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A medium-sized saucer-shaped ducted aircraft, which utilizes “edge electromagnetic driving”, was designed to address the issue of traditional rotary rotor motors being unable to provide sufficient output torque for large-sized blades. To verify the rationality of the design and evaluate the performance parameters of aircraft, structural strength simulation calculations were conducted for typical overload conditions of the aircraft. Furthermore, aerodynamic numerical simulations were performed for hovering and flying attitudes, and electromagnetic force simulation calculations were conducted for the selected electromagnetic coil configuration. The research results show that the edge electromagnetic drive system of the aircraft can output a torque of 3 700 N·m with a torque density of 33.76 N·m/kg, meeting the operational power requirements. Additionally, the aerodynamic capacity of the aircraft design, with a maximum takeoff weight at the one-ton level, was calculated, and the structural strength met the requirements under typical overload conditions, providing reference for the configuration design and driving scheme of medium and large saucer-shaped aircraft. [ABSTRACT FROM AUTHOR]

Fractional slot concentric winding (FSCW) machine features with short end winding, high torque density and good fault tolerance. However, this type of machine suffers from abundant MMF harmonics which causes high iron loss and partial saturation, etc. Hence, majority of the FSCW adopts surface-mounted PM (SPM) rotor which have large effective airgap to minimize the influence of the MMF harmonics while the interior PM (IPM) rotor is rarely used. The SPM rotor tends to induce high PM flux linkage and cause large fault current when experiencing a short-circuit failure. As a result, this paper presents a triple 3-phase FSCW-IPM for fault-tolerant applications. The triple 3-phase windings facilitate the uninterrupted fault tolerant operation, the more even distributed windings also induce a more sinusoidal MMF which enables the application of IPM rotor. The IPM rotor reduces the PM usage while reluctance torque can be explored to compensate the PM torque reduction which improves the machine fault tolerance. As a result, the proposed machine owns good performance and excellent fault tolerance. The machine is investigated by electromagnetic and thermal finite element analysis and prototyping tests. Both findings confirm that the proposed triple 3-phase FSCW-IPM is a competitive solution for high reliability application. [ABSTRACT FROM AUTHOR]

This paper presents a reanalysis of four axial‐flow rotor simulation datasets to study the relationship between thrust and axial induction factor. We concentrate on high‐thrust conditions and study variations in induction factor and loads across the span of the different rotor blades. The datasets consist of three different axial‐flow rotors operating at different tip‐speed ratios and, for one dataset, also at different blockage ratios. The reanalysis shows differences between the blade‐resolved CFD results and a widespread empirical turbulent wake model (TWM) used within blade element momentum (BEM) turbine models. These differences result in BEM models underestimating thrust and especially power for axial‐flow rotors operating in high‐thrust regimes. The accuracy of BEM model predictions are improved substantially by correcting this empirical TWM, producing better agreement with blade‐resolved CFD simulations for thrust and torque across most of the span of the blades of the three rotors. Additionally, the paper highlights deficiencies in tiploss modelling in common BEM implementations and highlights the impact of blockage on the relationship between thrust and axial induction factors. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper aims to design a deformable mechanism to drive amphibious rotor blade deform from an aerial shape to an aquatic one. The Bennett four-bar and spherical four-bar mechanisms are used as the basic units (B unit and S unit) to form the Bennett–spherical spatial scissor unit (BS unit). By analyzing the kinematic characteristics of the BS unit, it is found that the BS unit can achieve the spatial deformation of expansion and torsion, effectively improving the rotor's performance in water and air media. The wing rib support structure, which is fixed to the BS unit linkage, is designed. The coordinate transformation method describes the blade shape in aerial and aquatic modes using BS unit and rib parameters. To improve the rotor blade performance in air and water, the rotor blade design is carried out under the NSGA-II framework with BS parameters as the design variables. The Gaussian regression and CFD methods are applied to build a surrogate model to reduce the computational cost. The results show that the expansion–torsional deformation of the BS unit can effectively increase the air and water compatibility of the rotor blades. When the rotor is an aerial shape, the BS mechanism extends and decreases the torsion to increase the lift and efficiency. When it is deformed to an aquatic shape, the BS mechanism reduces its length and increases the torsion to reduce the torque effectively. The BS scissor unit and the design method can be effectively applied in the design of deformable rotor blades. [ABSTRACT FROM AUTHOR]

This manuscript examines the output characteristics of a dual three-phase synchronous reluctance motor (DT-SynRM) according to two winding arrangements under normal and half-control modes. In the case of the DT-SynRM, it can operate by using all of the dual three-phase systems (the normal control) or one of the dual three-phase systems (the half control). In this paper, conventional winding function theory (WFT) is applied, because the output characteristic can be predicted by the inductance behavior. According to the WFT, the inductance value can be affected by the winding function, the turn function, and the inverse air gap function. As a result, the rotor barrier shape as well as the winding configuration are the most important factors that have an effect on the performance of the DT-SynRM. Therefore, the effect of the rotor barrier design on the performance is analyzed when the winding configuration and control mode are different. Finally, the validity of the torque characteristic is substantiated through experimental verification. [ABSTRACT FROM AUTHOR]

