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In this paper, a Dual Winding Flux Modulation Machine (DWFMM) is proposed for variable speed application. The DWFMM is configured by adding windings to the Single Winding Flux Modulation Machine (SWFMM), consisting of a master winding that drives the motor and a slave winding that enables pole changing and performance enhancement. Through pole changing, the DWFMM can operate as two different machines: a Vernier Machine (VM) for varying speeds and torque operations and a Permanent Magnet Synchronous Machine (PMSM). In the VM mode, flux enhancement is applied to improve torque, and in the PMSM mode, Flux Weakening is applied to increase speed. The characteristics of the two different operating modes were analyzed using the Finite Element Method (FEM) to validate the machine's performance. Finally, the DWFMM and SWFMM were designed and compared as variable speed application machines to confirm their suitability and superiority. [ABSTRACT FROM AUTHOR]

In this paper, a fast positioning platform (FPP) is proposed, able to meet simultaneously the requirements of large stroke and high frequency response, developed based on a PZT (piezoelectric actuator) and a quad-parallel flexible mechanism, for application in precision machining. The FPP is driven by a high-stiffness PZT and guided by a flexible hinge-based mechanism with a quad-parallel flexible hinge. The proposed quad-parallel flexible hinge mechanism can provide excellent planar motion capability with high stiffness and good guiding performance, thus guaranteeing outstanding dynamics characteristics. The mechanical model was established, the input and output characteristics of the FPP were analyzed, and the working range (output displacement and frequency) of the FPP was determined. Based on the mechanical model and the input and output characteristics of the FPP, the design method is described for of the proposed FPP, which is capable of achieving a large stroke while responding at a high frequency. The characteristics of the FPP were investigated using finite element analysis (FEA). Experiments were conducted to examine the performance of the FPP; the natural frequency of the FPP was 1315.6 Hz, while the maximum output displacement and the motion resolution of the FPP in a static state were 53.13 μm and 5 nm, respectively. Step response testing showed that under a step magnitude of 50 μm, the stabilization times for the falling and rising edges of the moving platform were 37 ms and 26 ms, respectively. The tracking errors were about ±1.96 μm and ±0.59 μm when the amplitude and frequency of the signal were 50 μm, 50 Hz and 10 μm, 200 Hz, respectively. The FPP showed excellent performance in terms of fast response and output displacement. The cutting test results indicated that compared with the uncontrolled condition, the values of surface roughness under controlled conditions decreased by 23.9% and 12.7% when the cutting depths were 5 μm and 10 μm, respectively. The developed FPP device has excellent precision machining performance. [ABSTRACT FROM AUTHOR]

A novel asymmetric interior permanent magnet (AIPM) machine is proposed in this paper. The machine's rotor consists of asymmetric poles and auxiliary flux barriers. The torque ripple of the machine is weakened by the asymmetric design of the left and right sides of the magnetic poles. The magnetic‐field‐shifting (MFS) effect improves the electromagnetic torque after adding the auxiliary flux barrier to shift the magnetic axis. The influence of critical geometrical parameters on the electromagnetic performance of the machine is investigated under the condition that the stator and permanent magnet volume remain unchanged. The relevant geometrical parameters of the machine are optimized and designed through the improved Taguchi method. The performance of the AIPM machine and the conventional machine under no‐load and load conditions are further compared by simulation analysis with finite elements, verifying the increase in electromagnetic torque and the reduction in torque ripple. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Because of the complex and frequent multi-operation conditions of pumped storage machine and the difficulty of its numerical analysis, an optimized network parameter method (ONPM) is given to identify the second harmonic electromagnetic torque of large salient-pole generators. Different from the former research which only considers the positive and negative sequence components, the second harmonic electromagnetic torque of pumped storage machine under power generation state is identified in neutral point grounded system, which are displayed by the lumped parameters. Then, in order to test the validity of the theoretical analysis among power generation salient-pole generators, the finite element model of 300 MVA pumped storage machine under power generation is established. Through the comparison and analysis of the finite element result data with the actual experimental data in the steady state of no-load test and short-circuit test, the correctness of the finite element model is completely verified. Finally, in the case of small current asymmetry and large current asymmetry, the second harmonic electromagnetic torques obtained by ONPM and finite element method (FEM) are found respectively, and their relative errors are elaborately displayed. The results display that ONPM can accurately identify the electromagnetic torque parameters which indicate the specific operation and fault state of pumped storage machine under power generation state. This fault parameter identification has practical significance for monitoring and improving the operation state and stability of large salient-pole generator. [ABSTRACT FROM AUTHOR]

This paper is a comparative study of pole–slot combinations with fractional slot concentrated windings in an outer rotor permanent magnet synchronous generator (ORPMSG) for a hybrid drone system. Fractional slot machines have been studied for automotive applications because of their high performance and simple winding manufacturing, compared with those of integer slot machines. In this study, four pole–slot combinations of ORPMSG with fractional slot concentrated windings were selected for comparison with the performance of the hybrid drone system. Based on the results of a finite element analysis (FEA), the machines were analyzed for cogging torque, back electromagnetic force (BEMF), torque, and electromagnetic loss under the same conditions as the machine specifications. Among the four pole–slot combinations of the ORPMSM, a one pole–slot model of the ORPMSG was selected, considering the performances of the machines. The selected pole–slot model of the ORPMSG was manufactured, and experiments were conducted on the manufactured model to verify the FEA results. Finally, the effectiveness of the comparative study of pole–slot combination with fractional slot concentrated winding in ORPMSM was verified by comparing the FEA and experimental results. [ABSTRACT FROM AUTHOR]

