Magnetics integration scheme in interleaved fly-back topology for PV micro-inverters

Interleaved fly-back topology is widely used in PV micro-inverter due to its simple structure with the least component numbers. However, the efficiency in the fly-back transformer becomes a great challenge because of the high frequency fringing fluxes near the air-gap to cause great AC winding losses, especially with higher operation frequencies for increasing the power density. In order to reduce the winding losses and increase the power density, one of the solutions is to integrate or couple the two fly-back transformers which operate in phase-interleaved. The mechanics of the magnetic integration in reducing AC winding losses was revealed. The model for winding and core losses were built and the factors on winding and core losses were analyzed. Simulation and experimental results validate the effectiveness of the magnetic integration scheme.