Project 1

Project:1

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.

• The main function of battery management system BMS is to the battery is protected and any operation out of its safety limit is prevented

Topologies:

BMS technology varies in complexity and performance

• Simple passive regulators achieve balancing across batteries or cells by passing charging current when the cells voltage reaches a certain level. The cell voltage is a poor indicator of the cells SOC and for certain Lithium chemistries such as LiFePO4 it is no indicator at all thus making cell voltages equal using passive regulators does not balance SOC which is the goal of a BMS.
• Active regulators intelligently turning on and off a load when appropriate again to achieve balancing. If only the cell voltage is used as a parameter to enable the active regulators the same constraints note above for passive regulators apply
• A complete BMS also reports the state of the battery to a display and protects the battery

BMS topologies fall in 3 categories

• Centralized: a single controller is connected to the battery cells through a multiplied of wires
• Distributed: a BMS board is installed at each cell with just a single communication cable between the battery and a controller
• Modular: a few controllers each handing a certain number of cells with communication between the controllers

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

To build a Simulink model first of all we have to know about the total number of cells that we are going to use

Total number of cells =NO.OF cells in series*NO.OF cells in parallel

Nominal voltage = 3.6v

Max capacity = 3.5Ah

Total voltage of the battery = 3*3.6V=10.8V

Total capacity of the battery = 7Ah

Total simulation run time =3600s

The given battery configuration 3s2p I took the cell specifications of nominal voltage 3.6V

Capacity 3.5Ah

So the total voltage rating of the battery is 3*3.6 is 10.6V

Capacity of the battery is 2*3.5Ah is 7Ah the initial soc% is 0%

2 cells are connected in parallel in 3 pairs connected in series

The controller source voltage is set to 7 to charge the battery

The Simulink run time is set to 3600s