DITHER METHOD FOR LINEARIZATION OF STATIC CHARACTERISTIC OF A CLASS OF CONVERTERS

Anna Domańska

Abstract

The characteristics of actual converters, including sensors, are – to smaller or larger extent – nonlinearity. With respect to the mathematical model describing the characteristics, they can be characteristics with smooth nonlinearity or nonlinearity with discontinuities. The author presented the problem of linearization of the characteristic of converter with nonlinearity with discontinuity that appears in the small value area, i.e. with insensitivity area. In general, this is not an easy task because of the type of nonlinearity and the local character of linearization. A method utilizing the technique of added noise (dither) is applicable in this purpose. It effectively removes nonlinearities in output signal, caused by the area, i.e. removes nonlinear distortions of the signal processed. Using dither makes it also possible to process signals with values wholly contained in the area, which would be impossible in a converter without applying the method. Side effects of applying the method are: amplitude reduction and phase shift of the processed signal, because of amplification error and phase error of the AV/LPF system, respectively. If we apply averaging it extends the time of processing.

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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