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Epoxy granite (EG) is used for machine building applications owing to excellent dynamic properties compared to cast iron (CI). Steel is preferred to reinforce with EG to improve the static stiffness of structures. The effects of addition of steel content on stiffness and damping properties of EG composite were assessed through a specimen level study. Subsequently, the base, which is a primary structure that affects the dynamics of the vertical machining center (VMC) was taken up for investigation. The novelty of the present work is the development of scaled down model of EG base with optimum reinforcement ratio to improve the dynamic response of VMC without compromising the static rigidity of the existing CI base. An experimental study was carried out to validate the assumption made in numerical analysis that EG is isotropic and homogeneous. The results of similitude relations revealed that the EG base exhibited sixteen times higher damping compared to CI base. The influence of EG base on the overall dynamics of VMC was assessed by performing pre-stressed finite element modal analysis and harmonic analysis. Upto seven-fold improvements in directional stiffnesses of VMC with the EG base were observed compared to VMC with CI base. The results of stability lobe diagram revealed a three-fold improvement in material removal rate for VMC with EG base compared to VMC with CI base. Thus, the proposed steel reinforced configuration of EG base has demonstrated a better dynamic performance of VMC without compromising static rigidity. [Display omitted] • The suitability of epoxy granite (EG) as an alternate material for base of vertical machining center was investigated to achieve enhanced damping characteristics. • Scaled down model of EG base was fabricated. Static and experimental modal analyses were performed. • EG base exhibited higher natural frequencies and sixteen times higher damping compared to CI base. • Upto seven-fold improvements in directional stiffnesses of VMC with EG base compared to VMC with CI base. • A comparison of chatter stability revealed that EG base exhibited a three-fold improvement in material removal rate without chatter compared to VMC with CI base. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) presents a global challenge, carrying health and environmental risks without proper recycling and disposal methods. Mechanical-biological treatment (MBT) emerges as a promising solution capable of recycling MSW and reducing landfill volumes. However, the efficiency of MBT heavily relies on the bag opener machine, which extracts waste from bags. Therefore, enhancing the bag opener machine's performance is crucial for optimizing the MBT process. This paper introduces four blade models (A, B, C, and D) with different cutting angles (60°, 50°, 45°, and 30°, respectively) aimed at achieving high efficiency, low power consumption, minimal maintenance costs, and extended service life. The blade design was developed using the 3-D modeling software, SOLIDWORKS. Additionally, the paper presents primary calculations of the bag opener machine, which were informed by a review of MSW characterization studies. Static and fatigue finite element analyses (FEAs) were conducted under a pressure of 1 MPa to assess blade strength, performance, and durability. The results indicate that the proposed design can handle a capacity of approximately 30 tons/hr with a power consumption of 22 kW. Notably, blade model D, featuring the minimum cutting angle of 30°, exhibits the lowest Von Mises maximum stress at 15.18 MPa and the minimum factor-of-safety (FOS) at 18.12. Fatigue stress analysis reveals a life expectancy of 106 cycles for all blade models. In conclusion, model D demonstrates superior strength, FOS, and durability, making it the optimal choice for the bag opener machine. [ABSTRACT FROM AUTHOR]

Nomex honeycomb composites (NHCs) are commonly used in various industrial sectors such as aerospace and automotive sectors due to their excellent material properties. However, when machining this type of structure, problems can arise due to significant cutting forces and unwanted cell vibrations. In order to remedy these shortcomings, this study proposes to integrate RUM (rotary ultrasonic machining) technology, which consists of applying ultrasonic vibrations along the axis of rotation of the cutter. To fully understand the milling process by ultrasonic vibrations of the NHC structure, a 3D numerical finite element model is developed using Abaqus/Explicit software. The results of the comparative analysis between the components of the simulated cutting forces and those from the experiment indicate a close agreement between the developed model and the experimental results. Based on the developed numerical model, this study comprehensively analyzes the influence of the ultrasonic vibration amplitude on various aspects, such as stress distribution in the cutting zone, chip size, the quality of the machined surface and the components of the cutting force. Ultimately, the results demonstrate that the application of ultrasonic vibrations leads to a reduction of up to 50% in the components of the cutting force, as well as an improvement in the quality of the machined surface and a reduction in the size of chips. [ABSTRACT FROM AUTHOR]

The present work proposes a novel method for determining the influence of the machining tolerances on the effective contact area of Hirth joints. The proposed method is based on a general Finite Element Model (FEM) capable to simulate any meshing condition of Hirth joints including positioning and machining tolerances using the Monte Carlo method. The FEM was developed based on an accurate measurement campaign of several Hirth joints which allowed to determine the geometric parameters affecting the meshing and the related ranges of variation. The machining reference surfaces and the sequence of technological processes which produce the Hirth joint starting from a raw disc were identified through contactless measurement techniques. The related machining tolerances were measured by employing a high-precision Coordinate Measuring Machine (CMM). A mean value and a standard deviation were associated with each geometrical parameter of the joint. The proposed method can be used for the preliminary design and the quality check of the Hirth joint. In particular, the Prussian blue test, which represents the typical test used to verify the joint's compliance with the technical specification, was simulated. The results highlight the reduction of the effective contact area of the Hirth joint due to the presence of manufacturing tolerances, which can lead to worse mechanical performances and early failure, and could be used to define the machining tolerances limit of Hirth joints. • The manufacturing tolerances of standard Hirth joints were measured. • Optical and contact-based measuring machines were used. • The geometric parameters relevant for the contact were determined. • A parametric finite element model was used to simulate several contact conditions. • The influence of the manufacturing tolerances on the contact area was quantified. [ABSTRACT FROM AUTHOR]

Organic field effect transistors (OFETs), used in the fabrication of nano‐sensors, are one of the most promising devices in organic electronics because of their lightweight, flexible, and low fabrication cost. However, the numerical modeling of such OFETs is still in an early stage due to the minimal analytical as well as numerical models presented in the literature. This research aims to demonstrate an experimentally verified machine‐learning model by investigating an OFET with polyaniline as a p‐type organic semiconductor. OFET's threshold voltage, on/off current ratio, subthreshold swing, and device mobilities are studied as the primary output chiasmatic parameters. The random‐forest machine learning model has shown the criticality of the doping effect on turning the OFET to depletion mode, with positive threshold voltage, under doping higher than 5×1014$$ 5\times {10}^{14} $$ cm−3. Additionally, the study highlights the effectiveness of the gate oxide thickness in controlling the OFET threshold voltage. A 50 nm oxide thickness showed sufficiency to have a non‐depleted OFET operation. [ABSTRACT FROM AUTHOR]

This paper deals with the design of five-phase permanent magnet synchronous machines (PMSMs) exploiting the third harmonic for torque generation. Through the optimization of the stator size and rotor structure, the objective functions related to mass and electric losses are minimized for a targeted electromagnetic power (10 kW and 400 rpm) and a given volume. The study takes into account saturation, thermal, electrical and mechanical constraints. On that note, a 1D analytical magnetic model, considering the existence and use of the third harmonic, is presented. The design optimization then shows how the use of harmonic 3 can improve the machine's performance. It will be shown that, for a given electromagnetic torque, taking the third harmonic into account in the sizing process leads to a mass reduction that can reach 20% and electrical losses that can go up to 21%. A finite element analysis model of the five-phase PMSM is then established in order to verify the results of the optimization and validate them. [ABSTRACT FROM AUTHOR]

