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Author: Amirmasoud Takbash
Publisher:
ISBN:
Category :
Languages : en
Pages : 159
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Book Description
Permanent magnet synchronous machines (PMSMs) with rare-earth magnets are widely used especially in traction applications as a result of their higher efficiency and torque density in comparison with other electrical motors. Due to price fluctuations and limited production of rare-earth materials, it is essential to find alternatives to the rare-earth PMSMs for different applications. This thesis focuses on the application of Aluminum-Nickel-Cobalt (AlNiCo) magnets in PMSMs. AlNiCo magnets can theoretically provide torque densities comparable to rare-earth magnets in electrical machines. The application of AlNiCo magnets in electrical machines can improve the field-weakening performance, due to the possibility of varying their magnetic flux density using armature current pulses. As a result, these machines are named variable flux machines (VFMs). This thesis presents an analytical model for the VFM to calculate the no-load air gap flux density and consequently, the no-load back-EMF, torque peak to peak value, average torque, and magnetization current. The proposed model is used to develop an analytical design criterion for spoke type AlNiCo-based VFMs. An experimental characterization of an existing spoke type VFM at different magnetization levels is done of the torque waveform, the torque-angle characteristics, the no-load back-EMF and the magnetization/demagnetization energy. An optimization procedure to reduce the torque ripple and the magnetization current of the spoke type AlNiCo-based VFM is then proposed. A new VFM design with radially magnetized interior magnets is presented to enhance the torque density in the field-weakening operating condition. The torque-speed and power-speed characteristics of the VFM are calculated considering the demagnetization of the AlNiCo magnets in the field-weakening region. The proposed design keeps the fully magnetized condition at both no-load and full-load conditions and provides high power densities at a wider speed range. This design is also optimized to have reduced torque ripple. An improved core loss model is proposed and implemented in the finite element software, and an experimental method based on the flux controllability of the VFM is developed to measure the mechanical and core losses at the no-load condition. These results are then used to verify the proposed core loss model.
Author: Amirmasoud Takbash
Publisher:
ISBN:
Category :
Languages : en
Pages : 159
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Book Description
Permanent magnet synchronous machines (PMSMs) with rare-earth magnets are widely used especially in traction applications as a result of their higher efficiency and torque density in comparison with other electrical motors. Due to price fluctuations and limited production of rare-earth materials, it is essential to find alternatives to the rare-earth PMSMs for different applications. This thesis focuses on the application of Aluminum-Nickel-Cobalt (AlNiCo) magnets in PMSMs. AlNiCo magnets can theoretically provide torque densities comparable to rare-earth magnets in electrical machines. The application of AlNiCo magnets in electrical machines can improve the field-weakening performance, due to the possibility of varying their magnetic flux density using armature current pulses. As a result, these machines are named variable flux machines (VFMs). This thesis presents an analytical model for the VFM to calculate the no-load air gap flux density and consequently, the no-load back-EMF, torque peak to peak value, average torque, and magnetization current. The proposed model is used to develop an analytical design criterion for spoke type AlNiCo-based VFMs. An experimental characterization of an existing spoke type VFM at different magnetization levels is done of the torque waveform, the torque-angle characteristics, the no-load back-EMF and the magnetization/demagnetization energy. An optimization procedure to reduce the torque ripple and the magnetization current of the spoke type AlNiCo-based VFM is then proposed. A new VFM design with radially magnetized interior magnets is presented to enhance the torque density in the field-weakening operating condition. The torque-speed and power-speed characteristics of the VFM are calculated considering the demagnetization of the AlNiCo magnets in the field-weakening region. The proposed design keeps the fully magnetized condition at both no-load and full-load conditions and provides high power densities at a wider speed range. This design is also optimized to have reduced torque ripple. An improved core loss model is proposed and implemented in the finite element software, and an experimental method based on the flux controllability of the VFM is developed to measure the mechanical and core losses at the no-load condition. These results are then used to verify the proposed core loss model.
