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Theoretical and Experimental Analysis of the Rectifier
with Capacitive Filter

- Abstract -

Adrian Virgil CRACIUN, Sorin MORARU,
Liviu PERNIU, Dominic Mircea KRISTALY

Department of Electronics and Computers, "Transilvania" University of Brasov,
Bd. Eroilor nr.29, 500036 Brasov - Romania, e-mail: craciun@vega.unitbv.ro

This article presents a simple and rather precise method for analysis and design of a transformer-coupled input rectifier with a filter capacitor, which is used as a power supply for electronic circuits. It is based on an original logarithmic equation that determines the conduction angle of the rectifier diodes as a function of the transformer equivalent resistance. This equation can replace the classical design procedure that is based on coefficients taken from nonlinear graphical diagrams. Some experimental results that verify the proposed theory are also presented.
The ratio between the internal resistance and the load resistance is expressed as a function of the conduction angle, ki(q). The reverse function q (ki) can be found utilizing approximate analysis:
Equation theta(k_i)[°].
This function appears approximately linear when a logarithmic scale for ki is used and a linear approximation of it can be outlined for the usual domain of ki, as in the next figure. The approximate function can be used for ki=0.05…1 with an error less than 1.5%.

The conduction angle as a function of k_i

The graph of q (ki), its approximation (the dashed line) and
the error between the two curves (in %).


Keywords: Rectifier Analysis and Design, Filter Capacitor, Rectifier Model.