Influence of windings coupling in low-voltage DC/DC converters with single winding self-driven synchronous rectification

Single winding self-driven synchronous rectification (SWSDSR) is a very good technique to improve efficiency in low output voltage converters that require a fast dynamic response. The main disadvantage of this scheme is that its performance is highly dependent on windings coupling. In this paper, the influence of the coupling between the different windings is analyzed through simulations with different transformers. Models of transformers are generated with a finite element analysis tool and results are validated with an actual prototype. All the couplings are very important to optimize the power converter but auxiliary-primary coupling is critical to make possible the use of SWSDSR technique.