Abstract: The invention relates to a method for regulating a welding current source with a current transformer, which has a series resonant circuit on the primary side and a parallel resonant circuit on the secondary side, the series resonant circuit being supplied with a variable alternating voltage by a bridge circuit and the parallel resonant circuit providing energy to a welding process by way of a rectifier, and a control unit controlling the bridge circuit in dependence on at least one state variable of the welding current source. In order to develop the method in such a way as to make regulation possible at low cost and with as little power loss as possible, it is proposed according to the invention that only the primary current or a state variable on the primary side corresponding to the primary current is recorded as the electrical-current state variable of the welding current source and a control signal dependent on the primary current or on the state variable corresponding thereto is fed to the control unit.

Abstract: The invention relates to a method for regulating a welding current source with a current transformer, which has a series resonant circuit on the primary side and a parallel resonant circuit on the secondary side, the series resonant circuit being supplied with a variable alternating voltage by a bridge circuit and the parallel resonant circuit providing energy to a welding process by way of a rectifier, and a control unit controlling the bridge circuit in dependence on at least one state variable of the welding current source. In order to develop the method in such a way as to make regulation possible at low cost and with as little power loss as possible, it is proposed according to the invention that only the primary current or a state variable on the primary side corresponding to the primary current is recorded as the electrical-current state variable of the welding current source and a control signal dependent on the primary current or on the state variable corresponding thereto is fed to the control unit.

Abstract: According to the invention, parallel resonant converters which are or can be connected to a load circuit via a transformer in each case are provided with a common series circuit of the secondary sides of the transformers. Therefore, despite variation of the frequency-determining components, it is possible for all the resonant converters to supply an output-side load circuit with approximately identical powers when the bridge circuits of the resonant converters are clocked in a synchronous manner.

Abstract: The invention describes a method of controlling a welding current source (2) having a resonant circuit (27), whereby a bridge circuit (28) is controlled by a control system (4). A consumer, in particular a welding process, is supplied with energy via the bridge circuit (28) from a power source (29). In order to control the individual switching elements (32-35) of the bridge circuit (28), fixed pre-set control states S1 to S6 are stored and, during normal operation, the bridge circuit (28) is controlled on the basis of the control states S1 to S4 one after the other. If a change in resistance occurs at the consumer, the control system (4) switches to a special operating mode at the resonance frequency of the resonant circuit (27) and the bridge circuit (28) is controlled on the basis of the stored control states in order to run the special operating mode.

Abstract: The invention describes a method of controlling a welding current source (2) having a resonant circuit (27), whereby a bridge circuit (28) is controlled by a control system (4). A consumer, in particular a welding process, is supplied with energy via the bridge circuit (28) from a power source (29). In order to control the individual switching elements (32-35) of the bridge circuit (28), fixed pre-set control states S1 to S6 are stored and, during normal operation, the bridge circuit (28) is controlled on the basis of the control states S1 to S4 one after the other. If a change in resistance occurs at the consumer, the control system (4) switches to a special operating mode at the resonance frequency of the resonant circuit (27) and the bridge circuit (28) is controlled on the basis of the stored control states in order to run the special operating mode.

Abstract: The invention relates to a voltage switching device (23) consisting of a power rectifier (26), a boost chopper (34, 35) having at least one storage element (50, 51), a transformer (40), a switching device (59), a control device (4) and a plurality of mains leads (27 to 29), the power rectifier (26) being connected to an energy source (24) by the mains leads (27 to 29) and a consumer (25) with a secondary winding (42) of the transformer (40), a power evaluating device (32) supplied with voltage from the energy source (24) being provided, the output of which is connected to the switching device (59) or to the control device (4).