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 (primary) and a conventional two-level converter (secondary). This allows galvanic 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 operation in terms of efficiency and voltage harmonics. Measured waveforms on a 30 kW prototype confirm the expected performance.