A power supply unit for a resistance welding apparatus, said power supply unit comprising a converter circuit adapted to convert an alternating power supply current, AC, applied via a residual current protection circuit to an input of said converter circuit into a pulsed electrical current supplied from an output of said converter circuit to a primary coil of a transformer of said resistance welding apparatus, and at least one switching element provided between the output of said converter circuit and protective earth.

A programmable polarity module that permits rapid on-demand control of the polarities assigned to the welding electrodes retained on a welding gun is disclosed. The programmable polarity module is electrically connectable to the welding gun and a direct current power supply unit to provide direct current to the welding electrodes for exchange during spot welding. A first interchangeable polarity output lug and a second interchangeable polarity output lug of the programmable polarity module permit the polarities of the welding electrodes to be switched without having to electrically disconnect the module from the welding gun.

A programmable polarity module that permits rapid on-demand control of the polarities assigned to the welding electrodes retained on a welding gun is disclosed. The programmable polarity module is electrically connectable to the welding gun and a direct current power supply unit to provide direct current to the welding electrodes for exchange during spot welding. A first interchangeable polarity output lug and a second interchangeable polarity output lug of the programmable polarity module permit the polarities of the welding electrodes to be switched without having to electrically disconnect the module from the welding gun.

A metallic member bonding device includes a pressurizing unit, a current supply unit, and a deformation suppressing unit. The pressurizing unit pressurizes a first metallic member toward a hole portion of a second metallic member to press the first metallic member therein. The current supply unit supplies a welding current between the first metallic member and the second metallic member. The deformation suppressing unit suppresses deformation of one of the first metallic member and the second metallic member, the one member having a constituent metallic material with at least one of a proof stress and a melting temperature lower than that of the other member, the deformation being in a direction of a cross section crossing a direction of the press-in. Then, the deformation suppressing unit is provided in a region covering at least a plastic flow range in the press-in direction.

A resistance spot welding device for welding at least two overlapping steel sheets held between a pair of welding electrodes is provided. The resistance spot welding device includes the pair of electrodes, an electrode force gauge that measures an electrode force, and a controller that controls an electric current supply to the electrodes according to the electrode force measured by the electrode force gauge. The controller controls the electric current such that the electrode force F measured by the electrode force gauge after the start of the electric current supply is adjusted to a prescribed value.

The disclosure relates to a power component for providing an electric current, having plates aligned parallel to one another which are connected to the current inputs and the current outputs of power semiconductors embedded in a component carrier. High currents, for example for resistance welding, can thereby be controlled without excessive heat losses resulting in an increase in temperature of the entire arrangement and thereby in a reduction of the service life.

A high frequency power supply system provides highly regulated power and frequency to a workpiece load where the highly regulated power and frequency can be independent of the workpiece load characteristics by inverter switching control and an inverter output impedance adjusting and frequency control network that can include precision variable reactors with a geometrically-shaped moveable insert core section and a stationary split-bus section with a complementary geometrically-shaped split bus section and split electric terminal bus section where the insert core section can be moved relative to the stationary split-bus section to vary the inductance of the variable reactors.

This seam-welding device carries out seam welding while repeating one cycle comprising a melting period, an interruption period, and a heating period implemented either before or after the interruption period. A welding current is applied between a pair of roller electrodes so as to form a welded part between workpieces during the melting period, the application of the current between the roller electrode pair is interrupted so as to solidify the welded part during the interruption period, and a heating current smaller than the welding current is applied between the roller electrode pair so as to heat the laminated body within a solidification temperature range of the welded part during the heating period. Consequently, even when the welding speed is increased, formation of cracks and spatter is effectively suppressed such that a high-quality joined product is obtained.

A resistance welding apparatus includes a welding tool with a welding electrode configured to contact a component. A welding transformer is configured to feed an electric current to the welding tool and a control device is configured to control a polarity of welding transformer by transmitting polarity information to the welding transformer such that a polarity of the welding transformer is switchable. A circuit including two transistors is operably connected in series between the welding tool and an output of the welding transformer and a polarity one of the transistors is rotated relative to the other transistor, such that a polarity of a welding voltage at the welding electrode is switchable with the switching of the polarity of the welding transformer, and such that a polarity of a welding current at the welding transformer is switchable with the switching of the polarity of the welding transformer.

The invention relates to a power source (10) for providing a direct current, comprising a heavy-current transformer (12) with at least one primary winding (13) and at least one secondary winding (14) with center tapping, a synchronous rectifier (16) connected with the at least one secondary winding (14) of the heavy-current transformer (12) and comprising circuit elements (24), and a circuit (17) for actuating the circuit elements (24) of the synchronous rectifier (16), and a supply circuit (48) for supplying the synchronous rectifier (16) and the actuation circuit (17), and to a method for cooling such a power source (10). For reduction of losses and improvement of efficiency, the synchronous rectifier (16) and the actuation circuit (17) and the supply circuit (48) thereof are integrated in the heavy-current transformer (12).