Abstract:The core challenge in the factory fault testing of DC motors lies in the accurate extraction of weak fault features from operational acoustic signals. These signals are often contaminated by mechanical vibrations, electromagnetic noise, and environmental interference, leading traditional methods to suffer from mode aliasing and frequency band overlap disturbances. To address this challenge, this study proposes a novel DC motor fault diagnosis method based on improved Local Mean Decomposition (LMD) and Composite Multiscale Bubble Entropy (CMBE) fusion. Additionally, a Particle Swarm Optimization (PSO)-enhanced Extreme Learning Machine (ELM) is employed for classification modeling. Experimental results demonstrate that the proposed method effectively distinguishes motor states, including normal operation, rotor shaft bending, blade fracture, and bearing faults. In a specific test involving 320 samples, only 1 misclassification occurred. Consequently, this approach offers a new technical pathway for DC motor fault diagnosis, significantly enhancing motor reliability and operational efficiency.