Project 1
Q.1..?
firstly we have see Battery Management System...
A Battery management system(BMS) is said to be the brain of a battery pack. The BMS is a set of electronics that monitors and manages all of the battery’s performance. Most importantly, it keeps the battery from operating outside of its safety margins.
The battery management system is critical to the battery’s safe operation, overall performance of battery pack.
The primary function of the BMS is to protect the battery cells from damage caused by being overcharged or over-discharged. Additionally, the BMS calculates the remaining charge, monitors the battery’s temperature, monitors the battery’s health and safety by checking for loose connections and internal shorts.
Solution :-
Given data:-
Required Power = 150 KW
Required Voltage = 120 V.
Battery detalis :-
Batatry capacity = 3500 mAh= 3.5 Ah
Battery Nominal Voltage =3.6V
a) Design the battery pack configuration.
for desiginig the Battery pack Configaration ,Firstly we have to find the two parameters as followes :-
i) Number of cells connected in Series
ii) Number of cells connected in Parallel.
i) Number of cells connected in Series:-
For this solution let us,
Nominal volatge =3.6 v
Cell having capacity of cell(Ah)= 3500 mAh= 3.5 A
FORMULA :-
Cells Connected in Series = Requires Voltage / Nominal Cell Voltage
From the data,
Required Voltage :- 120 v
Nominal Voltage = 3.6 v
Therefore,
Cells connected in series = Required voltage (V) / Nominal cell Voltage(Ah)
The cells connected in series = 120 / 3.6
=33.3 cells
This Digits vallues are taken as rounding of caluctions as followes :-
Rounding of calculation:-
Rounding of Series Cell Values...
Lower Value = 33............Nominal Battery Voltage = 118.8
Higher Value =34 ........Nominal Battery Voltage = 122.4
When compare with rated voltage, the battery voltage is greater in case 2 then case 1.
So,
No.of cell in series= 34 S .....(1)
ii) Number of cells connected in Parallel:-
Formula for number of cells connectd in parallel:-
Cells connected in Parallel = Total Current / Nominal cell Voltage(v)
Given data:-
Required Power = 150 KW
Required Voltage = 120 V.
NMC Battery detalis :-
Batatry capacity = 3500 mAh= 3.5 Ah
Battery Nominal Voltage =3.6V
We know that ,
Power = Current * Voltage
threfore, Current = POwer / Voltage
hence, From formula,
Current(I) = power(P) / Voltage(V)
= (150 *1000) / 120
Current(I) = 1250 Amps
NMC Battery detalis :-
Batatry capacity = 3500 mAh= 3.5 Ah
Battery Nominal Voltage =3.6V
Therefore,
Number of cells Connected in paralle :-
Cells connected in Parallel = Total Current / Nominal cell Voltage(v)
from the data ,
Current(I) = 1250 Amps
Cell nominal Voltage = 3.6 V
then ,
Number of cells Connected in paralle = Required Current (I) / Cell Nominal Voltage(V)
=1250 / 3.6
=358 P .......(2)
Therefore,
From values (1) and (2)
No.of cell in series= 34 S
Number of cells Connected in paralle =358 P
We can conclude that
The Battery pack Configaration = 34S358P
Q.2...?
3S2P battery pack configuration :-
Procedure :-
Batteries in 3S2P configuration in Matlab/Simulink. That is 3 cells should be connected in series and 2 cells should be connected in parallel.
Therefor,
Total Number of cell in battry = No. of cells in series * no. of cells in parallel
Then ,
Total number of cells in battery pack = No. of cells in series * No. of cells in parallel
= 3 * 2 = 6 cells
Step 1 :-
Arrangement of 6 cells:-
The figure 1 shows the arrangement of 6 cells.
We have to place total number of cells in battery pack (6 cells)
Figure 1: Arrangement of 6 cells
Step 2:-
Parallel connection:-
The figure 2 shows the batteries connected in parallel.
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 ofother battery and negative terminal (-) of one battery with negative terminal (-) of other battery
Figure 2 : Battery connected in parallel connection
Step 3:-
Series and parallel connection:-
The figure 3 shows the battery 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 the negative (-) terminal of the other
battery and negative terminal (-) of one battery is connected with the positive terminal (+) of the other battery.
Figure 3 : Battery connected in series and parallel combination
Model Explanation:-
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 the battery pack. The constant blockis determined with battery capacity and it is given to the controlled current block.
The parameter given inside the battery is given below:-
- Nominal voltage of a cell 7.2V
- Rated capacity of a cell 5.4Ah
- Maximum voltage of a cell 8.3V
There fore ,
Nominal voltage of the battery pack = no.of cell in series * nominal voltage of a cell
= 3 * 7.2v
= 21.6 V
Rated capacity of the battery pack = no.of cell in parallel* rated capacity of a cell
= 2 * 5.4Ah
= 10.8Ah
The model is for an 21.6V 7 with 10.8Ah battery capacity
Overall voltage of the battery pack = maximum voltage of the battery * no. of cells in series
= 8.3V * 3
= 25 v
Overall voltage = 25 V
Total Battery pack model:-
Output Scope results :-
Voltage scope :-
Overall voltage of the battery pack = maximum voltage of the battery * no. of cells in series
= 8.3V * 3 = 25 V
From the Above Plot is we can observe that the the total battery pack voltage is reduced bt 10% of the initial value.
Battery pack details:-
From the Above graph we can observe that the
Top Plot is (Voltage):-
The voltage is around 8.3V. The increasing and decreasing voltage is with respect to the regenerative braking
Middle Plot (Current):-
The current signal is determined by the load and the decrease in current is due to regenerative braking.
Bottom Plot(SOC%):-
The SOC (state of charge) is started to reduce from 100% to 99 % corresponding to the load given
Conclusion :-
The battery pack configuration(3S2P) with generic battery block using Matlab/Simulink is created.