A Review of Transverse Flux Machines Topologies and Design

High torque and power density are unique merits of transverse flux machines (TFMs). TFMs are particularly suitable for use in direct-drive systems, that is, those power systems with no gearbox between the electric machine and the prime mover or load. Variable speed wind turbines and in-wheel traction seem to be great-potential applications for TFMs. Nevertheless, the cogging torque, efficiency, power factor and manufacturing of TFMs should still be improved. In this paper, a comprehensive review of TFMs topologies and design is made, dealing with TFM applications, topologies, operation, design and modeling

Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine

Optimal performance of the electric machine/drive system is mandatory to improve the energy consumption and reliability. To achieve this goal, mathematical models of the electric machine/drive system are necessary. Hence, this motivated the editors to instigate the Special Issue “Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine”, aiming to collect novel publications that push the state-of-the art towards optimal performance for the electric machine/drive system. Seventeen papers have been published in this Special Issue. The published papers focus on several aspects of the electric machine/drive system with respect to the mathematical modelling. Novel optimization methods, control approaches, and comparative analysis for electric drive system based on various electric machines were discussed in the published papers

Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Adaptive control system of slotless DC linear motor

Slotless DC linear motors (SDCLM) offer several benefits over traditional linear motors, including higher efficiency, smoother operation, and higher power density. These advantages make them a popular choice for a wide range of applications in various industries. One of the main benefits of a slotless DC linear motor is the absence of slot harmonics, which can cause vibration and noise in traditional slotted motors. This makes slotless motors ideal for applications that require precise and smooth motion, such as in medical equipment, robotics, and semiconductor manufacturing. However, one of the challenges of a Slotless DC linear motor is the presence of force ripple, which can limit the motor's performance, precision, and accuracy. Force ripple is caused by the mutual attraction of the translator's magnets and iron cores. It is independent of the motor current and is determined only by the relative position of the motor coils regarding the magnets. To overcome these challenges, motor redesign, magnetic field optimisation and the use of an adaptive control system. This research program focused on and investigated the above possible methods (i.e., motor redesign, magnetic field optimisation field and use of advanced control algorithms such as Sliding Mode Control SMC) to tackle the current challenges and improve the relevant industrial application performance and precision. The inquiry encompasses the analysis, design, and control of the SDCLM by proper modelling, building, and experimental validation of the modelled findings, applying both static and dynamic methodologies. Electrical, mechanical, and magnetic analyses were performed on the SDCLM design. The performance of the SDCLM was investigated using a finite element method (FEM), and the motor parameters were improved. Investigation and analysis are performed about additional difficulties such as force ripple and normal force, where the results indicated that the flux density in the airgap and the thrust force were different between the actual time and the simulation by 7.14% and 8.07%, respectively. Moreover, sliding mode control is designed to achieve desired system performance, such as reducing the power ripple of a slotless DC linear motor. where the proposed control shows experiments that it has stability despite disturbances and uncertainties. To improve the control method and reduce the steady-state error caused by the force ripple, the Bees algorithm has been used to tune the parameters of the controller. Finally, the outcomes indicate that the control method employing the disturbance observer and Bees algorithm has enhanced the performance of both position and speed, while concurrently reducing the force ripple. A comparison between simulation and experiment shows that there is a difference in the tracking performance, where the difference was around 13.6%. This error could have arisen from the omission of certain errors that cannot be accounted for within the simulation. These errors may stem from issues with the position sensor or discrepancies in the manual system design process

Lithium-Ion Ultracapacitor Energy Storage Integrated with a Variable Speed Wind Turbine for Improved Power Conversion Control

The energy of wind has been increasingly used for electric power generation worldwide due to its availability and ecologically sustainability. Utilization of wind energy in modern power systems creates many technical and economical challenges that need to be addressed for successful large scale wind energy integration. Variations in wind velocity result in variations of output power produced by wind turbines. Variable power output becomes a challenge as the amount of output power of the wind turbines integrated into power systems increases. Large power variations cause voltage and frequency deviations from nominal values that may lead to activation of relay protective equipment, which may result in disconnection of the wind turbines from the grid. Particularly community wind power systems, where only one or a few wind turbines supply loads through a weak grid such as distribution network, are sensitive to supply disturbances. While a majority of power produced in modern power systems comes from synchronous generators that have large inertias and whose control systems can compensate for slow power variations in the system, faster power variations at the scale of fraction of a second to the tens of seconds can seriously reduce reliability of power system operation. Energy storage integrated with wind turbines can address this challenge. In this dissertation, lithium-ion ultracapacitors are investigated as a potential solution for filtering power variations at the scale of tens of seconds. Another class of issues related to utilization of wind energy is related to economical operation of wind energy conversion systems. Wind speed variations create large mechanical loads on wind turbine components, which lead to their early failures. One of the most critical components of a wind turbine is a gearbox that mechanically couples turbine rotor and generator. Gearboxes are exposed to large mechanical load variations which lead to their early failures and increased cost of wind turbine operation and maintenance. This dissertation proposes a new critical load reduction strategy that removes mechanical load components that are the most dangerous in terms of harmful effect they have on a gearbox, resulting in more reliable operation of a wind turbine

