Project 1
Design a battery pack for a car roughly 150 Kw with 120 V. Use 3500 mAh 3.6V nominal NMC chemistry cell.
a. Design the battery pack configuration.
Given that,
Single cell voltage=3.6V
single cell capacity=3500 mAH=3.5AH
Battery pack capacity=150kw=150000w
battery pack voltage=120V
battery pack capacity in Ah=150000/120=1250
Cell connected in series= 120V/3.6v=34(Taking the higher limit)
cell connected in paralal=1250/3.5=357 (Taking the lower limit)
Total cell =34*357=12138
Therefore,we have to take 34S357P configaration for the car.
Draw the BMS topology for this battery pack.
we have 34 cell in series and it is a medium power battery pack means not so small not so big,so i choose master slave topology.Scince,we have 34 cells in series thus i take 2 slave as a AFE can handle max 18 cell at once.
Cell 1 to 17 connected to slave 1 and cell 18 to 34 connected to slave 2.slave 1 connected to slave 2 and slave 2 is connected to master mcu.Master mcu is the main commander here.There are many sensors like current sensor and temperature sensor thats also directly or indirectly connected to Master mcu.
If any fault occour in the circuit Master mcu can disconnect the battery by switching the on/off the switch/mosfet.these act very fast .it can work as a saftey protection for the vehicle.
CAN & RS485 is the external protocal for cotacting to all the other ectronics parts.
Build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink.
cell configaraion =3s2p
cell in series=3
cell in parallal=2
Tottal cell=3*2=6
cell nominal voltage=7.2 v
cell rated capacity=5.4AH
max voltage=8.3 V
pack voltage=cell voltage*no. of cell in series=7.2*3=21.6V
pack capacity=cell rated capacity*no of cell in parallal=5.4*2=10.8 AH
plot 1:This is the plot of soc.soc is decresing by load.
plot2:This is the plot of current.current is aso decreasing and increasing according to load and regenerative breaking.
plot3:This plot is for voltage.voltage is about 8.3 v.
max voltage of battery pack=max voltage of a cell*no of series cell
=8.3*3=24.9V
This graph is showing the output voltage of battery pack.