Project 1

Design a battery pack for a car roughly 150 Kw with 120 V. Use 3500 mAh 3.6V nominal NMC chemistry cell.

AIM: To Design a battery pack for a car by using NMC chemistry cell for given data and selection of BMS topology for the battery pack and to construct the Architecture of BMS topology

1.Design the battery pack configuration.

Given specifications of the car

Power = 150KW

Rated Voltage = 120V

Specifications of the Cell

Current = 3500mAh

Nominal Voltage = 3.6V

Chemistry – NMC

Let’s find the No. of Cells in series

No. of cells in series = Rated Voltage of Battery Pack/Nominal Voltage of Cell

No. of cells in series = 120/3.6 = 33.33

Now we have to round-off the No. of cells in series

Case-1 33 cells in series

33*3.6 = 118.8V

Case-2 34 cells in series

34*3.6 = 122.4V

We choose Case-2 As the Nominal Voltage of the Battery Pack is greater than the required system Voltage

No. of cells in series = 34

Parameters to be considered while selecting the BMS Topology

• of cells in series
• Application

As the No. of cells in series are more than 18, I’m choosing Master & Slave Topology to design the BMS

As each AFE can read 18 cells No. of AFE’s (Slaves) are 34/18 = 1.8 =2

I’m distributing 17 cells per each AFE

Slave-1(AFE-1) = 1 to 17 Cells

Slave-2(AFE-2) = 17 to 34 Cells

2.Draw the BMS topology for this battery pack.

Master & Slave BMS Topology Architecture

 

This above architecture is the Master and slave BMS topology architecture for a car having specifications

Power = 150KW

Rated Voltage = 120V

Battery capacity = 3500mAh

Nominal Voltage = 3.6V

Chemistry – NMC