Due to the configuration of coreless stators and two synchronously rotated rotors, hollow-cup machines (HCMs) enjoy the merits of negligible cogging torque and core loss. Consequently, HCMs have been successfully employed as high-speed electric machines in the aerospace field, which requires high precision and low thermal dissipation. However, the permanent magnet (PM) thickness and air-gap length of conventional HCM are uniform, resulting in various harmonics in the air-gap flux density as well as back-EMF. These harmonics inevitably produce an electromagnetic torque ripple, which has not met the increasing demand for ultraprecision in recent years. Since the inner rotor of HCMs only consists of an iron core, this paper proposes a novel sinusoidal-shaped inner rotor, which can change the harmonics of air-gap permeance, to adjust the harmonics of air-gap flux density and back-EMF. HCMs with the proposed inner rotors have a significant 87% reduction in torque ripple compared to conventional HCMs. Meanwhile, compared to conventional methods, HCMs with the proposed inner rotor exhibit comparable torque ripple and higher average torque. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis, electromagnetic evaluation, and prototyping of a novel motor structure called the sinusoidal rotor switched reluctance motor. In this innovative design, a significant departure from the conventional switched reluctance motor is observed, as modifications are made to the rotor with the goal of reduction torque ripple and radial force characteristics. Importantly, despite these advancements, the proposed motor retains the weight and volume characteristics of the traditional, type. The key attributes of these motors have been thoroughly assessed using the three‐dimensional finite element method, complemented by a sensitivity analysis aimed at identifying the most optimal configuration within the proposed design. The findings reveal that the suggested structure successfully achieves a notable reduction in torque ripple and radial force when compared to the traditional counterpart, albeit with an expected reduction in average torque. These features render the new topology particularly well‐suited for applications that prioritise noise and vibration reduction. Furthermore, the effectiveness of the proposed topology is corroborated through experimental tests, providing empirical evidence of its advantages and potential for practical applications. [ABSTRACT FROM AUTHOR]

Conventional energy sources like fossil fuels are no longer viable due to their limitations and environmental impact. The demand for cleaner, more efficient energy solutions has led to the development of electric machines with smaller volumes and higher output. The family of permanent magnet Vernier motors have high torque output at very low speeds while being very small in volume. In conventional SVPM, the core losses are high, which leads to heating and reducing the efficiency of the motor, and the power factor of the motor is also low, and the torque can increase in relation to the motor volume. The reluctance torque theory, along with the normal output torque of the motor, increases the final torque of the motor. In addition, the toothing of the rotor reduces the cross-sectional area and weight of the rotor. With the reduction of the cross-sectional area, the eddy currents in the core are reduced, the power factor increases and the efficiency of the motor improves. Therefore, in this paper, a spoke-type permanent magnet Vernier motor with a rotor similar to the reluctance rotor has been designed, which has higher torque, lower losses, and higher power factor compared to conventional spoke-type permanent magnet Vernier motors. [ABSTRACT FROM AUTHOR]

In this paper, the electromagnetic performance of variable flux memory (VFM) machines with series-magnetic-circuit is investigated and compared for different rotor topologies. Based on a V-type VFM machine, five topologies with different interior permanent magnet (IPM) arrangements are evolved and optimized under same constrains. Based on two-dimensional (2-D) finite element (FE) method, their electromagnetic performance at magnetization and demagnetization states is evaluated. It reveals that the iron bridge and rotor lamination region between constant PM (CPM) and variable PM (VPM) play an important role in torque density and flux regulation (FR) capabilities. Besides, the global efficiency can be improved in VFM machines by adjusting magnetization state (MS) under different operating conditions.

The stabilisation capabilities of unmanned aerial vehicles (UAVs) with bicopter underactuated swashplateless rotors are highly sensitive to motor-induced vibration. Due to the requirement of the active control of underactuated swashplateless rotors, conventional designs are limited in reducing vibration through control optimisation. A solution with customized passive spring-damping structures on a unique underactuated swashplateless rotor of a tiltrotor bicopter platform is presented. The implementation of this structure effectively reduces the self-coherent vibration in flights. As a result, a higher level of control authority has been achieved without setting excessive low-pass filtering for vibration. Experimentally obtained inertial measurement unit (IMU) data, rotor speed, rotor tilt angle, and the cyclic stator response are presented for comparison with Simulink model predictions. [ABSTRACT FROM AUTHOR]

