Search

The aim of this paper is to assess the efficacy of non-conformal meshing in mesh-based generated reluctance network modeling. A representative semi-numerical example is introduced to demonstrate the possibilities and accuracy offered by a non-conformal meshing. In a conformal mesh, two reluctance block elements share the same branch. This makes the computation faster and more accurate but is not convenient for motion processing or mesh relaxation and it does not solve the air-gap modeling problem (rotor/stator connectivity). To solve this, different approaches are used. The interpolation approach developed in this paper aims to render motion processing independent of discretization. This approach is also applied to couple different meshes (spatial discretization) and makes it possible to connect a lumped parameter model to a meshed one. The model is divided into independent zones that are connected via the interpolation coupling. Several reluctance network (RN) non-conformal meshes are presented and global quantities are compared to a fine-meshed finite-element model. Magnetic saturation is considered in the iron parts. Comparisons are provided under open-circuit and on-load configurations for flux linkage and force. The main advantage is to overcome the limitations of generic RN for which the movement modeling requires remeshing at each position. The drawbacks of the method are the increased number of variables (additional interface nodes) and a certain loss of accuracy due to the interpolation function order. [ABSTRACT FROM AUTHOR]

In this paper, the influences of design parameters on the on-load demagnetization behavior of a switched flux hybrid magnet memory machine (SF-HMMM) are evaluated, which aims to provide a useful design guideline to avoid this performance degradation. The machine topology and on-load demagnetization phenomenon are described, respectively. Furthermore, some key design parameters are selected to optimize to elevate the operating point of the low coercive force (LCF) permanent magnets (PMs). Then, some geometric modifications are suggested to alleviate the on-load demagnetization effects. Finally, an SF-HMMM prototype is fabricated and tested to experimentally verify the finite-element analysis. [ABSTRACT FROM AUTHOR]

This paper presents an analytical model of magnetic field of a permanent magnet synchronous motor (PMSM) with a trapezoidal Halbach permanent magnet array (THPMA). Compared with conventional Halbach array, the shape of each magnet in THPMA is transformed from rectangle to trapezium in polar coordinates. The THPMA is delaminated indefinitely radially and each layer is approximately considered to be a conventional Halbach array. The air-gap magnetic field of each layer is analyzed with the scalar magnetic potential. Then, the air-gap magnetic field of the THPMA is obtained by superposing magnetic fields of all layers. The validity of the analytical model is verified by a finite-element model (FEM). The air-gap flux density is optimized by adjusting the center angle coefficients of the THPMA, and a no-load phase back electromotive force (EMF) with the harmonic distortion rate (THD) of 0.75% is obtained by FEM. The back EMF is basically consistent with the measured result of a prototype motor. [ABSTRACT FROM AUTHOR]

In this paper, on the basis of a conventional 12-stator-coils/17-rotor-teeth (12/17) flux-switching permanent magnet (PM) (FSPM) machine and a 6/17 V-shaped FSPM machine, a novel 6/17 multi-tooth FSPM machine with a pair of magnets located in the upper apex of stator tooth is proposed. Then, four multi-tooth topologies sharing the same 6-stator-coils but with different rotor teeth combinations, namely, 6/17, 6/10, 6/11, and 6/13, are compared by the 2-D finite element analysis (2-D-FEA). The FEA-predicted results reveal the optimal combinations of stator coils and rotor teeth should be 6/17 for high-performance multi-tooth machines. Thereafter, an optimal design criterion of multi-tooth FSPM machines for the combinations of stator coils and rotor teeth is proposed. Afterward, electromagnetic performance evaluation between the 6/17 V-shaped and 6/17 multi-tooth machines is conducted, in terms of back electromotive force (back EMF), electromagnetic torque, cogging torque, phase inductance, unbalanced magnetic force (UMF), torque/magnet ratio, and efficiency. The comparative results indicate that the proposed 6/17 multi-tooth machine is superior to the V-shaped one, since it exhibits much higher torque/magnet ratio, larger torque, lower inductance, and much lower UMF, though the cogging torque and total harmonic distribution of phase back EMF are unfavorably larger. [ABSTRACT FROM AUTHOR]

In this paper, a new asymmetric planar V-shaped magnet arrangement for a linear PM synchronous motor is proposed. Several magnet arrangements for the track of the proposed linear permanent magnet (PM) synchronous motor such as un-skewed magnets, conventional magnet skew, and V-shaped planar magnets have been investigated. The performance results of the linear motor with skewed magnets are compared to those of previously designed PM linear synchronous motor with conventional un-skewed rectangular-shaped (CuSRS) magnets. The forcer is kept the same for all track structures and a thorough comparison is provided for low detent force and low force ripple with the CuSRS and proposed planar V-shaped magnet skew approaches. [ABSTRACT FROM AUTHOR]

