Project 1
ANS-1
Aim of the Project:-
The Main Of this project is Design the battery 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.
Theory:-
Battery Management Stysytem :-
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, and longitivity 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.
The BMS also balances the charge across the cells to keep each cell functioning at maximum capacity.
Fig--> Battery management system
Solution :-
Given data:-
Required Power = 150 KW
Required Voltage = 120 V.
Battery detalis :-
Battery 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 fing 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 Take the data from given:-.
Nominal volatge =3.6 v
Cell having capacity of cell(Ah)= 3500 mAh= 3.5 A
Formulae: Cell in series = Rated voltage / Nominal voltage
Given - Total voltage = 120 V
Nominal voltage = 3.6
Therefore,
*** Cells connected in series = Rated voltage (V) / Nominal cell Voltage(Ah) ***
The cells connected in series = 120 / 3.6
=33.3 cells
Rounding off decimal digit :
Assuming Cell max voltage = 4.2 V
cell minimum voltage = 2.7V
Case-1 Rounding off 33.33 to 33
Nominal Battery voltage = cell nominal voltage * 33
3.6 * 33 = 118.8V
Maximum battery voltage = cell maximum voltage *33
= 4.2 *33
= 138.6V
minimum battery voltage = cell minimum voltage *33
2.7*33 = 89.1 V
Case -2 Rounding off 33.33 to 34
Nominal battery voltage = cell nominal volage * 33
= 3.6*34
= 122.4V
Maximum battery voltage = cell max voltage * 34
= 4.2*34
= 142.8 V
Minimum battery voltage = cell minimum voltage *34
= 2.7*34
= 91.8 V
So we will choose Case-2 34 cells in Series . Its always better to have high voltage energy source .
Now to find Cells in parallel
given : Power = 150 Kw , capacity = 3500mAH = 3.5 Ah , Voltage = 120V
Power = Voltage *current
Current = 150* 1000 watt / 120
Current = 1250A
Number of Cells in series = Motor current / Cell nominal capacity.
= 1250 / 3.5
= 35.142
Case 1 357.142 to 357
Case 2 357.142 to 358
So we will take 358 for better capacity
So battery pack will be 34S358P
b. Draw the BMS topology for this battery pack.
we will choose Master and Slave topology for 34 series cells .
Ans-2
Aim- The main aim is design a given battery pack configaration by using theMatlab/Simulink Tool.
Given data :-
Battery pack configartion = 3S2P
Simulink model :-
For creating the Simulink model battery pack configartion we are used following blocks:-
Battery, scope, Controlled current source , Display, Bus selector .
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.
Therefore,
Total number of cells in battery pack = No. of cells in series * No. of cells in parallelThen ,
Total number of cells in battery pack = No. of cells in series * No. of cells in parallel
= 3 * 2 = 6 cells
Setep-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 block is 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
Therefore ,
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: 