This paper explores the unique functional safety challenges encountered when designing a wireless battery management system.
Battery manufacturers want to achieve the highest possible density of energy. This applies especially to electric or hybrid vehicles (EV/HEV) where achieving the maximum drive range attracts customers. With increasing energy density, the importance of battery management and monitoring is essential to avoid any kind of hazards related to overvoltage or overtemperature.
Batteries in EV/HEV reach nominal voltages of 400 V or 800 V. The batteries are typically organized in modules – groups of cells – that are managed by a dedicated battery management integrated circuit (BMIC). Typically one BMIC can monitor up to 16 cells connected in series.
Apart from other features that are not in the scope of this paper, the main role of the BMIC is to periodically measure the cell voltages and temperatures. These quantities are converted into digital form and conveyed towards a host BMS control microcontroller (MCU). The information from the BMIC is vital for calculating the state of charge and state of health. In the context of BMS, BMICs are also functional safety-relevant.