Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to A...Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed. Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.展开更多
基金National Natural Science Foundation of China(Grant 19904008)the Excellent Young Teachers Program of MOE,Chinathe Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China.
文摘Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed. Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.
