Development, System Integration and Experimental Investigation of an Active HVAC Noise Control System for a Passenger Car

Current developments in the automotive industry such as electrification and consistent lightweight construction increasingly enable the application of active control systems for the further reduction of noise in vehicles. As different stochastic noise sources such as rolling and wind noise as well as noise radiated by the ventilation system are becoming more noticeable and as passive measures for NVH optimization tend to be heavy and construction-space intensive, current research activities focus on active reduction of noise caused by the latter mentioned sources. This paper illustrates the development, implementation and experimental investigation of an active noise control system integrated into the ventilation duct system of a passenger car. Making use of a model-based design process, the development is based upon a holistic numerical simulation model integrating a reduced order acoustic model derived from finite element simulations as well as simplified loudspeaker and microphone characteristics. The numerical simulation assists the selection of a suitable loudspeaker/microphone configuration, taking into account the available installation space and the integration of low-cost loudspeakers and MEMS microphones. The ventilation duct is equipped with twelve loudspeakers and eight microphones in total. A frequency-domain adaptive feedforward controller is implemented on a rapid control prototyping system. Beside the investigation of the control performance for different ventilation settings, the paper highlights the implementation of a group-delay efficient multithreaded digital signal processing setup.