Development of a zero spillover controller for broadband cancellation of noise in ducts

In this paper, an active noise control (ANC) system for broadband cancellation of noise in ducts, where a nonacoustical reference is unavailable and thus the ANC structure is "spatially feedforward" is presented. In this structure, acoustic feedback that is known to be detrimental to system stability and performance must be taken into account into controller design. In this case, difficulties generally arise in implementing the ideal controller, or the zero spillover controller due to plant uncertainties. In the present study, an equivalent approach based on the 2-norm (H₂) optimal model matching principle is proposed in controller design. The control algorithm is implemented on a digital signal processor (DSP), by finite impulse response (FIR), infinite impulse response (IIR) and hybrid filters. The experimental results indicate that the proposed controller was effective in suppressing periodic noise and random noise sources, without and with airflow.