An Expanded Lyapunov-Function Based Control Strategy for Cascaded H-Bridge Multilevel Active Front-End Converters


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Jean-Pierre G., ALTIN N., Shafei A. E., Nasiri A.

IEEE Open Journal of Power Electronics, vol.4, pp.117-127, 2023 (Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 4
  • Publication Date: 2023
  • Doi Number: 10.1109/ojpel.2023.3239414
  • Journal Name: IEEE Open Journal of Power Electronics
  • Journal Indexes: Scopus
  • Page Numbers: pp.117-127
  • Keywords: Cascaded H-bridge, current control, LCL filter, Lyapunov function, proportional-resonant, voltage balancing
  • Gazi University Affiliated: Yes

Abstract

AuthorCascaded H-bridge multilevel (CHBML) active front-end (AFE) converters exhibit some enticing benefits, comprising high adaptability for numerous applications, such as tractions, solid-state transformers, electric vehicle charging stations, and medium and high power electric drives. Yet, when the CHBML- AFE is operating under an unbalanced load condition, it is crucial to utilize an advanced control technique to maintain system stability. In this research, a Lyapunov Function (LF)-based control approach is utilized for regulating a single-phase CHBML- AFE with LCL filter to achieve global asymptotic stability. A capacitor voltage feedback is introduced and added to the traditional LF-based control strategy to reduce the resonance of the LCL filter. Furthermore, the proportional-resonant (PR) control procedure is utilized to derive the grid current reference, offering improvement to the robustness of the current control design. A balanced DC voltage control method is also employed to suppress the unbalanced DC voltage conditions among CHBML- AFE cells. In addition, the transfer function of the reference grid current and the actual grid current is evaluated for the CHBML- AFE with LCL filter parameters and their eventual variations in the employed control technique. The effectiveness of this control strategy is validated utilizing simulation and experimental studies.