A novel dual-flux-modulation consequent-pole linear permanent-magnet (DFM-CP-LPM) machine is proposed in this paper, which can be regarded as the combination of a linear flux-switching PM machine and a linear vernier PM machine. Via two sets of interoperable PMs mounted on both the primary and the secondary, the proposed machine can work in a dual-flux-modulation mode, achieving higher thrust density. Meanwhile, the consequent-pole structure is introduced, reducing approximately half of the PM usage compared to a conventional surface-mounted linear PM vernier machine (LPMVM), which will greatly reduce the cost. In this paper, the configuration and the operation principle of the novel DFM-CP-LPM are presented. Then the optimization and several thrust ripple reduction methods are introduced to improve the performance of the machine. Thermal analysis is also carried out to check the demagnetization risk of primary PMs, due to the heat from coils. Finally, the proposed machine is compared to a conventional LPMVM and a consequent-pole linear vernier permanent magnet machine with only PMs set on the secondary. The results verify the superiority of the proposed DFM-CP-LPM. [ABSTRACT FROM AUTHOR]

A separate-stator modular machine with biased flux is proposed in this paper. In this machine, the windings and the permanent magnets are located in two separate parts of the stator, which favors the heat dissipation and magnetic saturation reduction of the machine. With the specially designed stator structure, a biased flux can be introduced to flexibly regulate the excitation field by injecting a zero-sequence current into the phase windings, so that a wide operation speed range can be achieved. Moreover, a modular structure is adopted to simplify the automated manufacture assembly. In this paper, the machine configuration and the working principle are first illustrated. The effect of the design parameters on its torque capability is then investigated. A coupled electromagnetic-thermal optimization method based on the genetic algorithm and finite-element method is proposed to improve the torque performance of the machine. [ABSTRACT FROM AUTHOR]

In conventional 12/8-pole doubly salient permanent magnet machines (DSPMMs) with outer type flux focusing method, the relatively thicker stator back iron next to magnets results in smaller slot area. This paper proposes a novel structure of DSPMMs in square envelope. In such structure, the thickness of stator back iron is roughly uniform and the magnets are inserted from the corners of square envelope to the slots. In addition, the tooth tips of all stator teeth are kept uniformly distributed on the stator bore while the tooth bodies of side stator teeth next to magnets are bended by an angle from the corresponding tooth tips. Meanwhile, the side stator teeth size should be optimized to achieve the balanced slot areas. The main parameters of the proposed and conventional structures with outer type flux focusing method are scanned for higher torque under the fixed copper loss and square envelope. The comparison between two structures shows that the proposed structure can achieve larger slot area, lower torque ripple, and 11.5% higher average torque with the same magnet usage. [ABSTRACT FROM AUTHOR]

In this paper, we propose a loss calculation method considering minor hysteresis loops for permanent magnet (PM) motors driven by pulsewidth modulated (PWM) inverters. In the governing equation of the proposed method, both the effects of the major and minor hysteresis phenomena are expressed by a reaction magnetic field. This field is determined by iterative calculations of finite-element analysis (FEA) with a simple hysteresis modeling that considers the minor loops. The proposed method is applied to a PM motor, and the experimental verification is carried out. It is clarified that the minor hysteresis loops affect not only the hysteresis loss but also the eddy current loss because the skin depth varies with the differential permeability of the minor loops. [ABSTRACT FROM AUTHOR]

This paper aims to disclose the noticeable effect of local tangential force on vibration performance in fractional-slot concentrated-winding permanent magnet synchronous machines (PMSMs). The mechanism to induce vibrations by tangential force is revealed at first. It is found that tangential force is able to deflect the yoke through the tooth's lever arm effect. This phenomenon is detailedly explained through finite element simulation and analytical description of the microscopic deformation in this paper. With the aid of a 10-pole/12-slot PMSM, the quantitative contribution of tangential force to the vibration is also investigated through simulation, vibration synthesis, and experiments. Results show that due to the strong lever arm effect and not so small force amplitudes as commonly expected, the contribution of tangential force to final vibration is comparable to that of radial force. Besides that, the synthesized vibrations indicate the contribution of tangential force decreases with the increase of non-zero spatial order, in a way similar to radial force. In order to underpin the findings, more situations such as with different pole-slot combinations are also analyzed at last. [ABSTRACT FROM AUTHOR]

This paper presents the comparative study of coreless-type permanent magnet linear synchronous machines with non-overlapping windings. An analytical expression that can be applied to any combinations of pole and coil numbers is developed for evaluating the electromagnetic performances. Subsequently, a simple factor called thrust factor is introduced to find the best ${\boldsymbol{C}_{\boldsymbol{pp}}}$ family depending on the variation of coil width ratio. From the comparative study, a significant result is reported that ${\boldsymbol{C}_{\boldsymbol{pp}}} = 1/4$ , i.e., multiple 4-pole/3-coil, is the best non-overlapping winding configuration of coreless-type permanent magnet machines owing to the highest value of thrust factor. Finally, the validity of the key analyses is confirmed by optimal results, finite element results, and experimental results from prototype machines. [ABSTRACT FROM AUTHOR]

