Power converters operate at varying low-, medium-, and high-voltage levels. Large electrolytic capacitors are usually used to sustain the associated dc-link current and stabilize the dc-link voltage. However, owing to different power converter applications, capacitors are affected by large ripples in the dc-link current, which increase heat exchange and reduce system reliability and lifespan. In this regard, this article proposes an innovative control technique for suppressing the ripple in the dc-link current and common-mode voltage (CMV) in hybrid active neutral point clamped inverters. The proposed control technique uses an improved dual-carrier-based pulsewidth modulation technique to create a new switching scheme by selecting the voltage vectors that contribute to the smallest ripples in the dc-link current according to each sector. Applying the proposed control technique significantly reduces the ripples in the dc-link current and CMV, which increases the reliability of the system and extends the lifetime of dc-link capacitors. The simulation and experimental results demonstrate the effectiveness of the proposed control strategy.
This work was supported in part by the Korea Institute of Energy Technology Evaluation and Planning, and in part by the Ministry of Trade, Industry and Energy of the Republic of Korea under Grant 20182410105160 and Grant 20206910100160
