Optimal Double-Tuned Filter Efficiency Analysis

Abstract

The rapid development of technology allows designing better and better filter systems. Active filters are more and more often used. They also have their drawbacks, including their price. Passive filters are still very often used. However, despite the passing years, for some filter structures, optimal design equations were not derived that take into account the equivalent impedance of the main and the filters detuning. This article presents an analysis of a double-tuned filter and the analytical maximization of harmonic reduction based on the location of the maximum impedance filter characteristics and the replacement impedance of the mains, which mainly determine the efficiency of filtration. Filter detuning from reduced harmonics is also considered. Formulae have been determined to design the optimal double-tuned filter as well as to design a filter with the assumed degree of reduction of one of the harmonics. The impact of incorporating the resistances of filter elements and of the mains into the analysis on the accuracy of the designated solution was also examined.