Design Of Synchronous Machine Research Articles

Improved Analytical Estimation of Rotor Losses in High-Speed Surface-Mounted PM Synchronous Machines

The prediction of rotor losses, primarily due to eddy currents (ECs) in either magnets or other rotor conductive parts, is of great concern for the design of surface-mounted permanent magnet synchronous machines. Particularly, in high-speed electrical machines, EC losses could be severe and seriously affect the machine performance in terms of thermal management and demagnetization, in turn influencing the efficiency. This paper proposes a novel and more comprehensive approach for analytically detecting rotor losses in such machines; broadening investigation techniques already well established by considering the slotting effect and its interaction with stator winding generated by magnetic field harmonics. Therefore, predicting the electromagnetic behavior of EC losses by means of the presented fast and accurate procedure represents a useful instrument for electromechanical designers to assess the machine performance.

Global-Simplex Optimization Algorithm Applied to FEM-Based Optimal Design of Electric Machine

Finite element analysis-based optimal design of electric machines takes up a considerable amount of time for characteristic analyses and the analysis region has many local optima. Thus, selecting the appropriate global search optimization algorithm, known as the with fast convergence characteristics is necessary in the optimal design of electric machines. In this paper, a novel global search optimization algorithm known as the global-simplex optimization (GSO) algorithm, is proposed. The GSO is an optimization algorithm that adopts the characteristics of the simplex method for searching the optimum point but utilizes its global searching capability by scattering many initial points at the beginning of the algorithm. The global searching capability and convergence speed of GSO is validated through a comparison with particle swarm optimization, which has already been proven for its global searching capability through its application in the well-known Goldstein-Price benchmark function. In addition, the GSO has been applied to the optimal design of an interior permanent magnet synchronous machine to reduce the torque ripple and total harmonic distortion in its back electromotive force.

Design and Analysis of a Novel PM-Assisted Synchronous Reluctance Machine With Axially Integrated Magnets by the Finite-Element Method

This paper presents the design and analysis of a novel permanent-magnet (PM)-assisted synchronous reluctance machine (PMA-SynRM) with axially integrated magnets for improving machine performance by using a finite-element method (FEM). The proposed PMA-SynRM features a simple structure with high performance by incorporating the advantages of a SynRM and a surface-mounted PM machine (SPMM). In particular, the rotor parts of the SynRM and SPMM are assembled to make the “q-axis” located 45° (elec.) from the d-axis. Thus, the magnetic torque and reluctance torque of the proposed PMA-SynRM reach the maximum values at the same current phase angle, for efficient production of the total torque. To highlight the advantages of the proposed PMA-SynRM, a conventional PMA-SynRM is adopted for comparison under the same operating conditions. The FEM analysis results finally demonstrate that the proposed PMA-SynRM has a higher total torque and power factor, as well as greatly reduced torque ripple, when compared to the conventional PMA-SynRM with the same magnet amounts. In addition, the Mises stress analysis indicates that the configuration of the proposed PMA-SynRM exhibits the advantage of avoiding stress deterioration in the rotor ribs.

회전자 위치추정을 위해 자기적 돌극성을 고려한 표면 부착형 영구자석 동기 전동기 설계

회전자 위치추정을 위해 자기적 돌극성을 고려한 표면 부착형 영구자석 동기 전동기 설계

Analysis and design of a high power density permanent magnet-assisted synchronous reluctance machine with low-cost ferrite magnets for EVs/HEVs

Purpose The purpose of this paper is to propose a permanent magnet-assisted synchronous reluctance machine (PMASynRM) using ferrite magnets with the same power density as rare-earth PM synchronous motors used in Toyota Prius 2010. Design/methodology/approach A novel rotor structure with rectangular PMs is discussed with respect to the demagnetization of ferrite magnets and mechanical strength. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2D finite element analysis. Findings The results of the analysis show that a high power density and high efficiency for PMASynRM can be achieved using ferrite magnets. Originality/value This paper proposes a novel rotor structure of PMASynRM with low-cost ferrite magnets that achieves high power density as permanent machines with rare-earth PMs.

The marine electrical power industry with the use of renewable energy carriers. Part 2. Axial multipole synchronous generators with permanent magnets for wind and wave offshore power plants

