On-line uninterruptible power supplies with two-relay bypass circuit and methods of operation thereof

Abstract

An on-line uninterruptible power supply (UPS) comprises an AC input configured to be coupled to an AC power source and an output configured to be coupled to a load. The UPS also includes an AC/AC converter circuit coupled to the AC input and operative to generate an AC voltage from the AC power source. A first mechanical relay (e.g., a single-pole single-throw (SPST) relay) is coupled between an output of the AC/AC converter circuit and the output. A second mechanical relay is coupled between the AC input and the output. The UPS further includes a control circuit operative to control the first and second mechanical relays to selectively place the UPS in an on-line mode in which the first mechanical relay couples the AC/AC converter circuit to the output and the second mechanical relay decouples the AC input from the output or a bypass mode in which the first mechanical relay decouples the AC/AC converter circuit from the output and the second mechanical relay couples the AC input to the output.

Dependencies are inferred from the claim text.