Permanent Magnet Vernier Machine: A Review

Permanent magnet vernier machines (PMVMs) gained a lot of interest over the past couple of decades. This is mainly due to their high torque density enabled by the magnetic gearing effect. This study will provide a thorough review of recent advances in PMVMs. This review will cover the principle of operation and nature of magnetic gearing in PMVMs, and a better understanding of novel PMVM topologies using different winding configuration as well as different modulation poles and rotor structures. Detailed discussions on the choice of gear ratio, slot-pole combinations, design optimisation and role of advanced materials in PMVMs will be presented. This will provide an update on the current state-of-the art as well as future areas of research. Furthermore, the power factor issue, fault tolerance as well as cost reduction will be discussed highlighting the gap between the current state-of-the art and what is needed in practical applications

Investigation of Novel Axial Flux Magnetically Geared Machine

As axial flux permanent magnet (AFPM) machines are currently the most appropriate topologies for limited axial space applications, a novel axial flux magnetically geared permanent magnet (AFMGPM) machine is investigated in this thesis. Based on a yokeless and segmented YASA machine, a new AFMGPM topology was designed and studied. The proposed AFMGPM machine consists of stator segments equipped with concentrated windings and two PM rotors with different pole-pair numbers: a high speed rotor (HSR) and low speed rotor (LSR). The proposed AFMGPM offers the merit of simple mechanical structure and is suitable for applications with limited axial space. Two possible rotor pole combinations were selected and designed with the same stator segments: MG12/5-7 with HSR pole pairs of 5 and LSR pole pairs of 7, and MG12/4-8 with HSR pole pairs of 4 and LSR pole pairs of 8. These were optimised for maximum torque capability. Performance comparisons at no-load and on-load conditions using 3D-finite element analysis (FEM) reveal that the machine torque performance is sensitive to the PM dimensions and better performance can be obtained with the MG12/5-7 topology. It is demonstrated that the MG machines are a valid alternative to the conventional planetary gear function in HEVs. Combining the conventional PM machine with the MG machine has made it possible to replace the power split components using only one electrical device. Additionally, the proposed machine can work as a conventional magnetic gear (MG) and a generator. It is shown that the new AFMGPM machine can realise the function of power split devices in conventional HEVs, as a mechanical planetary gear, motor and generator. It is further shown that the rotor manufacturing tolerance has a significant effect in terms of stator/LSR misalignment on the no-load and on-load performances of the machine. Finally, a performance comparison between the novel machine and the conventional axial flux YASA machine is performed. To validate the predicted results of finite element analysis, a prototype of the new topology and a conventional YASA machine are manufactured and tested. It has, showing that with the benefit of two rotors with different torques and speeds, the new AFMGPM machine has superior performance at all load conditions

On the Modeling, Analysis and Development of PMSM: For Traction and Charging Application

Permanent magnet synchronous machines (PMSMs) are widely implemented commercially available traction motors owing to their high torque production capability and wide operating speed range. However, to achieve significant electric vehicle (EV) global market infiltration in the coming years, the technological gaps in the technical targets of the traction motor must be addressed towards further improvement of driving range per charge of the vehicle and reduced motor weight and cost. Thus, this thesis focuses on the design and development of a novel high speed traction PMSM with improved torque density, maximized efficiency, reduced torque ripple and increased driving range suitable for both traction and integrated charging applications. First, the required performance targets are determined using a drive cycle based vehicle dynamic model, existing literature and roadmaps for future EVs. An unconventional fractional–slot distributed winding configuration with a coil pitch of 2 is selected for analysis due to their short end–winding length, reduced winding losses and improved torque density. For the chosen baseline topology, a non–dominated sorting genetic algorithm based selection of optimal odd slot numbers is performed for higher torque production and reduced torque ripple. Further, for the selected odd slot–pole combination, a novel star–delta winding configuration is modeled and analyzed using winding function theory for higher torque density, reduced spatial harmonics, reduced torque ripple and machine losses. Thereafter, to analyze the motor performance with control and making critical decisions on inter–dependent design parameter variations for machine optimization, a parametric design approach using a novel coupled magnetic equivalent circuit model and thermal model incorporating current harmonics for fractional–slot wound PMSMs was developed and verified. The developed magnetic circuit model incorporates all machine non–linearities including effects of temperature and induced inverter harmonics as well as the space harmonics in the winding inductances of a fractional–slot winding configuration. Using the proposed model with a pareto ant colony optimization algorithm, an optimal rotor design is obtained to reduce the magnet utilization and obtain maximized torque density and extended operating range. Further, the developed machine structure is also analyzed and verified for integrated charging operation where the machine’s winding inductances are used as line inductors for charging the battery thereby eliminating the requirement of an on–board charger in the powertrain and hence resulting in reduced weight, cost and extended driving range. Finally, a scaled–down prototype of the proposed PMSM is developed and validated with experimental results in terms of machine inductances, torque ripple, torque–power–speed curves and efficiency maps over the operating speed range. Subsequently, understanding the capabilities and challenges of the developed scaled–down prototype, a full–scale design with commercial traction level ratings, will be developed and analyzed using finite element analysis. Further recommendations for design improvement, future work and analysis will also be summarized towards the end of the dissertation