The influence of interactional effects on quadrotor performance in forward flight was evaluated taking into account square and diamond configurations, forward and backward tilt angles, and a range of hub spacings including overlapping blades. The analysis was based on the wind-tunnel measurements and simulations from four midfidelity computational methods and the high-fidelity tool. The outcome indicates that the efficiency of a diamond configuration improves by 5% in comparison with isolated rotors for nonoverlapping rotor spacings, while the interactions in square alignments are detrimental for all analyzed test cases with the optimum at 0.04D blade overlap. The trend is more pronounced for the backward rotor tilt with intensified interactions, for which the efficiency of the diamond configuration increases by 11% at 1.2D rotor spacing. The computational results showed good agreement with the measurement data for the forward rotor plane tilt; however, for the backward tilt angle, the spread between the calculated values, especially for torque, could be observed with the general trends maintained. The study shows negligible impact of the rotor phasing on the quadrotor efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research focuses on the effect of overlap ratio on the performance of Savonius rotor in the presence of inner blades in such a way that inner blade tip is parallel to the main blade tip and root. Findings reveal that at low overlap ratios, using inner blade that the inner blade tip is parallel to the main blade root leads to a higher power and torque coefficients than the other inner blade configuration and also conventional rotor. This research indicates that for the overlapped rotor and for the two inner blade configurations, the higher power and torque coefficients could be obtained at high and low tip speed ratios, respectively. Results show that for both inner blade configurations, the overlapped rotors overcome the negative torque generated by the non-overlapped one. It is also shown that at high overlap ratio, using inner blade has no advantage over the conventional rotor. [ABSTRACT FROM AUTHOR]

This article aims to realize the brushless operation of a wound rotor vernier machine (WRVM) by a third-harmonic field produced through stator auxiliary winding (X). In the conventional model, a third-harmonic current is generated by connecting a 4-pole armature and 12-pole excitation windings serially with a three-phase diode rectifier to develop a pulsating field in the airgap of a machine. However, in the proposed model, the ABC winding is supplied by a three-phase current source inverter, whereas the auxiliary winding (X) carries no current due to an open circuit. The fundamental MMF component developed in the machine airgap creates a four-pole stator field, while the third-harmonic MMF induces the harmonic current in the specialized rotor harmonic winding. The rotor on the other side contains the harmonic and the field windings connected through a full-bridge rectifier. The electromagnetic interaction of the stator and rotor fields generates torque. Due to the open-circuited winding pattern, the proposed machine results in a low torque ripple. A 2D model is designed using JMAG-Designer, and 2D field element analysis (FEA) is carried out to determine the output torque and machine's efficiency. A comparative performance analysis of both the conventional and proposed topologies is discussed graphically. The quantitative analysis of the proposed topology shows better performance as compared to the recently developed third-harmonic-based brushless WRVM topology in terms of output torque and torque ripples. [ABSTRACT FROM AUTHOR]

Rotor segment skew pole can effectively weaken the cogging torque, but the traditional rotor segment skew pole can also cause the unbalanced axial electromagnetic force, then add load to the bearing thus affecting the performance and decreasing the service life of the motor. It is complicated to study the effect of segment skew pole by the energy method. According to the generating mechanism of cogging torque, this paper presents an easy method. The relationship between rotor segment number and cogging torque harmonics weakening is analysed through the application of geometrical relation and Fourier series, and a simple method for determining segment number is obtained. By analysing the main source of axial force in rotor segment, a new type of rotor arrangement is proposed, which can avoid excessive axial force while retaining the effect of traditional skew mode on cogging torque weakening. The correctness of the conclusion is verified by finite element simulation and prototype experiment. [ABSTRACT FROM AUTHOR]

This paper introduces a technique aimed at improving the performance of an interior permanent magnet synchronous machine (IPMSM) by reducing torque ripple and radial force harmonics. Unlike conventional IPMSMs, the proposed method employs a variable airgap length that is defined by a mathematical function. Two distinct rotor shapes are investigated to determine the most efficient design. Finite Element Analysis is employed to assess both the electromagnetic and mechanical attributes of the proposed motors. It compares the results for three operating points of the shaped motor with those of a conventional one. The investigation delves into the influence of rotor geometry on key output parameters, including Back Electromotive Force (back‐EMF) harmonics, average torque, cogging torque, torque ripple, efficiency, power factor, and radial force harmonics. The findings indicate that optimising rotor shape can significantly enhance IPMSM performance by reducing torque ripples and radial force harmonics, while simultaneously increasing average torque and efficiency at different operating points. [ABSTRACT FROM AUTHOR]

The performance of an internal permanent magnet MISC machine (IPMMM) is improved by its cylindrical rotor, which dampens torque ripple. Changing the stator and rotor core materials, comparing with torque values to identify efficient motor and keeping that in consent, then change the magnet material for better ripple torque. The change in the rotor materials to vary the torque by the rotor angle is analyzed. The finite element method is applied to a MISC motor operating at 290 V, 20 A, and 3000 r/min with the goals of increasing torque and decreasing torque ripple. In this machine, changing stator and rotor materials improves the torque. The results are calculated and analyzed numerically, with the results being virtualized graphically. [ABSTRACT FROM AUTHOR]

