Improved soft-switching boost converter with coupled-inductor using passive EMI cancellation method

Non-isolated switching power supplies with coupled-inductor have more parasitic elements like the leakage inductance in comparison with the regular non-isolated converters. Due to the undesirable resonances between the leakage inductance and other parasitic capacitors, the conducted electromagnetic emissions increase. In order to improve electromagnetic compatibility, adopting passive or active parasitic cancellation methods can be used. In this paper, a passive cancellation circuit is combined with the converter`s coupled-inductor cell. Among the non-isolated converters, the boost converter where a lossless snubber with a coupled inductor is applied in its soft switching cell is selected to reveal the advantage of this proposed method with respect to EMC. To verify the advantage, the conducted EMI of this proposed converter is compared with the regular boost converter and boost converter with a lossless snubber. The experimental results indicate a considerable reduction in the conducted EMI levels. This proposed technique can be applied in other non-isolated topologies like buck, buck-boost, SEPIC, Cuk and converters with tapped inductor.