Steady-state analysis of the symmetrical push-pull power converter employing a matrix transformer

Steady-state operation and observed phenomena for the SPPPC (symmetrical push-pull power converter) are analyzed on the basis of magnetic and state-space equations. It is found that the complex behaviour of the generalized SPPPC topology, which differs from the conventional push-pull converter in that it employs a matrix transformer and floating capacitors, is similar to that of a conventional push-pull converter with an input filter. Although there is no physical input filter in the SPPPC topology, an effective input filter is realized by the input inductor and the parallel combination of the floating capacitors. This effective input filter explains the near-zero input current rippler reported in the literature. Thus, the floating capacitors function not only as lossless snubbers but also as filters. In spite of the floating capacitors, the currents in the primary windings in series with the same switch are the same. The unique topological arrangement of the floating capacitors and the matrix transformer windings reduces the RMS current in the primary windings (from that in a conventional push-pull converter) and winding loss. Equations are derived for the steady-state values in a generalized SPPPC with semiconductor conduction losses. These equations, as well as the expected waveforms, have been verified by computer simulation and by experimental data.<>