This study assesses the influence of engine dynamic characteristics on helicopter handling quality during hover and low-speed forward flight. First, we construct the helicopter–engine coupling model (HECM) based on the power-matching relationship between the engine and the rotor. The impact of the engine is evaluated by comparing HECM with a helicopter model without the engine. To assess the engine's influence quantitatively, we consider torque response, height response, and collective–yaw coupling characteristics in ADS-33E-PRF handling quality criteria. The results reveal that the engine power output lag can deteriorate the helicopter's torque and height response handling quality rate (HQR). After the increase in helicopter mass, the torque HQR caused by engine influence improved, and the altitude HQR further deteriorated. The engine dynamic characteristics can also reverse the yaw rate, decreasing collective–yaw coupling HQR. As the helicopter's flight speed increased, the engine's impact on the yaw rate increased by 41.8%. This study can provide valuable insight into the effects of engine dynamic characteristics on helicopter handling quality and offer a reference for the design of helicopter–engine coupling control laws. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the efficiency of advanced aero engines improves, the operational speed of their rotors increases. This heightened operational speed makes the rotor dynamics highly sensitive to changes in the rotor's mass asymmetry state, or unbalance state. During the use of a dual-spool turbofan engine, when its supercritical high-pressure rotor (HPR) exceeds a certain operational speed, the rotor's vibration spikes and continues to increase with the operational speed until it drops sharply near the maximum operational speed. Analysis of the bolt joints in the faulty rotor reveals various phenomena such as joint interface damage, changes in bolt loosening torque distribution, and alterations in rotor initial unbalance. This paper proposes that at high operational speeds, the bolt joint of the HPR undergoes sudden angular deformation, resulting in the slanting of the principal axis of inertia of the turbine disk. This slant leads to changes in the unbalanced state of the HPR. The additional unbalance causes a sudden rotational inertia load excitation, triggering the rotor vibration failure. Subsequently, a rotor dynamic model that incorporates the angular deformation of the joints is established to simulate how this joint deformation influences the dynamic response of the rotor. The simulation results align well with the observed failure phenomenon and validate the proposed failure mechanism. Finally, troubleshooting measures are proposed and implemented in the faulty engine, effectively mitigating the vibration fault. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

SRMs have high torque ripples. Modifying the stator and rotor shape of SRMs is one of their methods to remove torque ripples. In this study, new rotor and stator geometries have been proposed for SRM. Performance characteristics are obtained and dynamic analyses are carried out for both novel and classical 6/4 SRMs. FFT analyses of the torque characteristics are also performed for the both SRMs. The changes in performance and the FFT results of torque characteristics are determined for both the current-controlled and uncontrolled operations in both SRMs. 23.60% and 15.20% improvements in torque ripples are achieved for the uncontrolled and current-controlled operations in SRMs respectively. When the FFT analyses are applied to the torque characteristics, the THD values are obtained as 21.19% and 8.31% in the uncontrolled and controlled motor current operations respectively. A 122 W three-phase 6/4 SRM simulation based on the MATLAB–SIMULINK environment is performed to validate the improvement of the torque ripple of the proposed model. [ABSTRACT FROM AUTHOR]

The stabilisation capabilities of unmanned aerial vehicles (UAVs) with bicopter underactuated swashplateless rotors are highly sensitive to motor-induced vibration. Due to the requirement of the active control of underactuated swashplateless rotors, conventional designs are limited in reducing vibration through control optimisation. A solution with customized passive spring-damping structures on a unique underactuated swashplateless rotor of a tiltrotor bicopter platform is presented. The implementation of this structure effectively reduces the self-coherent vibration in flights. As a result, a higher level of control authority has been achieved without setting excessive low-pass filtering for vibration. Experimentally obtained inertial measurement unit (IMU) data, rotor speed, rotor tilt angle, and the cyclic stator response are presented for comparison with Simulink model predictions.

This article presents a new rotor with fractional slot distribution winding permanent magnet (FSDWPM) machine to improve the torque density of in‐wheel motor. In order to achieve the high torque/power density and reduced material weight with constrained rotor inner diameter and stator outer diameter, three traditional rotor topologies, including single‐layer V‐shaped, double‐layer V‐shaped, and delta‐type, are selected and compared with the proposed FSDWPM machine. Subsequently, the corresponding basic electromagnetic performances, including open‐circuit back‐EMFs, on‐load torque, and efficiency distributions, of the four machines are investigated and compared by finite element (FE) analysis. The simulated results shows that the proposed rotor arrangement exhibits the highest average torque, excellent field‐weakening capability, the largest high‐efficiency region compared with conventional rotor structures. Finally, a 50 kW FSDWPM machine prototype with double‐layer PM arrangement is manufactured, and some experimental results are conducted to confirm the feasibility and effectiveness of the proposed design. [ABSTRACT FROM AUTHOR]

