48 V Battery Management System (BMS)

48 V batteries tend to be created using Li-ion multi-cell battery packs suing 8-16 cells. From a safety perspective, but also to ensure the best efficiency and longest battery life these battery packs need to be carefully monitored and controlled. This requires accurate voltage, temperature and current as well as battery state of charge (SoC) and state of health (SoH) monitoring. In addition for most efficient battery use, good cell balancing and battery optimization is a must.

Block diagram

Highlighted components are Nexperia focus products

Design considerations

  • Depending on the current being drawn some systems can use internal cell balancing topologies, but where there is a higher current then external MOSFETs are recommended.
  • Engineers also have a choice between passive and active cell balancing, although active cell balancing is often more complex give, its need for charge storage elements
  • Zener diodes utilized in the cell balancing stage protect the FETs and battery cell

MOSFET and GaN FET Handbook

Drawing on over 20 years’ of experience, the MOSFET and GaN FET Application Handbook: A Power Design Engineer’s Guide brings together a comprehensive set of learning and reference materials relating to the use of MOSFETs and GaN FETs in real world systems.

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