Retificadores de três níveis tipos NPC, ANPC e com número reduzido de componentes.

Abstract

This work aimed to develop a mathematical model capable of representing the dynamic behavior of a zinc oxide varistor. To achieve such goal, system identification techniques were employed to propose a model that is able to determine the relation of cause and effect between a current impulse and the waveform of the voltage across a zinc oxide varistor, not necessarily giving physical meaning to the parameters of the model. To develop and validate the proposed mathematical model, a database was built with the responses of different varistor samples to current impulses with different amplitudes and front times. The parameter determination of the proposed model was realized with the standard 8/20 and 4/10 μs impulses, and the last was used only to improve the precision on the determination of the residual voltage. Some of the existing models of the dynamic behavior of a varistor were applied to the database developed at this work. The proposed mathematical model was capable of representing the behavior of the varistor with precision better or as good as the existing models in the determination of the residual voltage and was better in the representation of the waveform in all analyzed cases.