Browsing by Author "Tahami, Farzad"

Now showing 1 - 5 of 5
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    Comprehensive Reliability Assessment of Buck Quasi-Resonant Converter
    (2022) Hasanisadi, Mohammadhesam; Tarzamni, Hadi; Tahami, Farzad; Department of Electrical Engineering and Automation; Industrial and Power Electronics; Sharif University of Technology
    This paper explores reliability assessment of various Quasi-Resonant (QR) buck DC-DC converters including zero current/voltage switching and half-wave/full-wave topologies. The impacts of output power, input voltage, output voltage, and time duration on the failure rate of each component are investigated, then overall reliability performance of each converter is evaluated. A detailed comparison is performed in which reliability metric of buck soft switching topologies is compared with each other as well as their parent hard switching topology. Eventually, mean time to failure of the converters is analyzed. This approach provides insightful information for selecting the topology or components for the purpose of designing QR converters. To achieve the reliability of these converters, first, the required equations to evaluate the effective factors on the reliability are obtained. Then reliability metric values are calculated for three cases in each of which a key parameter of the converters varies over a specified range.
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    Improved Resonant Converter for Dynamic Wireless Power Transfer Employing a Floating-Frequency Switching Algorithm and an Optimized Coil Shape
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022) Ghohfarokhi, Shahriar Sarmast; Tarzamni, Hadi; Tahami, Farzad; Kyyra, Jorma; Sharif University of Technology; Department of Electrical Engineering and Automation
    This paper offers a new EF-class converter for dynamic wireless power transfer application. The proposed high-frequency converter employs a floating-frequency switching algorithm to control the converter in a continuous frequency range, eliminate the requirement to any additional operational data from the secondary (receiver) side, accelerate the load impedance match while moving, maximize the transferred power rate, reduce charging interval and compensate power transfer tolerances. Moreover, an optimized super elliptical shape coil is designed to cope with lateral misalignment, enhance coil coupling, and increase efficiency. In the proposed converter, (i) soft switching is implemented to increase switching frequency, decrease passive components size, and improve power density, (ii) undesired voltage harmonics are attenuated to reduce peak voltage stress of the power switch in a wide frequency range, (iii) the receiver side is enabled for higher mobility with stable power transfer, and (iv) the resonant frequency is updated to compensate non-accurate values of passive components in experimental prototyping. In this study, the operational analytics, compensation method, control algorithm, coil design and converter optimization are followed with some comparisons to present the converter capabilities. In addition, simulation and experimental results are provided under different degrees of misalignment to verify the accuracy of theoretical analytics.
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    An Overview of Lifetime Management of Power Electronic Converters
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022) Rahimpour, Saeed; Tarzamni, Hadi; Kurdkandi, Naser Vosoughi; Husev, Oleksandr; Vinnikov, Dmitri; Tahami, Farzad; Department of Electrical Engineering and Automation; Industrial and Power Electronics; Tallinn University of Technology; Sharif University of Technology
    An expected lifetime of converters is of great importance for optimal decision-making in the planning of modern Power Electronic (PE) systems. Hence, the lifetime management of power electronic systems has attracted a lot of attention in academia and industry. This paper is a guideline for managing the lifetime of power converters. Analyzing the different kinds of failures, failure modes and their corresponding mechanisms are investigated in the first section along with the failure data needed as input parameters of the assessment. In the second section, lifetime prediction in two aspects of component-level and system level is discussed and all the possible techniques to achieve them are investigated and compared. All the steps required to predict the lifetime in the component-level including electrothermal modeling, cycle counting, lifetime model, damage accumulation, parameter estimation, and lifetime distribution are described and then system level methods consisting of reliability block diagrams, fault-tree analysis, and Markov chains are examined and compared. The last section contains the roadmap of the lifetime extension including the reliable design and condition monitoring.
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    Reliability Assessment of Conventional Isolated PWM DC-DC Converters
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2021-03-22) Tarzamni, Hadi; Esmaeelnia, Farhad Panahandeh; Tahami, Farzad; Fotuhi-Firuzabad, Mahmud; Dehghanian, Payman; Lehtonen, Matti; Blaabjerg, Frede; Department of Electrical Engineering and Automation; Power Systems and High Voltage Engineering; University of Tabriz; Sharif University of Technology; George Washington University; Aalborg University
    This paper sets forth the reliability analysis of conventional isolated pulse width modulation DC-DC (IDC-DC) converters. The IDC-DC converters are categorized into isolated single-switch DC-DC (ISSDC-DC) or multiple-switch DC-DC (IMSDC-DC) converters. The proposed framework encompasses analyzing the impacts of duty cycle, input voltage, output power, transformer turns ratio, components characteristics and time duration on the overall reliability performance of the IDC-DC converters. The suggested reliability assessment is centered on Markov models characterized by taking into consideration all open and short circuit faults on the components in both continuous and discontinuous conduction modes. We further investigate the self-embedded fault tolerant capability of the IMSDC-DC converters under open circuit fault scenarios on the switches, diodes and blocking capacitors, where we offer new reliability analytics. Along with extensive analyses and comparisons, several experimental results are provided to verify the self-embedded fault tolerant capability of IMSDC-DC converters.
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    Thermal analysis of non-isolated conventional PWM-based DC-DC converters with reliability consideration
    (Institution of Engineering and Technology, 2021-02) Tarzamni, Hadi; Esmaeelnia, Farhad Panahandeh; Tahami, Farzad; Fotuhi-Firuzabad, Mahmud; Tohidi, Sajjad; Dehghanian, Payman; Lehtonen, Matti; Department of Electrical Engineering and Automation; Power Systems and High Voltage Engineering; University of Tabriz; Sharif University of Technology; George Washington University
    This paper proposes analytics for reliability assessment of non-isolated conventional pulse width modulation DC-DC (NIDC-DC) converters. This class of converters consists of conventional Buck, Boost, Buck-Boost, Cuk, Sepic and Zeta topologies. The proposed analytics are founded based on the Markov process principles and can effectively capture the effects of duty cycle, input voltage, output power, voltage gain, components characteristics and aging on the overall reliability performance and mean time to failure of the NIDC-DC converters. Furthermore, the suggested framework takes both continuous and discontinuous conduction modes of each converter into account, with which the open and short circuit faults in the components are analysed. As an important outcome, the most reliable operation region of the NIDC-DC converters are obtained with respect to different operational parameters, which is useful in design procedure. Eventually, extensive thermal experiments with an appropriate reflection of reliability metric are conducted to measure the components' temperatures and verify their performance in different operating conditions.