The paper deals with problems of selection of structures and optimum design of multipole permanent magnet synchronous machines (PMSMs) for operation in offshore wind- and wave-power plants under severe conditions for maintenance service. It is shown that multipole PMSMs are a new and very suitable electrical machine for direct connected turbogenerators in power plants and, at the same time, multipole PMSMs meet a number of other important demands, including high reliability, contactless construction, high efficiency, minimum mass and dimensions, and cost effectiveness. With the aim of systematization, an integrated classification scheme of PMSMs is presented to describe the variety of designs of stator and rotor configurations. With the help of a theoretical analysis based on a geometrical approach, analytical expressions for PMSM comparison are derived using the relationship between the criterion of optimization (maximum power density) and the main geometric parameters of PMSMs. Comparative analysis of the PMSMs with radial and axial magnetic fluxes for the case of various numbers of poles and different diameters of rotors has confirmed that axial multipole PMSMs are synchronous machines with maximum power density and an optimum variant for direct connected turbogenerator structures for offshore wind- and wave-power plants. It is noted that the advantage of axial PMSMs over radial PMSMs is monotonic growth in accordance with increasing number of poles p. Under the condition that p ≥ 20, which is strictly necessary for designing direct connected turbogenerators in offshore wind- and wave-power plants, we have more than doubled the power density at axial PMSMs as compared with radial ones.

Optimum Iron Pole Design of a Tubular Linear Synchronous Machine With Double-Sided Axially Magnetized Permanent Magnets Considering Leakage Flux

In this paper, the design optimization of tubular linear synchronous machines (TLSMs) was achieved by minimizing the mass of the iron pole, subject to satisfying the other performance specifications. Furthermore, to optimize the design of TLSMs with axially magnetized permanent magnets, an optimum design of the magnetic circuit of the machine with a reduced mass of ferromagnetic material was proposed while considering leakage flux. The leakage flux density at the iron pole on the surface of each side is an important consideration when choosing a suitable thickness ratio for the iron poles. The machine was optimized by maintaining a constant level of the back electromotive force, and considering the leakage magnetic flux at the iron pole. Finally, the total mass of the flux passing the iron pole of the optimized design is $\sim 39.31$ % of that in the conventional model.

Low‐torque ripple design of a ferrite‐assisted synchronous reluctance motor

This study illustrates the design of a low-torque ripple ferrite-assisted synchronous reluctance machine. The design strategy initially adopts a simplified analytical model in order to select the optimal values for the flux barrier angles that mainly affects the torque ripple. Then, synchronous reluctance rotor geometries selected on the basis of analytical results are analysed by finite elements (FEs) simulations. The simulated geometries are provided by ferrite permanent magnets (PMs) to enhance machine performance. The optimisation steps are properly coordinated in order to realise the maximum reduction of the torque ripple, taking into account the PM quantity and the flux barrier shape as well as the demagnetisation risk. Two optimal rotor geometries are presented and compared in terms of torque ripple by FEs simulations. Then, the comparison have been extended to other machine characteristics (as high-frequency saliency and demagnetisation tolerance) to the aim of selecting the more promising one. Available measurements on prototypes are reported to confirm the simulation results and the design approach.

Influence of stator slot openings on losses and torque in axial flux permanent magnet machines

Among the different geometrical parameters to be chosen during design of axial flux permanent magnet synchronous machines, the width of the stator slot openings near the air gap is an important parameter: it has a major influence on the power loss in the stator core and in the permanent magnets on the two rotors of the studied type of axial flux machines. Moreover, the stator slot openings parameter has a converse impact on both power losses. On the one hand, the increase in stator slot openings results in a reduction of the power losses in the stator core elements. On the other hand, it also results in increased loss in the permanent magnets. Also the torque is reduced for large but also for very small slot openings. This paper deals with axial flux machines of the YASA type: yokeless and segmented armature. It is shown that the slot openings contribute to an unequal flux density level over the different laminations in the stator core. Insight in the impact of the slot openings variation on both power losses (in stator iron and in permanent magnets) is provided, and an illustrative case is discussed in which the impact of the slot openings variation on both power losses is examined quantitatively.

Design of synchronous reluctance and permanent magnet synchronous reluctance machines for electric vehicle application

Purpose – The purpose of this paper is to minimize the optimization parameter number of synchronous reluctance machine (SynRM) and permanent magnet (PM) assisted SynRM, and compare their relative merits with interior permanent magnet (IPM) machine for electric vehicle applications, in terms of electromagnetic performance and material cost. Design/methodology/approach – The analysis of electromagnetic performance is based on finite element analysis, by using software MAXWELL. The genetic algorithm is utilized for optimization. Findings – The rotor design of SynRM can be significantly simplified by imposing some reasonable conditions. The number of rotor design parameters can be reduced to three. The electromagnetic performance of SynRM is much poorer than that of IPM, although the material cost is much cheaper, approximately one-third of IPM. The ferrite-SynRM is competitive and even better than IPM especially for high electric loading, in terms of torque capability, torque-speed characteristic, power factor, threshold speed and efficiency. In addition, ferrite-assisted SynRM has great advantage over IPM in material cost, 55 percent cheaper. The performance of NdFeB-assisted SynRM is close to IPM in terms of torque capability, torque-speed characteristic, power factor, torque ripple and efficiency. The material cost of NdFeB-assisted SynRM is ∼25 percent lower than IPM. Originality/value – Some conditions, which can simplify the optimization of SynRM rotor, are discussed. The electromagnetic performances and material costs of SynRM, ferrite-assisted, NdFeB-assisted SynRMs and IPM are quantitatively compared and discussed.

