Reconfigurable Bidirectional Interleaved Neutral-Point-Clamped Resonant DC/DC Converter for High and Wide Voltage Gain Range

This article proposes the reconfigurable bidirectional interleaved neutral-point-clamped (NPC) resonant dc/dc converter that supports a high and wide voltage gain range. The proposed converter is capable of operating as an interleaved three-level half-wave NPC converter in both forward and backward power-flow directions. In forward operation, the voltage gain range is extended from [2,$\boldsymbol{\infty}$] to [1,$\boldsymbol{\infty}$], and in backward operation, it is extended from [0, 0.5] to [0, 1]. The interleaved operation of NPC resonant dc/dc converter generates two asymmetric currents that alternately charge and discharge the secondary-side capacitors, thus inherently balancing their voltages. Comprehensive voltage gain expressions are derived for both power flow directions, along with a detailed design methodology. The proposed converter achieves a wide voltage gain with reduced transformer turns-ratio. The feasibility of the proposed topology, along with its switching modulation strategy, are validated experimentally using a 1-kW prototype with a 125-V input and an output voltage range of 275–1000 V.