A primary-switched line-side converter using zero-voltage switching

A new primary-switched ac/dc converter and its modulation are presented. It employs a single- or three-phase transformer, with a matrix converter (pri mary) and a conventional two-level converter (secondary). This allows galva nic isolation at medium-frequency zero-voltage primary commutation and five line-side voltage levels. Two distinct modulation methods are explained in detail, and it is shown how a combination of these allows optimal operatio n in terms of efficiency and voltage harmonics. Measured waveforms on a 30- kW prototype confirm the expected performance.