Model-based strategy for open-circuit faults diagnosis in n-level CHB multilevel converters

• Published in: IET power electronics Vol. 12; no. 4; pp. 648 - 655
• Main Authors: Mtepele, Kassim O, Campos-Delgado, Daniel U, Valdez-Fernández, Andrés A, Pecina-Sánchez, José A
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 10.04.2019
• Subjects: active filters; additive fault profiles; additive structure; CHB‐ n L converter; constant term sign; damaged switches; estimated constant terms; fast diagnosis stage; fault detection; fault diagnosis; fault isolation; fault profiles; FDI scheme; model uncertainty; model‐based perspective; model‐based strategy; multiple fault scenarios; n‐level CHB multilevel converters; observers; OCF; open‐circuit faults diagnosis; oscillatory components; power filters; power switches; Research Article; robust diagnosis stage; shunt active power filters; single fault scenarios; single‐phase cascaded H‐bridge converters; sliding‐mode integral observer; variable structure systems; voltage‐source convertors; fault diagnosis; damaged switches; constant term sign; fault detection; oscillatory components; power switches; model uncertainty; multiple fault scenarios; n-level CHB multilevel converters; fast diagnosis stage; single-phase cascaded H-bridge converters; CHB- n L converter; additive structure; model-based strategy; robust diagnosis stage; sliding-mode integral observer; fault isolation; fault profiles; active filters; power filters; shunt active power filters; voltage-source convertors; open-circuit faults diagnosis; OCF; model-based perspective; single fault scenarios; estimated constant terms; FDI scheme; additive fault profiles; variable structure systems; observers
• ISSN: 1755-4535; 1755-4543; 1755-4543
• DOI: 10.1049/iet-pel.2018.5478

Here, the authors study open-circuit faults (OCFs) in the power switches of multilevel converters with a model-based perspective. In specific, the authors address single-phase cascaded H-bridge (CHB) converters with n-levels in its output voltage (CHB-n L), which are designed as shunt active power filters. In this task, the OCFs are modelled by fault profiles with an additive structure in each subsystem of the CHB-n L converter. These additive fault profiles have constant and oscillatory components, where the constant term sign indicates the pair of damaged switches in the H-bridge. Hence, a sliding-mode integral observer is proposed to estimate the constant terms of the fault profiles. The complexity of the observer depends on the number of H-bridges in the CHB-n L converter. As a result, the proposed fault detection and isolation (FDI) scheme relies on the estimated constant terms of the additive fault profiles to achieve a robust and fast diagnosis stage. The proposed model-based FDI scheme is validated experimentally under single and multiple fault scenarios, and model uncertainty. During the evaluation, the derived methodology only requires less than one cycle of the fundamental frequency to isolate the faults, and show robustness to load changes and parametric uncertainty.