INVESTIGATION OF PERMANENT MAGNET SYNCHRONOUS MACHINES FOR DIRECT-DRIVE AND INTEGRATED CHARGING APPLICATIONS IN ELECTRIC VEHICLES

Electrified vehicles have proven to be potential candidates in the future for disrupting the automotive industry which is dominated by conventional gasoline vehicles. Electric vehicle (EV) technology has evolved rapidly over the last decade with new designs of EV drivetrain systems and components but no specific design has been able to serve as a solution that is affordable, reliable and performance-wise similar to existing gasoline vehicle equivalent. Extended driving range and overall cost of the vehicle still remain major bottlenecks. Understanding the state-of-the-art technologies and challenges in existing electric vehicle powertrain and charging systems, with major focus on permanent magnet synchronous machines & drives, this dissertation presents the following

Modeling And Analysis Of Multi–Phase Permanent Magnet Synchronous Machines: Direct–Drive Electric Vehicle Application

In commercially existing electric vehicles (EVs), power is transferred from the motor to the wheels through a fixed gear mechanical transmission system. However, such a transmission system contributes to a power loss between 2% to 20% of output power of the motor depending on the operating speed and torque of the motor. Therefore, by removing the transmission, a direct–drive EV configuration is obtained with lower component count, improved motor to wheel efficiency and frequency dependent losses. However, challenges in developing a single on–board permanent magnet synchronous machine (PMSM) for such a configuration include high torque density, low torque ripple and high torque per permanent magnet (PM) volume. Therefore, this dissertation proposes a novel PMSM addressing the aforementioned challenges for a direct–drive application. Initially, the design targets, stator and rotor configuration and phase numbers of the PMSM are chosen to satisfy the requirements of a direct drive application. A novel torque and torque ripple model based on multiple reference frames is proposed, in which the torque ripple from spatial harmonics of flux, inductances and the time harmonics of stator currents are included. Using the analytical model, optimal slot–pole combination of the machine is selected based on adaptive gradient descent algorithm. A new consequent pole rotor topology is proposed to improve the torque density and torque per PM volume thereby reducing the usage of expensive rare earth magnets. The proposed PMSM with novel rotor is further improved in terms of torque density, losses and cost by performing an intensive structural optimization based on novel hybrid analytical model, finite element analysis and supervised learning. The optimized PMSM is then analyzed for various drive cycles and performance in terms of torque, speed and efficiency are discussed. A scaled–down prototype of the proposed PMSM is developed and comprehensive experimental analysis in terms of torque ripple, torque–speed characteristics and efficiency are performed under different speeds and load conditions and are compared with the results obtained from proposed analytical model

Linear Permanent Magnet Vernier Generators for Wave Energy Applications: Analysis, Challenges, and Opportunities

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Harvesting energy from waves as a substantial resource of renewable energy has attracted much attention in recent years. Linear permanent magnet vernier generators (LPMVGs) have been widely adopted in wave energy applications to extract clean energy from oceans. Linear PM vernier machines perform based on the magnetic gearing effect, allowing them to offer high power/force density at low speeds. The outstanding feature of providing high power capability makes linear vernier generators more advantageous compared to linear PM synchronous counterparts used in wave energy conversion systems. Nevertheless, they inherently suffer from a poor power factor arising from their considerable leakage flux. Various structures and methods have been introduced to enhance their performance and improve their low power factor. In this work, a comparative study of different structures, distinguishable concepts, and operation principles of linear PM vernier machines is presented. Furthermore, recent advancements and innovative improvements have been investigated. They are categorized and evaluated to provide a comprehensive insight into the exploitation of linear vernier generators in wave energy extracting systems. Finally, some significant structures of linear PM vernier generators are modeled using two-dimensional finite element analysis (2D-FEA) to compare their electromagnetic characteristics and survey their performance.Peer reviewe

Design and Validation of a Synchronous Reluctance Motor With Single Tooth Windings

This paper presents for the first time the analysis and experimental validation of a six-slot four-pole synchronous reluctance motor with nonoverlapping fractional slot-concentrated windings. The machine exhibits high torque density and efficiency due to its high fill factor coils with very short end windings, facilitated by a segmented stator and bobbin winding of the coils. These advantages are coupled with its inherent robustness and low cost. The topology is presented as a logical step forward in advancing synchronous reluctance machines that have been universally wound with a sinusoidally distributed winding. The paper presents the motor design, performance evaluation through finite element studies and validation of the electromagnetic model, and thermal specification through empirical testing. It is shown that high performance synchronous reluctance motors can be constructed with single tooth wound coils, but considerations must be given regarding torque quality and the d-q axis inductances

