Open switch fault diagnosis in Cascaded H-Bridge multilevel inverters

ABSTRACT

This paper presents an accurate and quick diagnostic scheme for the open switch faults in a cascaded H-bridge multilevel inverter. The fault classification is based on variations in normalised half-cycle means of the bridge voltages under fault. The proposed method can precisely locate the fault within one cycle of the output voltage after the occurrence of fault without any domain transformations or complex mathematical analysis. This generalised diagnostic approach can distinguish the fault positions in the inverter irrespective of the number of levels at the output voltage for various modulation indices. Adaptability of the proposed scheme with different PWM schemes for a three-phase cascaded multilevel inverter under switch fault is substantiated using simulation and experimentation. The proposed technique is validated for different load conditions and under input voltage variations.

KEYWORDS:

• Cascaded H-bridge multilevel inverter
• fault detection
• normalised half-cycle mean
• open switch fault

Nomenclature

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Disclosure statement

No potential conflict of interest was reported by the author(s).