Power systems
Hamed Shadfar; Hamid Reza Izadfar
Abstract
Calculating the current of the rotor bars in a squirrel cage induction motor (SCIM) using stator data is difficult, but it is very useful. With the calculation of the rotor bars’ current, analysis and investigation of some different parameters of the motor can be done, precisely. One of the faults ...
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Calculating the current of the rotor bars in a squirrel cage induction motor (SCIM) using stator data is difficult, but it is very useful. With the calculation of the rotor bars’ current, analysis and investigation of some different parameters of the motor can be done, precisely. One of the faults faced by SCIM is the broken rotor bar (BRB) fault. The breakage of one or more bars causes a change in the healthy bars' current and the motor's behavior and parameters. This paper introduces the method of calculating the rotor bars’ current in the SCIM in two healthy and defective states (breakage of 1 bar and 2 adjacent bars) using the multiple-coupled circuit (MCC) model. In addition to currents, some important parameters, such as speed, magnetic field, etc., will be calculated. For validation of results, a two-pole SCIM with a nominal specification of 1.1 kW, 220/380 V, and 50 Hz is subjected to experimental testing. The results are confirmed by practical tests and simulations using the Ansys Maxwell software.
Industrial Electronics
Saleh Mohammadi; Hamid Reza Izadfar; Naser Eskandarian
Abstract
This research aims to provide a comprehensive review of various CCM control strategies for flyback inverters. The study is carried out based on published data in reports, papers and other available online documents. The introduced control strategies make use of different approaches to dominate the constraints ...
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This research aims to provide a comprehensive review of various CCM control strategies for flyback inverters. The study is carried out based on published data in reports, papers and other available online documents. The introduced control strategies make use of different approaches to dominate the constraints on determining the feedback control system gains caused by the zero put on right-half-plane (RHP) and dynamics of LC filter. Thus, the tracking of the considered output current is accurately implemented and the introduced control systems carry out the attenuation of disturbances. Moreover, zero steady-state error and the stability requirements are fulfilled by properly regulating the control signal. The best control structure should be enough fast employing the fewest number of delays in its structure resulting the burden in computational system to be considerably decreased.
Power systems
Hamed Shadfar; Hamid Reza Izadfar
Abstract
One of the main components of a power transformer is the transformer insulation system, namely, transformer insulation oil and transformer insulation paper. Any failure can cause the transformer to fail temporarily or permanently. As a result, regular and non-destructive monitoring of transformers is ...
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One of the main components of a power transformer is the transformer insulation system, namely, transformer insulation oil and transformer insulation paper. Any failure can cause the transformer to fail temporarily or permanently. As a result, regular and non-destructive monitoring of transformers is of particular importance for early detection and prediction of any faults. Frequency response analysis (FRA) is known as a high-accuracy, fast, economical, and non-destructive method for diagnosing the condition of a transformer, which can be used independently or as a complementary method to ensure the results of other diagnostic tests and based on the operational conditions of the transformer, it can be implemented in two methods, online and offline. This paper provides an in-depth discussion of measuring and interpreting FRA results and the ability of this method to detect and locate power transformer faults, especially insulation faults, which have been given less attention in the past. The information confirmed in this survey is expected to provide an important roadmap for future research in monitoring the condition of transformer insulation systems
Industrial Electronics
Hamed Shadfar; Hamid Reza Izadfar
Abstract
Audible noise radiated by electrical machines is gaining more and more importance in the design process of electrical machines. The radial electromagnetic forces in induction motors play an important role in the production of audible noise and vibrations. The magnetic flux pulsations at the iron surfaces ...
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Audible noise radiated by electrical machines is gaining more and more importance in the design process of electrical machines. The radial electromagnetic forces in induction motors play an important role in the production of audible noise and vibrations. The magnetic flux pulsations at the iron surfaces produce these radial forces which act on the stator and rotor structures. A squirrel-cage induction motor produces electromagnetic vibration and noise caused by interaction between many harmonic fluxes in the air gap. In this paper, a new structure of the squirrel cage rotor to improve the distribution of the air gap magnetic flux and reduce the electromagnetic forces and, consequently, the electromagnetic noise in a single-phase induction motor will be introduced. For this purpose, in the proposed design the rotor bars are located on the rotor according to a sinusoidal form. The results show that this structure of the rotor improves the dynamic behavior and many parameters such as electromagnetic forces, harmonic distortion of magnetic flux, and torque ripple.
