Reliability analysis and performance degradation of a boost converter

In general, power converters are being operated in closed-loop systems, and any characteristic variations in one component will simultaneously alter the operating point of other components resulting in a shift in overall reliability profile. This interdependence makes the reliability of a converter a complex function of time and operating conditions; and therefore, the application may demand periodic replacement of converters to avoid downtime and maintenance cost. By knowing the present state of health and remaining life of a power converter, it is possible to reduce the maintenance cost for expensive high-power converters. This paper presents a reliability analysis for a boost converter although this method could be used to any power converter being operated in closed-loops. Through the conducted study it is revealed that the reliability of a boost converter with control loops degrades with time, and this paper presents a method to calculate time varying reliability of a boost converter as function of characteristic variations in different components in the circuit. In addition, the effects of operating and ambient conditions have been included in the reliability model as well. It was found that any increase in the ON-resistance of the MOSFET or equivalent series resistance (ESR) of the output capacitor decreases the overall reliability of the converter. However, any variation in the capacitance has more complex impact on the converter's reliability. This conducted research is a step forward to the power converter reliability analysis because the cumulative effect of multiple degraded components has been considered in the reliability model.