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The Brushless Doubly-Fed Machine (BDFM) is a new kind of doubly-fed machines which incorporates the robustness of the squirrel cage induction machine and the speed and power factor control of a synchronous machine. All of these advantages are obtained from a relatively low rating power electronic converter. The stator of a BDFM is furnished with two balanced three phase windings of conventional design. At this thesis the effects of an unbalanced grid on the operation of a BDFM has been studied. A balanced grid contains three phases with the same amplitude and the phase angle of 120 degrees between each two phases. The unbalanced grid is defined by any turbulent grid. There are some kinds of... 

In this thesis, losses of steady state operation of brushless doubly-fed induction machines (BDFM) are analyzed and optimized. Since the final objective of engineering systems is economic advantage, after brief introduction to BDFM, economic model of wind farms is presented and BDFM benefits and deficits are studied. Among BDFM’s research topics, power density and efficiency were recognized of most importance, according to the economic model. In absence of analytical model of core loss for BDFM, a maximum torque per ampere optimization for BDFM is presented, including torque equation derivation, optimal current angle extraction and machine design objective function calculation. The... 

The Brushless Doubly-Fed Machine (BDFM) has the potential to be employed either as a motor in drive applications or as a generator in variable speed wind power applications. The Doubly-Fed Induction Machine (DFIM) is, currently, the main generator used for wind power applications while it suffers from the existence of slip-ring and brushes. The BDFM can potentially achieve the characteristics such as those of the DFIM while it benefits from the brushless operation. This dissertation aims to show the efficacies of the BDFM for variable speed power generation by developing and implementation of a suitable vector control structure. For this purpose, at first a vector model is developed for the... 

Constantly rising fossil fuel consumption and the resulting air pollutants have caused hybrid electric vehicles to be considered as the most efficient mid-term solution for decreasing problems resulting from environmental pollutions and rising fuel prices. Various types of hybrid electric vehicles and power transmission schemes are studied in this thesis. Electric motors utilized in electric vehicles and hybrid electric vehicles such as induction motor, brushless permanent magnet motor, DC motor and switched reluctance motors are investigated based on previous studies and researches, and are compared for all basic criteria. For completing the comparison procedure and selecting the most... 

Wind has been shown to be one of the fastest growing sources of energy among renewable energy resources during recent decades. Widespread utilization of wind power during recent years imposes considerable effects on modern power systems in which the renewable energy supplies are included. Also power systems reliability evaluations have received significant attentions during recent years so studying wind farm's reliability would be of great importance in modern power systems whether it is studied as a part of the power grid or as an isolated system.In addition, the competitive environment of the power markets thrusts the power suppliers to follow the most economical patterns of operation,... 

The matrix converter is an array of controlled bidirectional semi-conductor switches that allows direct ac–ac conversion without an intermediate dc link. This converter has several attractive features that have been investigated in the last two decades. Multilevel converter technology has become increasingly popular in recent years due to high power quality,high-voltage capability, low switching losses and low EMI issues.This paper is concerned with applying multilevel techniques to direct ac–ac power converters and concentrates on developing the concepts of space vector modulation for a multilevel matrix converter. The common-mode voltage produced by a modern power converter has been... 

Current transformers are one of the key equipment of power networks that play a vital role in measuring, protecting and controlling the system. The proper operation of these equipments depends on the proper management of their temperature, because an increase in temperature can lead to a decrease in useful life, loss of efficiency and even irreparable failures. For this reason, analyzing and controlling the thermal behavior of these equipments, especially in critical conditions, is of particular importance. One of the biggest challenges in the operation of current transformers is the occurrence of a short-circuit fault, which leads to a sharp increase in temperature and can cause serious... 

The Brushless Doubly-Fed Machine (BDFM) is a machine which incorporates the robustness of the squirrel cage induction machine and the speed and power factor control of a synchronous machine. All of these advantages are obtainable from a relatively low rating power electronic converter (e.g. 30% of the machine’s rating). The stator of a BDFM is furnished with two balanced three phase windings of conventional design (power and control winding). These windings differ in pole number and are often excited at different frequencies. Hence, there is no direct magnetic coupling between them. The power winding is connected to a constant-voltage, constant-frequency source and the control winding is... 

Today, various industries rely on high-power, high-voltage induction motors for diverse applications. Given the critical role these motors play, any reduction in their lifespan or occurrence of failures can lead to substantial financial losses and even pose risks to lives. One significant factor influencing motor life is the temperature of its components. Manufacturers strive to enhance motor power while minimizing dimensions for economic reasons, but this increases power density and subsequent losses, elevating motor temperature. Consequently, thermal analysis becomes crucial, posing a significant challenge for companies producing high-power induction motors. In this study, a thermal model... 

Brushless DC (BLDC) motors and their drives are penetrating the market of home appliances, HVAC industry, and automotive applications in recent years because of their high efficiency, silent operation, compact form, reliability, and low maintenance. Traditionally, BLDC motors are commutated in six-step pattern with commutation control by position sensors. To reduce cost and complexity of the drive system, sensorless drive is preferred. In BLDC motors, stator winding is energized with appropriate sequencing. The sequence of energizing is determined by rotor position and rotor position is detected by the phase back EMF (BEMF). Motor is energized using an inverter which is controlled by PWM... 

