Abstract: PFC (Power Factor Correction) circuit plays an important role in harmonic current suppression and improving power factor for air conditioner. With the development trend of high-frequency and miniaturization of air conditioner driver, the carrier frequency of PFC circuits is constantly increasing, and currently has reached the range of 60 kHz. The issue of conducted interference caused by high-frequency switching in PFC circuits is becoming increasingly prominent. Aiming at the issue, an interference suppression method is proposed. The differential mode interference and Common-mode interference in conducted interference are respectively processed by near-field coupling suppression and high-frequency noise absorption. Based on the above methods, the amplitude of interference has been reduced. The method is proved by experiments on 3 HP air conditioner. Through these experiments, it can be seen that before the EMI improvement the average value of the highest point in the PFC conducted interference test curve has a relative margin of 0 dB to the national standard, and after adding the improvement method, the margin value is 11 dB. The test results comply with national standards, verifying the effectiveness of the method. Also, the method has low cost advantage and is suitable for mass application in air conditioner products.

Key words: PFC circuit, Conducted interference suppression, Near-field coupling, Snubber circuit, Test margin