Project 1
Ans.1- Given data,
Required Power = 150 KW
Required Voltage = 120 V.
Batatry capacity = 3500 mAh or 3.5 Ah
Battery Nominal Voltage =3.6V
For finding the current we know that ,
Power(P) = Current(I) * Voltage(V)
Current(I) = power(P) / Voltage(V)
= (150 *1000) / 120
Current(I) = 1250 Amps
a) Design the battery pack configuration.
For designing the Battery pack Configuration, we need to findout;
- Number of cells connected in Series
- Number of cells connected in Parallel.
i) Number of cells connected in Series:
Cells connected in series = Required voltage (V) / Nominal cell Voltage (Ah)
So,
The cells connected in series = 120 / 3.6
= 33.3 cells
This Digits values are taken as rounding of calculation
Rounding of calculation:-
| Case1: | Case2: |
| Lower Value =33 | Higher Value=34 |
| Nominal battery voltage =Cell Nominal voltage * cell in series | Nominal battery voltage =Cell Nominal voltage * cell in series |
|
Nominal battery voltage=3.6*33 =118.8 |
Nominal battery voltage=3.6*34 =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
Number Of Cells Connected in Series = 34S -------------(1)
ii) Number of cells connected in Parallel:-
So, according to the Formula:-
Number of cells Connected in parallel = Required Current (I) / Cell Nominal Voltage (V)
= 1250 / 3.6
= 348 P
Therefore,
Number of cells Connected in parallel =348 P--------------(2)
From eq(1) and eq(2)
Number Of Cells Connected IN Series = 34S
Number of cells Connected in paralle =358 P
We can conclude that,
The Battery pack Configaration = 34S348P
b.Draw the BMS topology for this battery pack:-
BMS Topology: Basically BMS topology is classified into following foure(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 greater than 18 cells in a series.
- High Energy storage purpose.
3)Modular Topology:
- This Topology is used for pack of 18 cells or greater 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
From the Architecture of BMS we can said that the "AFE" allows ony 18 cells connected in series per one unit of module.
Hence ,we required series cells is 34 cells
Therefore we are dividing these 34 cells in group of 17,17 each with 2 slave(AFE) with 1 MCU(master) unit as follows:
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 battery pack Topology design.
Above figures is For BMS Topology of 34S348P battery pack Configuration model:
This Topology consistes a 2 numbers of slave of AFU units with each AFE units slave Consists a 17 numbers Of Cells connectd in series.
Ans.2- Build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink:
Total number of cells in battery pack = no.of cells in series * no.of cells in parallel
= 3*2
=6 cells
Series connection of a battery:
Batteries are connected from teminal to terminal in a way that the +ve terminal one battery is connected to -ve termnal of the other battery and -ve terminal of one battery is connected to +ve terminal of other battery.
Parallel connection of a battery:
Batteries are connected from terminals to same terminals of the other batteries that is +ve terminal of one battery is connected to +ve terminal of other battery and -ve terminal of one battery is connected to -ve terminal of 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 * 7.2v => 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
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:
First Plot(SOC%):-The SOC (state of charge) is started to reduce from 100% to 99.85 % .
Second Plot is (Voltage): The voltage drops from 8.38v to 8.31v.
Third Plot (Current): The current of the battery pack is near about 2.6A.
Conclusion :
- We can conclude from above calculations
- The battery Pack configaration is 34S348P
- Battery BMS Topology is "Master and Slave” Topology is designed and explained they regarding BMS topology.
- The battery pack configuration(3S2P) with generic battery block using Matlab/Simulink is created.