This paper gives a way to analyze the flux characteristic of a single-phase tubular permanent magnet linear motor (TPMLM) based on the 3-D magnetic equivalent circuit (MEC) method. By studying the flux tubes of this single-phase TPMLM with the finite-element analysis software—FLUX, a 3-D MEC model of this motor can be constructed, and the flux linkage of the single-phase TPMLM can also be calculated. The static and dynamic performances of the single-phase TPMLM calculated with the 3-D MEC model are compared with the 3-D finite-element model and experimental results, which verify the correctness of the proposed 3-D MEC model. [ABSTRACT FROM AUTHOR]

This paper presents a magnetic safety evaluation of the static magnetic field produced by magnetic floors with permanent magnet properties utilized in the construction industry. The magnetic floors analyzed in this paper are composed by a concentration of 85% of isotropic strontium (Sr) ferrite powder mixed with chlorinated polyethylene. The magnetic floors are magnetized and tested in the laboratory to measure the magnetic field levels in different regions of the magnetic floors and magnetic subfloors. Finite-element (FE) simulations are carried out to compute the magnetic field produced by magnetic floors. The numerical results and laboratory tests are compared and analyzed. Values of the magnetic field between 2 and 50 mT are computed and measured in different regions of magnetic floors. Finally, the static magnetic field levels obtained in the magnetic floors are compared with the permitted magnetic field values for different electronic devices, pacemakers, and other common objects utilized by persons in buildings. The results obtained in this paper show that magnetic floors are safe, and they can be employed in buildings without putting in risk electronic devices or persons with pacemakers. [ABSTRACT FROM AUTHOR]

This paper presents an electromagnetic design of a permanent magnet superconducting wind power generator with different stator teeth structures and armature winding arrangements. The main contribution of this paper is that a novel stator configuration is proposed, which is beneficial for superconducting machines. The topology of tapering poles makes it possible for the machine to carry larger current without severe magnetic saturation in the stator teeth. Meantime, the distributed arrangement of wires in the stator slot can reduce the ac loss in the same output power condition. Finite element analysis with commercial software is used to support these results. [ABSTRACT FROM AUTHOR]

This paper is a study on the application position of skew in order to reduce the cogging torque of a magnetic geared synchronous motor (MGM). The cogging torque affects the noise and vibration of the motor, so it should be reduced as much as possible. To solve this problem, a conventional permanent magnet (PM) synchronous motor is skewed to a PM. However, unlike other synchronous motors, the MGM has pole pieces (PPs), and a larger cogging torque is generated due to a larger reluctance difference. There have been few studies on the reduction of cogging torque of MGM, so it is essential to study the skew structure of MGM. Therefore, this paper has derived the optimum skew method by comparing and analyzing three models of MGM skewed to PM, PP, and PM and PP simultaneously. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution of the eddy currents in the permanent magnets (PMs) in the axial flux PM synchronous machine using a coupled solution of Maxwell’s equations and electric circuit network. This is based on calculating the axial field in an accurate way on the surface of the PM. This method is able to consider the effect of armature field and slots. The eddy currents are obtained by imposing this solution on the PM which is modeled by a simple electric network. This network is composed of simple resistances and inductances. The inductances are used to model the reaction field effect of the eddy currents flowing through the PM and also the skin effect. To show this effect, the machine is excited with different sources at different speeds. In addition, a variant of the model is made that neglects the inductances, in order to show in which conditions this low-frequency approximation is acceptable. It is concluded from this paper that inclusion of the reaction field is necessary when the machine is excited by a pulsewidth modulated (PWM) current, while for a sinusoidal excitation, the reaction field effect has minor contributions to the total eddy losses. In addition, the reaction field has major influence at higher speeds rather than lower speeds for PWM injection. In conclusions, for a preliminary design, the resistance model without the reaction field computation would be enough for the calculation of the PM losses. The circuit model is also capable of obtaining the solution with PM segmentation. In this paper, different PM segments were studied from the circuit model and the finite-element (FE) model point of view. Compared with the FE model, the circuit model has the advantage of flexibility in geometrical machine parameters, less CPU time, and accurate results for the PM losses up to 10%. [ABSTRACT FROM AUTHOR]

This paper investigates the partial irreversible demagnetization characteristics of magnets in flux-switching permanent magnet (FSPM) machines. Two different partial demagnetization mechanisms in the FSPM machines are modeled and demonstrated. The 2-D finite-element analysis (FEA) results for a baseline 10 kW 15 kr/min ferrite FSPM machine verify the validity of the proposed partial demagnetization model. Performance degradation due to demagnetization is evaluated for the baseline machine based on the FEA results. This paper also proposes a novel design to enhance the demagnetization withstand capability. This research reveals the most vulnerable region of the magnet to irreversible demagnetization in the FSPM machines. It also provides a guideline for developing demagnetization withstand capability improvement techniques. [ABSTRACT FROM PUBLISHER]