Author: Aleksandar Borisavljevic
Publisher: Springer Science & Business Media
ISBN: 3642334571
Category : Technology & Engineering
Languages : en
Pages : 229
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Book Description
There is a growing number of applications that require fast-rotating machines; motivation for this thesis comes from a project in which downsized spindles for micro-machining have been researched. The thesis focuses on analysis and design of high-speed PM machines and uses a practical design of a high-speed spindle drive as a test case. Phenomena, both mechanical and electromagnetic, that take precedence in high-speed permanent magnet machines are identified and systematized. The thesis identifies inherent speed limits of permanent magnet machines and correlates those limits with the basic parameters of the machines. The analytical expression of the limiting quantities does not only impose solid constraints on the machine design, but also creates the way for design optimization leading to the maximum mechanical and/or electromagnetic utilization of the machine. The models and electric-drive concepts developed in the thesis are evaluated in a practical setup.
Author: Matthew Gates Angle
Publisher:
ISBN:
Category :
Languages : en
Pages : 285
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Book Description
Improvement of performance of robots has necessitated technological advances in control algorithms, mechanical structures, and electric machines. Running, legged robots have presented challenges in the area of electric machinery in particular. In addition to the low-speed, high-torque, low-mass requirements on the machines, the act of running results in an unconventional drive cycle that consists of brief periods of high torque followed by long stretches of minimal torque requirement, a performance envelope that is not matched by commercially-available machines. An optimized motor would dissipate the minimum possible power over the given drive cycle, lowering temperatures and potentially reducing required battery mass or extending range. These performance requirements have motivated faster modeling techniques to enable optimization of designs for these unconventional applications. This thesis presents a novel, fast modeling method for permanent magnet synchronous machines consisting of a hybrid model comprising an explicit Maxwell solution and a Flux Tube solution. The Maxwell solution is performed for the rotor and airgap of the machine, where geometries are simple and materials are homogeneous. The stator, with its geometric complexities and non-linear materials, is modeled with a lumped-parameter model based on ux tubes. The two models are then stitched together, forced to be self-consistent with boundary conditions, and allowed to converge. This captures effects such as cogging torque as well as saturation of the core materials. The method is approximately four orders of magnitude faster than a reference finite element program (0.01 s versus 100 s) for the same accuracy. The modeling method is implemented for two topologies of surface-mount permanent-magnet machines, an internal-rotor machine and an external-rotor machine. It is then used to optimize machine design to a given drive cycle, including effects of core loss. A machine is built to demonstrate the validity of the model and optimization method and test results match predictions of instantaneous torque to within 5% at the worst point. Cogging torque is another aspect of performance that is important to machines for robotics and other applications. These pulsations in torque caused by magnet alignment with geometric features in the stator result in undesired vibrations and issues with control. One method, based on skew, for reducing or eliminating cogging torque is explored, and a simple analytical technique to predict the eect of skew is presented. Based on the machine optimized for the Cheetah, two additional machines were built to explore the effects of cogging: a skewed-rotor machine, and a skewed- stator machine. Each demonstrated reduction of a particular cogging harmonic or all of the cogging. The skewed machines reduced cogging by approximately 85%. Novel magnet shapes which further reduce cogging are presented and finite element modeling suggests that they can further reduce cogging by 60% over a straight skew. The design and optimization tools developed herein and described above were used to optimize a motor for the MIT Cheetah Robot. The resulting motor showed nearly an order of magnitude increase in torque density when compared to commercial, off-the-shelf machines (1.3 kg vs 820 g and 10 Nm vs 28 Nm) with simultaneous improvements to efficiency.
