A system and method for an uninterruptible power supply (UPS) includes a first converter assembly, a second converter assembly, a third converter assembly, a first controlled device configured for disconnecting at least two converters of the first converter assembly from and AC source, and a second controlled device configured for connecting at least two of the first converters together, and comprising the step of: opening the first controlled device and closing the second controlled device such that the first converter assembly transfers energy between split DC link halves to maintain voltage regulation of the DC link with respect to the midpoint reference.