Featured Application: This study represents a breakthrough in the engineering of turning processes for manufacturing. By examining dynamic properties and vibration response during turning, it provides key insights for real-time machining system monitoring. The findings can improve surface quality and stability, particularly for slender, flexible shafts. Industries such as automotive, aerospace, and heavy equipment manufacturing can leverage these insights to optimize machine performance, reduce downtime, and boost productivity. This marks a significant stride towards more efficient manufacturing. The chatter that occurs during the turning operation, especially when cutting a slender and flexible shaft, determines the surface quality of the workpiece and the stability of the machining system. However, when building a dynamic model of a slender workpiece with a chuck and tailstock, it is generally regarded as a cantilever or simply supported beam, without consideration of the axial force and supported stiffness effect. In this work, a dynamic model for thin and flexible workpieces with different clamping boundary conditions was first built. Then, a finite element analysis (FEA) was used to study the influence of the axial force and supporting stiffness on the mode frequencies of the workpiece. A further analysis found that the relationship between support stiffness, axial force, and the dynamic response of the workpiece is nonlinear and far more complex than that of the simply supported beam model. The clamping force directly influenced the magnitude of the vibration response with the decrease of shaft stiffness during the turning process. These results were verified experimentally by measuring the vibrational response of slender shafts with different clamping modes using an on-rotor sensing (ORS) system. It proved that the proposed model shows advantages for the identification of dynamic vibration and quality control when machining slender workpieces. [ABSTRACT FROM AUTHOR]

Induction machines are the working horses in a lot of industries. Inter‐turn short‐circuit (ITSC) fault is one of the most common failure modes taking place in them. It can generate large fault currents that lead to a local temperature rise in the faulty stator slot, which deteriorates the working performance of the machine or even cascades to a complete machine breakdown. This article focuses on developing transient thermal models for an induction machine under ITSC faults. The aim of these thermal models is to understand the thermal behaviour of the induction machine at different ITSC fault propagation stages. The first thermal model is based on finite element method (FEM) simulation that includes a physics‐based model for the thermal contact resistance. The second thermal model is a lumped parameter thermal network that models the stator as inter‐connected slot‐number parts. They are both capable of modelling the characteristic of non‐uniform temperature along the circumferential direction for the induction machine operating under ITSC fault conditions. After area‐weighted averaging the results of the FEM simulation, it is found they are quantitatively consistent, with an average relative error magnitude of 5%, as well. [ABSTRACT FROM AUTHOR]

In view of the problems of excessive magnetic flux leakage of the traditional permanent magnet fault-tolerant vernier rim-driven machine, low utilization rate of permanent magnets, and high price of permanent magnet materials, this paper proposes a flux-concentrating consequent-pole permanent magnet fault-tolerant vernier rim-driven machine structure. Firstly, combined with the magnetic field modulation theory, the no-load air gap magnetic density of the machine is analyzed, and the working principle of the multi-harmonic operation of the machine is explained according to the harmonic analysis. Secondly, parametric modeling is used to screen the critical structural parameters that can significantly affect electromagnetic performance of the machine, and the response surface method and sensitivity analysis are used to rank the sensitivity of the critical parameters. Then, the high-sensitivity parameters are first subjected to multi-objective optimization, and then adjusted according to the low-sensitivity parameters. Finally, the air gap magnetic density, back-EMF, cogging torque, and permanent magnet numbers of the machine before and after optimization are compared and analyzed by finite element analysis. The results show that the flux-concentrating consequent-pole permanent magnet vernier rim-driven machine has higher torque density, less torque ripple, and higher utilization of permanent magnets. [ABSTRACT FROM AUTHOR]

Based on the magnetic gear effect, the field-modulated permanent-magnet machine (FMPMM) can realize the unequal pole design of the rotor PM field and the stator armature magnetic field. With the advantages of high torque density and high efficiency, the FMPMM has been widely studied in low-speed direct-drive applications. As a kind of machine excited by PMs, the performance of the FMPMM was affected by the demagnetization state. However, the method for establishing the FMPMM demagnetization model based on a finite element analysis (FEA) presented some problems, including tedious repeated modeling work and long calculation time-consuming under fine subdivision. Therefore, in this paper, a six-phase surface-mounted FMPMM was taken as an example, and an equivalent magnetic network (EMN) model was proposed for evaluating the machine performance under demagnetization. In order to realize the rapid establishing EMN models under diverse demagnetization types, the variable coercivity of PM was introduced. Furthermore, for the purpose of improving the calculation accuracy and shortening the calculation time, the least square method was used in fitting and analyzing the discrete results. Then, in order to verify the validity of the proposed EMN model, a prototype was fabricated and a testing platform was built. The air-gap flux density and the no-load back EMF obtained by the FEA, the proposed EMN model, and the experimental testing were compared. The results showed that the proposed EMN model can realize the rapid modeling and accurate analysis of the six-phase surface-mounted FMPMM under diverse demagnetization types. [ABSTRACT FROM AUTHOR]

The high-precision machine tool's dynamic, static, and rigid nature directly affects the machining efficiency and surface quality. Static and dynamic analyses are essential for the design and improvement of precision machine to ensure good tool performance under difficult and demanding machining conditions. In this study, the performance of a high-precision machine tool was analyzed using its virtual model created using CAD. Static and model analysis using ANSYS Workbench software was conducted to establish the tool's static deformation and static stiffness. Furthermore, the static and dynamic characteristics of the tool were explored using a finite element modeling approach to study their performance. In particular, the structure, static force, modal, frequency spectrum, and topology optimization of machine tools were primarily analyzed. Using model analysis, we found the first four different frequencies (22.5, 28.9, 40.6, and 47.4 Hz) and vibration type, which suggested of a weak link. Further static structural analysis revealed that the deformation of the spindle was 67.26 μm. An experimental static rigidity analysis was performed, and the experimental deformation values of the tool and spindle were obtained. The static and dynamic characteristics, as well as the accuracy and efficiency of the finite element model, were verified by comparing the data with the finite element analysis (FEA) results. Subsequently, we modified the settings and analysis model to ensure that the analysis results were consistent with the experimental findings. The error between the two results was within 1.56%. For an applied load of 5000 N on the spindle nose, the tool nose transient response was 0.5 s based on transient analysis. Under the condition that the structural deformation is as constant as possible, the lightweight structure may achieve the minimum weight and enhance the natural frequency; thus, the ideal structure will be obtained, and finite element analysis will then be performed. The optimal conditions for topology optimization include a lightweight structure, reduced structural deformation, and increased natural frequency of the structure. The developed method improves structural optimization, increases the ability of the product to be manufactured, and offers designers a variety of price-effective options. [ABSTRACT FROM AUTHOR]

