Project 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 battery pack configuration by using the Matlab/simulink tool.

Theory :-

Battery Management System :-

• A Battery management system(BMS) is said to be the brain of a battery pack.
• Battery management systems (BMS) are electronic control circuits that monitor and regulate the charging and discharge of batteries.
• The battery characteristics to be monitored include the detection of battery type, voltages, temperature, capacity, state of charge, power consumption, remaining operating time, charging cycles, and some more characteristics.
• The task of battery management systems is to ensure the optimal use of the residual energy present in a battery. In order to avoid loading the batteries, BMS systems protect the batteries from deep discharge and over-voltage, which are results of extreme fast charge and extreme high discharge current.
• . In the case of multi-cell batteries, the battery management system also provides a cell balancing function, to manage that different battery cells have the same charging and discharging requirements.

Battery Managment System

Solution :-

Given data :-

Required power = 150 kw

Required voltage = 120 V

Battery Detail :-

Battery Capacity = 3500mAh = 3.5Ah

Cell Nominal Voltage = 3.6 V

a. Design the battery pack configuration.

for Desiginig the Battery pack configuration ,Firstaly we have to find two parameter as follow :-

1) Number of cell connected in Series.

2) Number of cell connected in parallel.

1) Number of cell connected in Series :-

for Solution let us take the data from given :-

Nonimal voltage = 3.6V

cell having Capacity of cell (Ah) = 3.5 Ah

Formula :-

Cells connected in Series = Required voltage (V)/Nominal cell voltage (V)

From data :-

Required voltage = 120V

Nominal voltage = 3.6V

Cells connected in Series = Required voltage (V)/Nominal cell voltage (V)

Cells connected in series = 120/3.6 = 33.33 cells

This value are taken as rounding of calculation as followes,

Rounding of Calculation :-

Case 1 :-

cell lower value = 33 cell

Nominal battery voltage = cell Nominal Voltage *cell in series

Nominal battery voltage = 3.6 * 33

Nominal battery voltage = 118.8 V

Case 2 :-

cell Higher value = 34 cell

Nominal battery voltage = cell Nominal Voltage *cell in series

Nominal battery voltage = 3.6 * 34

Nominal battery voltage = 122.4 V

When Compare with rated voltage ,the battery voltage is greater in case 2 then case 1.

No.of cell in series = 34

2) Number of cell connected in parallel :-

Formula :-

Number cells connected in parallel = Required continuous Current / cell Nominal voltage (V)

Given data :-

Required power = 150 kw

Required voltage = 120 V

Battery Detail :-

Battery Capacity = 3500mAh = 3.5Ah

Cell Nominal Voltage = 3.6 V

we know ,

power (P) = current (I) * Voltage (V)

current (I) = power(P)/Voltage (V)

current (I) = (150*1000)/120

current (I) = 1250 Amps

Formula :-

Number cells connected in parallel = Required Current / cell Nominal voltage (V)

from data ,

current (I) = 1250 Amps

cell Nominal voltage = 3.6 V

Number cells connected in parallel = Required Current / cell Nominal voltage (V)

Number cells connected in parallel = 1250/3.6 = 347.22

Therefore ,

Number of cells connected in parallel = 348 P

Therefore,

No.of cell in series = 34

Number of cells connected in parallel = 348 P

The battery pack Configuration = 34S348P

b. Draw the BMS topology for this battery pack.

BMS Topology :-

Fig :- BMS Topologies Block Diagram.

Basically BMS Topologies is classified into following 4 types :-

1)Centralised Topology:-

his 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.

Solution :-

From the Architecture of BMS we can said that the "AFE"(Analog front End) Allowes ony 18 cells connected in series per one unit of modulae.

Hence ,

we required series cells is 34 cells

There fore we are dividing these 34 celss as 2 slave sets with 1 number of MCU master unit as followes

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 Topology design.

BMS Topology MODEL :-

Master and Slave Topology:-

BMS Topologies 34S348P Pack Configuration

Above Model is For BMS Topology of 34s348P battery pack Configarationmodel

This Topology consistes 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 34S348P

Battery BMS Topology is "Master and Slave " Topology is is designed and explained thery regarding BMS topology.

Q2. Build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink.

Aim :-

he 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

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,

Formula :-

Total number of cells in battery pack = 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)

Step 2 :-

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.

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.

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

Therefore ,

Nominal voltage of the battery pack = no.of cell in series * nominal voltage of a cell

= 3 *7.2 = 21.6

Rated capacity of the battery pack = no.of cell in parallel* rated capacity of a cell

= 2 * 5.4 = 10.8

The model is for an 21.6V with 10.8Ah battery capacity

Overall voltage of the battery pack = maximum voltage of the battery * no. of cells in series

= 8.3 * 3 = 25 V

Overall voltage = 25 V

Total Battery pack Model :-

Output Scope Result :-

Overall voltage of the battery pack = maximum voltage of the battery * no. of cells in series

= 8.3 * 3 = 25 V

Overall voltage = 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.

Conculsion :-

The battery pack configuration(3S2P) with generic battery block using Matlab/Simulink is created.