HALF-BRIDGE INVERTER OR A CIRCUIT ARRANGEMENT DERIVED FROM A FULL-BRIDGE INVERTER BY HALFING CALCULATION IN THE FORM OF A HALF-BRIDGE INVERTER AND METHOD FOR THEIR CONTROL

摘要

The present invention concerns a half-bridge inverter and a method for controlling such a welding inverter which has a nominal output power Pn and a nominal operating angular frequency omega t, the inverter being comprised of a DC power source (E); of a capacitor configuration comprising at least one capacitor (Cn), the circuit being connected at its first end to one end of the DC power source (E) and at its other end to a point A; of two switching elements (T1, T2) connected in series over the DC power supply (E), the switching elements being capable of controlling the pulse width tau of the current to the welding load, and thus the power to the welding load, whereby tau max determines the nominal power output of the inverter; and of a transformer primary (Lp) connected at its first end to point A and at its second end to the center point of the switching elements (T1, T2), and the current switched through the primary has a peak value Ii. At output power levels which exceed the critical output power Pk, the total capacitance SIGMA C of the capacitor circuit (Cn) is smaller than the product of the current Ii and the pulse width tau divided by the voltage E of the DC power source ( SIGMA C(Iix tau )/E), and the resonant angular frequency omega r (=1/ 2ROOT Lp tau C) determined by the total inductance Lp of the transformer primary and the total capacitance of the capacitor configuration (Cn) is essentially lower than the operating angular frequency omega t of the inverter.