Question

Two major functions of the Battery Management System (BMS) are Contactors Control and Cell Protection.
a. What are the information (data) needed to perform cell protection in battery pack?

Answer 1

a) The most important function of the battery management system is cell protection.

Lithium ion batteries have two major design issues. If you overcharge them they will get damaged or even cause an explosion. So it is impotant to have overvoltage protection for the batteries. If the batteries are discharged below their threshold they will get damaged and their capacity might even reduced permanently.

To prevent the battery from discharged over or below the limits, battery management system has a safegaurd evice called dedicated lithium ion protector.

Every battery protection circuit has two electronic switches called MOSFETs. MOSFETs are semiconductors used to switch electronic signals on or off the circuit.

A batter management system has a discharge MOSFET and a Charge MOSFET.

If the protector detects that voltage acriss the cell is exceeds a certain limit, it will discontinue the charge by opening the Charge MOSFET chip. Once the charge has gone down to safe levels then the switch will close again.

Similarly when the cell drains to certain voltage the protector will cut off the dicharge by opening the Discharge MOSFET chip.