Due to increase in nonlinear loads in today’s applications, the percent of harmonic content has been increased. Transformers are one of the electrical system components that are subjected to these harmonics. The failure of such equipment is an important consideration. Such failure is because of the hotspot temperature rises over the normal temperature withstanding of internal insulation. The increments of hotspot temperature can decrease the transformer insulation life. Totally, because of the presence of many parameters, precise investigation of loss of life is very difficult. Hence, the only meaning of loss of life in this project is the loss of insulation life under heat stresses.... 

In recent decades, electricity generation using renewable energy sources especially wind has gained considerable attention worldwide. Various generating systems have been proposed for wind turbines to convert wind mechanical power into electrical power. Up to 70% of the installed wind turbines incorporate Doubly-Fed Induction Generator (DFIG) and a fractionally rated power converter. Other schemes still have technological and economic penalties such as high cost of active materials, complexity of machine manufacturing and control systems and large and expensive converter, which limit their spread in wind power plants. Among these, Brushless Doubly-Fed Induction Generator (BDFIG) has... 

In this project, the main purpose is attaining the optimum controller for DFIG under permanent voltage unbalances. To achieve this purpose, firstly, the wind turbines’ control strategies, and main control subsystems including DFIG’s controller, Pitch control system, as well as Yaw’s control system are reviewed. The efficient control algorithms to achieve the control purposes for these three subsystems are introduced. To continue, it is focused on generator’s controller, and the different methods besides their performance are discussed. In order to improve DFIG’s controller performance under permanent grid voltage’s unbalance condition, at first, the problems of operating during such a... 

Because of environmental problems of fossil fuel energies and the rise in petroleum products, the tendencies to the renewable sources like wind power and solar power have been increased. In some particular applications like electric vehicles, satellites power system and all stand-alone unites that are using solar and wind powers are the only solutions. On the other hand, because of intermittent behavior of renewable sources, use of back-up supplies e.g. batteries are necessary to make a balance in power consumptions and productions. To interface between different ports some independent two port converters are used in traditional techniques. Multiport converters, used in... 

In this thesis, we consider design, modeling, and analysis of a single-phase Brushless Doubly-Fed Machine (BDFM). Generally, this type of machine is called the Brushless Doubly-Fed Induction Machine (BDFIM), that is a new class of induction machines. BDFM is a type of AC machines that requires two alternative power sources. One of the stators windings, called Power Winding, is connected to the network grid and the other one, which is called Control Winding, is connected via a converter, which is in the order of one-third of the nominal power of the machine, to the grid. Like the other types of induction machines, BDFM can also work as a generator or motor. The important criteria of this... 

Doubly fed machines require lower converter rating in comparison to single fed machines, and this is the most important advantage of doubly fed machines. Among them, Brushless Doubly Fed Machines (BDFMs) have some advantages, including higher reliability and longer maintenance period. Determination of the converter rating is an important issue that has been not sufficiently investigated. Determination of the minimum converter rating, or in other words, converter current and voltage, in order to minimize the cost to commercialize the BDFM is mandatory. In this thesis, the problem is presented properly, and the optimal voltage and current of each machine side and grid side converters are... 

Constantly rising fuel prices and environmental consciousness have caused alternative transport solutions to be considered.Recently, batteries and electric vehicle industries have developed to become a reasonable alternative for gasoline powered cars. Plug-In hybrid electric vehicles could be connected to the electrical grid to be recharged. To ease the charging process, one solution could use an on-board charger to charge the electric vehicle. This charger should be able to be connected to a conventional outlet for convenience reasons and moreover, it should be a grid friendly charger in order not to pollute the electrical network. After studying the introduced structures for electric... 

The Brushless Doubly Fed Induction Machine (BDFIM) has the potential to be used as a generator or motor in adjustable speed variables. But the most important application for the BDFM is to work as a wind generator. Due to this ability it can be considered as a rival for the Doubly Fed Induction Generator (DFIG) that is the most common type of the wind power generators nowadays. Because of problems of relater to brushes in DFIG, the BDFM has more resisted structure compared to the DFIG. Thanks to the special “nested loop” structure of rotor and two different coils on the stator without direct coupling between them, three different operation modes are possible for the BDFM.The synchronous... 

The demand for electrical energy is increasing. The main source of energy at this moment is fossil fuels. High price, great amount of pollution, uneven distribution and global warming are major disadvantages of fossil fuels. Using renewable resources can tackle these issues. Hence, the demand for renewable energy are highly increased. The wind energy is one type of renewable energy. Increasing the wind power penetration impairs the functionality of power system and causes the environmental issues. In order to have a stable power system this effect should be investigated thoroughly. Due to the inherent uncertain characteristics of wind energy, it is desirable to determine the characteristics... 

Recently, the linear switched reluctance motor with segmental translator has been introduced as a new type of improved linear switched reluctance motor, which uses less iron compared to conventional motor. Therefore, this motor has lower iron losses and higher power/volume ratio. In order to model linear switched reluctance motor with segmental translator, the finite element method often gives accurate results. However, in finite element analysis, if the details of meshing or many other analyzes are considered, a lot of time must be spent. Therefore, it is necessary to use faster methods to obtain the characteristics of this motor. In this research thesis, a magnetic equivalent circuit model...