## 6 Simulation  
Simulations were conducted on the 3D model described earlier using ANSYS 2023 R1 within its mechanical environment. The aims of these simulations were to determine the natural frequencies of the IGBT module through a modal analysis and a random vibration analysis, as follows:  
Figure 6: Mounting platform with fixed support and gravity direction. * **Natural Frequency Analysis and Resonance Risk Assessment:** The natural frequencies are critical in determining whether the module may be subjected to resonant vibrations that could lead to excessive stresses and potential failure. To minimize the risk of resonance, it is essential that the natural frequencies are sufficiently separated from the load frequencies. In this part, the natural frequencies of the IGBT module are calculated to assess the potential for resonance under operational loading conditions. The first 15 natural frequencies of the IGBT module are listed in Table 4, with the lowest frequency being 18,972 Hz. After comparing the natural frequencies obtained from the ANSYS simulations with the expected load frequencies mentioned in Section 4 during the operation of the IGBT module, it was found that the load frequencies are significantly different from the module's natural frequencies, which are around 19 kHz. The operating load frequencies, typically caused by mechanical vibrations, fall far outside the range of the natural frequencies. As a result, there is no risk of resonance, which is a condition that can amplify vibrations and lead to potential performance issues or damage. Since the load frequencies do not overlap with the natural frequencies, the IGBT module is unlikely to experience resonance effects, ensuring stable operation without concerns related to vibrational amplification. * **Random Vibration Analysis and Fatigue Evaluation:** In this part, random vibration loading is applied to the IGBT module to simulate the operational vibrational environment experienced within the wind turbine nacelle. The primary objective of this analysis is to assess how these vibrations affect the fatigue life of the IGBT module. This approach is crucial for understanding the long-term reliability of the module under dynamic loading conditions. In this way, PSD data from [8] have been employed and implemented in ANSYS to study the effects of random vibration on the IGBT module's lifetime. The goal was to understand which parts of the module are most affected by deformation under different vibration conditions. Both 1\(\sigma\) and 3\(\sigma\) analyses were performed to assess how deformation varied across the module. In this study, the IGBT module was analyzed as a whole, assuming that the spatial placement of individual IGBTs within the module (including the six inverter IGBTs and the brake chopper IGBT) does not significantly influence the overall results. This assumption is based on the structural uniformity of the module, which ensures that all IGBTs experience similar vibrational characteristics. Since the primary focus of this research is on the \begin{table}
\begin{tabular}{c c} \hline
**Mode** & **Frequency (Hz)** \\ \hline
1 & 18,972 \\
2 & 19,053 \\
3 & 19,398 \\
4 & 19,424 \\
5 & 19,496 \\
6 & 19,523 \\
7 & 19,702 \\
8 & 19,713 \\
9 & 19,769 \\
10 & 20,814 \\
11 & 20,845 \\
12 & 20,853 \\
13 & 20,856 \\
14 & 20,881 \\
15 & 21,826 \\ \hline \end{tabular}
\end{table} 
Table 4: First 15 natural frequencies of the IGBT module (in \(\mathrm{Hz}\)). vibration effects on IGBT lifetime, minor variations in placement are considered negligible in comparison to the overall vibrational response of the module. The results highlighted that the bond wires are particularly sensitive to the effects of random vibration, as seen in Figure 7. Table 5 provides the minimum, maximum, and average deformation values for both the 1\(\sigma\) and 3\(\sigma\) studies. To further assess the potential impact, ANSYS's fatigue analysis tool has been used to estimate the expected lifetime and damage factor of the module components.