Abstract
In this work a particular association of AC/DC multilevel converters is proposed to update
classical half wave diode or thyristor rectifiers. Nowadays, in the frame of Medium and High
Power applications, new requirements on power quality lead the classical diode/thyristor
rectifiers obsolete and they should be replaced. Modular multilevel structures have become
very attractive for High and Medium voltages applications because they allow working at high
voltage level with a high waveform quality. In this paper a new topology based on a Modular
Multilevel structure, using a zigzag transformer, is proposed. After a comparison, in terms of
sizing, between this new structure and the classical MMC topology, the new topology is
proposed in order to upgrade the obsolete half wave rectifiers based on diodes/thyristors.
The upgrading is carried out by keeping the same grid transformer and therefore the voltage
and current levels. Simulations are performed in order to validate the study and evaluate the
advantages.