Nowadays, magnetic gears (MGs) have become an alternative choice for mechanical gears because of their low maintenance, improved durability, indirect contact between inner and outer rotors, no lubrication, and high efficiency. Generally, although these advantages, MGs suffer from inherent issues, mainly the cogging torque. Therefore, cogging torque mitigation has become an active research area. This paper proposed a new cogging torque mitigation approach based on the radial slit of the ferromagnetic pole pieces of MGs. In this method, different numbers and positions of slits are applied. The best results are gained through an even number of slits which shows promising results of cogging torque mitigation on the inner rotor with a small mitigation in the mean torque on both rotors. This work is done by using Simcenter and MATLAB software packages. The inner rotor’s cogging torque has mitigated to 81.9 %, while the outer rotor’s cogging torque is increased only by 2.75 %. [ABSTRACT FROM AUTHOR]

In this paper, an asymmetric rotor interior permanent magnet (ARIPM) motor with high demagnetization prevention capability and robust torque performance is proposed. The key contribution of this paper lies in two aspects. On the one hand, a novel asymmetric rotor with a shifted magnet axis is proposed to improve the demagnetization prevention capability and torque density. In order to obtain a proper asymmetric rotor topology of the ARIPM motor, the multi-physical performances, especially the PM demagnetization characteristics of five types of PM arrangements, are analyzed. Furthermore, an asymmetric rotor with V- and VV-type PM arrangement is preliminarily designed, considering the multi-physical performance balance and the potentially high anti-demagnetization ability. On the other hand, it is found that the asymmetric rotor structure can not only improve the nominal value of motor performance but also can enhance the resistance to the influence of manufacturing uncertainties. Therefore, multi-objective optimization of the ARIPM motor with rotor notch design is carried out to obtain an optimal motor structure with both high nominal value and robustness of motor performances. By comparing the simulation results with those of a benchmark motor, the superiority and validity of the proposed ARIPM motor are confirmed. Experimental tests will be carried out in the future to further verify the effectiveness of the proposed motor. [ABSTRACT FROM AUTHOR]

Due to the lack of magnets and suitable final price, Synchronous Reluctance Motors (SynRMs) are potential candidates for household electric appliances and so on. However, in general, they have a major drawback, i.e., high torque ripple. The optimized design of a synchronous reluctance rotor structure is presented for two different types of barrier shape with the aim of reducing the torque ripple and increasing the average torque. In this paper, optimization of rotor geometries with a fixed machine size for two types of C-shaped and circular barriers is investigated. Most of the rotor parameters such as the width of the iron parts as well as the width of the barriers along d and q axes are optimized by a new method using the Particle Swarm Optimization (PSO) algorithm. In addition, the angle of the end points for each barrier with constant rib and insulation factor are considered in the optimization process. Minimizing the torque ripple without losing or even increasing the average torque is the most critical optimization achievement. Two prototypes of the optimized rotor with the C-shaped and circular barriers were fabricated and experimentally compared. The results obtained from the 2D finite element simulation of the recommended machine conformed well to the experimental result. [ABSTRACT FROM AUTHOR]

Axial Flux Permanent Magnet (AFPM) machines with ironless rotors are an attractive and recently studied solution in low-speed applications, due to their potentially high power/weight ratio, high aspect ratio, and high efficiency. Nevertheless, these machines are prone to be affected by manufacturing tolerance during its fabrication process and consequently, the magnets may move freely inside the rotor structure. This work presents a statistical analysis of manufacturing tolerances of an AFPM machine with an ironless rotor, considering several magnet fault types. A computationally efficient superposition method is developed and implemented to obtain both the cogging torque and rated torque considering several tolerance combinations with acceptable accuracy. The results obtained from a statistical analysis of 10,000 designs of a two-stator one rotor tooth coil winding AFPM (TCW-AFPM) machine allowed us to identify the parameters with the most impact on relevant performance indicators and disclosed a substantial increase in cogging and ripple torque when unavoidable combined tolerances are present. [ABSTRACT FROM AUTHOR]

An interior permanent magnet synchronous motor (IPMSM) with "VV—" shape rotor topology structure is proposed, and its performances are compared with "V" shape and "V—" shape rotor topology structure. The results show that the performances including output average torque, reluctance torque, torque ripple, cogging torque, iron loss of the IPMSM with "VV—" shape is better than the other two rotors. Firstly, the parameters which have great influence on the torque and the efficiency of the IPMSM are analyzed and optimized. The no‐load back electromotive force (EMF) of three different optimized rotor topology structures are analyzed and compared, the results show that the no‐load back EMF of the IPMSM with "VV—" shape topology structure has the lowest total harmonic distortion rate (THD). Secondly, the torque of the IPMSM with "VV—" shape under different current angles, current densities and speeds are analyzed and compared with the other two rotors. The results show that the torque performance of the IPMSM with "VV—" shape rotor topology structure is better than that of the other two. Finally, aiming at the problems that the torque ripple and cogging torque of the IPMSM with "VV—" shape rotor topology structure are greatly increased when the iron loss is reduced, This paper proposes to add a set of circular flux isolation holes between the second layer and the third layer of permanent magnets, and the position and diameter of this set of circular flux isolation holes are optimized and adjusted. The results show that the torque ripple and cogging torque of the IPMSM with the further optimized "VV—" shape rotor topology structure are greatly reduced, and the THD of no‐load back EMF is also further reduced, which has great significance to reduce vibration and noise, improve the control accuracy of the IPMSM. [ABSTRACT FROM AUTHOR]

