Project 1

Aim:

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

1. Design the battery pack configuration. 
2. Draw the BMS topology for this battery pack.

Ans:

1.) Taking the values into consideration:

150kw, 120v, 3500mAh nominal-3.6V

No. of cells in parallel-

Np= total current / cell capacity

= 3.5/3.5 = 1

No. of cells in series-

Ns = Max.voltage / Nominal Voltage

= 120/3.6 = 33.33. Taking a round figure lets take 33.

So the battery pack configuration is 33S1P.

2.) For a pack of 33 cells in series we will use Master & slave topology.

For 33 cells we will distribute the cells in 18 and 15 cells respectively for AFE1 and AFE2 

Here AFE stands for Analog Front End.

The second AFE is connected to Master MCU in series.

As shown this MCU takes input as temperature sensor and battery discharge current. The communication goes through CAN and RS485.

The BMS topology of Masters and Slave is as shown below :