This paper introduces open-fault diagnosis of dual active bridge (DAB) converters using convolutional neural networks (CNN). This paper proposed open-fault diagnosis of a DAB converter using CNN. The operating characteristics of the DAB converter were examined, and the waveform variations under open-switch fault conditions were analyzed to extract distinctive features. A 1D-CNN framework was constructed based on the voltage and current waveforms for fault identification. Simulation results confirmed that the proposed method achieved accurate classification of fault types within a few switching cycles.