This study investigates the effects of rotor magnetic isolation dimensions on the no‐load performance of ultra‐low speed high torque spoke type permanent magnet motor. The studied spoke type permanent magnet motor structures are shown, where the rotor magnetic isolation parts include a magnetic barrier near the air gap (MB‐NAG), a magnetic barrier near the magnetic isolation sleeve (MB‐NMIS), a magnetic isolation sleeve (MIS). The magnetic circuit model is performed and the finite element analysis method is used to analyse the no‐load performance. Through analysing no‐load performance with three MB‐NAG shapes, the way to narrow the optimise dimension range considering reducing the cogging torque and increasing the back‐EMF synchronously is concluded. The results with different MB‐NMIS and MIS dimensions show that: (a) the optimised MB‐NMIS dimensions can increase the back‐EMF with a thin MIS in a certain dimension range of MB‐NMIS, and (b) the increasing proportion of back‐EMF influenced by the MB‐NMIS is inversely proportional to the thickness of MIS. The feasibility and effectiveness of the proposed motor structure and conclusion are experimentally verified. [ABSTRACT FROM AUTHOR]

Although it is crucial to design the magnetic flux path and the maximum torque per ampere (MTPA) current reference under the current limitation, it is challenging to simultaneously consider these features in developing an interior permanent magnet synchronous motors (IPMSM) due to complicated coupling effects. In this article, to overcome the above issue, the motor-design parameters are estimated by conducting electromagnetic finite element (FE) analysis two times at every iteration of topology optimization. Then, the MTPA current phase angle can be analytically expressed in terms of an elementwise relative density (i.e., design variable in topology optimization). In addition, the structural safety is assessed by conducting the structural FE analysis under design-dependent loads to reflect a high-speed rotation. The proposed two-stage topology optimization enables us to simultaneously optimize both a structural design and current phase angle to achieve the maximum electromagnetic performance. Structural safety and manufacturability are also considered to obtain a practically meaningful design. With two different types of permanent magnets, the optimized IPMSMs are obtained and manufactured to validate the proposed method. Simulation and experimental results demonstrate the validity and potential of this work. [ABSTRACT FROM AUTHOR]

This article proposes a magnetic flux saturation model that well represents the cross saturation of synchronous reluctance machines (SynRMs) and a parameter estimation method of the proposed saturation model. Existing magnetic flux models do not satisfy the reciprocity condition or express cross saturation well. The proposed flux saturation model consists of terms for self-saturation and cross saturation, and it expresses well the nonlinear relationship between current and flux of SynRMs, as well as satisfies the reciprocity condition. The data of flux saturation are obtained at standstill using the hysteresis voltage injection method. Using the flux saturation data, the parameters of the flux saturation model are estimated. Because the proposed magnetic flux saturation model includes an arctangent function, it is not possible to estimate parameters directly using the linear least-squares method (LSM). However, the proposed parameter estimation method integrates the self-saturation model and transforms it into a polynomial to which linear LSM can be applied. In addition, parameters related to cross saturation are also estimated using linear LSM. Therefore, the proposed parameter estimation method is easy to implement and can be applied to general-purposed inverter products. The effectiveness of the proposed model and its identification method are experimentally evaluated with a 1.5-kW SynRM. Additionally, the identified model is verified with the accuracy of the maximum torque per ampere table and the performance of sensorless control of the tested motor. [ABSTRACT FROM AUTHOR]

This article presents the dynamic modeling and analysis of an electric motor with integrated magnetic spring (EMMS) when it is coupled to a weaving loom application. The EMMS can provide the majority part of the oscillating part of the load in a passive way by the magnetic spring. The electric motor provides the average torque and the remaining oscillating part in an active way. This reduces the energy consumption. To create an accurate dynamic model for the EMMS, lookup tables are generated from a finite-element model. Further, a 4-bar linkage mechanism is employed to emulate the behavior of the shedding mechanism of a real weaving loom application. Eventually, the whole system dynamic model was created in Matlab environment. Moreover, a complete experimental setup was constructed to validate the effectiveness of the proposed dynamic model and the EMMS behavior. It is shown that the proposed dynamic model effectively predicts the performance of the EMMS system. Besides, it is proved that the EMMS can effectively reduce the energy consumption of the weaving loom application. The amount of reduction in the energy consumption depends on the designed magnetic spring. For the considered application, it can reach 57%. [ABSTRACT FROM AUTHOR]

