Abstract
An electric power converter is specified by its system performance indices. Many system performance indices like efficiency are important in design process of system. However, that doesn't mean the converter performance is necessarily adequate for a practical application. At the end of design process of a converter, some desired specifications may not be achieved. In this chapter, reliability as a figure of merit in design of a system is presented and compared with other indices. We want to highlight the effect of reliability considerations on the design methodology of a power converter. The most important specification of a power supply or power converter is its robustness. Because any failure in power supply leads to failure of the whole of the system. A power converter may have poor performance but operate reliably and vice versa. In fact, this is a reliability based design approach to achieve a long useful life. It is shown that in many systems, high efficiency is not a good choice for selection of system operating point. A system can be inefficient but very reliable. Two complex examples are presented to show undesired results of neglecting reliability in design process. Methods for more reliable operation of electric power converters than high performance operation are proposed. A discussion about correct and intelligent optimization of a system parameters and operating set point is presented.