An improved SVPWM neutral-point control strategy for plasma generator applications

This paper investigates the neutral-point potential (NPP) imbalance issue in three-level neutral-point-clamped (NPC) converters under dynamic plasma generator loads. To address this challenge,an improved space vector pulse-width modulation (SVPWM) strategy is proposed to achieve both high output power and low harmonic distortion. Conventional SVPWM methods exhibit limitations in dynamically adjusting switching sequence weights, resulting in aggravated NPP imbalance and increased harmonic distortion. The proposed strategy features dynamic weight optimization for SVPWM through systematic analysis of the coupling relationship between capacitor voltage differences and neutral-point current, leading to the development of an innovative vector selection algorithm. This approach significantly enhances output power while maintaining total harmonic distortion (THD) below 3%, providing a high-precision and highly reliable power supply solution for industrial plasma processing systems.Experimental results demonstrate that the proposed method reduces NPP fluctuation, maintains THD under 3%, and increases output voltage by 15%. This work not only effectively resolves the NPP control challenges in high-power plasma systems,but also contributes theoretical innovations and practical engineering references for converter design under complex industrial load conditions.