Saturation monitoring arrangement and method of control for a frequency-converter welding deivce

摘要

A measuring winding (208) which is connected to a signal frequency generator is additionally disposed on the core (206) of a welding transformer (TR2). A voltage depending on the state of saturation of the core (206) is tapped off at the measuring winding (208) by a detector circuit (204). An amplitude demodulator (204b) delivers a direct voltage signal which is inversely proportional to the saturation. By comparison with a reference value, a discriminator circuit determines whether a threshold value related to saturation has already been reached or not. If it is reached, the firing of the power semiconductors is interrupted by a blocking signal. With this saturation monitoring arrangement, the welding device can be operated more easily and the welding transformer can be utilized in the optimum manner. The method of control becomes considerably simpler because the welding time no longer needs to be split up into individual impuses by the operator.