Ensuring volt-second balance in high-power-density phase-shifted full-bridge converter design

The phase-shifted full-bridge (PSFB) converter topology provides a platform which enables the achievement of high power-density through low-loss operation at high frequency. However, this topology is also subject to the risk of flux imbalance in the main power transformer if precautions are not taken to prevent its occurrence. This paper evaluates the power-density implications of the several known mechanisms described in the literature for ensuring flux balance in the context of this converter topology. Additionally, the details of a high-power PSFB prototype converter design are reported and the performance of this system is used to evaluate the practicality of implementing a novel technique for addressing the volt-second balance issue without compromising the converter bus design required to achieve higher power density.