Fault diagnosis and condition monitoring of synchronous machines running under load is a key determinant of their lifespan and performance. Faults such as broken rotor bars, bent shafts and bearing issues lead to eccentricity faults. These faults if not monitored may lead to repair, replacement and unforeseen loss of income. Researchers who attempted to investigate this kind of machine stopped at characterizing and deduced ways, types and effects of rotor eccentricity fault on the machine inductances using the winding function method. A modified closed-form analytical model of an eccentric synchronus reluctance motor (SynRM) is developed here taking into cognizance the machine dimensions and winding distribution for the cases of a healthy and unhealthy SynRM. This paper reports the study the SynRM under static rotor eccentricity using the developed analytical model and firming up the model with finite element method (FEM) solutions. These methods are beneficial as they investigated and presented the influence of the degrees of static eccentricity on the machine performance indicators such as speed, torque and the stator current and assess the extent to which the machine performance will deteriorate when running with and without load. The results show that static eccentricity significantly affects the machine's performance as the degree of eccentricity increases. [ABSTRACT FROM AUTHOR]

During the service of rotating machinery, the pedestal bolts are prone to looseness due to the vibration environment, which affects the performance of rotating machinery and generate potential safety hazard. To monitor the occurrence and deterioration of the pedestal looseness in time, this paper proposes a data-driven diagnosis strategy for the rotor-bearing system. Firstly, the finite element model of a rotor-bearing system is established, which considers the piecewise nonlinear force caused by pedestal looseness. Taking the vibration response as output and periodic unbalanced force as input, the system's NARX (Nonlinear Auto-Regressive with exogenous inputs) model is identified. Then GALEs (Generalized Associated Linear Equations) are used to evaluate NOFRFs (Nonlinear Output Frequency Response Functions) of the NARX model. Based on the first three-order NOFRFs, the analytical expression of the second-order optimal weighted contribution rate is derived and used as a new health indicator. The simulation results show that compared with the conventional NOFRFs-based health indicator, the new indicator is more sensitive to weak looseness. Finally, a rotor-bearing test rig was built, and the pedestal looseness was performed. The experiment results show that as the degree of looseness increases, the new indicator SRm shows a monotonous upward trend, increasing from 0.48 in no looseness to 0.90 in severe looseness, a rise of 89.7%. However, the traditional indicator Fe2 has no monotonicity, which further verifies the sensitivity of the first three-order NOFRFs-based second-order optimal weighted contribution rate and the effectiveness of the proposed data-driven feature extraction strategy. [ABSTRACT FROM AUTHOR]

Back electromagnetic force (back EMF) is one of the most significant performance characteristics of the machine which significantly affects the machine current, efficiency, power factor, and power angle. Studies showed that the precise analytical formulas to calculate the back EMF of Counter-rotating dual rotor axial flux permanent magnet synchronous machines (CRDR-AFPMSMs) were not presented so far. While by helping the analytical formulas, back EMF is calculated faster than the finite element method (FEM). Therefore, the novelty of this article is calculating the back EMF of CRDR-AFPMSMs considering its harmonic components. To fulfill this goal, Maxwell's equations are used. The back EMF waveform obtained from the proposed formulas is compared with the results of FEM. Comparing the results confirms that the obtained results from the finite element (FE) simulation and analytical formulas are in good accordance. Besides, the shifting technique is used to reduce harmonic components of the back EMF. By helping proposed formulas and shifting techniques, the Total Harmonic Distortion (THD) of back EMF has decreased from 12.12 to 4.88%. [ABSTRACT FROM AUTHOR]

In longitudinal vibration-assisted milling (LVAM), the tool flute is retracted from the bottom of the machined surface along the axial/longitudinal direction. Nevertheless, there is still a limitation in the knowledge of LVAM during Ti-6Al-4 V cutting regarding the cutting forces pattern in analysis using finite element (FE) simulations and analytical prediction comparatively. This study developed an FE model of the cutting force using ABAQUS and a mathematical model of the cutting force using MATLAB. The FE model was developed based on the Johnson–Cook plastic deformation and the Johnson–Cook damage model. The analytical prediction was developed based on the fluctuated undeformed axial chip thickness and the influence of the longitudinal vibration on the undeformed chip thickness. According to this comparative study, the analytical prediction of the cutting force coded in MATLAB has remarkable similarity with the FE simulation model cutting force. The experimental cutting forces were also carried out to validate both the FE simulation model and the mathematical model. According to the comparison results in the LVAM, the FE simulation model has higher quantitative error than that in the mathematical model, with the highest error in the mathematical model being about 7.146% and the highest error in the numerical model being about 9.913%. In addition, a comparative study between LVAM and CM in terms of the experimental cutting temperature, machined surface morphology, and chip morphology was also carried out. In evidence, LVAM provides better machining performance than CM. [ABSTRACT FROM AUTHOR]

The rigidity and natural frequency of machine tools considerably influence cutting and generate great forces when the tool is in contact with the workpiece. The poor static rigidity of these Vertical Machining Centre machines can cause deformations and destroy the workpiece. If the natural frequency of the machines is low or close to the commonly used cutting frequency, they vibrate considerably, resulting in poor workpiece surfaces and thus shortening the lifespan of the tool. The main objective of this study was to develop an experimental technique for measuring the effect of machine tool stiffness. The static rigidity of the X-axis was found to be 2.20 kg/μm, while the first-, second-, and third-order natural frequencies were 27.3, 34.4, and 48.3 Hz, respectively. When an external force of 1000 N was applied, the Y-axis motor load was found to be approximately 2740 N-mm. In this study, the finite element method was mainly used to analyze the structure, static force, modal, frequency spectrum, and transient state of machine tools. The results of the static analysis were verified and compared to the experimental results. The analysis model and conditions were modified to ensure that the analysis results were consistent with the experimental results. Multi-body dynamics analyses were conducted by examining the force of each component and casting of the machine tools and the load of the motor during the cutting stroke. Moreover, an external force was applied to simulate the load condition of the motor when the machine tool is cutting to confirm the feed. In this study, we used topology optimization for effective structural optimization designs. The optimal conditions for topology optimization included lightweight structures, which resulted in reduced structural deformation and increased natural frequency. [ABSTRACT FROM AUTHOR]

