Original Article
Mohammad Amin Moqadasi; Mahmood Hoseini Ali Abadi; Hamid Radmanesh
Abstract
The present study discusses a new structure of single layer magnetic gear (SL-MG) with Halbach array in external rotor, which is named single layer magnetic gear with Halbach array (HSL-MG). The key point in this design is using three segment Halbach array instead of the conventional permanent magnets ...
Read More
The present study discusses a new structure of single layer magnetic gear (SL-MG) with Halbach array in external rotor, which is named single layer magnetic gear with Halbach array (HSL-MG). The key point in this design is using three segment Halbach array instead of the conventional permanent magnets in magnetic pole pairs of external rotor in single layer magnetic gear, and this leads to increasing the magnetic couple between wound stator and permanent magnets of external rotor. Electromagnetic function and FEM two dimensional analysis are done on both magnetic gears and these two magnetic gears of wound stator are compared with each other. The results show that the magnetic gear under study has a higher torque density than its conventional version; therefore, this kind of magnetic gear is more suitable for low-speed engines and high torque direct drive applications.
Original Article
Hamed Hekmati; Mohammad Siamaki; Arsalan Hekmati
Abstract
As a technology, superconductivity has had a great contribution to the advancement of medical science, electronics, astronomy and transportation. With the improvements in the field of superconductivity, the discovery of new materials with better properties, commercialization of these materials, and regarding ...
Read More
As a technology, superconductivity has had a great contribution to the advancement of medical science, electronics, astronomy and transportation. With the improvements in the field of superconductivity, the discovery of new materials with better properties, commercialization of these materials, and regarding the importance of rotary equipment in major industry, trends in research and development of superconducting magnetic bearings is broadened day by day. High efficiency compared to the cost of manufacturing and maintenance of these bearings as well as the increasing need to economic save in key industry, could reinforce the tendency to use these bearings instead of conventional bearings. Superconducting magnetic bearings have various structures, all of which can be used for various applications. In recent decades efforts have been made to design new structures for specific applications. In this paper a general review of magnetic bearings’ history as well as their existing structures is investigated and the theoretical and experimental results have been presented for a studied bearing system.
Original Article
E. Dehjoo; R. Haghmaram; A. Mosallnejad
Abstract
In this paper, the problem of starting an induction motor is investigated and a solution is presented. The large current and considerable torque pulsation of the starting can damage the motor and other consumers connected to the feed line, and increasing the startup time will cause more heat and damage ...
Read More
In this paper, the problem of starting an induction motor is investigated and a solution is presented. The large current and considerable torque pulsation of the starting can damage the motor and other consumers connected to the feed line, and increasing the startup time will cause more heat and damage to the winding insulators. Various methods exist for startup of the induction motor, including the stator voltage control via wye-delta circuit breaker, autotransformer, and new methods such as soft starter, as well as methods for controlling the rotor's resistance, and control of V/f. However, in this research, by connecting a torsion spring between the motor shaft and the load, a new method of startup has been proposed. Therefore, due to the delay in the rotation of the load during the absorption of energy in the torsion spring it is possible to rotate loads with a torque beyond the motor starting torque, and to reduce the motor startup time as much as 77%. These cases increase the lifetime of the motor, and reduce economic costs.
Original Article
Abolfazl Halvaei Niasar; Yahya Abdollahi
Abstract
Due to some inevitable restrictions during fabrication of permanent magnet brushless (PMBL) motors, some of them have neither sinusoidal nor trapezoidal back-EMF voltages, that we name them as non-ideal PMBL motors. Employing conventional control strategies of permanent magnet synchronous motors (PMSMs) ...
Read More
Due to some inevitable restrictions during fabrication of permanent magnet brushless (PMBL) motors, some of them have neither sinusoidal nor trapezoidal back-EMF voltages, that we name them as non-ideal PMBL motors. Employing conventional control strategies of permanent magnet synchronous motors (PMSMs) and brushless DC motors (BLDCMs) leads to lower efficiency and performance and causes unwanted torque ripple, vibration and acoustic noises that in unfavourable for special applications. This paper investigates the torque response of non-ideal PMBL motor while is controlled with conventional control strategies and presents a novel torque ripple minimization method. Simulation results indicate the non-ideal PMBL motor by novel proposed method develops smoother torque and lower torque ripple rather than all mentioned control strategies.
Original Article
R. Alipour-Sarabi; Z. Nasiri-Gheidari; H. Oraee
Abstract
Resolvers, as magnetic position sensors, are increasingly used in motion-control systems. Due to electro-magnetic structure, they preserve more accurate and reliable operation than optical encoders in stressful conditions. Usually, to evaluate the performance of a resolver, total harmonic distortion ...
Read More
Resolvers, as magnetic position sensors, are increasingly used in motion-control systems. Due to electro-magnetic structure, they preserve more accurate and reliable operation than optical encoders in stressful conditions. Usually, to evaluate the performance of a resolver, total harmonic distortion (THD) of output signals is calculated. In this study, by using analytical expressions, it is shown that THD of output signal is not a reliable indicator of the performance of a resolver.
Original Article
Ali Khaksari; A. Rezazadeh; Majid Ebadifard
Abstract
This paper deals with the problem of designing a robust dynamic output feedback controller for the wind machine. This paper for the first time exploits the designing controller problem of the wind turbines in the presence of time varying delay and uncertain parameters. In this paper, a novel algorithm ...
Read More
This paper deals with the problem of designing a robust dynamic output feedback controller for the wind machine. This paper for the first time exploits the designing controller problem of the wind turbines in the presence of time varying delay and uncertain parameters. In this paper, a novel algorithm is proposed which designs a proper controller based on the idea of Lyapunov Krasovskii functional and Finsler’s Lemma. To validate the result of the proposed algorithm, comparative simulation examples are given which are two different dimension turbines to investigate the performance of the design methodology as compared to those of previous approaches.
