A Novel Bidirectional Three-Level LCL-T Resonant Converter Applied to Onboard ESHS Based on Quasi-Constant-Current

For the popularization of constant-current charging to onboard energy storage hybrid systems (ESHS) and requirements of higher voltage and higher current. A novel bidirectional three-level inductor-capacitor-inductor-T type structure (LCL-T) resonant converter applied to onboard ESHS based on quasi-constant-current (QCC) is proposed by combining the LCL-T resonance with the three-level cascaded neutral-point clamped active bridges (3L-CNPC). Each sub-NPC-arm of 3L-CNPC can work solely or in tandem with a coupling transformer, which is adopted to design different modulation methods to control the input voltage of the resonant tank module (RTM) that can establish once and double QCC modes. While a characteristic of unified power transmission in two-way is achieved by a symmetrical design of the RTM parameters that can access an LCL-T resonant QCC output open-loop configuration only depended on
${f} _{\mathrm {n}}$
and
${Q}$
. Besides, an approach to QCC for getting operating frequency
${f} _{\mathrm {s}}$
that meets the restricted given judgment criteria of QCC is designed under reactive power control and realizing ZVS of switches. At last, the simulations and prototype experiments both prove that the proposed converter almost implements the QCC output within judgment criteria in each mode.