This paper presents the optimal design of the permanent magnet brushless DC (BLDC) motor for electromobility propulsion applications. Two BLDC machines were analyzed: (a) – exterior rotor machine, and (b) – interior rotor machines The optimization of both motors structures was executed by the Taguchi method. The device structure was described by three design variables. The functional parameter (efficiency) and the economic parameter (total mass of the permanent magnets) were included in the objective function. The BLDC motors have been modelled using a finite element method (FEM). Finally, the functional parameters for both motor constructions were compared. The selected results of the calculations were presented and discussed. [ABSTRACT FROM AUTHOR]

Consuming energy sources and greenhouse gas emission are one of the most prominent problems of the latest century. Most of the energy consumed globally and carbon dioxide emissions originate from electric motors used in the industry. Therefore, researchers have recently focused on the production of highly efficient, eco-friendly, and low-priced machines: Synchronous Reluctance Machines. In this study, the design and comprehensive Finite Element Analysis of a TLA-SynRM including the effects of the number of conductors per slot and wire diameter directly affecting stator slot fill factor and crucial for obtaining more realistic results from experiments has been initially carried out. Moreover, power factor, saliency ratio, and efficiency of the novel SynRM are enhanced by utilizing a fine-tuning process based on d- and q-axes flux paths. Additionally, the layer structure of the initial design is changed to a double-layer structure to improve the performance of the machine in the fine-tuning process. In the final step of this study, the machine has been manufactured, and experiments have been accomplished. This study has concluded that the novel SynRM have low torque ripple, high power factor, saliency ratio, and efficiency, whose value is within the range of IE5 efficiency class. [ABSTRACT FROM AUTHOR]

A novel DC‐Excited Flux‐Switching Linear Motor (DC‐FSLM) is investigated in this paper, where a simple secondary is used as the machine stator. The phases and excitation windings are placed on the primary, which contributes to a low‐cost and simple structure linear motor with acceptable dynamic performance. The motor operation under dynamic load is analysed by a parametric Magnetic Equivalent Circuit (MEC), and the core saturation is modelled by the non‐linear reluctance of the flux tubes. Moreover, the end‐effect is considered by virtual zones at both entrance and exit ends of the primary. In the considered MEC, the model accuracy can be selected as desired as well as different DC‐FSLMs with various properties can be modelled. Finally, the machine capabilities and performance characteristics are discussed by simulation results, and validation is performed by the Finite Element Method (FEM). [ABSTRACT FROM AUTHOR]

This paper presents a new topology of an axial flux-switching memory machine with series-type permanent magnets (SPMs) to improve the flux regulation capability. The key idea was to combine low coercive force (LCF) PMs, which can be magnetized and demagnetized readily, with high coercive force (HCF) PMs in series to provide a variable air-gap magnetic flux. The flux regulating principle and the forward magnetization effect of HCF PMs on LCF PMs are presented and discussed. Based on 3D finite element analysis (FEA), the magnetization variation of LCF PMs and the electromagnetic performances of the machine under different magnetization states were investigated. Simulation results showed that the air-gap magnetic flux could be weakened by up to 45% by using a magnetization current impulse, significantly extending the PM motor's flux-weakening speed range. Finally, a prototype machine was built, and experiments were performed to validate the predictions. The basic experimental validation shows that the measured back-EMF and the flux regulating characteristic matched the 3D FEA results well. [ABSTRACT FROM AUTHOR]

Drilling, which constitutes one third of the machining operations, is widely used in many areas of the manufacturing industry. Various difficulties are encountered in the drilling process since the chip is formed in a closed limited chip flows. These difficulties directly affect the output parameters such as energy consumption, surface quality, and cutting force. Therefore, it is necessary to determine the ideal processing parameters to achieve the best performance. However, experimental research on machining processes requires both a long time and a high cost. For these reasons, machining outputs can be estimated by conducting drilling simulations with the finite element method. In this study, the finite element method is used in order to investigate the influence of different cutting parameters and different helix angles on the power and thrust force of Ti–6Al–4V (grade 5) alloy that is commonly used in the aviation industry. The study selected three different cutting speeds, feed rates, and helix angles as the cutting parameters. The experimental design was made according to the response surface method (RSM) Box–Behnken design in the Design-Expert program. Drilling simulations were performed using the ThirdWave AdvantEdgeTM software. The lowest thrust force measured is 1241.39 N at 40° helix angle, 2000-rpm revolution rate, and 0.05-mm/rev feed rate, while the lowest power consumed is 765.025 W at 30° helix angle, 1500-rpm revolution rate, and 0.05-mm/rev feed rate. As a result, it was determined that the most effective parameter for power and thrust force was the feed rate. [ABSTRACT FROM AUTHOR]

The static and dynamic performances of a machine tool structure are considered to constitute the primary factors affecting the load-carrying capacity, geometric accuracy and surface precision of the workpiece. The machining performance of a large machine tool under stable conditions is effectively determined by its dynamic response to the cutting force at low-frequency excitation. This study, therefore, investigated the static and dynamic characteristics of a large heavy-duty lathe machine tool in which the headstock and tailstock comprised critical component modules supporting a large workpiece during low-speed machining. Using a finite element model, the influences of the structural modules on the static and dynamic characteristics of the lathe were analyzed, considering the effects of the workpiece load. The results indicated that the fundamental vibration modes of the lathe were primarily dominated by headstock, tailstock, and workpiece behaviors. The maximum compliances of the lathe under the rated load were found to occur at relatively low frequencies (22, 40.7, and 82.7 Hz) and increase with the reduction in workpiece weight. Notably, these modal frequencies were significantly higher than the maximum rotational speed of the spindle (450 rpm). In addition, the dynamic rigidity corresponding to the rated speed was higher than that induced at the natural frequency. These results indicate that the subject lathe possesses sufficient capacity to sustain the cutting load during stable turning machining. This study can, therefore, help designers improve the performance of machine tools for future fabrication. [ABSTRACT FROM AUTHOR]

