Model-based control strategy for the three-phase n-level CHB multilevel converter

• Published in: International journal of electrical power & energy systems Vol. 147; p. 108883
• Main Authors: Valdez-Fernandez, Andres A., Escobar, Gerardo, Campos-Delgado, Daniel U., Hernandez-Ruiz, Moises E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2023
• Subjects: Closed-loop systems; Model-based design; Multilevel converter; Power system harmonics; Power system harmonics; Closed-loop systems; Multilevel converter; Model-based design
• ISSN: 0142-0615; 1879-3517
• DOI: 10.1016/j.ijepes.2022.108883

This paper presents a control methodology for a three-phase cascaded H-bridge (3ph-CHB) converter in the general case of n-levels (3ph-CHB-nL). The proposed method is used to compensate reactive power and to eliminate the harmonic currents caused by non-linear loads. For this, a generalized modeling process of the CHB-nL converter is first introduced, which includes the effect of the line impedance. The control objectives comprise a current tracking loop, as well as regulation and balance voltage loops for all H-bridges. The proposed controller solution includes an internal control loop to ensure line current tracking towards an extended reference that includes additional degrees of freedom. The current reference has been designed in such a way that, in the steady state, it becomes proportional to the fundamental component of the line voltage. The proposed controller also includes outer voltage loops to guarantee regulation and balance of the involved capacitor voltages. Experimental results have been realized in a three-phase and five-level CHB (3ph-CHB-5L) prototype to assess the performance of the proposed generalized controller. •A generalized modeling process of the three-phase CHB n-level converter is introduced.•The current and voltage system dynamics are decoupled using a proposed transformation.•The controller includes a current loop, and voltage regulation and balance loops.•The proposed two-loop feedback control structure is independent of model parameters.•Experimental results validate the proposed control structure.