Design of a Battery Management System for Extracorporeal Life Support Devices

The objective of this master’s thesis is to design a Battery Management System (BMS) for a medical device, in particular an extra corporeal life support device developed by an Italian company. Since the device may also be used outside the hospital and therefore transported, the development of the BMS must take this into account, requiring a reliable and safe power supply to ensure continuous operation in a critical situation. The power supply for the system in this situation is provided by a lithium-ion battery pack equipped with a BMS that provides all the safe protection against overvoltage/undervoltage, overcurrent and overtemperature/undertemperature. The process of thermal runaway will be discussed, referring to the main causes that could lead the battery to catch fire. The work also involves the selection of improved components compared to BMS currently on the market. Different algorithms for State of Charge (SoC) and State of Health (SoH) estimation are compared to guaranty accurate monitoring of battery status throughout its whole life. The schematic and PCB design for the first prototype are developed taking into account the safety standards regarding lithium batteries, such as IEC 62133 and UN 38.3 which involve severe electrical and mechanical tests to certify their safety. Finally, a comparison between the BMS currently on the market and the BMS under development will be reported to evaluate the overall performance improvements.