Electronic Power Amplifiers
ELMA-Tech GmbH has introduced into the market thousands of IGBT-Inverter, partly in quasi-resonance technology, for the application in arc and resistance welding machines.
In co-operation with the market leader on the sector of plasma-coating, parallel switchable DC-generators with a single power-rating of 0,15 MW were produced. These can be interconnected to generators with a power-rating up to 0,5 MW for the application with plasma spraying method as well as for the tube and pipe manufacturing.
For the special technological variants a commutator for AC processes was developed and introduced into the market to generate alternating currents in the range up to 1500 A and frequencies up to 300 Hz. In the field of plasma application succeed a so-called HF-free commutation of electric arcs by monitoring the reduction of the rest-ionisation under consideration of the influences by the Edision-Effect of the glowing wolfram electrode.
The inverter used in the standard resistance welding machines supplying direct currents of 12 kA. The associated transformer with rectifier could be constructed compactly in such a way that the weight of the unit is less than 4 kg and could be integrated into the welding gun.
The latest generation of resistance spot welding machines is working with a virtual measurement technology to generate the process parameters with the welding sheets directly at the contact points of the electrode caps.
By this measurement technology the generator (virtual generator) will be transfered in a further step on exactly that point, that directly on the electrode cap surfaces any characeristic can be synthesized to reach favorably process properties.