METHOD FOR CONTROLLING WELDING PROCESS AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 2004 - IPC

FIELD: welding processes and equipment, possibly development of DC and AC sources for manual and semiautomatic welding with use of HF current.

SUBSTANCE: method comprises steps of measuring current value of electric current of supply circuit; comparing it with reference value; turning off switches electrically conducting in given cycle of inverter operation when electric current achieves reference value; providing controlled time interval whose duration is calculated from time moment of switch turning-on and it is no more than saturation time period of core of outlet transformer; turning off switches electrically conducting in given cycle after termination of controlled time interval; simultaneously inhibiting turning on of all switches for period from time moment of supplying signal for turning off switches until time moment of providing constant voltage in windings of outlet transformer in given cycle of inverter operation. Welding power source includes mains rectifier with capacitor filter, push-pull stabilized transistorized inverter with outlet transformer and control unit. The last includes comparator, threshold unit with pickup, timer, unit for inhibiting turning on. According to first variant of invention control unit includes threshold unit with pickup, timer, unit for inhibiting turning on. The last unit includes control transistor whose collector is connected with one terminal of power source introduced for satisfying inner needs; other terminal of said source through additional resistor is connected with outlet of unit for inhibiting turning on. Base of control transistor through two circuits of connected in series diode and capacitor is connected to first two inlets of unit for inhibiting turning on. Common point of said diode and capacitor through additional diodes and emitter of control transistor are connected with third inlet of unit for inhibiting turning on. In second variant of invention unit for inhibiting turning on includes control transistor whose base is connected with two first inlets of unit for inhibiting turning on. Emitter of control transistor through capacitor and base of control transistor through resistor are connected with third inlet of unit for inhibiting turning on. Collector of control transistor through resistor is connected with outlet of unit for inhibiting turning on. Base of control transistor through diode is connected with emitter of control transistor. Inventions allow to control time period of inverter operation cycle due to tracking magnetic flux of core or due to controlling turning on period of power switches in given cycle.

EFFECT: enlarged functional possibilities of source, lowered electric currents of transformer and transistors during idle mode, possibility for separately readjusting portions of outer volt-ampere characteristics, increased outlet power at preset currents of power transistors.

5 cl, 4 dwg