Abstract: With the improvement of living standards, household appliances have increasingly rich functions, and electromagnetic compatibility (EMC) has become a key design indicator. As a widely used household appliance, the electromagnetic compatibility performance of air conditioners directly affects their operational reliability and the degree of interference with other devices. Taking the electromagnetic interference (EMI) problem of the switching power supply of variable frequency air conditioners as the research core, analyzes its generation mechanism, and proposes optimization solutions. Research shows that the high-frequency switching devices in the switch power supply generate differential and common-mode noise during rapid switching, and the loop design of the power circuit, the leakage inductance of the transformer, and parasitic parameters are the main sources of interference. Through theoretical analysis and experimental verification, the following suppression measures are proposed: optimized design of the transformer, circuit improvement, shielding and layout optimization. In a case of a voice air conditioner with 600 kHz~700 kHz conducted interference exceeding standards, experiments found that the design defect of the transformer shielding layer was the main cause of interference. By optimizing the shielding structure, the peak noise was significantly reduced, verifying the effectiveness of the solution. The research results provide practical guidance for the EMC design of air conditioners and emphasize the importance of reducing interference from the source.

Key words: Electromagnetic compatibility(EMC), Switching power supply, Variable-frequency air conditioner, Transformer design, Conducted interference