Permanent magnet (PM) materials are nowadays widely used in the electrical machine manufacturing industry. The eddy-current loss models of PMs used in electrical machines are frequently discussed in research papers. In magnetic steel materials we have, in addition to eddy-current losses, there are hysteresis losses when alternating current or a rotating flux travels through the material. Should a similar phenomenon be also taken into account in calculating the losses of PMs? Every now and then, authors seem to assume that some significant hysteresis losses are present in rotating machine PMs. This paper studies the mechanisms of possible hysteresis losses in PMs and their role in PMs when used in rotating electrical machines. [ABSTRACT FROM PUBLISHER]

This paper proposes a vector control strategy for independent control of two permanent-magnet synchronous motors (PMSMs) using a single four-leg inverter (4LI). An expanded two-arm modulation to obtain a balanced three-phase output voltage is described. This paper also proposes a method to compensate for the fluctuations in the neutral point voltage of two split capacitors in the dc link. The experimental results show that independent speed and position control of two PMSMs can be achieved using a single 4LI with the proposed vector control method. [ABSTRACT FROM AUTHOR]

In recent years, the increasing need in small satellite solutions triggers the miniaturization of attitude control systems. Reaction spheres were proposed as promising replacements of conventional reaction wheels for their $4\pi $ rotations. Since the generated control torques could be about any desired axes, a single reaction sphere is sufficient for three-axis stabilizations of spacecraft. This paper presents an innovative design of reaction spheres. Its driving unit is a combination of permanent magnets (PMs) and electromagnetic induction. This enables the generation of torques about three principle axes simultaneously. Meanwhile, a contactless bearing is integrated into the actuator design. Detailed designs and working principles of the reaction sphere are described. To investigate performance characteristics of the actuator, field modeling is of great importance and provides the basis for dynamics modeling. In this paper, an improved analytical model for dynamic fields excited by slotless distributed windings is presented for the first time. To study the cross coupling between PMs and electromagnetic induction, the static field generated by PMs is also modeled analytically. These developed models are validated through comparisons with numerical simulations. Electromagnetic torques generated by the actuator are calculated through the approaches of the Maxwell stress tensor and the Lorentz force law. Torque calculations based on the analytical field models deviate from those based on the numerical model slightly, with the maximum error within 4%. This means the presented analytical models allow to predict the electromagnetic field distribution and torques precisely. [ABSTRACT FROM AUTHOR]

This paper presents a complete design procedure for in-line evanescent mode filters using an innovative pseudoelliptic structure, namely, the strongly coupled resonator triplet (SCRT). The SCRT can be seen as the combination of a strongly coupled resonator pair (SCRP) and a third resonator next to the pair. Compared to the SCRP, which at the passband frequencies generates a pole and a transmission zero, the new SCRT is capable of generating an additional passband pole, thus leading to the design of more compact in-line filters. Similar to the SCRP, the basic structure for filter design purposes is obtained by embedding the SCRT between two outer resonators. The coupling mechanisms and functional properties of this basic structure are explained. A suitable circuit model for the SCRT is introduced, thus allowing the synthesis of a low-pass prototype as well as the evaluation of the coupling coefficients and resonating frequencies to assign to the physical filtering structure. The proposed design procedure is validated by means of several examples, one of which including the detailed dimensions and experimental results of a manufactured prototype. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the direct- and quadrature-axis inductances for linear tubular actuators with permanent magnet arrays, highlighting and featuring how they are affected by the end effects. A semi-analytical and an experimental analysis are performed to prove the influence of end effects on self- and mutual inductances. The synchronous parameters, i.e., d - and q -axis inductances of the actuator, are determined using a semi-analytical method and an experimental method. Once the synchronous parameters are all identified, high performance control methods (such as direct force control and vector control) may be implemented. [ABSTRACT FROM AUTHOR]

This paper deals with equivalent 2-D finite-element (FE) models of permanent magnet lead screw (PMLS), to accurately predict the thrust force. Due to the helical-shape permanent magnets (PMs), the magnetic fields of PMLS are typically 3-D and non-symmetric. However, the PMLS is approximately symmetric in some cases and an equivalent 2-D axis-symmetric FE model is developed instead of 3-D models. The problem lies in that no evaluation about the accuracy and applicability of the 2-D axis-symmetric FE model was offered in previous literature. In this paper, the 2-D axis-symmetric FE model is derived based on the concept of equivalent current sheets of PMs. The limitations of the existing 2-D axis-symmetric FE model are clarified, and a novel equivalent 2-D torque FE model is then proposed to predict thrust force with the gear ratio when the 2-D axis-symmetric FE model is not appropriate. It is shown that the choice of equivalent 2-D FE model depends on the lead angle of PMLS, 2-D axis-symmetric FE model is applicable in the range of (0°, 15°), and 2-D torque FE model is preferred in the range of (65°, 90°). [ABSTRACT FROM AUTHOR]

