battery management system (Li-Ion) (BMS)
Battery management systems (BMS) are electronic control circuits that monitor and control the charge and discharge of batteries. Battery parameters to be monitored include battery type detection, battery voltage, battery cell temperature and voltages, battery capacity, state of charge, current draw, remaining operating time, chargecycle, and several more parameters.
The task of battery management systems is to ensure the optimal use of the residual energy present in a battery. To prevent damage to the batteries, BMS systems protect the batteries from deep discharges, from overvoltages, from charging too fast and from a discharge current that is too high. In the case of multi-cell batteries, the battery management system ensures battery balancing, which is expressed as the different battery cells having equal states of charge and discharge.
The battery management system for monitoring battery characteristics
A battery management system is an electronic circuit with control mechanisms. When checking the battery cells and their charge, the BMS system works passively; on the other hand, it intervenes actively when the limits of certain parameters are exceeded. Such a system is supplied by the power grid. The DC voltage is processed in a power module( PM) so that it can be used for battery charging. The power module can be integrated in the mobile device, as well as in electric vehicles, in UPS systems or in photovoltaic systems. It can also be an external AC adapter. The processed DC voltage can be used to charge the batteries.
To prevent damage to lithium-ion batteries, the batteries have deep discharge protection. For regulation, the battery management systemchecks the residual energy, State of Health( SoH) and the state of charge, State of Charge( SoC). The values are transmitted to a processor running the BMS software and implementing the SoC algorithm.
In addition to monitoring and controlling the battery characteristics, the battery management system can also collect data and output reports and statistics. The battery management system communicates with other connected units via a serial interface such as the I2C bus or the CAN bus.
Battery management in PV systems
InPV systems with home storage, the battery management system ensures proper control of charging currents and consumption currents. For example, for the charging current from the solar modules to the quarter storage or for self-consumption via the inverter into the house. If there is a surplus of electricity, the BMS system feeds it into the low-voltage grid or into the house battery. If solar power is not available, then the consumption power from the storage batteries is routed to the house or the low-voltage grid via inverters for self-consumption. The battery management system monitors the voltage, current and temperature in the battery cells, it calculates the remaining residual energy of the batteries, it detects thermally critical conditions and ensures the cooling of the battery cells in case of overheating, and it optimizes the balancing between cell charges.