Loss study and reliability analysis of a new reconfigurable fault-tolerant multilevel inverter topology

A high reliable inverter with photovoltaic systems improves the efficiency and longevity of the entire system. Recent research emphasises on developing new fault-tolerant multilevel inverter (FTMLI) topologies. However, these topologies are not able to maintain rated voltage and power with a minimum switch count under switch fault conditions. This study proposes a new multilevel inverter with a reduced device count, which can handle both single switch fault and multi-switch fault by preserving its rated voltage and power. Sine-carrier-based level-shifted pulse-width modulation is used to generate control signals. The carriers are reconfigured based on the type and location of the fault. The loss contribution of each switch is calculated in all modes of operation by considering variations in junction temperature using a Powersim (PSIM) thermal model tool. This study helps to choose an appropriate heat sink for the switches. The reliability density function is calculated using a Markov chain model. A comparative study is presented to assess the notable benefits of the proposed topology over other existing similar topologies. The experimental results from the laboratory prototype are provided to verify the efficacy and practicality of the proposed FTMLI configuration.