Project 1

Aim:

• To design a battery pack for a car roughly 150 Kw with 120 V. Use 3500 mAh 3.6V nominal NMC chemistry cell.
• To design the battery pack configuration for given problem.
• To draw the BMS topology for this battery pack for given problem.
• To build a 3S2P battery pack configuration with generic battery block using Matlab/Simulink.

1.

Given,

Nominal voltage = 3.6V

Cell capacity = 3500mAh = 3.5Ah

Power= 150KW

Rated voltage = 120V

Battery Current= Power/Voltage

= 150000/120

= 1250 A

No. of cells in series= Rated battery voltage/Nominal cell voltage

= 120/3.6

= 33.3

Case 1: Rounding off 33.3 to 33

Nominal battery voltage= Cell nominal voltage*33

= 3.6*33 = 118.8 V

Maximum battery voltage= Cell maximum voltage*33

= 4.2*33 = 138.6 V

Minimum battery voltage= Cell minimum voltage*33

= 2.7*33 = 89.1 V

Case 2: Rounding off 33.3 to 34

Nominal battery voltage= Cell nominal voltage*34

= 3.6*34 = 122.4 V

Maximum battery voltage= Cell maximum voltage*34

= 4.2*34 = 142.8 V

Minimum battery voltage= Cell minimum voltage*34

= 2.7*34 = 91.8 V

Since the Nominal battery voltage in case 1 is less than required,

No. of cells in series is taken as 34.

No. of cells in parallel= Total current/Cell capacity

= 1250/3.5

= 357.4

No. of cells in parallel is taken as 358

Battery pack configuration:

BMS topology (Master and slave topology):

2. 3S2P battery pack configuration:

Total no. of cells in a battery pack = No of cells in series*No of cells in parallel

= 3*2

= 6

Model: Connection in series and parallel combination

Parameters:

Nominal voltage of a cell= 3.6 V

Rated capacity of a cell= 3.5 Ah

Nominal voltage of battery pack= 3*3.6 = 10.8 V

Rated capacity of battery pack= 2*3.5 = 7 Ah

Result:

• Single battery output for SOC,Current and Voltage

• Overall output voltage of the battery pack

• SOC reduced from 100% to 96%.
• The current value is 1.75 A and is determined by the load.
• The voltage is around 4.2 V. The increasing and decreasing value is with respect to regenerative braking.
• The overall voltage decreases exponentially.