Fronius International Gmbh

Fronius Schweissmaschinen Produktion Gmbh & Co. Kg

Walter Pammer

Friedrich Oberzaucher

Andreas Prinz

Günter Achleitner

Alfred Hiesmayr

Hubert Aigner

Uwe Kroiss

Gerald Hieslmair

Stephan Holzinger

Jügen Pirchenfellner

Jürgen Pirchenfellner

The invention relates to a method and to an apparatus for protecting transistors (S, S; S, S) arranged in at least one path, wherein transistors (S, S; S, S) connected in series to which an input voltage (Ue) is applied are arranged in a path (), and the transistors (S, S; S, S) of a path are alternately switched between a conductive state and a blocking state in order to generate an output voltage (Ua) at the center of the path. In order to prevent both transistors (S, S; S, S) of a path from triggering, the blocking state of the second transistor (S; S) of the path is checked before switching a transistor (S; S) into the conductive state, and the switching is released by way of a signal generated during the check.

Method and apparatus for protecting transistors

The invention relates to a method for the contactless ignition of a welding arc, in addition to a circuit () for the contactless ignition of an electric arc, comprising a charging circuit (), at least one pulse capacitor (), a decharging circuit containing a circuit, and a high tension converter () which is used to inject the high frequency ignition pulses discharged by the pulse capacitor () via the circuit to the welding electrode (). In order to create said type of ignition method and an ignition circuit () which enables the welding arc to be ignited in an exact and/or safe and rapid manner and/or to create an improved ignition quality, the charge circuit () is connected to a pulse compression circuit () comprising the pulse capacitor (), the high tension converter () and the circuit, the circuit being formed by a magnetic throttle valve (), such that a high frequency circuit of the ignition pulse can be obtained.

Method and circuit for contactless ignition of a welding arc with high frequency ignition pulse packets

The invention relates to a voltage switching device ( ) consisting of a power rectifier ( ), a boost chopper ( ) having at least one storage element ( ), a transformer ( ), a switching device ( ), a control device ( ) and a plurality of mains leads ( to ), the power rectifier ( ) being connected to an energy source ( ) by the mains leads ( to ) and a consumer ( ) with a secondary winding ( ) of the transformer ( ), a power evaluating device ( ) supplied with voltage from the energy source ( ) being provided, the output of which is connected to the switching device ( ) or to the control device ( ). A boost chopper ( ) is provided respectively in a positive and a negative supply line ( ) from the power rectifier ( ), the storage elements ( ) provided in the boost choppers ( ) each being connected independently of one another to a respective high frequency inverter ( ), the high frequency inverters ( ) being connected respectively to a primary winding ( ) of one or more transformers ( ).

Voltage switch-over device

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Bad Hall, Austria

Walter Pammer