A Power-Balance Modulation Strategy with Low Switching Frequency Based on Carrier Reconstruction

The modulation strategy based on carrier reconstruction usually achieves low harmonic distortion of inverter output line voltage and balanced output power of each unit at the expense of high switching frequency. This paper proposes an improved modulation strategy based on carrier reconstruction. By adjusting the arrangement of traditional phase-disposition carriers in the horizontal direction, a new carrier is reconstructed to avoid additional switching operations caused by mutations of instantaneous value of the carrier in the vertical direction. This paper first deduces the output average power expression of each module of the parallel-interleaved inverters in a reconstructed carrier period, and proves that the output power balance among the parallel modules of the inverters is balanced; secondly, the reason why the carrier wave reconstructed in the vertical direction introduces additional switching operations is analyzed, and the expression for the switching frequency of the inverters under different modulation strategies in one modulation wave period is derived, and it is proved that the proposed modulation strategy does not introduce additional switching operations by reconstructing in the horizontal direction. Finally, an experimental platform is built to verify the correctness and feasibility of the above theoretical analysis.