For the purpose of saving energy resources, it is extremely expected to develop highly efficient electric motors. Different types of permanent magnet (PM) arrangement can significantly affect the performance of the motors. Conventionally, the arrangement of the PMs is determined by designer’s experience. This paper focuses on the optimal design of PM arrangement in PM synchronous motors (PMSMs). We present a general pattern of the PM arrangement in PMSM. By varying the parameters of the general pattern, it can produce different types of PM arrangement in the rotor. The employed approach combines the global optimization method with the finite-element method for solving the optimization of the PM structures. Based on the proposed general pattern and optimization methods, the best PM arrangement in the motor can be automatically determined. In order to reduce computing loading, this paper employs the response surface models for reducing the computing time of objective functions. In the end, numerical tests are designed to showcase the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents an engineering modeling methodology for magnetostrictive materials based on a simplified piezo-electric governing equation. For verifying the modeling performance, a proof-of-concept non-contact strain sensor utilizing a prototype magnetostrictive (Fe–Ga alloy, Galfenol) strip on a steel plate is used to evaluate sensor performance prediction. Typically, the performance of Galfenol is measured in a compressional load region because it has a higher response. However, in this paper, we are aiming to develop a sensor for tensile stress measurement. To achieve a compression effect from a tension load in the sensing element, a Galfenol strip is aligned perpendicular to a tension bar so that tension in the bar creates compression in the strip via the Poisson effect. The experimental setup in this paper consists of a polycrystalline Galfenol strip bonded in the horizontal direction of a steel dog-bone shaped tension specimen. Permanent magnets are attached at each end of the Galfenol strip to provide an even magnetic bias field through the strip. The magnetic flux through the Galfenol strip is measured with non-contact Hall sensors during the tensile load test. The simulation results agree well with the experiments for the value of $H$ studied. [ABSTRACT FROM AUTHOR]

In this paper, a changeable winding brushless DC (BLDC) motor for the expansion of the speed region is described. The changeable winding BLDC motor is driven by a large number of phase turns at low speeds and by a reduced number of turns at high speeds. For this reason, the section where the winding changes is very important. Ideally, the time at which the windings are to be converted should be same as the time at which the voltage changes. However, if this timing is not exactly synchronized, a large current is generated in the motor, and the demagnetization of the permanent magnet occurs. In addition, a large torque ripple is produced. In this paper, we describe the demagnetization of the permanent magnet in a fault situation when the windings change, and we suggest a design process to solve this problem. [ABSTRACT FROM AUTHOR]

Typical vibrational harvesters using a high-permeability beam in a cantilever configuration exploit the field generated by a couple of counter-polarized permanent magnets facing the vibrating strip at the free end. Such a canonical position of the magnets does not permit one, however, to highlight the importance of the bias field pattern. A proof of concept archetype is realized in this paper, by which the influence of the magnetization profile along the length of the vibrating ferromagnetic beam is put in evidence. It demonstrates, in particular, that significant variations, even by a factor of three, of the output power can be obtained by a modification of the magnets arrangement. We discussed in this paper the behavior of a cantilever-based generator, where an Fe–Co high-permeability beam is made to vibrate inside an inhomogeneous magnetic field generated by permanent magnets, whose arrangement can modified in order to vary the magnetization profile along the vibrating laminae. The effects of such a profile are measured and analyzed by means of a simple 2-D numerical model, showing that the generated power can be enhanced by conveniently acting on the magnets configuration. The measurements show that, with a host acceleration of $5g$ rms ( g = 9.81$ m/ \text{s}^{2} ), a 6.72 mW time average output power is obtained for operating frequencies around 60 Hz. [ABSTRACT FROM AUTHOR]

In this paper, an analytical torque ripple model for interior permanent magnet synchronous machine (IPMSM) is introduced at first, which can be used to estimate the torque ripple. Then, the inductance variation due to magnetic saturation is analyzed through experimental investigations, which demonstrates that magnetic saturation has a great influence on the inductances, and hence the torque ripple minimization performance. Thus, this paper proposes an online parameter identification approach to estimate the inductances and incorporates them into the torque ripple minimization. The proposed parameter identification approach can estimate the dq-axis inductances accurately such that it brings significant torque ripple minimization improvement for IPMSMs. Numerical and experimental investigations have been conducted to validate the proposed approach based on a laboratory IPMSM. [ABSTRACT FROM AUTHOR]

Globally, the efficiency of industrial motors is regulated through minimum energy performance standards (MEPS) to reduce energy consumption and CO2 emission. Induction motor, used as a representative industrial motor, has a limit to efficiency improvement as the result of the additional copper loss of the rotor. To replace the induction motor, design of synchronous reluctance motor (SynRM) and permanent magnet assisted synchronous reluctance motor (PMa-SynRM), and the application of a small amount of permanent magnet, is actively studied in the industry. However, it is necessary to develop an ultrapremium efficiency motor beyond the superpremium efficiency to fulfill MEPS, which will be strengthened in the future. Therefore, this paper presents the optimal design method of SynRM by using the finite element method and response surface method to achieve superpremium efficiency. Furthermore, the redefinition of the loading ratio with shape parameters, and the design method of PMa-SynRM, using the loading ratio, is proposed to meet the ultrapremium efficiency. It is an effective design method that can shorten the time and process when designing ultrapremium efficiency PMa-SynRM from the existing SynRM, which is already mass-produced. [ABSTRACT FROM AUTHOR]