Author: IEEE Staff
Publisher:
ISBN: 9781728161280
Category :
Languages : en
Pages :
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Book Description
The scope of ECCE 2021 includes all technical aspects of research, design, manufacturing, devices, components, circuits and systems related to energy conversion, industrial applications and power electronics
Author: Gennadi Sizov
Publisher:
ISBN:
Category : Electric machinery
Languages : en
Pages :
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Book Description
In this dissertation, a model-based multi-objective optimal design of permanent magnet ac machines, supplied by sine-wave current regulated drives, is developed and implemented. The design procedure uses an efficient electromagnetic finite element-based solver to accurately model nonlinear material properties and complex geometric shapes associated with magnetic circuit design. Application of an electromagnetic finite element-based solver allows for accurate computation in intricate performance parameters and characteristics. The first contribution of this dissertation is the development of a rapid computational method that allows accurate and efficient exploration of large multi-dimensional design spaces in search of optimum design(s). The computationally efficient finite element-based approach developed in this work provides a framework of tools that allow rapid analysis of synchronous electric machines operating under steady-state conditions. In the developed modeling approach, major steady-state performance parameters such as, winding flux linkages and voltages, average, cogging and ripple torques, stator core flux densities, core losses, efficiencies and saturated machine winding inductances, are calculated with minimum computational effort. In addition, the method includes means for rapid estimation of distributed stator forces and three-dimensional effects of stator and/or rotor skew on the performance of the machine. The second contribution of this dissertation is the development of the design synthesis and optimization method based on a differential evolution algorithm. The approach relies on the developed finite element-based modeling method for electromagnetic analysis and is able to tackle large-scale multi-objective design problems using modest computational resources. Overall, computational time savings of up to two orders of magnitude are achievable, when compared to current and prevalent state-of-the-art methods. These computational savings allow one to expand the optimization problem to achieve more complex and comprehensive design objectives. The method is used in the design process of several interior permanent magnet industrial motors. The presented case studies demonstrate that the developed finite element-based approach practically eliminates the need for using less accurate analytical and lumped parameter equivalent circuit models for electric machine design optimization. The design process and experimental validation of the case-study machines are detailed in the dissertation.
Author: Jacek F. Gieras
Publisher: Springer Science & Business Media
ISBN: 1402082274
Category : Technology & Engineering
Languages : en
Pages : 365
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Book Description
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. This timeless and revised second edition deals with the analysis, construction, design, control and applications of AFPM machines. The authors present their own research results, as well as significant research contributions made by others.
Author: Pedram Asef
Publisher:
ISBN:
Category :
Languages : en
Pages : 318
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Book Description
This Ph.D. thesis illustrates a novel study on the analytical and numerical design optimization of radial-flux permanent magnet synchronous wind generators (PMSGs) for small power generation in an urban area, in which an outer rotor topology with a closed-slot stator is employed. The electromagnetic advantages of a double-layer fractional concentration non-overlapping winding configuration are discussed. The analytical behavior of a PMSG is studied in detail; especially for magnetic flux density distribution, time and space harmonics, flux linkages, back-EMF, cogging torque, torque, output power, efficiency, and iron losses computation. The electromagnetic behavior of PMSGs are evaluated when a number of various Halbach array magnetization topologies are presented to maximize the generator's performance. In addition, the thermal behavior of the PMSG is improved using an innovative natural air-cooling system for rated speed and higher to decrease the machine's heat mainly at the stator teeth. The analytical investigation is verified via 2-D and 3-D finite element analysis along with a good experimental agreement. Design optimization of electrical machines plays the deterministic role in performance improvements such as the magnetization pattern, output power, and efficiency maximization, as well as losses and material cost minimization. This dissertation proposes a novel multi-objective design optimization technique using a dual-level response surface methodology (D-RSM) and Booth's algorithm (coupled to a memetic algorithm known as simulated annealing) to maximize the output power and minimize material cost through sizing optimization. Additionally, the efficiency maximization by D-RSM is investigated while the PMSG and drive system are on duty as the whole. It is shown that a better fit is available when utilizing modern design functions such as mixed-resolution central composite (MR-CCD) and mixed-resolution robust (MR-RD), due to controllable and uncontrollable design treatments, and also a Window-Zoom-in approach. The proposed design optimization was verified by an experimental investigation. Additionally, there are several novel studies on vibro-acoustic design optimization of the PMSGs with considering variable speed analysis and natural frequencies using two techniques to minimize the magnetic noise and vibrations. Photovoltaic system design optimization considered of 3-D modeling of an innovative application-oriented urban environment structure, a smart tree for small power generation. The horizon shading is modeled as a broken line superimposed onto the sun path diagram, which can hold any number of height/azimuth points in this original study. The horizon profile is designed for a specific location on the Barcelona coast in Spain and the meteorological data regarding the location of the project was also considered. Furthermore, the input weather data is observed and stored for the whole year (in 2016). These data include, ambient temperature, module's temperature (open and closed circuits tests), and shading average rate. A novel Pareto-based 3-D analysis was used to identify complete and partial shading of the photovoltaic system. A significant parameter for a photovoltaic (PV) module operation is the nominal operating cell temperature (NOCT). In this research, a glass/glass module has been referenced to the environment based on IEC61215 via a closed-circuit and a resistive load to ensure the module operates at the maximum power point. The proposed technique in this comparative study attempts to minimize the losses in a certain area with improved output energy without compromising the overall efficiency of the system. A Maximum Power Point Track (MPPT) controller is enhanced by utilizing an advanced perturb & observe (P&O) algorithm to maintain the PV operating point at its maximum output under different temperatures and insolation. The most cost-effective design of the PV module is achieved via optimizing installation parameters such as tilt angle, pitch, and shading to improve the energy yield. The variation of un-replicated factorials using a Window-Zoom-in approach is examined to determine the parameter settings and to check the suitability of the design. An experimental investigation was carried out to verify the 3-D shading analysis and NOCT technique for an open-circuit and grid-connected PV module.
