Reliability evaluation of electric vehicle charging systems including the impact of repair

This paper presents a framework to analyze and assess the reliability of the power electronic circuits utilized in electric vehicle (EV) charging systems. These charging systems are anticipated to be a significant portion of the utility load in the near future. A general structure of electric vehicle charging systems is described including multi-phase interleaved charger topologies and different charging levels are discussed. The multi-phase interleaved charging system can be fault-tolerant so that the controller is capable of fault detection, isolation, and reconfiguration with perfect coverage. Component level reliability is calculated using MIL-HDBK-217. A Markov model is proposed to analyze the reliability of the fault tolerant multi-phase interleaved charger topology including the impact of repair. Reliability indices such as mean time to failure (MTTF) and mean time to first failure (MTTFF) are discussed and calculated. The impact of repair is investigated and evaluated on overall system reliability and the reliability indices for repairable and non-repairable charging systems are calculated and compared. The proposed systematic framework can be extended to reliability assessment and comparison of other types of EV chargers and can help understand and improve future charging infrastructure designs.