BADANIE WPŁYWU UŁAMKOWEJ LICZBY SZCZELIN BIEGUNÓW NA GENERACJĘ TURBINY WIATROWEJ PRZY UŻYCIU ULEPSZONEGO ALGORYTMU OPTYMALIZACJI CĘTKOWANEJ HIENY

The design of machines with permanent magnets is actively developing day by day and is often used in wind energy. The main advantages of such variable speed drives are high efficiency, high power density and torque density. When designing a wind generator with two rotors and permanent magnets, it is necessary to solve such a problem as the correct choice of the number of poles and slots to increase efficiency and minimize the cost of the machine. In this work, an improved spotted hyena optimization algorithm is used to obtain the optimal combination of slots and poles. This optimization algorithm makes it possible to obtain the number of fractional slots per pole and evaluate the operating efficiency of a wind generator with a double rotor and ferrite magnets. At the first stage of machine design, various combinations of slots are installed. Next, the optimal combination is selected from various slot-pole combinations, taking into account the Enhanced Spotted Hyena Optimization (ESHO) algorithm, in which a multi-objective function is configured. Accordingly, the multi-objectives are the integration of reverse electromotive force, output torque, gear torque, flux linkage, torque ripple along with losses. Analysis of the results obtained shows that the proposed algorithm for determining the optimal slot combination is more efficient than other slot combinations. It has also been found that the choice of slot and pole combination is critical to the efficient operation of permanent magnet machines.Projektowanie maszyn z magnesami trwałymi aktywnie rozwija się z dnia na dzień i jest często wykorzystywane w energetyce wiatrowej. Głównymi zaletami takich napędów o zmiennej prędkości są wysoka sprawność, wysoka gęstość mocy i gęstość momentu obrotowego. Podczas projektowania generatora wiatrowego z dwoma wirnikami i magnesami trwałymi konieczne jest rozwiązanie takiego problemu, jak prawidłowy dobór liczby biegunów i szczelin w celu zwiększenia wydajności i zminimalizowania kosztów maszyny. W niniejszej pracy zastosowano ulepszony algorytm optymalizacji hieny plamistej w celu uzyskania optymalnej kombinacji szczelin i biegunów. Ten algorytm optymalizacji umożliwia uzyskanie liczby ułamkowych szczelin na biegun i ocenę wydajności operacyjnej generatora wiatrowego z podwójnym wirnikiem i magnesami ferrytowymi. Na pierwszym etapie projektowania maszyny instalowane są różne kombinacje szczelin. Następnie wybierana jest optymalna kombinacja spośród różnych kombinacji szczelin i biegunów, biorąc pod uwagę algorytm Enhanced Spotted Hyena Optimization (ESHO) (ulepszony algorytm optymalizacjihieny cętkowanej hieny), w którym skonfigurowana jest funkcja wielocelowa. W związku z tym, celami wielozadaniowymi są integracja odwrotnej siły elektromotorycznej, wyjściowego momentu obrotowego, momentu obrotowego przekładni, połączenia strumienia, tętnienia momentu obrotowego wraz ze stratami. Analiza uzyskanych wyników pokazuje, że proponowany algorytm określania optymalnej kombinacji szczelin jest bardziej wydajny niż inne kombinacje szczelin. Stwierdzono również, że wybór kombinacji szczelin i biegunów ma kluczowe znaczenie dla wydajnej pracy maszyn z magnesami trwałymi

Design of High Efficiency Brushless Permanent Magnet Machines and Driver System

The dissertation is concerned with the design of high-efficiency permanent magnet synchronous machinery and the control system. The dissertation first talks about the basic concept of the permanent magnet synchronous motor (PMSM) design and the mathematics design model of the advanced design method. The advantage of the design method is that it can increase the high load capacity at no cost of increasing the total machine size. After that, the control method of the PMSM and Permanent magnet synchronous generator (PMSG) is introduced. The design, simulation, and test of a permanent magnet brushless DC (BLDC) motor for electric impact wrench and new mechanical structure are first presented based on the design method. Finite element analysis based on the Maxwell 2D is built to optimize the design and the control board is designed using Altium Designer. Both the motor and control board have been fabricated and tested to verify the design. The electrical and mechanical design are combined, and it provides an analytical IPMBLDC design method and an innovative and reasonable mechanical dynamical calculation method for the impact wrench system, which can be used in whole system design of other functional electric tools. A 2kw high-efficiency alternator system and its control board system are also designed, analyzed and fabricated applying to the truck auxiliary power unit (APU). The alternator system has two stages. The first stage is that the alternator three-phase outputs are connected to the three-phase active rectifier to get 48V DC. An advanced Sliding Mode Observer (SMO) is used to get an alternator position. The buck is used for the second stage to get 14V DC output. The whole system efficiency is much higher than the traditional system using induction motor