A new reliability evaluation technique for multi-level inverters

Multi-level inverters play a key role in today´s micro grids with renewable energy sources. The reliability of multi-level inverters, as the interface of renewable units, has critical impacts on providing electricity requirement of the customers connected to the grid. Therefore, this paper presents a new reliability evaluation technique for multi-level inverters. The method is on the basis of the state enumeration approach. Unlike the previous methods, the new approach engages harmonic distortion levels produced by the inverter in the reliability index calculation. Without loss of generality, only single failure of capacitors and semiconductor switches are considered here which can be easily extended to incorporate the other elements. Employing the developed technique, one can estimate the reliability of various multi-level topologies and hence, make her decision by compromising between reliability, efficiency, and investment cost. In the simulations, a set of reliability indices for several multi-level inverter topologies are computed to demonstrate the effectiveness of the proposed approach.