Research on the Active Noise Control Technology for the Reduction of the Air Conditioner Noise in a Vehicle Cabin

In this study, an attempt to reduce the flow-induced noise generated by heating, ventilation, and air-conditioning (HVAC) systems for commercial electric vehicles using feedback active noise control with real-time filter update in frequency domain was conducted to improve the quietness of a running vehicle. In active noise control (ANC), the frequency-domain gradient descent algorithms (FDGD) to adapt the noises was studied. In the experiment, air conditioner noise was measured using a microphone placed at the driver's left ear and referenced by a microphone at a map lamp for ANC. Results shows that in the 1/3-octave band, the sound pressure level in driver's left ear was 7.2 dB smaller at maximum when the control was operated. The effective frequency bands were between 50 and 150 Hz. Its reduction was 4.7 dB on average.