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 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. A quantity of power transfer through the DC-DC power conversion circuitry is determined based on power and voltage characteristics of electrical components. A duty cycle and a switching frequency for the first switch or second switch is determined based on the quantity of power to be transferred. The primary and secondary switches are controlled using switching.