As the climate change & CO2 emissions are becoming prime
concerns over the globe, Electric Vehicles (EV) are proving to be
promising eco-friendly mobility solution. In India, the drive for
transition to EV is gaining momentum. Batteries constitute a major
chunk of EV cost. Battery Management systems (BMS) are of paramount
importance from the aspect of safety, performance, usability &
lifetime of EV. Along with fundamental function of monitoring (Cell
Voltage, Pack voltage, pack current, cell/pack temperature), BMS
must perform function of controlling (Charger/Load Connect,
disconnect, Pre-charge) the battery pack in case of failure. In
most vehicles, loads & chargers have high capacitance, causing
high inrush currents into and from the BMS. This can not only
damage the contactors (connect/disconnect circuits) and other load
components but also affect the lifetime of cells within battery
pack. Conventionally contactor-based cut-off & pre-charge
circuits are present in EV's. However, semiconductor-based
cut-off control & pre-charge are gaining momentum in 2W/3W EV
battery packs considering advantages like compactness, robustness
against mechanical vibrations & shocks, controllability,
competitive cost & functional safety. This paper focuses on
various semiconductor-based pre-charge and cutoff circuit
architectures & their advantages. Simulations & practical
results of conventional pre-charge circuits &
semiconductor-based pre-charge circuits are discussed. It is
concluded that, for effective design of BMS for small battery
packs, semiconductor-based cut-off & pre-charge techniques will
provide an added advantage with respect to reliability, safety
& controllability.