Method for regulating and/or controlling a welding current source with a resonance circuit

Method of controlling a welding current source (1) having a resonant circuit (27), provided in the form of a serial/parallel converter, whereby a bridge circuit (28), comprising individual switching elements (32-35), is controlled by a control system (4) and a consumer, in particular a welding process, is supplied with energy, in particular with voltage and current pulses from a power source (29), controls the bridge circuit (28), whereby the control system (4) controls the bridge circuit (28) during normal operation in such a way that the bridge circuit (28) is switched by the control system (4) consecutively on the basis of the control states (S1-S4) stored in the control system (4) so that the bias point (57) on a character curve of the resonant circuit (27) lies outside a resonance frequency and whenever a change in resistance occurs at the consumer, the control system (4) operates with the bridge circuit (28) is operated at the natural frequency of the resonant circuit (27) on the basis of the control states and sequence stored for the special operating mode, characterised in the control states (S1-S4) fixed for normal operation of the bridge circuit (28) provided as a full bridge are a positive drive phase—control state (S1)-, a positive freewheeling phase—control state (S2) —, a negative drive phase—control state (S3)—and a negative freewheeling phase—control state (S4)—and, in the special operating mode, the bridge circuit (28) is switched from a drive phase—control state (S1 or S3)—preferably consecutively, into one of several alternative control states (S5 or S6) in which the switching elements (34;

• 35) of one bridge branch are deactivated and the switching elements (33;
• 32) of the other bridge branch remain activated and the control system (4) monitors how often a switch is made from one special mode (S5;
• S6) to the other special mode (S6;
• S5).