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.
b. Draw the BMS topology for this battery pack
AIM-To design pack configuration ,Draw the BMS topology for this battery pack using given data and also build 3s2p battary pack configaration by using the MATLAB/SIMULINK tool.
1.To design the battery pack configuration
we have to find the No of cell in series
No of cells in parallel
A)No of cell in series=Required voltage /Nominal cell Voltage
given
Required Voltage = 120 v
Nominal Voltage = 3.6 v
No of cell in series=120 /3.6
=33.33
=34(approx)
No.of cell in series= 34 S
No of cell in Parallel= Total continous current/cell nominal capacity
Given data:-
Required Power = 150 KW=150,000W
Required Voltage = 120 V.
=3500 mAh
Change to Ah=3500/10^3
=3.5Ah
formula-
power=v*i
i=power/v
=150,000/120
=1250A
nominal cell Battery capacity = 3500 mAh= 3.5 Ah
therefore,
Number of cells Connected in parallel=1250/3.5
=357.14
=358 p
so, we got
no of cell in series=34S
no of cell in parallel=358P
We can conclude that
The Battery pack Configaration = 34S358P
b. Draw the BMS topology for this battery pack.
Basically BMS topology 4 types
1)Centralised Topology
This Topology is used for only pack of 18 cells or less than 18 cells in a series only.
2)Master and Slave topology
This Topology is used for pack of 18 cells or grater than 18 cells in a series .
High Energy storage purpose
3)Modular Topology
This Topology is used for pack of 18 cells or grater than 18 cells in a series .
Large Energy storage purpose
4)Distributed Topology
This Topology is used for pack of 18 cells or grater than 18 cells in a series .
Very large Large Energy storage purpose
The Battery pack Configaration = 34S358P
Solution:-
From the Architecture of BMS we can said that the "AFU" Allowes ony 18 cells connected in series per one unit .
Hence ,
we required series cells is 34 cells
Therefore we are dividing these 34 cell as 2 slave sets with 1 number of MCU master
Slave 1= 17 cells
Slave 2= 17 cells
Based on this cells connected in series and Architecture of BMS we Choose the Master and Slave topology of BMS for this Ev battery pack
Above Model is For BMS Topology of 34s358P battery pack Configarationmodel
This Topology consist of a 2 numbers of slave of AFU units with each AFU units slave Consists a 17 numbers Of Cells connectd in series.
Conclusion :-
We can conclude from above calculations
The battery Pack configaration is 34S358P
Battry BMS Topology is "Master and Slave " Topology is is designed and explained thery regarding BMS topology.
2. Build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink
The objective to connect batteries in 3S2P Configuration in Matlab/Simulink.That is 3 cell should be connected in series and 2 cell should be connected in parallel
=3*2=6 cells
Step1:Arrangement of 6 cells
The first shows the arrangement of 6 cell .we have to placetotal no of cell in battery pack(6cells)in simulink.
Step2-Parallel connection
The figure2 shows the batteries connected in parrallel.For parallel connection , batteries are connected from terminals to same terminals of other batteries that is positive terminal (+) of one battery is connected with positive (+)terminal of other battery and negative terminal(-) of one battery with negative terminal(-) of other battery.
STEP3-Series connection
the figure shows the battery connected in series and parallel combination. Batteries are connected in series and parallel combination. Batteries are connected from terminal to Terminal in a way that the positive(+) terminal of one battery is connected with negative(-) terminal of the other battery and negative terminal(-) of one battery is connected with the positive terminal(+) of the battery.
Model Explanation -
the Figure4 shows the 3S2P battery pack simulink model .the voltage measurement block is connected across the battery pack to measure the Battery pack voltage.The scope output used for the battery pack consists of SOC(state of charge), Current and Voltage . The controlled current signal is given as the load to battery pack. The constant block is determined with Battery capacity(5.4ah) and it is given to the controlled current block.
Nominal voltage of a cell 7.2V
Rated capacity of a cell 5.4Ah
Maximum voltage of a cell 8.3V
given-
Nominal voltage of a cell 7.2V
Rated capacity of a cell 5.4Ah
Maximum voltage of a cell 8.3V
so Nominal voltage of the battery pack=No of cell in series*Nominal voltage of a cell
=3*7.2V
= 21.6V
Rated capacity of the battery pack= No of cell in parallel * Rated capacity of a cell
=2*5.4
=10.8Ah
The model is for an 21.6V with 10.8 Ah Battery capacity
Overall voltage=25.13V
Simulink model of Battery pack of configuration3S2P
SCOPE RESULT-
PLOT1-The SOC(state of charge) is started to reduce from 100% to 50% corrsponding to load given
PLOT2-The current signal is detrmined by load and the decrese in current is due to regenertive braking
PLOT3-The voltage is around 8.3V .The increasing and decresing voltage is with respect to the Regenerative braking
now the overall output voltage of the battery pack.the calculation for the overall output voltage of the battery pack
overall voltage of the battery pack=Maximum voltage of the battery * no of cell in series
= 8.3V*3
=24.9
Conclusion-
The battery pack configuration(3S2P) with generic battery block using Matlab/Simulink is created.