A power transfer system includes DC-DC power conversion circuitry that has a first switch and a second switch on either side of a transformer connected via a common ground with a first capacitor and a second capacitor cross-connected across the transformer. A direction of power transfer is determined, and primary and secondary sides of the DC-DC power conversion circuitry are aligned based on the direction of power transfer. An amount of on-time for the first switch or the second switch is determined based on a quantity of power transfer through the DC-DC power conversion circuitry. The primary and secondary switches are controlled using switching.