Project 2 Thermal modeling of battery pack

Q. 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.

A.

Steps for building the circuit

1. 10 generic battery model blocks of the following specifications are arranged and connected in series

Aging parameters:

2. A cycle generator block is created using MATLAB Function block to generate charge/ discharge cycles based on the different charge/discharge currents

3. Different charge/discharge current values are given through stair generator blocks

4. Different temperatures are provided through stair generator blocks

5. SoC, Cell & Ambient temperature, current and age (equivalent full discharge cycles) are ploted from one of the battery models to the scope

RESULTS

1. The simulation is run for 36000 seconds.
2. The results can be divided into two: One half from 0 – 18000s where ambient temperature is 20 °C and other half from 18001 to 36000 seconds where ambient temperature is increased to 40°C
3. The output from the battery is plotted and isshown in the figure below.
4. For the first quarter of the simulation, charging and discharging is in 0.5C rate at 20°C. By the end of the quarter-
   1. The age has increased only by 1.6 equivalent full cycles.
   2. The cell temperature has increased by 12°C
5. For the second quarter of th simulation, charging and discharging is in 1C rate at 20°C. By the end of half of simulatioin
   1. The age has increased by 8 equivalent full cycles
   2. The cell temperature increased by 13°C
6. Similar pattern as steps 4 and 5 are repeated for the last half of the simulation, but for 40°C ambient temperature. By the end of 3^rd quarter,
   1. The age has increased only by 5 equivalent full cycles.
   2. The cell temperature has increased by 7°C
7. By the end of simulation:
   1. The age has increased only by 13 equivalent full cycles.
   2. The cell temperature has increased by 14°C

CONCLUSION

1. As the charging/discharging current increass, aging increases
2. As the ambient temperature increases, aging increases due to rise internal temperature