Open‑circuit switch fault diagnosis in single‑phase cascaded H‑bridge five‑level converters under signal noise

Qingqing Yuan; Yao Du; Youyan Liu; Kun Xia

Open‑circuit switch fault diagnosis in single‑phase cascaded H‑bridge five‑level converters under signal noise

Vol. 26, No. 4, pp. 907-919, Apr. 2026

10.1007/s43236-025-01117-y

Single-phase cascaded H-bridge

Five-level converter

Open-circuit switch fault

Noise reduction

Fault diagnosis

Abstract

The effective acquisition of fault data is a prerequisite for accurate open-circuit fault diagnosis in power converters. During signal sampling, random noise spreads across the entire frequency range, causing fault features to overlap with noise interference and complicating fault identification. This paper proposes an improved open-circuit switch fault diagnostic method for a single-phase cascaded H-bridge five-level converter to address signal noise challenges. The novelty of the proposed method lies in the development of a hybrid denoising framework that combines energy-correlation constrained variational mode decomposition (ECC-VMD) with singular value decomposition (SVD) to enhance signal denoising. Subsequently, a grey wolf optimization-based support vector machine (GWO-SVM) is utilized for fault diagnosis. First, ECC-VMD adaptively optimizes the mode number K and the threshold μ through dual constraints, extracting primary components from sampled signals. Second, residual components are further denoised using SVD, where differential spectrum analysis selects effective singular values for reconstruction. Subsequently, wavelet packet decomposition extracts energy entropy from the denoised signals as fault features. The GWO algorithm optimizes the SVM kernel parameters γ and the penalty factor c to achieve optimal fault diagnosis performance. Experimental results demonstrate significant improvements: at an initial signal-to-noise ratio (SNR) of 17 dB, the proposed method achieves 92.06% diagnosis accuracy (35.04% higher than non-denoised cases), and at 27 dB, the accuracy further increases to 99.49%.

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Cite this article

[IEEE Style]

Q. Yuan, Y. Du, Y. Liu, K. Xia, "Open‑circuit switch fault diagnosis in single‑phase cascaded H‑bridge five‑level converters under signal noise," Journal of Power Electronics, vol. 26, no. 4, pp. 907-919, 2026. DOI: 10.1007/s43236-025-01117-y.

[ACM Style]

Qingqing Yuan, Yao Du, Youyan Liu, and Kun Xia. 2026. Open‑circuit switch fault diagnosis in single‑phase cascaded H‑bridge five‑level converters under signal noise. Journal of Power Electronics, 26, 4, (2026), 907-919. DOI: 10.1007/s43236-025-01117-y.