To address the increasing interest towards more environmentally friendly naval transportation and the introduction of IMO2020 restrictions on pollutant emissions onboard ships, the present work details the preliminary design of a mini gas turbine engine, i.e., a gas turbine engine with an output power up to 5 MW, for onboard energy generation. In comparison to conventional propulsion systems, gas turbine units benefit from known compactness, which can be further enhanced by employing single-stage uncooled radial machines, according to similar works in the field. As such, the present paper aims to set up a complete procedure that allows a reliable and fast (i.e., requiring a limited computational effort) preliminary design of one-stage centrifugal compressors and radial turbines operating at a high pressure ratio via the use of classical one-dimensional theory. The aerodynamic design outputs in terms of forces and torques are then used to perform a preliminary mechanical design of the shaft by means of a one-dimensional finite element model with commercial software to estimate the corresponding shaft line stress. Despite some necessary geometrical and modeling simplification of the design problem, which results in the unavailability of detailed information on individual components, the employed procedure nevertheless allows a comprehensive overview of the possibilities in terms of maximum machine performance achievable at an early design stage with the associated limited computational requirements. The design procedure and the geometry achieved for the application are presented along with aerodynamic and structural results. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous machines (PMSMs) have garnered increasing interest because of their advantages such as high efficiency, high power density, wide speed range, and fast dynamics. They have been employed recently in several industrial applications including robotics and electric vehicles (EVs). However, PMSMs have highly nonlinear magnetic characteristics, especially interior PMSMs, due to the existence of reluctance torque. Nonlinearity complicates not only machine modeling but also control algorithms. An accurate machine model is the key aspect for the prediction of machine performance as well as the development of a high-performance control algorithm. Hence, this paper presents an accurate modelling method for PMSMs. The proposed model method is applicable for all PMSMs, even multiphase machines. This paper considers a fractional slot concentrated winding 12/10 interior PMSM (IPMSM) for this study to demonstrate the effect of magnetic saturation and special harmonics. The developed model considers accurately the magnetic saturation, mutual coupling, spatial harmonics, and iron loss effects. It utilizes finite element analysis (FEA) to estimate the precise magnetic characteristics of IPMSM. The finite element model is calibrated precisely using experimental measurements. The iron losses are estimated within the simulation model as d- and q-axes current components. The model accuracy is validated experimentally based on a 12/10 IPMSM prototype. [ABSTRACT FROM AUTHOR]

This paper suggests a method to improve the performances of the Dual Stator Axial Flux Spoke-type Permanent Magnet (DSAFSPM) machines with phase group concentrated coil (PGCC) windings, by incorporating continuous and discrete step-skewing along with a special winding connection. The purpose of the study is to mitigate the cogging torque and torque ripples while increasing the output torque so it ameliorates the machine performance at minimum cost for various applications such as wind power plants and electric vehicles (EVs). Cogging torque produces noise and vibrations which degrade the machine's performance and reduces its life span. The proposed winding sequence enhances the output torque by improving its distribution factor along with the use of continuous skew and step-skew magnets. This research work improved the cogging torque and torque ripples with the help of skew techniques while output torque is increased by the proposed winding sequence. Further harmonics and ripples are also mitigated by the proposed winding sequence. The overall machine volume is kept constant along with the magnet size and the design parameters for fair performance analysis. Comparative analysis of these machines is performed using three-dimensional (3-D) time-stepped finite element analysis (FEA). Proposed model I and proposed model II reduce the harmonics by 42% and 23%, respectively. By using continuous skew and discrete step-skew magnets, cogging torque is reduced up to 81.5% and 75%, respectively. This reduction in cogging torque reduces the noise and vibration in machines which assists the machines to perform a smooth operation. The reduction in output torque ripples in proposed model I is 60.8% while that of proposed model II is 59.3%. [ABSTRACT FROM AUTHOR]

This study represents a new hybrid analytical method for predicting magnetic flux distribution and electromagnetic performance criteria of induction machines. This hybrid analytical method proposes to combine magnetic equivalent circuit (MEC) and subdomain. The combined method's fundamental contribution is that an easy calculation of magnetic flux density is presented by considering steel permeability. On the other hand, the induction machine takes a lot of computation time in both steady-state and transient regimes while analyzing the finite element method. Therefore, another contribution is that the proposed method provides a great time saving since it performs the analysis directly in the stable regime. Firstly, the subdomain method, which uses the Fourier series to calculate magnetic flux distribution in the air-gap, is applied to improve the simplicity of the induction machine's modeling in this study. Therefore, magnetic flux distribution at an infinite permeability state is easily obtained. The magnetic saturation effect is then calculated through reluctances on the magnetic core simultaneously in each machine's movement. Furthermore, the proposed combined MEC and subdomain are applied to improve electromagnetic performance prediction, taking into winding leakage and steel core saturation. Defined reluctances in the hybrid analytical model can be selected resiliently according to magnetic saturation. Moreover, the electromagnetic criteria such as back-EMF and output torque at both no-load and on-load state are calculated by the proposed combined MEC and subdomain. Finally, the proposed analytical model is verified by the finite element method. Comparing results shows that the hybrid analytical model agrees well with the finite element method. [ABSTRACT FROM AUTHOR]

In this article, an axial-flux permanent-magnet (PM) Vernier machine with the triple-stator, spoke-type PM rotor, and toroidal winding wound on the innerstator is proposed. Benefited from the flux focusing spoke-type PM rotor and short end length toroidal winding, the proposed machine has a high torque density and the improved power factor. Based on the air-gap permeance function, the analytical expression of the proposed machine is derived to qualitatively analyze the machine's performance. The quasi-three-dimensional (3-D) finite element analysis (FEA) is adopted to optimize the design parameters, such as innerstator diameter, PM thickness, and slot opening width. The quasi-3-D FEA results match well with the 3-D FEA. The 3-D FEA results show the torque densities of the proposed machine reach 49.4 Nm/L and 11.4 Nm/kg, respectively, under the 232 A/cm average electrical loading. The performances, such as overload capacity, PM demagnetization, and PM and core losses, are also analyzed by 3-D FEA. The comparison with the other axial-flux PM Vernier machine is conducted, and the results reveal that the proposed machine has the great advantages of the torque density and power factor. Since the prototype is not built, in this article, the assembly scheme and thermal behavior of the proposed machine are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a new method, a fast prediction method based on the Cartesian stiffness model and equivalent spring stiffness (FPM-CSES), to calculate displacement errors of deformation caused by low stiffness for industrial robot. First, the Cartesian stiffness model based on the Jacobian matrix was established for a robot, and then the displacement error model of deformations caused by external force was established based on Cartesian stiffness. Second, the transmission system of the robot's joint was analyzed, and an equivalent method for joint stiffness was presented based on a series spring system. Meanwhile, the stiffness of the key components including the servo motor, harmonic reducer, and timing belt was deduced in detail. Finally, a compared simulation and a measurement experiment were conducted on a 6-joint series robot. It was found that the FPM-CSES could calculate any configuration among the robot's workspace. Compared with the finite element analysis (FEA) method, the presented method is feasible and more efficient. The experimental results showed that the prediction accuracy of the FPM-CSES is rather high, with an average rate of more than 83.72%. Hence, the prediction method presented in this study is simple, fast, and reliable, and could be used to predict and analyze the displacement errors caused by the cutting force, and provide the basis for trajectory planning and error compensation, enhancing the robot's machining performance. [ABSTRACT FROM AUTHOR]

