Ring Bus Architecture with Static UPS for Critical Power Applications

Mission critical applications require UPS for power conditioning and back-up, and multiple UPS units may be combined in redundant architectures to maximize reliability. However, both upfront investment as well as operating costs are penalized by the required deployment of excess capacity.So-called Iso-parallel or Ring Bus architecture employing rotary UPS systems is a cost effective and efficient alternative. This paper discusses the extension of such concept, proposing the deployment of static UPS in Ring Bus arrangement.First, rotary and static UPS topologies and associated characteristics are reviewed. Then, the Ring Bus architecture and associated load sharing technique is detailed. Finally, the paper focuses on handling of fault scenarios, as the main challenge with using static UPS is their limited fault current capability. Overcoming such limitation unlocks the benefit of static UPS deployment in Ring Bus systems.