Non-inverting and Non-isolated Magnetically Coupled Buck-Boost Bidirectional DC-DC Converter

A new non-isolated dc-dc converter with non-inverting output and buck-boost operation, named magnetically coupled buck-boost bidirectional (MCB3) converter, is presented in this article. The MCB3 passive components arrangement connects the input and output ports getting an equivalent behavior to that of the dual active bridge (DAB) converter, but in a non-isolated topology. This equivalency allows applying Triple Phase Shift (TPS) modulation to MCB3. TPS is known to minimize conduction losses and to achieve soft switching at any load in the DAB converter. Throughout the article, the features of the DAB converter are used as a reference to show the main features of the proposed converter. Moreover, other modulation strategies based on TPS modulation are used in MCB3 to operate within the minimum losses path. The multiple operation modes found on the MCB3 under TPS modulation are identified, classified, and used to find the operating points that minimize the switching and conduction losses over the power range. The analysis is shown for the boost mode that is the worst case design. MCB3 and DAB topologies are designed and simulated for the same specification to validate the theoretical study. Finally, experimental measurements on 460-W prototypes for both topologies corroborate the equivalent operation and the main features of the MCB3.