Improved Markov Model for Reliability Assessment of Isolated Multiple-Switch PWM DC-DC Converters

Abstract

This paper proposes a comprehensive Markov model to study the reliability performance of the conventional isolated multiple-switch pulse width modulation DC-DC (IMSDC-DC) converters including full-bridge, half-bridge and push-pull DC-DC topologies. The suggested model helps to achieve more precise outcomes with a better reflection of the real-world operation characteristics by (i) relying on self-embedded fault tolerant capability of the IMSDC-DC converters, (ii) considering the probability of both short and open circuit (SC and OC) faults in each component, (iii) assessing the effect of semiconductors' SC/OC probability on the converters' reliability, (iv) analyzing the continuous and discontinuous conduction modes, (v) updating the operational characteristics of the converters after each fault occurrence, and (vi) evaluating control of the converters to have more durable power transfer in some post-fault cases. Then, the model is applied to assess the effects of duty cycle, output power, voltage gain and transformer turns ratio on the overall reliability and mean time to failure. Practical analytic conclusions are followed by some experimental results to verify the accuracy of the proposed model.