An uninterruptible power supply (UPS) and methods of operation are provided. The UPS includes a transformer configured to receive power from a utility. The transformer includes a primary winding, a secondary winding, and a tertiary winding. The UPS also includes a rectifier coupled to the secondary winding and an inverter coupled to an output of the rectifier, wherein a connection between the rectifier and the inverter defines a DC link. The inverter is configured to output a first regulated voltage configured to be provided to a load. The UPS further includes a voltage-boost converter coupled to the tertiary winding and is configured to output a second regulated voltage to be combined with the first regulated voltage.