In this paper, a finite element analysis (FEA) based fast optimization method to optimize a lightweight in-wheel switched reluctance machine is presented. This method speeds up the switched reluctance machine optimization procedure by running the FEA simulations with single-phase constant current excitations for half electrical cycle and estimating the machine performance metrics using the gathered FEA data. Hence, the machine's dynamic performance estimation process takes shorter for each design candidate. The optimization algorithm employs designs of experiments (DOE), response surface (RS) analysis method, and differential evolution algorithm (DE). Here, the DOE method is used to reduce the search space by narrowing down the upper and lower boundaries of each design variable based on the RS analysis. Although this process does not guarantee getting the Pareto front, it places the search space close to the actual one. Hence, the multi-objective DE optimization finds the Pareto optimal solution set without requiring a large number of iterations as well as a large number of candidate designs for each iteration. The method is applied to a 24/16 SRM that is intended to be used in a lightweight race car as a hub motor. Six dimensionless geometric variables are optimized to satisfy three objective functions, namely torque ripple, motor mass, and copper loss. While the conventional DE takes at least 3000 candidate designs, the proposed method considers only 559 designs to reach a similar Pareto front. It is observed that the proposed method takes about 6 h 30 min compared to the conventional method that takes 32 h 50 min using the same computer. Therefore, the computation time is reduced almost five times with the proposed method. [ABSTRACT FROM AUTHOR]

In order to explore the clamping fatigue properties of shrink-fit holders, ANSYS software was used in this study to analyze the thermal and contact stresses during the clamping process of the shrink-fit holder, and the fatigue analysis was performed by selecting the dangerous areas based on the two stresses. A numerical control shrink-fit holder clamping fatigue test device was manufactured, and the automatic clamping of the shrink-fit holder was executed in this study. After 500 clamping repetitions, a milling test was carried out on the shrink-fit bracket. By collecting the vibration signal of the workpiece during processing and measuring the change in the surface roughness of the workpiece, and then analyzing the change in the machining performance of the shrink-fit holder under different clamping times, we were able to compare and verify the accuracy of the finite element fatigue analysis. [ABSTRACT FROM AUTHOR]

One of the most former and widely utilized unconventional machining is known as the process of electric discharge machining (EDM). This is a procedure, where a serialized set of electric discharges are applied to eliminate the material from a workpiece (i.e., electrically conductive). This article proposes a bi-objective optimization of process arguments in machining of stainless steel of 630 (SS630) grade using both experimentation and thermal investigation. Here, flushing pressure ( P F ), pulse on-time ( T ON ), peak current ( I p ), and pulse off-time ( T OFF ) are assumed as the input process parameters to conduct a series of experiments on die-sinking EDM (DS-EDM) of SS630 to predict the output characteristics of machining optimization using grey relation analysis (GRA). Both material removal rate (MRR) and surface roughness (SR) are used for evaluating the output response obtained using the machining performance. In addition, thermal investigation is performed using finite element method (FEM) analysis to compute theoretical MRR (T-MRR) for the distribution of temperature on workpiece. Further, GRA is employed to obtain the optimal process parameter combination for best output responses. From the confirmation test results, the optimal combination obtained using GRA approach is at I p = 6 A , T ON = 35 μ s , T OFF = 90 μ s , and P F = 4 MPa. [ABSTRACT FROM AUTHOR]

Machining dynamics plays an essential role in machine tools (MTs) and machining operations, directly impacting the material removal rate, surface quality, and dimensional accuracy. With the increasing use of numerical control (NC) MTs and increasing automation of production, machining inaccuracy due to thermal deformation has become a significant issue. Furthermore, since the rotation speed and feed rate have risen, more heat is produced in MTs. In addition, since high machining precision is now required, techniques to avoid or regulate thermal deformation are also needed. Traditionally, researchers used the finite element method, support vector method (SVM), regression analysis method, neural network, and other methods to predict and compensate for the thermal deformation of MT spindles. However, these methods do not directly reduce the thermal errors caused by the heat source to improve the accuracy of MTs. Therefore, in this study, a cooling control method is proposed to reduce the impact of heat on the spindle by using a thermal suppression technique accompanied by the adaptive neuro- fuzzy inference system (ANFIS) control method to predict the static thermal behavior of a spindle. The root mean square error (RMSE) is used as the ANFIS evaluation index to reflect the quality of the prediction model. This method is implemented in Simulink to simulate the dynamics of the coolant during the real-time monitoring of the cutting and resting positions of the MT. Finally, a thermal deformation prediction model is generated to demonstrate that the cooling control method developed in this study can be applied to the intelligent cooling of an MT. It is shown that the developed ANFIS prediction model is efficient for controlling cooling. A simulation also shows that this method can reduce the running cost, energy consumption and accurately predict the thermal deformation of MT spindles. It is predicted that the most suitable coolant pump operating frequencies for the spindle at rotation speeds of 2000, 8000, 10000, and 12000 rpm are 20, 40, 40, and 60 Hz and the reductions of the spindle heat are 92.4, 99.9, 80.1, and 60.2%, respectively, with a prediction accuracy within 4.745 µm. [ABSTRACT FROM AUTHOR]

The vibration in the milling process plays a key role in machining, which can significantly affect the machining quality of the workpiece. Some vibrations have negative influences on the workpiece surface, while other vibrations can improve machining stability. Therefore, it is critical to distinguish the influence of different types of vibration on machining quality. A simulation method of undeformed chip thickness considering process vibration is presented in this article, in which a finite element model is established to analyze the dynamic milling process of 7075-T651 aluminum alloy from the aspects of cutting force and temperature. A series of experiments are carried out to verify the effectiveness of the simulation model, and the results show that the proposed model is accurate in predicting both milling force and temperature. Furthermore, the effect of milling vibration on machining performance is studied with the proposed method, in which the relationship between the amplitude-frequency characteristics of vibration and milling force-temperature fluctuation is revealed. The results show that the proposed method can determine the influence of milling vibration and provide a basis for distinguishing favorable and unfavorable vibration parameters of machining quality in milling. [ABSTRACT FROM AUTHOR]

