A Fault-Tolerant Control Architecture for Different Battery Topologies in Electric Vehicles

In this paper a variety of battery configuration topologies for electrified vehicles are investigated with regard to reliability and expected lifetime along with the possibility of applying active fault detection to provide early warnings for the driver. Different configurations are investigated ranging from a simple single serial string of battery cells providing only the lowest level of fault tolerance, to a highly elaborate and still practically relevant triple string configuration providing fault detection and reconfiguration possibilities as well as repair. All configurations are analyzed with regard to the associated reliability profile assuming non-ageing cell failure model. A novel method for active early fault detection is presented based on encoding faults into a parametric dynamic cell model, where parameters are continuously estimated under the influence of an auxiliary test signal designed to optimize parametric sensitivity. Finally reliability profiles for all investigated configurations are compared mutually and with standard requirements on the basis of mean time to failure statistics.