摘要： Recent renewable energy system is heavily dependent upon power electronic devices like multilevel converter (MLC), for integrating renewable energy sources to the grid or to provide power to loads in islanding mode. However, the power electronic switches used in these converters have high failure rates (approximately 34%). Therefore reliability study of these converters is of paramount importance. Most of the research has been done to develop an efficient, cost-effective, fault-tolerant topology and to reduce the number of device count, but reliability study of these topologies has not been explored much. In this paper, comparison of some of the existing five-level topologies has been made on the basis of device count, peak device current, number of dc voltage sources and capacitors required to produce the same peak output voltage. The best among these topologies are selected for reliability modeling and evaluation. The failure rate of different elements of this topology is computed (i) by assuming junction temperature same for all the devices (ii) by deriving junction temperature from the measured power loss of the elements with the help of simulation using PSIM version 9.0 thermal block. Each element exhibits different failure as these elements have different power loss across them. The reliability from both the approach is computed and compared and found that the total failure rate of converter computed from power losses of switches is 2.5% higher and accurate than the failure rate computed from the second one.