Conjugate Gradient-based Algorithm for Active Control of Vibroacoustic Noise from Seat HVAC System in an Autonomous Bus

The paper presents the conjugate gradient algorithm for the active cancellation of vibroacoustic noise radiated from the compressor installed under each passenger’s seat in an autonomous bus. The sound radiated from the compressor of the HVAC system corresponds to a high-frequency annoyance noise caused by vibroacoustic noise due to the shell vibration of the compressor. The dominant frequency components of the vibroacoustic noise are harmonics of the rotation frequency of the reciprocating compressor. The HVAC system generates vibroacoustic noise dominantly in the frequency range between 300 Hz and 600 Hz. This type of noise is not only distinctly perceptible but also contributes to passenger discomfort and negatively impacts the perceived quality of the vehicle. The aim of this study is to attenuate the vibroacoustic noise of the HVAC system by developing an active noise control(ANC) system. Generally, the widely recognized filtered-X least mean squared(FXLMS) algorithm has been successfully implemented to active noise control of reciprocating compressor. However, its performance was found lacking outside the peak frequency of compressor operation noise. To address this, the conjugate gradient algorithm was employed to enhance ANC performance.