The Impact of Parasitic Elements on Spurious Turn On in Phase Shifted Full Bridge Converters
This paper presents a comprehensive analysis of the spurious turn on phenomena in phase shifted full bridge (PSFB) converters. The conventional analysis of the spurious turn on phenomenon does not establish in the PSFB converter as realizing zero voltage switching (ZVS) Firstly, a circuit model is proposed taking into account the parasitic capacitors and inductors of the transistors, as well as the parasitic elements of the power circuit loop. Second, an exhaustive investigation into the impact of all these parasitic elements on the spurious turn on is conducted. It has been found that the spurious turn on phenomenon is mainly attributed to the parasitic inductors of the power circuit loop, while the parasitic inductors of the transistors have a weak impact on this phenomenon. In addition, the operation principle of the PSFB converter makes the leading and lagging legs have distinguished differences with respect to the spurious turn on problems. Design guidelines are given based on the theoretical analysis. Finally, detailed simulation and experimental results obtained with a 1.5 kW PSFB converter are given to validate proposed analysis.