Methodology for quantitative assessment of fault tolerance of the multi-state safety-critical systems with functional redundancy

This paper describes a methodology of quantitative assessment of the fault tolerance of the multi-state safety-critical systems with functional redundancy. Such systems are the traction drives of electrical vehicles, consisting of the multiphase traction electric motor and multilevel electric inverter. It is suggested to consider such traction drive as a system with several degraded states. As a comprehensive parameter for the quantitative evaluating the fault tolerance, it is proposed to use the criterion of degree of the fault tolerance. For the approbation of proposed methodology, based on the multi-state system reliability Markov Model, the fault tolerance assessment of the traction train of an electrical helicopter has been carried out.