ACTIVE NOISE CONTROL OF A COOLING FAN IN A SHORT DUCT

In this paper we develop a data based model, design a high performance robust controller and apply the controller in realtime to reduce narrowband acoustic noise from a cooling fan. A custom, portable enclosure houses the cooling fan. One end of the enclosure is fitted with four speakers and four microphones, inside of a short duct, connected to a data acquisition system and a personal computer Passive materials mounted at the other end of the enclosure reduce backside noise. The frequency of the narrrowband noise is assumed unknown and therefore a control design that can be updated in realtime is needed The control design that is presented uses a nominal model and a nominal controller The nominal controller is enhanced by using closed loop signals and taking into account the modeling error. The end result is a data-based method for updating a nominal controller to improve performance.