This paper presents the modified core loss calculation of the high-speed (HS) permanent magnet synchronous machines (PMSMs) with amorphous metal (AM) stator cores. In the initial stage of the HS PMSM design, the calculation of stator core loss is obtained according to the data of AM ribbon provided by the manufacturer, which causes a large error of AM core loss. So how to make the accurate calculation of the AM core loss with only the AM ribbon data from the manufacturer is impending in the initial and advanced design stages of HS PMSM development. In this paper, the characteristics of AM ribbon and AM stator core is measured and compared. According to the experimental results, the modification factor for the accurate calculation of AM core loss is obtained based on the loss characteristics of AM ribbon. Then, the no-load loss of a HS PMSM prototype with an AM stator core is analyzed by numerical methods and verified by experiments. The proposed modification factor of the AM core loss calculation can provide a reference for the design and analysis of HS AM PMSMs in the industry. [ABSTRACT FROM AUTHOR]

A modified configuration for Permanent Magnet Assisted Synchronous Reluctance Motors (PMaSyRM) is studied in this paper. Conventionally, the PM materials are inserted in the flux barriers region of the rotor. Consequently, the PMs sizing parameters will be restricted to the available space that may limit the efficient use of PMs benefits. In this study, a portion of the rotor structure is replaced with an Interior PM (IPM) rotor so that an axially segmented integration of IPM and SyRM is obtained. Thus, the PMs design is performed specifically in the IPM segment independent of the SyRM scheme, while the SyRM segment remains PM-less. The main motivation of this concept is to improve the contribution of the PM material in the total torque as well as utilizing the special property of the proposed rotor configuration for pulsating torque reduction. A computationally cost-effective algorithm is proposed for the optimal design of IPM-SyRM motor by which a low-power design is carried out for a lightweight electric vehicle. The results for torque profile characteristics, PM volume, power-factor, and efficiency are compared with a conventional PMaSyRM that has been optimally designed as the reference case. Finally, a prototype is constructed to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes a novel algorithm which made it feasible to predict the harmonic fault signatures under dynamic eccentricity in Permanent-Magnet synchronous machines with concentrated non-overlapping winding for any slot-pole combination. In the literature, only the appearance of the fractional harmonic components related with the pole number has been proposed but there are no studies to predict which exact components will rise in each topology. Initially, a mathematical equation is derived for the machine EMF under dynamic eccentricity based on the air gap permeance model. Later on, the terms of this equation are inserted in a Fault Signature Block Binary Array in which the position of each cell expresses a specific harmonic frequency component. After substitution of the machines parameters, the array results with zero and nonzero terms. The positions of the nonzero terms express the frequency components excited by this particular fault. 3-D FEA and experimental results of a Permanent-Magnet Axial-Flux Machine are used to validate the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper proposes a novel analytical model which combines subdomain method and magnetic equivalent circuit (MEC) method to predict the no-load performance of V-shape interior permanent magnet (IPM) motors with any slot-pole combination considering the nonlinearity of magnetic bridges (MBs). The V-shape magnets are equivalent to the form of distribution along radial and tangential directions, and the motor is divided into two corresponding structures to facilitate the establishment of subdomains. To consider the saturation of MBs, the MEC method are employed to obtain the permeability of MBs to establish the boundary conditions. The no-load magnetic field of slotless motor can be obtained by solving the equations established by boundary conditions, and the conformal mapping is used to consider the effect of slotting. The proposed model can be used to calculate the no-load magnetic field, back electromotive force, and cogging torque of IPM motor. The results are verified by finite element analysis (FEA) and experiments, which confirms the validity of the model for facilitating the motor design and optimization. Compared with FEA, the proposed method has the advantages of faster modeling, shorter time consuming and meanwhile achieves the approximate accuracy. In addition, U-shape motors with MBs can also be analyzed by this model. [ABSTRACT FROM AUTHOR]

Flux linkage estimation based on the voltage model has been widely employed in surface-mounted permanent magnet synchronous machine (SPMSM) sensorless drives due to its simple implementation. To deal with dc-offset and dc-drift problems, the pure integrator is modified as a programmable low pass filter (LPF)in practice. However, the estimation accuracy of the rotor position is affected by the adopted filter. Although the position deviation is compensated in steady-state based on the frequency characteristics of the filter, the compensation effect deteriorates during a dynamic process which severely degrades the sensorless control performance. In order to effectively tackle this problem, a novel compensation strategy based on the linear extended state observer (LESO) is proposed in this paper. With the constructed LESO in the estimated synchronous rotating reference frame, the position estimation error can be detected and compensated both in the steady and dynamic state. Moreover, the observer is enhanced to improve the estimation accuracy in linear acceleration and deceleration. Finally, the feasibility of the proposed method is verified under various operating conditions with a 5.5 kW SPMSM drive system. [ABSTRACT FROM AUTHOR]

Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree of insulation degradation of one turn in the winding of a PMSWG. Cosimulation method by combining finite element model and external circuits is used. Hilbert–Huang transformation is applied to detect the very early stage fault in interturn insulation by analyzing the stator current. Detection results show that the minimum detectable severity degree of interturn fault in this paper is 0.1488%, which is much better than the best record in the literature. [ABSTRACT FROM AUTHOR]

Cogging torque is a source of vibration and noise in PM machines. Its reduction is always sought by electrical machine designers. While its study, in radial-flux PM machines, can often be done using 2-D finite element analysis (FEA), 3-D FEA is always required when it comes to its study in axial-flux PM machines (AFPM). AFPM machines have an inherent 3-D electromagnetic structure. There is a rich literature concerning the study of cogging torque in AFPM machines. Indeed, most of the authors use 3-D FEA for its study. However, 3-D FEA is time consuming and always requires expertise to be done correctly. The goal of this paper is to show that alternative techniques, to study cogging torque in AFPM machines, do exist. It is shown that the analytical approach, used in this paper, can be as efficient as the 3-D FEA while saving a huge amount of time and necessitating less initial expertise. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has been undergoing dynamic development in recent years. The latest evolution of AM has been recognised as a key enabling technology in a wide range of applications, some of which include medical, aerospace and automotive industries. The use of AM opens new avenues for design solutions, otherwise challenging or impossible to realise when using more conventional techniques for manufacture. No- or low-material waste and high-flexibility are some of the attributes of modern AM. This expanded paper aims to provide an up to date overview of the existing examples of employing AM in construction of electrical machines. The paper reviews research and development work related to all integral components of an electrical machine assembly. These include active parts like coils/windings, electrical insulation, stator/rotor magnetic core packs, permanent magnets (PMs). The machine structural/mechanical and thermal management components are also discussed in the paper. Further to these, the authors make some comments/forecasts on how the AM could improve performance and manufacturability of the future electrical machines. [ABSTRACT FROM AUTHOR]

In this paper, the modular consequent-pole (MCP) rotor is adopted in the fractional-slot interior permanent magnet (IPM) machine to utilize the strong flux-focusing effect and reduce the leakage flux. Hence, the torque density and utilization ratio of permanent magnet (PM) material can be improved. However, the unacceptable unbalanced magnetic force (UMF) may arise due to asymmetric airgap flux density produced by consequent-pole topology. Thus, a pole-shaping method based on three-sectional arcs is proposed to suppress it. Due to the relatively complex rotor structure, the multiobjective optimization combined finite-element method with genetic algorithm is performed in this paper. Furthermore, the electromagnetic performance of the IPM machine with MCP rotor (namely IPM-MCP machine), including the open-circuit airgap flux density, phase back EMF, torque, PM utilization ratio, efficiency, flux-weakening capability and UMF, are compared with the conventional surface-mounted PM (SPM), IPM, and consequent-pole IPM (IPM-CP) machines. It is demonstrated that the IPM-MCP machine obtains the largest output torque in these machines. Meanwhile, the IPM-MCP and IPM-CP machines respectively have >30% and >20% higher PM utilization ratio than the conventional SPM and IPM machines while they obtain similar torque ripple and efficiency. Moreover, the IPM-MCP machine can obtain much lower UMF than the IPM-CP machine due to the effective suppression of asymmetric airgap flux density. Finally, a 12-slot/10-pole IPM-MCP machine is fabricated to verify the analyses. [ABSTRACT FROM AUTHOR]

In order to improve the performance of interior permanent magnet synchronous machine (IPMSM) based on space voltage vector modulation schemes, this paper presents a highly accurate online method to find the proper maximum-torque-per-ampere (MTPA) angles. This algorithm fully considers the nonlinear characteristics of the d-axis inductance, q-axis inductance, and permanent magnetic flux together. Additionally, the influences of temperature are taken into account. In this paper, the proposed method injects a small virtual angle signal into the current angle mathematically to track the stator current reference angle that is close to real MTPA points. Moreover, following a theoretical analysis method, the error of the virtual signal injection method is analyzed. Then, based on the results of error analysis, this paper proposes a compensation strategy that can significantly reduce the current angle error between the tracking point and real MTPA point. At last, various experiments on an IPMSM test bench verify the proposed control technique and overall performance. [ABSTRACT FROM AUTHOR]

