Magnetically Coupled Buck-Boost Bidirectional DC-DC Converter

A new nonisolated bidirectional dc-dc converter with noninverting output and buck-boost operation is proposed and described in this article. The passive components arrangement in the proposed magnetically coupled buck-boost bidirectional dc-dc (MCB3) converter makes it possible to use triple-phase shift (TPS) modulation, originally intended for the classical dual active bridge (DAB) converter. TPS allows the MCB3 converter to achieve soft switching and conduction losses minimization for any load and voltage requirement. In this article, the mathematical analysis of the proposed converter operation is shown for the step-up operation, which is the worst-case design. The multiple operation possibilities that allow the use of the three TPS control variables are identified, classified, and used to find the operating points that minimize the power losses for any voltage and power range. Besides, the theoretical study demonstrates that MCB3 converter operation is equivalent to that in the classical DAB converter; thus, the DAB converter know-how can be employed in the proposed converter, but for nonisolated applications. MCB3 converter feasibility is validated by comparing the simulation-level results to the experimental measurements for a 460-W-scaled prototype.