Patent Application
20130334179
This application claims priority under 35 U.S.C. ยง 119 to patent application no. DE 10 2013 003 183.4, filed on Feb. 26, 2013 in Germany, and to patent application no. DE 10 2012 012 056.7, filed on Jun. 19, 2012 in Germany, the disclosures of which are incorporated herein by reference in their entirety.
The disclosure relates to a method for monitoring the remaining service life of power semiconductors of a resistance welding device that are exposed to current during the operation of the resistance welding device.
Numerous components of machines, electrical installations or motor vehicles that are exposed to great mechanical or thermal stress have a material aging or wearing behavior that advances more quickly with increasing temperature. Power semiconductors may be mentioned here as examples.
If such components are exposed to thermal stress in a particular way beyond normal operation, unexpected adverse operational effects or even operational failures may occur. This can be countered either by the components being serviced at sufficiently frequent safety intervals or, where that is not possible, by them being exchanged in good time. However, servicing generally involves laborious intervention in the component concerned, it often only then being found that the component is still unrestrictedly operational, and consequently not yet in need of servicing. In the case of a routine exchange of components for safety reasons, such as for example electrical components where the extent to which they have aged cannot be established without destroying the component, there are often instances where components that are still quite able to operate for a considerable time are discarded.
There is therefore the need for a possible way of monitoring the aging or wearing behavior of components or other temperature-dependently aging articles by simple means.
In the case of the present systems, only loading limits of the power semiconductors are monitored. Once these limits have been reached and the monitoring takes effect, it is usually already too late.
The aim of the disclosed method is to provide preventive servicing that predicts the likely service life while taking into consideration the wear that has taken place up to that time.
For this, the disclosure provides a method as described herein.
The method makes it possible for the remaining service life of the power semiconductor of a resistance welding device, depending on the wear of the power semiconductors, to be communicated to a user, so that the latter can take the required measures at an early stage.
The disadvantages known from the prior art are thereby overcome.
The method according to the disclosure can be used for all power semiconductors, for example the welding diodes in the welding transformer or the power semiconductors in the welding inverter or welding rectifier.
After each welding point, the temperature increase of the power semiconductor is determined by means of the welding current occurring during the welding, a scale graduation, various constants that are characteristic of the power semiconductor and the thermal resistance, corresponding to the welding time. On the basis of the welding cycles and in dependence on the temperature increase of the power semiconductor, the proportion of each welding point that is relevant to the service life of the power semiconductor can be summated and, using the manufacturer's specifications, the remaining service life can be automatically determined by the welding control.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 012 056.7 | Jun 2012 | DE | national |
| 10 2013 003 183.4 | Feb 2013 | DE | national |
