POWER SUPPLY FOR DUAL-MODE PLASMA TORCH

摘要

A dual-mode plasma torch is operated by including a proper amount of non-transferred arc in a transferred arc in order to prevent unstable operation which is a problem of a known transferred plasma torch. The known power supply for a dual-mode plasma torch uses two rectifiers. However, the present invention uses one rectifier and two insulated gate bipolar transistor (IGBT) stacks to adjust the electronic currents of the transferred and non-transferred arcs in the dual-mode plasma torch. One of the two IGBT stacks determines the sum of the currents of the transferred and non-transferred arcs, and the opening time thereof varies continuously depending on the variation of electrical conductivity in an arc path. In addition, the other IGBT stack determines the current of the non-transferred arc, and the opening time thereof is constantly maintained. The above-mentioned power supply of the dual-mode plasma torch reduces equipment costs, is equipped stably, improves the heating efficiency of molten metals and extends the electrode life of the torch, in comparison with the power supply using two rectifiers.