Abstract: In order to solve the problem of high-frequency sharp noise during low-frequency operation of the compressor of air conditioning under heat-pump condition. Firstly, by identifying the vibration source, determine the mechanism of high-frequency sharp sound generation; Secondly, by modulating the carrier frequency, the improvement of sharp noise is achieved. Research has shown that sharp high-frequency noise is caused by the excitation of the compressor and fan by the carrier frequency, and the carrier frequency spectrum exhibits a significant octave relationship. For the compressor carrier frequency (5 kHz) and fan carrier frequency (15 kHz), the second harmonic of the compressor carrier frequency and the fundamental frequency of the fan carrier frequency have a significant contribution to sharp noise. Increasing the carrier frequency or modulating the compressor carrier frequency and fan carrier frequency in a staggered manner can effectively reduce sharp high-frequency sounds. The results of the research can provide a reference for suppressing high-frequency noise in motors.

Key words: High-frequency noise, Carrier frequency, Modulation, Compressor, Fan