Project 1
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.
ANSWER:
Given, battery pack specification;
rated power rating = 150kW continuous battery current/rated current
rated voltage =120V
nominal cell voltage = 3.6V
cell capacity = 3500mAh = 3.5Ah
Assumed data;
Maximum cell voltage = 4.2V
Minimum cell voltage = 2.7V
A)Calculating no of cells in series = Rated Voltage/nominal cell voltage
= 120/3.6
= 33.33
Case 1.Rounding of the no of cell in series to 33 cells.
nominal battery voltage = 33*3.6 = 118.8V
maximum battery voltage = 4.2*33 = 138.6V
minimum battery voltage = 2.7*3.6= 89.1V
Case 2. Rounding of the no of cells in series to 34 cells.
nominal battery voltage = 3.6*34 = 122.4V
maximum battery voltage = 4.2*34 = 142.8V
minimum battery voltage= 2.7*34 = 91.8V
Comparing both the cases; Requied battery voltage is 120V,therefore we will go with case 2 ,as the total output voltage of battery pack is more than the required voltage.
Therefore no of cells in series = 34 cells.
Continuous battery current/rated current =(150*1000)/120
=1250Ah
cell nominal capacity = 3500mAh = 3.5Ah.
B)Calculating no of cells in parallel = battery continuous current /cell nominal capacity
=1250Ah/3.5Ah
=357.42 cells
Case a) Rounding off the no of cell in parallel to 357.
= 357*3.5 = 1249.5Ah
Case b) Rounding of the no of cells in parallel to 358.
= 358*3.5 = 1253Ah.
required capacity = 1250Ah
Therefore ,we will go with case 2.
So,the required battery pack configuration is 34S358P.
Total no of cells in battery pack = 34*358 = 12172 cells
Let us consider no of modules = 17
no of cells per module =716 cells.
no of cells in series = 34/17
= 2 cells
no of cells in parallel in each module = total no of cells in parallel = 358 cells.
So,each battery module cell configuration will be 2S358P,which will give 7.2V,1253Ah.
Total output of battery pack = 122.4 V,1253Ah.
Therefore the new battery pack configuration is 2S358P.
b. Draw the BMS topology for this battery pack.
ANSWER:for the above battery configuration Master and Slave topology is best suited because this topology can house upto 7000 cells.Here we are using 17 slaves with 716 cells each.
The BMS toplogy is shown below.
2. Build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink.
ANSWER:given,battery pack configuration = 3S2P.
total no of cells = 6.
Nominal cell voltage = 3.6V
Rated capacity of cell = 3.5Ah
nominal voltage of battery pack = 3*3.6 = 10.8V
nominal capacity of battery pack = 2*3.5 = 7Ah.
SCOPE RESULT:
Conclusion:Battery pack designed for the given configuration and BMS topology is designed
simulink model is build for the 3S2P battery pack configuration.