Permanent magnet synchronous machine design for hybrid electric cars with double e-motor and range extender

The design of a 6-pole inner-rotor permanent magnet synchronous machine with buried V-shaped NdFeB-magnets for a power of 24 kW (contin.), 48 kW (short-term overload) at \(4167~\mbox{min}^{-1}\), with a maximum speed \(10\,000~\mbox{min}^{-1}\), is described for the use in a medium-sized hybrid-electric car with double-E-drive and range extender. Based on the specifications of this vehicle with a two-stage transmission and two identical electrical machines, one of these synchronous machines is designed electromagnetically, mechanically and thermally for a high power-to-weight ratio via an intensified liquid jacket cooling. This led to the construction of a prototype machine, which was thoroughly tested. The test results at no-load and load conditions are discussed. The effectiveness of the chosen cooling system is verified by temperature measurements; the tests show that the prototype machine has a certain reserve, so that the final machine design can be done cheaper and more compact.

A Novel Memetic Algorithm Using Modified Particle Swarm Optimization and Mesh Adaptive Direct Search for PMSM Design

In this paper, we propose a novel memetic algorithm, which is explorative particle swarm optimization (ePSO), combined with mesh adaptive direct search and apply it to the design of a permanent magnet synchronous machine (PMSM). The ePSO, which is modified from the PSO, drastically improves search time and iteration number at an exploration search stage. Unlike the existing methods, the proposed rule of start point selection takes an advantage of minimizing the search time. By applying the proposed algorithm to PMSM, we clarify the effectiveness of the proposed algorithm.

Design of an Axial Flux Permanent Magnet Synchronous Machine Using Analytical Method and Evolutionary Optimization

The design optimization of an axial flux permanent magnet synchronous machine with a coreless stator and double external rotor is accomplished by using evolutionary optimization with a genetic algorithm and an analytical evaluation of objective functions. On the basis of eight variable geometry parameters, five objective functions are optimized in order to determine the maximum volume torque density and weight torque density, the minimum volume and weight of permanent magnets per Newton-meter, and the minimum machine price per Newton-meter. Based on the geometric parameters for minimum machine price per Newton-meter, a prototype is built for the rated torque. Optimized and analytically evaluated machine characteristics are validated with a finite-element method (FEM) and the measurements of a prototype. Evolutionary optimization with the analytical evaluation of objective functions significantly shortens the computational time required for design optimization in comparison with the FEM.

Estimation of Stator Resistance and Rotor Flux Linkage in SPMSM Using CLPSO with Opposition-Based-Learning Strategy

Electromagnetic parameters are important for controller design and condition monitoring of permanent magnet synchronous machine (PMSM) system. In this paper, an improved comprehensive learning particle swarm optimization (CLPSO) with opposition-based-learning (OBL) strategy is proposed for estimating stator resistance and rotor flux linkage in surface-mounted PMSM; the proposed method is referred to as CLPSO-OBL. In the CLPSO-OBL framework, an opposition-learning strategy is used for best particles reinforcement learning to improve the dynamic performance and global convergence ability of the CLPSO. The proposed parameter optimization not only retains the advantages of diversity in the CLPSO but also has inherited global exploration capability of the OBL. Then, the proposed method is applied to estimate the stator resistance and rotor flux linkage of surface-mounted PMSM. The experimental results show that the CLPSO-OBL has better performance in estimating winding resistance and PM flux compared to the existing peer PSOs. Furthermore, the proposed parameter estimation model and optimization method are simple and with good accuracy, fast convergence, and easy digital implementation.

Design And Rotor Geometry Analysis Of Permanent Magnet–Assisted Synchronous Reluctance Machines Using Ferrite Magnet

Abstract Various electric machines can be the candidate for electric vehicles applications, including induction machines, permanent magnet synchronous machines, switched reluctance machines, etc. Another class of machine, which has been relatively ignored, is synchronous reluctance machines. In order to enhance and increase torque density of pure synchronous reluctance machines, the low cost permanent magnet can be inserted into rotor lamination to contribute torque production, which is so-called permanent magnet-assisted synchronous reluctance machines. This paper presents the design and rotor geometry analysis of low cost ferrite permanent magnet-assisted synchronous reluctance machines with transversally-laminated rotor. The advanced finite element method will be employed to calculate d-axis and q-axis inductance variation with rotor geometric parameters. The electromagnetic performance of optimized permanent magnet-assisted synchronous reluctance machines will be evaluated as well.

