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Abstract-This paper introduces a reliability-oriented design tool for a new generation of grid connected PV-inverters. The proposed design tool consists of a real field Mission Profile (MP) model (for one year operation in USA-Arizona), a PV-panel model, a grid connected PV-inverter model, an Electro-Thermal model and the lifetime model of the power semiconductor devices. A simulation model able to consider a one year real field operation conditions (solar irradiance and ambient temperature) is developed. Thus, one year estimation of the converter devices thermal loading distribution is achieved and is further used as an input to a lifetime model. The proposed reliability oriented design tool is used to study the impact of MP-variation, Gate-Driver (GD) parameters variation and device degradation in the PVinverter lifetime. The obtained results indicate that in order to improve the accuracy of the lifetime estimation it is crucial to consider also the device degradation feedback. Moreover the MP of the field where the PV-inverter is operating and the GDparameters selection has an important impact in the converter reliability and it should be considered from the design stage to better optimize the converter design margin.

This paper deals with the design, control, efficiency and thermal cycling estimation of associated Si and SiC based three-phase PV-inverters. A novel Electro-Thermal Model able to consider the thermal coupling within the Transistor and Diode integrated on the same package is proposed. For each topology, three different cases study are simulated, according to the heatsink repartition: one-leg heatsink, shared heatsink and individual heatsink. Based on the model, it has been determined the minimum required heatsink thermal impedance in order not to overpass the device physically thermal limitations. Finally, simulation results are analyzed in order to decide which topology has a higher efficiency and a better thermal loading distribution within the devices.

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This paper introduces a real field mission profile oriented design tool for the new generation of grid connected PVinverters applications based on SiC-devices. The proposed design tool consists of a grid connected PV-inverter model, an Electro-Thermal model, a converter safe operating area (SOA) model, a mission profile model and an the evaluation block. The PVsystem model involves a three level bipolar switch neutral point clamped (3L-BS NPC) inverter connected to the three phase grid through a LCL-filter. Moreover, the SOA model calculates the required converter heatsink thermal impedance Z th_H in order to perform in a safe mode for the whole operating range. Furthermore, the proposed design tool considers the mission profile (the measured solar irradiance and ambient temperature) from the real field where the converter will operate. Thus, a realistic loading of the converter devices is achieved. To consider one year real field measurements of the mission profile, an accurate long term simulation model is developed. The model predicts the junction and case temperature of the converter devices, for three different case scenarios. In the first case, a one year mission profile is used into the model with a sampling rate of five minutes. For the second and third case, a more detailed analysis is performed for one week mission profile (in the wintersummer time) with a sampling rate of 25 s. The simulation results shows the thermal loading distribution among the converter devices (MOSFET, IGBT+FD) in terms of junction (average, peak, ∆T) and case (average) temperature for all three simulation cases. Finally, the evaluation block is used to analyze the results in order to perform a thermal loading-based classification of the converter devices.