Optimizing Transfer Switch N+1 Redundant Power Architectures
by by Viktor Vogman, Power Conversion Consulting, Olympia, Wash., How2Power Today, May 15 2019
Focus:
In data center power distribution networks, automatic transfer switches (ATSs) provide fail-
safe ac power redundancy but they can also advance dc redundant architectures by supporting
seamless dc power flow to the server when one of the power modules fails. This
article examines opportunities for optimizing ATS techniques, thereby reducing the cost and
size of server power subsystems that provide both ac and dc redundancy. These benefits are
achieved by separating the safety isolation and power transfer functions in the ATS, reducing
the switched power level. Examples of optimized transfer switch implementations for 2+1 and 3+1
redundant configurations are presented. Then, a look at the power levels transferred during the
different stages of operation in a 2+1 configuration reveals how the configuration determines
power capacity and requirements for the ATS, and these requirements are compared across 2+1,
3+1, and 4+1 configurations. Finally, some experimental results are presented, which confirm
the predicted switching operation and robustness of a 2+1 redundant power system with ATS.
What you’ll learn:
- How to understand the benefits of splitting safety isolation and power transfer functions in redundant server power subsystems with automatic transfer switches
- How to reduce the cost and size of server power subsystems with ac + dc power redundancy
- How to speed up power transfer in redundant power systems with automatic transfer switches
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