Design and Analysis of a Novel Brushless Wound Rotor Synchronous Machine

Permanent magnet synchronous machines (PMSMs) utilize permanent magnets to generate the rotor flux needed to produce torque. They are ideal for high-accuracy fixed-speed drives. But rise in the price of rare earth magnet caused by its scarcity is a key consideration while developing such kind of machines. In this situation, wound rotor synchronous machines (WRSMs) have benefits compared to PMSMs as it does not need magnetic material and can be operated in a wide range of speeds [1]. In a WRSMs field windings are used, which is supplied with a DC current that generates the rotor flux. DC current can be applied to the rotor winding either using the brush and slip-ring structure or brushless excitation method. The brushes and slip rings have losses and maintenance issues, so they are used for small synchronous machines. For brushless excitation, additional (auxiliary) stator windings are used to excite the rotor field winding. Several patents are granted according to this excitation method [2]-[4]. The conventional method faces issues, since both the stator windings are located in the same stator core and require a large stator volume for making place for the both windings. Using a single winding in the stator to perform the brushless operation for the WRSMs is presented in [5]. But in that case concentrated windings are used to develop the higher harmonics for the excitation which will result in more losses. Thus a new idea for brushless WRSMs is proposed in which single stator winding is used to excite the rotor as well as generate the fundamental air gap harmonic for electromagnetic torque. A 2D finite element analysis (FEA) have been done to analyze and verify the proposed brushless WRSMs.

Optimization design of an interior permanent-magnet synchronous machine for a hybrid hydraulic excavator

A hybrid power transmission system (HPTS) is a promising way to save energy in a hydraulic excavator and the electric machine is one of the key components of the system. In this paper, a design process for permanent-magnet synchronous machines (PMSMs) in a hybrid hydraulic excavator (HHE) is presented based on the analysis of the working conditions and requirements of an HHE. A parameterized design approach, which combines the analytical model and the 2D finite element method (FEM), is applied to the electric machine to improve the design efficiency and accuracy. The analytical model is employed to optimize the electric machine efficiency and obtain the stator dimension and flux density distribution. The rotor is designed with the FEM to satisfy the flux requirements obtained in stator design. The rotor configuration of the PMSM employs an interior magnet structure, thus resulting in some inverse saliency, which allows for much higher values in magnetic flux density. To reduce the rotor leakage, a disconnected type silicon steel block structure is adopted. To improve the air gap flux density distribution, the trapezoid permanent magnet (PM) and centrifugal rotor structure are applied to PMSM. Demagnetization and armature reactions are also taken into consideration and calculated by the FEM. A prototype of the newly designed electric machine has been fabricated and tested on the experimental platform. The analytical design results are validated by measurements.

Analysis of High Torque and Power Densities Outer-Rotor PMFSM with DC Excitation Coil for In-Wheel Direct Drive

In recent years, flux switching machines (FSMs) have been an attractive research topic owing to their tremendous advantages of robust rotor structure, high torque, and high power capability suitable for intensive applications. However, most of the investigations are focusing on the inner-rotor structure, which is incongruous for direct drive applications. In this study, high torque and power densities of a new 12S-14P outer-rotor permanent magnet (PM) FSM with a DC excitation coil was investigated based on two-dimensional finite element analysis for in-wheel direct drive electric vehicle (EV). Based on some design restrictions and specifications, design refinements were conducted on the original design machine by using the deterministic optimization approach. With only 1.0 kg PM, the final design machine achieved the maximum torque and power densities of 12.4 Nm/kg and 5.93 kW/kg, respectively, slightly better than the inner-rotor HEFSM and interior PM synchronous machine design for EV.

Optimization of In-Wheel Permanent Magnet Synchronous Motor for Electric Car

The objective of this work is to find the optimal geometric parameters for the design of permanent magnet synchronous machines (PMSM) with inversed structure (outer rotor) for electric vehicles applications. Firstly, the machine model is presented with a special attention given to the calculation of the mass and engine efficiency. A multi objective optimization based on the genetic algorithm is then implemented. It will determine the parameters values that optimize the chosen criteria while respecting the specifications: to minimizing the total mass and maximizing the machine efficiency. Finally, 2D steady-state finite element analysis is used for to verify the results given by the optimization method.

Different Slot Configurations for Direct-Drive PM Brushless Machines

This work describes the design and optimization process of a direct-drive permanent magnet synchronous machine that is suitable for electric motorcycles. The machine is designed to de-velop approximately the same power than a conventional 250cc motorcycle internal combustion engine. The main goal of this work is to design an outer-rotor machine that is coupled directly to the wheel (direct-drive or in-wheel motor), so it is necessary to know the dimensions and arrangements of the wheels. The direct-drive systems don't need any gearbox to drive the vehicle, so that the global efficiency is higher than conventional systems employing a gearbox. The design and performance of the machine are assessed by means of simulations using the finite element method. The finite element method is the main tool to optimize the machine's design.