Magnetic Material Modelling of Electrical Machines

The need for electromechanical energy conversion that takes place in electric motors, generators, and actuators is an important aspect associated with current development. The efficiency and effectiveness of the conversion process depends on both the design of the devices and the materials used in those devices. In this context, this book addresses important aspects of electrical machines, namely their materials, design, and optimization. It is essential for the design process of electrical machines to be carried out through extensive numerical field computations. Thus, the reprint also focuses on the accuracy of these computations, as well as the quality of the material models that are adopted. Another aspect of interest is the modeling of properties such as hysteresis, alternating and rotating losses and demagnetization. In addition, the characterization of materials and their dependence on mechanical quantities such as stresses and temperature are also considered. The reprint also addresses another aspect that needs to be considered for the development of the optimal global system in some applications, which is the case of drives that are associated with electrical machines

Studies in Electrical Machines & Wind Turbines associated with developing Reliable Power Generation

The publications listed in date order in this document are offered for the Degree of Doctor of Science in Durham University and have been selected from the author’s full publication list. The papers in this thesis constitute a continuum of original work in fundamental and applied electrical science, spanning 30 years, deployed on real industrial problems, making a significant contribution to conventional and renewable energy power generation. This is the basis of a claim of high distinction, constituting an original and substantial contribution to engineering science

Advanced control strategies for partially levitating multi-sector permanent magnet synchronous machines

The thesis presents solutions to improve the performance of a partially levitating bearingless permanent magnet synchronous machine with a multi-three-phase winding. A combined winding topology, which consists of three independent three-phase sub-windings, is installed in the stator where each phase contributes to both the suspension force and the motoring torque. This work focuses on control algorithms, including fault-tolerant controls, a current limitation technique, and a current-sharing technique. Firstly, the thesis presents an analytical formulation of the force and torque generation in healthy operative conditions. Following, the three-phase and single-phase open-circuit fault conditions are also analysed. The analytical model of the machine is presented in a generic matrix form so that it can be applied to any machine with a multi-three-phase winding structure if the coupling among sectors is negligible. The fault-tolerant control algorithms address the issues of open-circuit faults of an entire three-phase sub-winding, of a single-phase in a three-phase sub-winding, or of two phases belonging to two different three-phase sub-windings. The theoretical analysis is verified with both Finite Elements Analysis and experimental tests. Then, the thesis proposes a current limitation technique. The main challenges with the combined winding configuration consist of decoupling the suspension force and torque generation and designing a proper current limitation technique. The latter is required in order to maintain the machine in safe operative conditions according to its current-voltage rating and its operative thermal limits. This thesis addresses the limitation technique based on the analytical models, considering both healthy and faulty conditions. In particular, the proposed current limitation technique allows prioritising the suspension force, which is considered a safety-critical output with respect to the torque in order to avoid the rotor touchdown. Numerical simulation results and experimental validation are provided to validate the algorithm. Finally, the thesis proposes a modular approach for a current-sharing control of the machine. A thorough explanation of the methodology used is presented, as well as control algorithms to consider the torque and force control combined with the current-sharing management of the machine. Particular emphasis is also placed on validating the modelling hypotheses based on a finite element characterisation of the machine electro-mechanical behaviour. The proposed control strategy is also extended to cater to the possibility of one or more inverters failure, thus validating the intrinsic advantage of the redundancy obtained by the system's modularity. An extensive experimental test is finally carried out on a prototyped machine. The obtained results validate the current-sharing operation in either healthy or faulty scenarios, both at steady-state and under transient conditions. These outcomes show the potential of the proposed strategy to increase the versatility of fault-tolerant drives applied to this machine topology

Fourth International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document