Two-dimensional finite element simulation and stress analysis of a full bridge DC-DC power converter

The power MOSFETs used in DC-DC converters undergo excessive electrical and thermal stress as a result of higher switching frequency operation for size and cost reduction. The next generation of power MOSFETs have to be designed and optimized at the application level, which involves identification of tradeoffs among critical circuit and device performance and reliability parameters. This paper presents the results obtained from measurements and two-dimensional (2-D) finite element simulations conducted to evaluate the various electrical stresses applied to a power MOSFET in a 350 V-3.5 V, 225 A full-bridge (FB) phase-shifted ZVS DC-DC converter. MOSFETs were found to fail under no-load converter operation in the field.