A three-phase high-frequency AC/DC converter with power-factor correction

Resumo

A circuit design of an ac/dc three-phase converter with an isolated output is proposed. The converter consists of identical phase modules with forward pulse transformers, the primary windings of which are fed with phase voltage through power switches. The secondary windings of the transformers are connected to rectifiers, the outputs of which are connected in series. The energy of magnetizing inductance is also transferred to the load through an auxiliary low-power converter. The presented circuit design provides control of the converter currents that makes it possible to perform an active power-factor correction. The design is characterized by a small number of semiconductor switches in the power circuit due to the use of a direct-conversion principle. In addition, the proposed circuit design makes it possible to use power switches with a reduced permissible voltage. High-frequency energy conversion makes it possible to reduce the mass and dimensions of the device. The converter can be used as a power supply for an electric arc for welding and plasma processes. It is possible to generate output characteristics of any type, from direct-voltage to direct-current regulation. If necessary, it is possible to provide increased open-circuit voltage to simplify electric-arc ignition.