Fail-Safe Power for Hybrid Electric Vehicles: Implementing a Self-Sustained Global Energy Management System

This article studies the energy management of a hybrid electric vehicle (HEV) equipped with a battery, an ultracapacitor system (UCS), and a fuel cell system (FCS). The energy management strategy (EMS) is designed to enable degraded operation should an energy source fail. In the considered architecture, the vehicle is not operational without a battery because it imposes the dc bus voltage; therefore, degraded operations are only considered for failures in the FCS or UCS. The objective is not to develop a new EMS for each degraded operation mode but, rather, to slightly modify the global EMS developed for normal operation. The article presents simulation and experimental validation results.