The simple and reliable method for doubling a given frequency by the use of a transformer-like device is investigated both qualitatively and quantitatively. The principle of generating an output voltage having a double frequency dominant harmonic component consists in associating two identical core transformers, each equipped with a supplementary dc winding. Their role is to pre-magnetize in opposite directions the two identical nonlinear iron cores. The secondary windings are connected in seriesopposition to provide the double frequency dominant output voltage, which can be then separated if necessary by the use of a simple low-pass filter. The present study proposes an alternative connection of the primary windings, beneficial also for the inrush current mitigation, accompanied by a calculation procedure conducted analytically up to a point beyond which a numerical computation is performed. A numerical example is presented for illustrating and evaluating the proposed solution.

Keywords: Frequency doubler, Transformer, Magnetic core, B-H characteristic modelling