含隔直电容的移相全桥变换器EMI抑制方案研究OA

In phase-shifted full-bridge converters,although the blocking capacitor can suppress transformer bias saturation,the high-frequency voltage components across it may aggravate the complexity of conducted electromagnetic interference(EMI).Furthermore,existing transformer models lack precision in revealing the resulting common-mode noise coupling mechanism.To address these issues,a two-capacitor equivalent transformer model was constructed based on the principle of displacement current conservation.The quantitative relationship between the internal displacement current paths and the inter-winding parasitic capacitances was characterized by this model.Subsequently,this model was utilized to simplify and analyze the common-mode interference circuit,based on which three synergistic suppression strategies were proposed.Experimental results from a 1400 W prototype demonstrate that the comprehensive suppression scheme reduces the common-mode noise resonance peak by approximately 20 dB within the frequency range of 150 kHz to 30 MHz.These results verify the correctness of the proposed two-capacitor transformer model and confirm the effectiveness of the comprehensive EMI suppression scheme designed based on it.