Application of Nonlineanty Measurng Method Using Two Frequencies to Electrcal Components

Abstract

Information of nonlinearity in voltage and current characteristics of electrical components has been used for finding their defect. A commonly used method is that the third-harmonic frequency produced by the nonlinearity is picked up as a measure of the nonlinearity, when a current of single frequency is given to the component. A method using two frequencies is introduced in this paper. In this method, two currents of different frequencies are fed into a component under test, and one of newly produced frequencies by intermodulation caused by the nonlinearity is selected as the measure of the nonlinearity of the component. Features of this method are: 1) distortion in the current sources is allowed; 2) detecting frequency can be made very much lower than that of the sources; 3) filters to select the detecting frequency from the source frequencies can be made simpler; and 4) measurement of multi-orders of distortion became possible, while keeping the same connection, by changing the source frequency. The measuring method and some characterized measured results are shown. The results obtained by this not only show existence and amount of very small nonlinearity, but also show characters of the nonlinearity of the component with large exaggeration. It is expected then that the results may be used for analysis of physical phenomena of electrical conduction in the component, as well as for finding its defect.