To overcome energy crises, attention is being paid to saving energy from household appliances. Traditional compressors are in need of being replaced by efficient linear compressors. This paper presents a new tubular moving magnet linear oscillating actuator (TMM-LOA) for compressor application. The proposed topology utilizes outer mover topology with separators between the mover and stator modules. The number of stator and mover modules can be increased or decreased based on the requirement. The addition of a separator avoids the flux cancellation and makes the proposed topology fault-tolerant. The design variables are optimized by using a parametric sweep, and the performance in terms of thrust force is observed. Both the static and transient analyses were performed to analyze the machine performance at various currents and stroke. Both mechanical and electrical resonance phenomena are discussed. The efficiency of the proposed TMM-LOA is calculated for one, two and three modules. Finally, the proposed topology is compared with other topologies proposed in the literature to show the superiority of the proposed design. [ABSTRACT FROM AUTHOR]

This paper presents the development of a numerical model for predicting and studying the effects of tool nose geometries and its interactions with cutting parameters during orthogonal cutting of AISI 1045 steel. The process performance characteristics studied were cutting temperature, effective stress, cutting forces and tool wear. The cutting simulations were done using the commercial DEFORM-2D R V 11.3 software, based on the finite element method (FEM). The cutting tool used had a round nose with various nose radii (0.01–0.9 mm), while the machining parameters tested were the feed rate (0.1–0.3 mm/rev), the cutting speed (100–500 m/min) and the rake angle (–5° to +10°). The interactions between the tool nose radius and the cutting parameters (speed, feed) were found to affect mostly the cutting stress and, slightly, the tool wear rate. These interactions did not much influence the cutting temperature, that was found to be high when the tool nose radius and/or the cutting speed were high. The maximum temperature was found to occur at the middle of the tool-chip contact length and at the interaction of nose radius and flank face of the tool. Except for some fluctuations, there was no significant difference in tool wear rate between small and large nose radius scales. [ABSTRACT FROM AUTHOR]

In high-speed and high-frequency electric machines, one of the major issues that impacts the performance and capability of a machine is the high-frequency eddy current losses in the windings. This work deals with AC winding losses in flat rectangular conductors. Aiming for eddy current loss mitigation, two different materials are investigated and compared for the same winding design, namely copper and aluminum. Using the finite element method (FEM), the conductor loss and current density behavior are simulated at the strand level. Further, in order to verify the simulated losses, the AC losses are measured and compared over a wide range of frequencies. Finally, recommendations are provided based on the obtained measurements to identify the best winding topology that is most suitable for automotive applications. [ABSTRACT FROM AUTHOR]

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Asynchronous machines are predominantly preferred in industrial sectors for its reliability. Power quality perturbations have a greater impact on industries; among the different power quality events, voltage fluctuations are the most common and that may cause adverse effect on machine’s operation since they are longer enduring. The article discusses a numerical technique for evaluating asynchronous motors while taking into account magnetic saturation, losses, leakage flux, and voltage drop. A 2D linear analysis involving a multi-slice time stepping finite element model is used to predict the end effects. As an outcome, the magnetic saturation and losses are estimated using a modified 2D nonlinear time-stepping finite element formulation. The method takes the electromagnetic fields at the ends of the motor into account using limited computer resources. The proposed method will greatly reduce computation time with limited computer resources for analyzing the machine’s performance with high precision. The analyzed findings assist in preventing voltage variance issues in the power network system and provide suggestions for developing a robust system. [ABSTRACT FROM AUTHOR]

Synchronous reluctance machine (SynRM) is one of the candidates of high‐speed application drives. The rotor of this machine, as the most important and most challenging part of the design, has various tangential and radial ribs. Therefore, the quantity, thickness and length of the ribs are significant SynRM design parameters. If ribs' thickness is increased in order to enhance the mechanical robustness, its magnetic properties will be substantially deteriorated and vice versa. In this paper, by employing interior claws, a new rotor for SynRM is designed in a way that while increasing the mechanical robustness of the rotor for high speeds application, its magnetic characteristics enhanced, too. For this purpose, the proposed design method is applied on a two‐flux barrier rotor of a 24 stator slot SynRM. The designed machine electromagnetic performance is evaluated by finite elements method (FEM) simulation and compared with other designs. Also, the mechanical strength of the proposed rotor with two alternative claws for the speeds up to 50krpm are evaluated and confirmed by structural FE analysis. At the end, the designed interior claw rotor is prototyped and tested. Prototyped SynRM magnetic characteristics that are extracted by experiment confirmed simulations results with acceptable accuracy. [ABSTRACT FROM AUTHOR]

In this paper, superposition methods including the superposition of a single stator tooth and the superposition of a single rotor tooth, are proposed to predict the open-circuit performances of flux-reversal permanent magnet (FRPM) machines. By the proposed superposition methods, the electromagnetic performances, such as air-gap flux density, electromotive force, cogging torque, and unbalanced magnetic pull (UMP) are investigated and verified by 2D finite element analysis (FEA). Further, according to the superposition methods, cogging torque reduction techniques can be acquired from both stator side and rotor side. In addition, the influence of stator-slot/rotor-pole-pairs (slot/pole) combination on UMP is also studied, and consequently, a reasonable slot/pole combination rule is suggested to avoid UMP. Then, an improved configuration for UMP reduction is also investigated and verified by FEA. Finally, the prototype machines are manufactured and tested to further verify the theoretical analysis and FEA predictions. [ABSTRACT FROM AUTHOR]

The rotor of self-bearing machines can be in an off-centered position as they lack of physical bearings. The air-gap length and effective area with respect to each phase become nonuniform, which results in inductance and back EMF non-linearities. Evaluation of self-bearing machines performance in time domain is inaccurate without a model that includes non-linear inductance and back EMF constants. To reflect non-linearities, finite element analysis (FEA) is often used. However, FEA requires large computational power to run in time-domain simulation. In this article, a 7-D lookup table (7-D LUT) model of inductance and back EMF constants, suspension forces, and torque is proposed for time-domain simulation, including non-linearity from the rotor translational and rotational displacement. Pre-evaluated FEA results are post-processed to construct the 7-D LUT model to enable fast and accurate time-domain simulation reflecting non-linearities from the input of rotary position (slotting effect), translational position in horizontal and vertical directions (unbalanced air-gap field effect), and magnetic saturation effect. A combined winding self-bearing machine is evaluated using the proposed method and verified with FEA and experimental results. [ABSTRACT FROM AUTHOR]