Project 2 Thermal modeling of battery pack

1. 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:

Aim:

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.

Theory:

• Now a days lithium ion battery are mostly used in electric vehicles we must know its charge and discharge rates to operate this batterys in efficient manner and with out damage when this batterys in operation this temperature of it must be kept in limit we simulate the thermal effect of this cell.
• By knowing the how much temp rise take place we can provide efficient cooling to the batterys so that the life cycle of the battery increases we will see a model on this issue below and explaination as follows.
• Cells connected in series and one of the cell is faulty so what will be thermal effect . This example shows how to simulate a battery pack consisting of multiple series-connected cells in an efficient manner.
• It also shows how a fault can be introduced into one of the cells to see the impact on battery performance and cell temperatures. For efficiency, identical series-connected cells are not just simply modeled by connecting cell models in series. Instead a single cell is used, and the terminal voltage scaled up by the number of cells.
• The fault is represented by changing the parameters for the Cell 10 Fault subsystem, reducing both capacity and open-circuit voltage, and increasing the resistance values.

Simscape model:

• The battery simscape 10 cell series lithium ion battery model developed by using necessary blocks
• Discussed thermal effects and compare life cycle performance at various temperatures, charge & discharge rates.
• A battery is discharging a fixed amount of current whilst being heated by a temperature source

Max battery capacity is 27 Ah and 4.2A of current is being discharged for 3600 sec.

1. 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:

Aim:

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.

Theory:

• Now a days lithium ion battery are mostly used in electric vehicles we must know its charge and discharge rates to operate this batterys in efficient manner and with out damage when this batterys in operation this temperature of it must be kept in limit we simulate the thermal effect of this cell.
• By knowing the how much temp rise take place we can provide efficient cooling to the batterys so that the life cycle of the battery increases we will see a model on this issue below and explaination as follows.
• Cells connected in series and one of the cell is faulty so what will be thermal effect . This example shows how to simulate a battery pack consisting of multiple series-connected cells in an efficient manner.
• It also shows how a fault can be introduced into one of the cells to see the impact on battery performance and cell temperatures. For efficiency, identical series-connected cells are not just simply modeled by connecting cell models in series. Instead a single cell is used, and the terminal voltage scaled up by the number of cells.
• The fault is represented by changing the parameters for the Cell 10 Fault subsystem, reducing both capacity and open-circuit voltage, and increasing the resistance values.

Simscape model:

• The battery simscape 10 cell series lithium ion battery model developed by using necessary blocks
• Discussed thermal effects and compare life cycle performance at various temperatures, charge & discharge rates.
• A battery is discharging a fixed amount of current whilst being heated by a temperature source

Max battery capacity is 27 Ah and 4.2A of current is being discharged for 3600 sec.

Output Analysis

Temperature Analysis

• The battery performance parameters like Voltage, SOC has to be analysed at different temperatures.

Figure shows the battery pack model with 10 cells connected in series. All these cells are connected such that it can transfer heat by conduction and convection. The ambient temperature can be changed to different values to analyse the battery pack performance at different temperatures.

• An AC source has been connected to analyse the cyclic charge and discharge performance. The positive cycle will charge the battery and negative cycle will discharge the battery.
• For series connection we are using lithium-iron battery pack of details are given below.

• A convective heat transfer block in which we put the heat transfer coefficient is 20 w/(k*m^2) and one end of the block is connected the thermal source and other is connected to the particular cell.

• In below plotted at different ambient temperatures of 303.15K (30 degC), 313K (40 degC). We can see that after 3600sec, the temperatures are settling to ambient temperature.

303.15K (30 degC)

313K (40 degC)

Conclusion:

• MATLAB library model parameters were evaluated for its life cycle and thermal effects parameters.
• A battery pack with 10 cells connected in series also made with a source of charging and discharging cycle.
• The thermal effects of battery pack at different ambient temperatures of 293.15K (20 deg C), 303.15K (30 degC), 313K (40 degC) for cycling charging/discharging has been analysed and plotted.