Power devices are among the reliability-critical components in the Photovoltaic (PV) inverter, whose failures are normally related to the thermal stress. Therefore, thermal modeling is required for estimating the thermal stress of the power devices under long-term operating conditions of the PV inverter, i.e., mission profile. Unfortunately, most of the thermal models developed for the power device are not suitable for a long-term thermal stress analysis (e.g., days to months), and there is usually a trade-off between the model accuracy and the computational efficiency. To address this challenge, a reduced-order thermal model for PV inverters is proposed in this paper, where the model simplification is based on the thermal impedance characteristic and the mission profile dynamics. The modeling accuracy is evaluated by comparing the estimated thermal stress with the experimental results from a PV inverter test-bench, where daily mission profiles with various dynamics are tested. According to the results, the proposed method offers a relatively high model accuracy (similar to the full-order thermal model) while the computational efficiency is improved significantly, making it suitable for long-term thermal stress modeling applications.

中文翻译：

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考虑任务曲线动力学的光伏逆变器降阶热建模

功率设备是光伏（PV）逆变器中至关重要的组件，其故障通常与热应力有关。因此，在PV逆变器的长期运行条件（即任务曲线）下，需要进行热建模来估算功率器件的热应力。不幸的是，为功率器件开发的大多数热模型都不适合长期热应力分析（例如几天到几个月），并且通常在模型精度和计算效率之间进行权衡。为了解决这一挑战，本文提出了一种用于光伏逆变器的降阶热模型，其中模型的简化基于热阻抗特性和任务曲线动力学。通过将估算的热应力与PV逆变器测试台的实验结果进行比较，可以评估建模精度，该平台会测试具有各种动态特性的每日任务概况。根据结果​​，该方法提供了较高的模型精度（类似于全阶热模型），同时计算效率得到了显着提高，使其适合于长期热应力建模应用。