Project 2 Thermal modeling of battery pack

PROJECT-2: 

Discussion of steps:  

• Taking 10 Nos. of table-based battery packs from the Simulink library. Enabling the thermal port and connecting all of them in series with each other. Battery Pack Capacity: 24Ah 
• Taking current controlled source to discharge the battery. We connected the +ve terminal of the battery to the –ve terminal of CCS and vice versa. We are withdrawing 4.2A of constant current from the battery pack by using a PS-constant block. 
• We have connected a voltmeter across the battery pack to measure the total voltage and an ammeter to measure the current.  
• All the thermal ports of the individual battery are connected in series with each other. This connection is further connected in series with a temperature source and convective heat transfer. We have also connected a temperature sensor to measure the temperature across the battery. 
• Since all the cells are connected in series we cannot take the SOC of the battery directly for that we have to use “Coulomb counting method”. The formula is as follows: 
• SOC = [1 - (∫I.dt/Battery Capacity)]. To get this equation we have used a integrator block to integrate the current flowing in the battery pack and dividing the battery capacity by using a gain block. After doing this we get ‘∫I.dt/Battery Capacity’. We subtract this value from 1 and the output is SOC. 

Discussion of model: 

• When the battery pack is connected to the current controlled source, it discharges the battery pack.  
• We are now providing external temperature to the battery for a specific area and observing the SOC. We took 3 reading for the same with keeping the temperature constant and changing the area of contact. 
• In the next part, we took 3 readings for the same keeping the area of contact constant and changing the temperature. 
• By doing this we observed the change in SOC levels of the battery by changing the thermal parameters of the battery pack. 

Discussion of answers:

• We have taken battery voltage, SOC, and battery temperature as the parameters.  
• We can observe the changes in the battery temperature rise as we increase the temperature from the temperature source.
• When we increase the discharge current constant (PS-Constant) we can observe that the battery doesn't get completely discharged and when we decrease the discharge current constant (PS-Constant) we can observe that the battery gets completely discharged before the given simulation time.

All the necessary documents are attached herewith.