Transient Behavior of Solid-State Modulators With Matrix Transformers

Solid-state modulators based on pulse transformers offer the advantage that, with the turns ratio of the transformer, the primary voltage could ideally be adapted to available switch technology, and a series connection of switches could be avoided. To increase the power level, several semiconductor switches must be connected in parallel, and a balancing between the different switches must be guaranteed. Here, the matrix transformer concept, which is based on multiple primary and/or secondary windings, as well as flux adding, offers superior performance with respect to the achievable rise times. However, the influence of the parasitic elements on the voltage and current distribution is quite involved. In this paper, the influence of the parasitic elements of the matrix transformer on the current balancing and on the winding voltages is investigated based on reluctance models. Additionally, the inherent current balancing of the matrix transformer for windings mounted on different cores is explained. Furthermore, the influence of parasitic load/transformer capacitances on the turnoff transient is discussed in detail.