A while ago, I published a blog entitled “A technology developed for a long service life and sustainable development,” which compared the substantial improvements in robustness of the .XT joining technology with standard aluminum wire bonding and soft-soldering joining technologies . The result of these improvements is the basis of our updated .XT power-cycling lifetime model, which can be used for estimating lifetime cycles based on application missions and cooling profiles [2, 3]. Taking a closer look at these great improvements, you might raise the question as to whether this “unbreakable” .XT joining technology is really necessary in your application, or if it has perhaps been overdesigned for the requirements of your application. There is no general answer to this question, as applications vary, depending on their operating conditions and user needs. We therefore want to be more specific about one critical application, wind turbines, and their design-relevant operating conditions.
In a single wind turbine as part of a wind farm, failure safety and longevity, in addition to overall system efficiency, are essential criteria for the design of the wind turbine converter. Using the example of a wind-turbine mission profile, we illustrate the benefits of the system with regard to lifetime based on our updated power-cycling curve. Possible defects in the converter could result in a day or even weeklong failure of the turbine, with high follow-up costs. At the heart of such converters, power modules must meet these high demands.
For the example discussed here, a popular wind power system has been considered with a 690 VACrms double-fed induction generator (DFIG) converter and a pulse-width modulation voltage source and two-level voltage output .
To predict the lifetime of a power module, it is necessary to calculate the cycling load during converter operation based on the mission profile, and transform it into a resulting power-module lifetime estimation. Figure 1 depicts an example of the steps taken from the calculation of an application-mission profile of a wind turbine to the resulting module lifetime.
The expected wind system lifetime is calculated for two different converter designs. The first design is equipped with three 1.7 kV IGBT4 PrimePACK™ FF1400R17IP4 power modules in parallel, while the second design is based on 1.7 kV .XT PrimePACK power modules FF1800R17IP5.
In Figure 2, the resulting cycling loads of the diode are shown on the generator-side converter by three FF1400R17IP4 modules in parallel.
In Figure 3, the cycling loads of the diode on the generator-side converter are illustrated in a similar way as in Figure 2, but with only two .XT FF1800R17IP5 modules in parallel.
The simulation results and lifetime calculations based on the updated .XT power-cycling curve show that the lifetime requirement of 25 years is possible even today by using only two .XT FF1800R17IP5 power modules in parallel. Despite a slightly higher junction temperature and temperature swings compared to the first design, the .XT PrimePACK solution shows a lifetime consumption of only 6% after 25 years with only 2pcs. FF1800R17IP5 in parallel instead of 3pcs. with standard technology. Furthermore, without changing the configuration, the .XT PrimePACK solution shows the potential for increasing the converter power.
Additional .XT advantages include the increased surge-current capability or enhanced short-circuit capability, which make your wind converter design much more robust in various system or grid failure modes.
The PrimePACK™ IGBT5/.XT in a wind turbine application offers various possibilities for optimizing wind turbine converters by extending lifetime cycles, generating more power or using fewer modules. This optimizes the factor of cost vs. power, and extends the range of operation.
PrimePACK™ IGBT/.5T supports your next converter development for a "future-proven" converter design for demanding wind turbine applications.
 W. Rusche, “A technology developed for a long service life and sustainable development,” Infineon blog, 2021
 T. Methfesssel and H. Jähme, “End-of-life mechanism due to cyclic thermomechanical loading of power modules with .XT joining technology,” CIPS, 2020.
 T. Methfessel, F. Sauerland, K. Mainka, O. Schilling, “Enhanced lifetime and power-cycling modelling for PrimePACK™ .XT power modules,” PCIM, 2020.
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