Interior permanentmagnet (IPM) motors have been the most promising solutions for electric vehicles (EV) drives in terms of torque/power density, compactness, and efficiency. However, IPM motors are vulnerable to large torque ripple and high-level electromagnetic vibrations due to the differences of d-&q-axis inductance and abundant spectrum of exciting forces. This article presents an intensive comparison of IPM motors with three design approaches to reduce cogging torque, torque ripple, and electromagnetic vibration. The design approaches compared cover skewing slot and segmented rotor approaches commonly used in industry, as well as a new asymmetric pole approach. A commercial 10 kW 8-pole/ 48-slots V-shaped IPM motor for EV traction is taken as the reference base. Extensive performance comparisons, including cogging torque, back-EMF, load current, load torque profiles, PM reliability, and torsional force were carried out. Besides, vibration aspects in terms of exciting force, modal property, and electromagnetic vibration response were also analyzed and compared. Finally, the prototypes with the mentioned three design approaches are produced, respectively, and intensive experimental tests were done to verify the analysis and comparison. [ABSTRACT FROM AUTHOR]

Aiming at such problems as poor consistency of bolt preload in aero-engine assembly, the decline rule and distribution characteristics of bolt preload in sequential tightening and star tightening were studied based on the FEM of bolted rotors. The experimental study of bolt preload was carried out, the influence of tightening sequence and tightening speed on the bolt preload were analyzed, and then the decline mechanism of the preload over time was revealed. The results showed that the preload decreases significantly when the adjacent bolts are tightened,and increasing tightening speed will make the bolt get larger preload, which makes the connection structure more stable. After tightening the bolts, the preload will decline significantly in a short period of time, and the decline rule is closely related to the torque amplitude. Therefore, in engine assembly, the decline of preload in a short period of time cannot be ignored while strictly controlling the bolt tightening process. [ABSTRACT FROM AUTHOR]

Spherical motors capable of omnidirectional rotations in a ball joint provide a highly dexterous actuator system yet also present great challenges in developing a high-performance regulation and tracking controller due to the complex rotor dynamics. This article presents a complementary H2-H∞(C-H2-H∞) control method for precisely controlling the multidegree of freedom (DOF) orientation of spherical motors in presence of external disturbances as well as model uncertainties and inaccuracies. In order to deal with the tradeoff between the robustness and control performance resulted from conventional control methods, the proposed controller featured with a 2-DOF structure presents an H2 controller for a nominal plant and then complements it with an additional regulator designed in H∞sense to assure robustness. Unlike traditional H∞ or mixed H2and H∞ controller, the H∞regulation is conducted online in accordance with the monitored modeling mismatch in a way that does not adversely degrade the performance delivered by H2 control, hence, improving the conservativeness of the total control performance and leading to significant improvements of tracking accuracy and response time at same time. Both numerical simulations and experiments on a spherical motor testbed are conducted to validate the superior performance of the proposed controller versus conventional control methods. [ABSTRACT FROM AUTHOR]

This article proposes a series of split-tooth stator permanent magnet (PM) Vernier machines with zero-sequence current excitation, which integrates enhanced torque density and flux adjustment capability. The key is to design the split tooth to exert desired dual magnetic field modulation effect so as to efficiently utilize the hybrid magnetic fields by the PM and zero-sequence current. Meanwhile, with the split-tooth design, the paralleled flux paths are achieved to offer improved flux regulation capability and reduced PM demagnetization risk. In this article, the machine topologies and operation principle are introduced. Hybrid excitation magnetic field is analyzed with the consideration of dual magnetic field modulation of split-tooth structure. Influences of split tooth and PM on torque and flux regulation capability are analyzed. Electromagnetic performances of the proposed machine are analyzed and compared. A prototype is manufactured and tested to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

The mechanical parameters, including the Coulomb and viscous friction coefficients together with the moment of inertia, are of great interest for the performance optimization and condition evaluation of surface-mounted permanent magnet synchronous motor (SPMSM) drives. This article contributes a speed-controller-independent mechanical parameter identification scheme using open-loop speed response due to signal injection, which has not been reported in existing works. It is designed based on the premise that the viscous friction torque is disproportional to the rotor speed, which is a new progress toward estimating the mechanical parameters with high precision. Moreover, as a practical full-participation-type solution, this scheme involves a new electrical parameter estimation technique based on differential algebra to assist in identifying the mechanical parameters. This auxiliary technique attains the current-controller-free estimation of the electrical parameters with the inverter nonlinearity eliminated, thereby addressing the current controller self-commissioning and serving to acquire the accurate electromagnetic torque. The experimental evaluations on two prototype SPMSM drive systems validate the feasibility of this suggested scheme. [ABSTRACT FROM AUTHOR]

