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      • Open Access Article

        1 - A Generalized Relationship for Calculation of Critical Inductance in an n-Input Buck DC-DC Converter
        K.  Varesi S. H. Hosseini M. Sabahi E. Babaei
        critical inductance is one of the factors that decides continuous, boundary or discontinuous conduction mode of dc-dc converters. In applications like mining, the Continuous Conduction Mode (CCM) and consequently safety of converter can be guaranteed by proper selection More
        critical inductance is one of the factors that decides continuous, boundary or discontinuous conduction mode of dc-dc converters. In applications like mining, the Continuous Conduction Mode (CCM) and consequently safety of converter can be guaranteed by proper selection of inductance. So, calculation of critical inductance and proper sizing of inductor is an important issue in designing of dc-dc converters. In this paper, a non-isolated n-input buck dc-dc converter is introduced. Then, the operational modes and energy transfer process is investigated and discussed in detail. The critical inductance is calculated for 3 and 4-input versions. Using the inductive reasoning, a generalized relationship is proposed for calculation of critical inductance of converter with any number of inputs (n-input version). The proposed generalized relationship not only reduces the amount and time of calculation in design stage, but also presents a better view of performance of converter. The 3 and 5-input version of converter has been modeled and simulated in PSCAD/EMTDC software. Also, the 3-input version of converter has been practically implemented. The obtained simulation and experimental results confirm the validity of proposed generalized relationship for critical inductance calculation of n-input buck dc-dc converter. Manuscript profile
      • Open Access Article

        2 - One Analytical Method Based on Winding Function Theory and Magnetic Equivalent Circuit Model for Electromagnetic Analysis of Induction Motors under Healthy Condition and Broken-Rotor Bar Fault
        Farhad Rezaee-Alam Abdolsamad Hamidi Vahid Naeini
        In this paper, one hybrid analytical model (HAM) based on winding function theory (WFT) was presented for cage-rotor induction motors (CRIMs), which helps from the magnetic equivalent circuit (MEC) for considering the effect of slots and magnetic saturation in stator an More
        In this paper, one hybrid analytical model (HAM) based on winding function theory (WFT) was presented for cage-rotor induction motors (CRIMs), which helps from the magnetic equivalent circuit (MEC) for considering the effect of slots and magnetic saturation in stator and rotor cores. A non-linear MEC model is used to calculate the magneto motive force (MMF) drops in iron parts of stator and rotor for every operating point under the healthy condition and broken-rotor bar (BRB) fault. The distribution of MMF drop in stator and rotor is separately expressed in terms of the distribution of equivalent virtual currents and the virtual winding function. The inductances are then calculated using WFT while considering the effect of slots and magnetic saturation. To model the starting of no-load CRIM, the system of electrical and mechanical differential equations is solved using the finite difference method (FDM) under the healthy condition and BRB fault. Hague's solution and one simple conformal mapping (CM) are used to calculate and analysis of air-gap magnetic field. To verify the proposed model, some analytical results are compared with the corresponding results obtained through finite element method (FEM). Manuscript profile
      • Open Access Article

        3 - Optimal Design and Analysis of Fault Current Limiter Based on Variable Air-Core Series Reactor
        Moslem Amini Faskhoodi Aliakbar Damaki Aliabad
        With the ongoing growth of the power networks and the increase of the short circuit current level in the power network, it’s necessary to use the equipment for limiting the short circuit faults. One of these equipment is fault current limiters (FCLs) based on variable r More
        With the ongoing growth of the power networks and the increase of the short circuit current level in the power network, it’s necessary to use the equipment for limiting the short circuit faults. One of these equipment is fault current limiters (FCLs) based on variable reactor that they have simple structure and effective performance. This paper presents an optimal design of new fault current limiter based on variable series reactor. It is very important to obtain the optimal dimensions of the proposed FCL to achieve the best performance with considering parameters of the FCL such as performance time, initial inductance and final inductance. Hence, at the first, the proposed plan is introduced and then an analytical modeling based on equations of the reactor is used to evaluate and optimize the proposed FCL. Finally, the results of optimization are compared with results of primary design. These results confirm that the performance of optimal plan is much better than the primary plan. Manuscript profile