Document Type
Article
Publication Date
2021
Keywords
Silicon carbide; Silicon; Switches; Modulation; Support vector machines; Hybrid power systems; MOSFET; Hybrid modulation; multilevel converter; space-vector-modulation (SVM); zero-sequence injection
Abstract
This paper proposes a hybrid modulation strategy for a medium-voltage hybrid seven-level (7-L) converter, which consists of a three-phase silicon (Si) IGBT-based active-neutral-point-clamped (ANPC) stage and a cascaded silicon carbide (SiC) MOSFET-based H-bridge (HB) stage in each phase. Within the framework of the proposed modulation strategy, three floating HB converters are controlled using a high-frequency three-level (3-L) space-vector-modulation (SVM), while a low-frequency modulation is applied to the ANPC converter. To regulate the DC voltages across floating capacitors, a zero-sequence voltage (ZSV) injection method is adopted. The proposed method possesses three major advantages. First, it enables the simplification from a 7-L to a 3-L SVM, which significantly reduces the computational burden. Second, with all the high-frequency switching actions assigned to SiC devices in the HB stage, the power loss of the hybrid 7-L converter is reduced. Third, the hybrid modulation together with the ZSV injection enables a wider stable operating range compared to the existing 7-L SVM method. Finally, both simulation and experimental results performed on the scale-down and the full-scale 1 MVA prototype validate the effectiveness of the proposed hybrid modulation strategy.
Citation
Diao, F., Li, Y., Du, X., & Zhao, Y. (2021). An Active Hybrid Modulation Strategy for a Si/SiC Hybrid Multilevel Converter. IEEE Open Journal of Power Electronics, 2, 401-413. https://doi.org/10.1109/OJPEL.2021.3104608
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