Author: Nicola Bianchi
Publisher: IET
ISBN: 1839532637
Category : Science
Languages : en
Pages : 368
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Book Description
The comprehensive reference on synchronous reluctance machines, which offer high power density at low cost and support the electrification in the transport sector. This book, written by top academic and industry experts, covers all topics required to design these machines.
Author: Gianmario Pellegrino
Publisher: Springer
ISBN: 3319322028
Category : Technology & Engineering
Languages : en
Pages : 142
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Book Description
This book offers an essential compendium on the analysis and design of synchronous motors for variable-speed applications. Focusing on synchronous reluctance and ferrite permanent-magnet (PM) synchronous reluctance machines, it provides a broad perspective on three-phase machines for variable speed applications, a field currently dominated by asynchronous machines and rare-earth PM synchronous machines. It also describes synchronous reluctance machines and PM machines without rare-earth materials, comparing them to state-of-the-art solutions. The book provides readers with extensive information on and finite element models of PM synchronous machines, including all relevant equations and with an emphasis on synchronous-reluctance and PM-assisted synchronous-reluctance machines. It covers ferrite-assisted machines, modeled as a subcase of PM-assistance, fractional slot combinations solutions, and a quantitative, normalized comparison of torque capability with benchmark PM machines. The book discusses a wealth of techniques for identifying machine parameters, with an emphasis on self-commissioning algorithms, and presents methods for automated machine design and optimization, including a software tool developed for this purpose. Addressing an important gap in the field of PM-less and less-PM electrical machines, it is intended as a self-contained reference guide for both graduate students and professional machine designers, and as a useful text for university courses on automated and/or optimized design of electrical machines and drives.
Author: Kai Wang
Publisher: Springer
ISBN: 981130629X
Category : Technology & Engineering
Languages : en
Pages : 216
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Book Description
This book investigates the utilization of harmonics in the permanent magnet (PM) or rotor shape to improve the torque density of PM brushless AC machines including three-phase inner rotor and outer rotor machines, five-phase machines, dual three-phase machines, linear machines, by means of analytical, finite element analyses, and as well as experimental validation. The torque density can be improved while the torque ripple remains low in PM shaping utilizing the 3rd harmonic. In this book, the analytical expression of output torque is derived for PM machines with rotor shape using the 3rd harmonic, and then the optimal 3rd harmonic for maximizing torque is analytically obtained. The book compares the PM shape in surface-mounted PM (SPM) machines and the rotor lamination shape in interior PM (IPM) machines utilizing the 3rd harmonic, and it becomes clear that their shaping methods and amount of torque improvement are different. In a five-phase PM machine, the 3rd harmonic can be utilized in both the current waveform and PM shapes to further improve the output torque. For the dual three-phase SPM machines without deteriorating the torque more than 30% when the optimal 3rd harmonic into both the current and PM shape are injected. The harmonics in airgap flux density have significant influence on the cogging torque, stator iron flux distribution, and radial force between the rotor and stator. These effects has been investigated as well in this book.
