Original Article
Modeling, analysis and design of electromechanical systems
Amirhossein Koushki; Zahra Nasiri Gheidari
Abstract
Coreless Permanent Magnet (CPM) machines are increasingly used in many industrial applications, such as automotive and aerospace applications, wind turbines, medical equipment, robotics, servo drives, and so on. In coreless permanent magnet DC machines, the rotor has a coreless winding structure and ...
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Coreless Permanent Magnet (CPM) machines are increasingly used in many industrial applications, such as automotive and aerospace applications, wind turbines, medical equipment, robotics, servo drives, and so on. In coreless permanent magnet DC machines, the rotor has a coreless winding structure and due to the absence of an iron core, the permanent magnet plays a significant role in these machines. Also, the shaft’s material can change the flux distribution and is another effective parameter on machine performance. Thus, in this paper, a typical coreless PMDC brushed machine is simulated and the effects of magnetization direction and the amount of the residual flux density of permanent magnet, and also the influence of ferromagnetic and non-ferromagnetic material of the shaft on machine performance, are studied and analyzed through three-dimensional finite element analysis. The results show that using a ferromagnetic shaft with a diametrical magnetized permanent magnet can improve the machine's performance in motor mode.
Original Article
Control of Electromechanical systems
Ali Abdul Razzaq Altahir
Abstract
An electric drive controller for AC microgrids with renewable energy sources is a system that controls the flow of electricity in an alternating current (AC) microgrid. The role of distributed generation in the electricity industry has been expanding in recent years. Distributed (DGs) are small, scalable ...
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An electric drive controller for AC microgrids with renewable energy sources is a system that controls the flow of electricity in an alternating current (AC) microgrid. The role of distributed generation in the electricity industry has been expanding in recent years. Distributed (DGs) are small, scalable units, generally with a capacity of less than 10 MW which can be connected to the grid, distribution feeders or customer levels. Nowadays, the high penetration of distributed resources in power systems is increasing. Since these units can play an important role in electricity markets and provide ancillary services for system operators, integrating these resources within power systems has been considered. Therefore, this paper focuses on modelling, designing and simulating a suitable controller to ensure AC microgrids stability and stable performance (AC M.G) in both grid-connected and islanded modes. Meanwhile, all simulations have been fulfilled in MATLAB environment. After designing the controllers and ensuring the performance of their frequency response using the bode diagram and the system step response, these controllers were used to command the voltage and current in real scenarios. After applying the controllers, the performance has dramatically improved in the voltage and current controller presence. As a result, the controller can be programmed to respond into changes in the energy supply and demand, adjusting the output of the green resources and managing energy storage systems within the microgrid. This allows the system to operate in a stable and sustainable manner, even when there are fluctuations in the energy supply or demand.
Review Article
Modeling, analysis and design of electromechanical systems
Amin Nobahari; Antti Lehikoinen
Abstract
Finite element (FE) method, is the most popular numerical approach to low-frequency electromagnetic modeling, especially in the field of electrical machines. Although FE method is nowadays widely used by experts, still it can find widespread efforts toward additional developments that make it more applicable ...
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Finite element (FE) method, is the most popular numerical approach to low-frequency electromagnetic modeling, especially in the field of electrical machines. Although FE method is nowadays widely used by experts, still it can find widespread efforts toward additional developments that make it more applicable to various problems. This paper takes a look at the state of the arts in the electromagnetic modeling of electrical machines via FE analysis. The addressed subjects cover new techniques for loss calculation in electrical machines, the state of art toward more efficient computation, which is a serious challenge for numerical methods, and modeling efforts for the hysteresis phenomenon. The paper tries to address a portion of the recent hot topics of FE analysis of electrical machines. The authors believe that the paper will give a brief but useful insight into the challenges and developments of FE applications in electrical machine analysis, as the most practical numerical tool in this area.
Original Article
Control of Electromechanical systems
Mohsen Dashtbani; Majid Hasanzadeh; Reza Roshanfekr
Abstract
The conventional direct torque control (DTC) method suffers a flux drop at low speeds, which is due to the long selection of zero (neutral) voltage vectors in these speed areas. Past studies with the continuous switch of direct and reverse active vectors to achieve proper flux adjustment, this procedure ...
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The conventional direct torque control (DTC) method suffers a flux drop at low speeds, which is due to the long selection of zero (neutral) voltage vectors in these speed areas. Past studies with the continuous switch of direct and reverse active vectors to achieve proper flux adjustment, this procedure causes high and consecutive overshoots in the hysteresis band that causes a sharp increase in the switching frequency and increase in the torque and current ripple, which means decrease in the drive efficiency. In this article, a modified method for setting the standard DTC current is introduced, which can be achieved by controlling only one band (low or high band) at low speeds. The introduced method by reducing the selection of zero voltage vectors and at the same time minimizing the number of reverse voltage vectors prevents the loss of flux in low speed areas. In addition, it is effective in reducing torque ripple and current in low speed mode and a significant reduction in switching frequency will also be achieved. The effectiveness of the proposed method in the simulation which is done in MATLAB software will be proved.
Original Article
Thermal modeling, analysis and design
Mohammad Ebadollahi; Majid Amidpour
Abstract
Energy consumption in Iran has high rate due to its geographical location as well as high industrial and residential energy consumption. Drought and the impossibility of using some hydroelectric power plants, global warming and extravagant electricity consumption, as well as novel technologies (e.g., ...
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Energy consumption in Iran has high rate due to its geographical location as well as high industrial and residential energy consumption. Drought and the impossibility of using some hydroelectric power plants, global warming and extravagant electricity consumption, as well as novel technologies (e.g., cryptocurrency mining) are the reasons to cause the increment of electricity consumption. The main reason for national power outages is the instability of energy production and consumption balance. Such events disturb the balance between the production and consumption of electricity. The utilization of renewable energies is one of the primary solutions to eliminate the gap between energy production and consumption. Taking into consideration the current conditions and the 20-year forecast of energy consumption and production in Iran, a vast gap can be observed between these two cases. In this paper, by considering two different scenarios using renewable energy, this gap is addressed, causing the amount of power production to exceed the amount of consumption in the long term.
Original Article
Control of Electromechanical systems
Adel Mohseni; Aref Doroudi; Mehdi Karrari
Abstract
The excitation system is one of the most crucial components of a power plant. Knowing the exact parameters of the excitation system and their changes over time is essential for efficient and accurate power system dynamic studies. In this paper, the parameters of a typical and well-known type of excitation ...
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The excitation system is one of the most crucial components of a power plant. Knowing the exact parameters of the excitation system and their changes over time is essential for efficient and accurate power system dynamic studies. In this paper, the parameters of a typical and well-known type of excitation system are estimated using different types of Kalman filters, including unscented Kalman filter (UKF), spherical-simplex Kalman filter (SS-UKF), and cubature Kalman filter (CKF). The efficacy of these Kalman filter methods in the excitation system parameters estimation problem is investigated under three different planned and unplanned events as the input of the methods. The planned disturbances will be internal type (a reference voltage step) and external type (unit transformer tap changing) whereas the unplanned disturbance is caused by power grid events (neighbor generator outage). Comparison is done between the simulation results and experimental ones and the best appropriate approach is selected.
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