cycle performance at various temperatures, charge & discharge rates using MATLAB.
Solution:
Battery Thermal Management Systems (BTMS) :
The battery pack for safety, performance (both power and capacity) and lifespan reasons should be stored in a controlled surrounding where the temperature is controlled and there is no risk of thermal runaway. According to a foundational research (Pesaran, 2001), the BTMS should be equipped with four essential functions to ensure the right operation conditions of the battery pack.
- Cooling: Due to inefficiency, battery cells will not only generate electricity but also heat. This heat should be moved from the battery pack when battery temperature reaches the optimum temperature or even in advance. Thus, a cooling function is required in BTMS.
- Heating: In cold climates, battery pack temperature probably falls below the lower temperature limit. Hence, a heating function, such as PTC heater, is required to assist the battery pack to reach the proper temperature range in a shorter time.
- Insulation: In extreme cold or hot weather, the temperature difference between the inside and outside of the battery pack is much larger than that in mild weather. Battery temperature will thus fall (cold) or rise (hot) sooner out of the proper temperature range. To prevent this, good insulation can slow down the falling or rising of battery temperature, especially when the vehicle is parked outdoors.
- Ventilation: Ventilation is required to exhaust the hazardous gases within battery pack. In some systems, such as air systems, this function is combined with cooling and heating functions.
Component Requirement For a 10 cell series lithium ion battery model:
Battery (Table-Based)
Thermal Reference
This block represents a reference point in a thermal network where the temperature is equal to absolute zero.
Temperature Sensor
This block measures temperature in a thermal network. There is no heat flow through the sensor. The physical signal port T reports the temperature difference across the sensor. The measurement is positive when the temperature at port A is greater than the temperature at port B.
Convective Heat Transfer
Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes of conduction(heat diffusion) and advection.Convection is usually the dominant form of heat transfer in liquids and gases.
Temperature Sensor
PS-Simulink Converter: to convert some physical quantity to Simulink data
Electrical Reference
Electrical reference port. A model must contain at least one electrical reference port (electrical ground).
Solver Configuration
Scope for output waveform
Controlled Current Source for Discharge the battery with some constant discharge current
The block represents an ideal current source that is powerful enough to maintain the specified current through it regardless of the voltage across it. The output current is I = Is, where Is is the numerical value presented at the physical signal port.
Circuit Diagram:
I am Testing the series batteries with the constant discharge current on different operating temperatures of 300K , 350K and 400k
First lets take 350k temperature and 100s as time
scope for 350K and 100s
We can see the with the rise in temperature the SoC decreasing.
Now lets take 400k temperature and 100s as time
scope for 400K and 100s
We can see with the rise in temperature the SoC decreasing.
then take 300k temperature and 1000s as time
scope for 300K and 1000s
We can see with the rise in temperature the SoC decreasing.
CONCLUSION :
With the rise in temperature the SoC decreases which means that if we operate the battery at a high temperature than the rated temperature then the battery will discharge fast andthe life of the battery will decrease accordingly.