Abstract
This article introduces a capacitor-voltage-balancing method based on optimal zero-sequence voltage injection in a stacked multicell converter (SMC). The proposed method is implemented using hybrid carrier pulsewidth modulation and is capable of balancing and regulating the voltages of dc-link capacitors and floating capacitors in the topology. The dynamic model of voltage fluctuation and the coupling relationship of voltage-balancing control between dc-link capacitors and floating capacitors are analyzed. The optimal zero-sequence voltage selection method is presented to address the voltage deviations of dc-link capacitors with the maximal regulation ability for floating capacitor-voltage-balancing control. Compared with the active capacitor-voltage-balancing (ACVB) method, the proposed method calculates the compensation current of the neutral point (NP) and chooses the optimal zero-sequence voltage in the whole available range. As a result, the low-frequency voltage ripples in NP can be suppressed with excellent dynamic performance under wider load conditions. Simulation and experimental results are presented to verify the effectiveness of the proposed method.
Published Version
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