Examinando por Autor "Zolghadri, Mohammad Reza"

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    Ítem
    Improvement of Post-Fault Performance of a Cascaded H-bridge Multilevel Inverter
    (Institute of Electrical and Electronics Engineers Inc., 2017-04) Ouni, Saeed; Zolghadri, Mohammad Reza; Khodabandeh, Masih; Shahbazi, Mahmoud; Rodríguez, Jose; Oraee, Hashem; Lezana, Pablo; Schmeisser, Andres Ulloa
    This paper is focused on improving the post-fault performance of cascaded H-bridge multilevel inverters by decreasing the common-mode voltage. First, an algorithm is proposed to determine the optimal post-fault state among all possible states, which have the same maximum available voltage. Furthermore, a modified technique is proposed to calculate the references of inverter phase voltages under faulty conditions. This technique leads to a decrease in the common-mode voltage when the required output voltage is less than its maximum value. These solutions are mutually employed in the post-fault control system. Simulation and experimental results confirm the effectiveness of the proposed solutions in comparison with the existing methods in different cases. © 2017 IEEE.
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    Ítem
    Quick diagnosis of short circuit faults in cascaded H-bridge multilevel inverters using FPGA
    (Korean Institute of Power Electronics, 2017) Ouni, Saeeda; Zolghadri, Mohammad Reza; Rodriguez, Jose; Oraee, Hashema; Schmeisser, Andres Ulloa; Lezana, Pablo
    Fast and accurate fault detection is the primary step and one of the most important tasks in fault tolerant converters. In this paper, a fast and simple method is proposed to detect and diagnosis the faulty cell in a cascaded H-bridge multilevel inverter under a short circuit fault. In this method, the reference voltage is calculated using switching control pulses and DC-Link voltages. The comparison result of the output voltage and the reference voltage is used in conjunction with active cell pulses to detect the faulty cell. To achieve this goal, the cell which is active when the Fault signal turns to “0” is detected as the faulty cell. Furthermore, consideration of generating the active cell pulses is completely described. Since the main advantage of this method is its simplicity, it can be easily implemented in a programmable digital device. Experimental results obtained with an 11-level inverter prototype confirm the effectiveness of the proposed fault detection technique. In addition, they show that the diagnosis method is unaffected by variations of the modulation index. © 2017 KIPE.