Investigation on prediction of noise characteristics in full-frequency spectrum of DC charging pile and design for noise mitigation

• A novel frequency-partitioned method combined with FE, Hybrid FE-SEA and SEA is specially proposed for direct current charging pile in full-frequency domain. • The proposed method is able to describe the acoustic behaviors of charging pile. • Compared with single method, the accuracy and the calculation speed of full-frequency prediction is enhanced greatly. • This method can supervise the low-cost noise reduction design with orthogonal experimental design. The objective of this study is to swiftly and precisely forecast the acoustic properties across full-frequency of a 120 kW direct current (DC) charging pile and enhance the noise reduction design. Firstly, the modes of the subsystem serve as the basis for frequency partitioning. This is utilized to develop low, medium, and high-frequency noise prediction models employing the Finite Element (FE) method, Hybrid method (FE-SEA), and Statistical Energy Analysis (SEA) method, respectively. Subsequently, the damping loss factors influenced by frequency are calculated using theoretical formulas, and the high-frequency sound propagation through honeycomb-type ventilation holes is simulated using equivalent leakage area. A full-frequency noise prediction for the pile was executed, followed by an acoustic test to provide a verification benchmark. Additionally, a noise reduction strategy is formulated for the full-power operation of the pile with acoustic contribution analysis, grounded in orthogonal experiments. This elucidates the primary and secondary correlations among the materials, the thickness of the layer, and the coverage area. The results indicate that the simulation values align with the test in the spectral trends throughout each frequency band and the overall sound pressure level difference is confined to 2 dB(A), signifying that the predictions are dependable. Acoustic orthogonal experimental design was employed to optimize the entire pile outdoor noise. The results show that the combination of A1, B3, C4 represents the optimal noise combination, and orthogonal design can efficiently achieve cost savings in product design.