Practical considerations in the design of power system architectures for fault tolerant systems

Systems engineers are rarely well versed in the intricacies of detailed power circuit design. Power design engineers are rarely well versed in the intricacies of fault tolerant system design. As a result, the marriage of systems designers translating requirements to power designers in an attempt to develop a fault tolerant power architecture may render a product which is lacking the anticipated reliability its designers envisioned. Because subtle and latent faults are the nature of inadequacies in fault tolerant power systems, design flaws may not be discovered in the development phase. Continued unforeseen component overstress may reveal itself only upon system failure. Pitfalls can easily be overlooked if one is not familiar with abnormal operating modes resulting from faults. Fault tolerant power systems design requires knowledge of fault tolerance techniques, power electronics, analog electronics, component characteristics, and electromagnetic compatibility. Once design deficiencies are pointed out, they make perfect sense, but they are rarely intuitively obvious. This paper seeks to provide systems designers with an increased knowledge of implementing fault tolerance requirements so that potential problems are avoided. In doing so, common design flaws are pointed out, and practical solutions are suggested.