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F. Kardan Halvaei

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8 records found

Journal article (2026) - F. Kardan, A. Shekhar, P. Bauer
Failures associated with thermo-mechanical fatigue are one of the dominant reasons for faults in power electronic converter-based electrical systems. This review explores such thermal stress-induced reliability challenges in power converters, focusing on key package-related failure mechanisms such as bond-wire fatigue, solder degradation, and chip metallization wear-out. The study emphasizes the importance of mission-profile-based reliability assessment, highlighting the effects of operational and environmental conditions on the long-term performance of power modules. Key findings reveal how repetitive thermal cycling and environmental variations lead to critical failures, underscoring the need for effective thermal management and design-for-reliability strategies. The primary goal of this paper is the quantitative, comparative reliability analysis across multiple high-power applications, moving beyond qualitative summaries. This review aims to support future research on predictive reliability modeling, mission-profile-based lifetime estimation, and robust design strategies for wide-bandgap-based high-power converters. Ultimately, the insights provided are intended to guide the development of more robust power electronic systems for emerging energy and mobility infrastructures. ...
Journal article (2025) - Faezeh Kardan, Aditya Shekhar, Pavol Bauer
Properly addressing uncertainties in reliability analysis is essential for realistic lifetime predictions of power devices. This paper investigates parameter uncertainties on the lifetime estimation of power devices using an empirical lifetime model and Monte Carlo simulations. Key parameters such as junction temperature swings (ΔT j), minimum junction temperature (T j, min), and lifetime model constants are analyzed for their impacts on lifetime outcomes. Sensitivity analysis reveals significant effects from variations in parameters like β 1 and ΔT j on the expected lifetime and its variability. Simultaneous variations across all parameters further highlight the dominant influence of β 1 on lifetime predictions. The analysis suggests that a 5 % uncertainty margin appears to offer a balanced trade-off between realistic lifetime estimations and predictability. This Study underscores the importance of considering parameter uncertainties for precise reliability evaluations. It addresses a critical gap by examining the rationale behind commonly assumed 5 %, and 10 % uncertainty margins in lifetime modeling. By systematically evaluating these margins’ impacts on key reliability parameters, the study provides a framework for selecting reasonable assumptions based on physical insights and variability analysis, advancing the reliability modeling of power devices. ...

A Comparative Study of MIL and Mission Profile Methods

Conference paper (2024) - Miad Ahmadi, Faezeh Kardan, Aditya Shekhar, Pavol Bauer
Power electronics converters are essential for power generation, transmission, and distribution. The modular multilevel converter (MMC) is highly valued for its versatility, high efficiency, and robust control capabilities. Since MMC is composed of many components, its reliability is crucial for maintaining the availability of electrical power systems. The reliability of the MMC can be evaluated using different methods, such as the military handbook (MIL) and the Mission Profile (MP) methods. By comparing the reliability estimation of the MMC using the MIL and MP methods, this study offers insights into the effectiveness of these approaches. Also, it shows the significant difference in final results between the two applied methods. These findings contribute to the understanding and improvement of the reliability assessment of power electronics converters. Also, the impact of redundancy is scrutinized to make the comparison more thorough. ...
Journal article (2024) - Faezeh Kardan, Aditya Shekhar, Pavol Bauer
In the realm of electric mobility, fast chargers for electric vehicles (EVs) play a critical role in mitigating range anxiety while driving. The converter in these chargers usually has a load profile consisting of a high-current pulse to swiftly recharge the EV battery, followed by a cooling-off phase when the charging process is over. This pattern results in thermal cycles on the devices resulting in mechanical fatigue that leads to gradual deterioration of the power electronic components. Consequently, evaluating the power electronic converters reliability is critical to facilitating fast EV charging. This paper focuses on the reliability analysis of the phase-shifted full-bridge DC/DC converter within EV fast chargers, with a specific emphasis on the battery charging profile. The primary objective is to demonstrate how the charger load characteristics and number of charging sessions influence device reliability and, consequently, overall system reliability. Additionally, the investigation explores the effects of altering devices heatsinks and current ratings on system reliability. It was observed that in worst-case scenarios, increasing devices current rates extended the system lifetime from 0.7 to about 23 years, with 3p.u. ratings achieving 10.8 years, meeting industry targets, while reducing heatsink thermal resistance improves that to around 2 years. ...
Conference paper (2023) - Faezeh Kardan, Aditya Shekhar, Pavol Bauer
EV fast chargers are essential in addressing the concern of limited driving range for E-mobility applications. However, the load profile of a converter for fast charging involves a high-current pulse that can last for a few minutes to efficiently replenish the EV battery, which is followed by a cooldown period after the charging process is finished. This results in thermal cycles that can lead to thermo-mechanical fatigue and degradation of power electronic components, thereby impacting device lifetime. This paper presents a comparative study on the reliability of power devices in isolated half-bridge and full-bridge DC-DC converters in EV fast chargers. The study focuses on the differences in thermal stresses that Si switches experience in each converter during charging cycles and how it impacts the end-of-life of each device. This study provides valuable insights for selecting reliable power converters for EV fast charging applications. ...
The reliability of semiconductor power devices can be studied by performing a thermal and power cycling test. In order to create the desired temperature cycles, there are four free variables to select during the power cycling test, namely the heating current, heating time, cooling time, and heatsink temperature. In this paper, the relation between the selected variables and the minimum and maximum junction temperature is extensively tested for the silicon IGBT with serial number IKP06N60T. Furthermore, the thermal model is discussed and verified and a rough estimate of the electrical resistance, thermal time constant, thermal resistance, and thermal capacitance are calculated. ...
EV Fast chargers are crucial to alleviate the driving range anxiety for E-mobility applications. A typical converter load profile consists of a short high-current pulse to rapidly refill the EV battery followed by a cooling-off period once the charging is completed. Power electronic components experience thermal cycles as a result, which can hasten the degradation of such components. In this context, the reliability evaluation of the power electronic converters enabling fast EV charging is of importance. This paper presents the reliability assessment of the IGBT module in EV Fast chargers to show how the load profile of the charger impacts the device’s lifetime. ...
Conference paper (2023) - Faezeh Kardan , Aditya Shekhar, Pavol Bauer
The load profile of the power converter in EV Fast charging applications involves a short high-current pulse for rapid charging of the EV battery leading to thermal cycles on the power electronic devices. These thermal cycles can cause thermo-mechanical fatigues, which consume the power devices’ lifetime. Also, different timescales and magnitude of temperature swings lead to various failure modes. This paper compares different empirical lifetime models quantitatively in order to suggest the most appropriate model to predict the end of life of power electronic devices used in EV fast chargers. It is suggested that the selected model takes into account the most relevant failure mechanism based on the different timescales and magnitude of thermal cycles to indicate the lifetime of power electronic device used in a fast charger depending on the number of charging sessions. ...