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Closed-form Solution for Multi-Objective Optimal Analytical Balance Control Strategy for a Single-Stage Isolated MVAC-LVDC Converter
  • Jaydeep Saha ,
  • Naga Brahmendra Yadav Gorla ,
  • Sanjib Kumar Panda
Jaydeep Saha
National University of Singapore

Corresponding Author:[email protected]

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Naga Brahmendra Yadav Gorla
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Sanjib Kumar Panda
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Abstract

The inevitable issue of parameter mismatch in single-stage isolated multilevel medium-voltage AC - low-voltage DC (MVAC-LVDC) converters leads to unbalanced power transfer and losses in the constituting submodules. This paper analyses the drawbacks of the conventional power balance control (PBC) approach and proposes a multi-objective optimal analytical balance control (MOABC) as a remedy. The analysis of PBC strategy reveals its non-optimal pulse-width and phase-shift evaluation, leading to imbalance in losses (due to dissimilar ZVS modulations) and current stresses in the constituting submodules. The proposed MOABC follows an analytical solution approach to fulfill multiple objectives of LVDC bus voltage tracking, maximizing ZVS range of front-end (FE) and back-end (BE) MOSFETs, equalizing conduction losses among submodules and restricting grid-side current harmonics as per grid-code limits. An 11.7 kVA(pk) experimental setup is used where the proposed MOABC is implemented directly on a commercial microprocessor, and the test results verify each objective’s accomplishment. Experimental comparison of MOABC with other control methods clearly present the proposed method’s advantages.