In this article, a postfault control technique is proposed for a rotor field-oriented induction motor (RFO-IM) drive fed from a cascaded H-bridge multilevel (CHB-ML) converter. The control strategy is to vary the magnitude and phase shift of the injected fundamental common mode voltage (FCMV) according to the motor’s operating condition. The addition of the proposed FCMV with the reference phase voltages, not only ensures maximum line voltage in the postfault operating condition but also shares equal power among the remaining healthy cells of the converter. Moreover, in the postfault operation, a detailed analysis is performed on both motor and converter, and an integrated control is presented to maintain the command speed and load torque of the RFO-IM. This includes the mathematical equation explaining the new operating point of the motor for different fault configurations, traversal of operating point, and the variation in power factor of each leg of the converter in postfault conditions. From the above analysis, the dynamic FCMV is calculated from the new operating point of the stator current components in the current dq-plane and the fault configuration of the CHB-ML converter. The proposed control technique is validated using simulation and experimental results conducted on a 3-hp IM. [ABSTRACT FROM AUTHOR]

This article proposes a novel method to reduce rotor movement when estimating magnetic flux models for interior permanent magnet synchronous motors (IPMSMs) and synchronous reluctance motors (SynRMs). A rotation reduction technique that considers the flux saturation effect is proposed. A hysteresis controller is used to inject voltages only into the q-axis and simultaneously into the dq-axes. The rotation of the IPMSM is reduced by calculating the current at the point where the integral of the q-axis current over time becomes zero. In the case of SynRM, the rotation is reduced by calculating the injection voltage magnitudes such that the oscillation frequency of the q-axis current is higher than that of the d-axis current. The effectiveness of the proposed method was experimentally demonstrated using an 11-kW IPMSM and 1.5-kW SynRM. The proposed technique can be used for the self-commissioning of IPMSMs and SynRMs at a standstill, without rotor locking, or position sensors. [ABSTRACT FROM AUTHOR]

Axial-flux permanent magnet (AFPM) machines are gaining popularity in low-speed and high torque applications due to their high torque density, high efficiency, and compact structure. In this article, a dual-rotor slotless AFPM (DRSAFPM) machine equipped with equidirectional toroidal winding (EDTW) is proposed and compared with that equipped with conventional single-layer and double-layer concentrated windings (CWs). First, the differences between the DRSAFPM machine with EDTW and that with conventional CWs in coil layout, electromotive force (EMF), and winding magnetomotive force are revealed. Considering the special coil layout of the EDTW, the coil factor and size equations of the DRSAFPM machines with EDTW and conventional CWs are presented. Second, the electromagnetic performance including air-gap field, back-EMF, torque, and efficiency of the DRSAFPM machines with EDTW and conventional CWs are analyzed based on the three-dimensional finite-element method. The simulation results validate the correctness of the coil factor and size equations and indicate the EDTW–DRSAFPM machine has superiority in back-EMF amplitude and torque density. Finally, a prototype of the EDTW–DRSAFPM machine is manufactured and tested, which validates the feasibility of the EDTW–DRSAFPM machine and the correctness of the analysis. [ABSTRACT FROM AUTHOR]

This paper analyzes the feasibility of converting brushed direct current (BDC) to brushless direct current (BLDC) motor by substituting the wound rotor with a permanent magnet. The aim is to overcome the low quality of rewinding of wound rotors. The conversion was performed by redesigning the motor, referring to the old stator dimensions and motor specifications. Some suitable speed control systems were also examined. Technical analysis was executed by simulating motor characteristics, covering torque-speed curve, cogging, and ripple torques. Afterward, an economic analysis was done to determine the cost of making one rotor unit and the speed control and then compare it with the price of a new BDC motor with equivalent power. The results show that the motor produces 3.6 kW, 18.86 V, 176.71 A, and 28.53 Nm at 2,460 rpm with 2 phases configuration. The maximum cogging torque is 2.9 Nm. The cost of making one rotor unit plus speed control is higher than that of a new BDC motor. These results show that it is technically feasible to convert BDC into a BLDC motor but not economically or vice versa. [ABSTRACT FROM AUTHOR]

Model predictive flux control (MPFC) is an alternative control solution to the classic model predictive torque control (MPTC) for driving induction motors (IMs) without the complexity of tuning the weighting factors. However, when applied in motor drives fed by a two-level converter, it results in higher flux and torque ripples. To improve its performance, this article proposes a virtual three-level MPFC (V3-MPFC) method. The virtual vector method increases the total number of voltage vectors crucial for improving the closed-loop performances of the model predictive control. To reduce the computational burden, direct torque control and novel deadbeat (DB) control strategies are proposed. Compared with existing methods, the proposed DB-based method reduces V3-MPFC to a suboptimization problem and still ensures that the suboptimal solution is equivalent to the global optimal solution provided by V3-MPFC. In addition, the redundant states are exploited to lower the switching frequency (SF) without extending the cost function. The simulation and experiment results show that, compared with existing methods, the proposed strategy effectively reduces the flux and torque ripples, and requires a lower SF and execution time. [ABSTRACT FROM AUTHOR]