In most multiobjective optimization problems of electrical machines, the weighted function method is used to convert them into single-objective optimization problems. This paper applies a kind of new multiobjective evolutionary algorithms (MOEAs), called adaptive multiobjective black hole (AMOBH) algorithms, to achieve effective multiobjective optimization of a tubular coreless linear permanent magnet synchronous motor (LPMSM). To reduce the computation cost of the MOEAs, a one-layer analytical model (AM) is presented for the tubular coreless LPMSM in this paper. The accuracy of the simplified one-layer AM is verified by comparisons with multilayer AM and finite element analysis (FEA) under different structure parameters. It is found that the simplified AM has good accuracy and can decrease the computation cost significantly. AMOBH algorithm is subsequently introduced. The optimal Pareto front with regard to thrust, copper loss, and permanent magnet volume are analyzed, and more diversified optimization results are provided. The final Pareto solution can be selected directly by practical physical values according to the application requirements. Finally, a prototype is fabricated for the selected design; its experimental results are provided and compared with those of the FEA results. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on current loop auto-tuning for self-commissioning of sensorless interior permanent magnet synchronous machine (IPMSM) drives. Well-tuned current controllers are essential for both high-performance operation and self-commissioning procedure. However, current controller design parameters, i.e., $L_{d}$ and $L_{q}$ , are not known at the beginning of the self-commissioning procedure where their estimation also has unique challenges. For example, an initial rotor position to determine the actual d- and q-axes is not known. Also, feedback controllers cannot be used in the estimation because they are not tuned yet. As a solution, this paper proposes a method to estimate the spatial inductance map by spatially scanning the motor via sinusoidal voltage injection in a controlled manner. Then it uses the estimated inductance values to tune the current controllers. The proposed method identifies $L_{d}$ and $L_{q}$ values using open-loop voltage injection without needing actual d- and q-axis positions. The whole procedure takes around a second. Practical considerations such as an automatic selection of the injection voltage, and digital control and dead-time effects are carefully addressed. The findings are experimentally verified on a 3-phase IPMSM drive. Furthermore, its applicability to different motor types is also demonstrated. [ABSTRACT FROM AUTHOR]

The rotor structure of synchronous reluctance machines (SynRel) is conventionally retained mechanically by iron ribs. In this paper, a novel structure for high-speed synchronous reluctance rotor is presented. The novelty of this paper is the proof of a concept of SynRel machine without iron ribs. Structurally, the rotor iron lamination segments are embedded in an adhesive resin material with high temperature resistance and mechanical strength. Three four-pole SynRel machines have been designed with the target of improving motor torque, and compared for different ribs configuration. It has been shown that the proposed motor performs enhanced torque, power factor, and efficiency with respect to conventional SynRel with iron ribs. An extensive sensitivity analysis of the ribless rotor geometry is carried out, followed by both mechanical analysis and experimental over speed test to guarantee its robustness above the operating speed range. The manufacturing procedure of this novel rotor is introduced. Finally, the experimental results on both SynRel prototypes are presented, showing the increase in torque, power factor, and efficiency of the proposed solution. This paper is a first step toward the definition of a viable and novel solution of SynRel machines with improved performance. [ABSTRACT FROM AUTHOR]

In order to suppress the torque ripple of an open-end winding permanent-magnet synchronous machine (OEW-PMSM), a q-axis current injection method is typically employed but the disturbances caused by the third flux linkage parameter mismatch can augment the torque ripple. To solve this problem, in this paper, first, a zero-sequence current (ZSC) and zero-sequence back-EMF observer (ZCBO) are proposed based on an adaptive sliding mode control, which is able to simultaneously estimate ZSC and zero-sequence back EMF under varying conditions. Based on this ZCBO, the estimated ZSC and zero-sequence back EMF could compensate for the one-step control delay and suppress the aforementioned disturbances. Second, although central hexagon modulation is employed in the predictive current control (PCC) scheme, zero-sequence voltage (ZSV) still exists in the zero-sequence path due to the dead time of the inverter, affecting the predictive accuracy of the ZCBO. To accurately establish the ZCBO, the ZSV caused by the dead time of the inverter is considered in the ZCBO. Finally, a comparative study of two types of methods is presented, and simulations established by MATLAB software and experimental confirmations are carried out to verify the effectiveness of the proposed PCC scheme in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a sensorless vibration harmonic frequency estimation for a servo system driven by a permanent magnet (PM) synchronous machine. Traditional vibration harmonic estimation relies on the measurement using external sensors. An accelerometer is typically installed in the servo system to measure the vibration harmonic signal. Because the accelerometer must be attached on the visibly vibrational location inside the system, this vibration detection results in both issues about installation and reliability. To overcome this drawback, this paper proposes a disturbance observer to estimate the vibration harmonic by using current and position signal. A real-time signal process is developed to identify the vibration frequency from estimated harmonic. A servo system with a 400-W PM machine is built to verify the proposed vibration harmonic and frequency estimation. This paper includes the comparative evaluation between the accelerometer-based vibration harmonic measurement and the sensorless estimation. [ABSTRACT FROM AUTHOR]

This paper presents the impacts of manufacturing tolerances on a 1 MW slotless permanent magnet synchronous motor used in an aircraft propulsion system. The motor was designed using multiphysics analysis of electromagnetics, mechanical structure and thermal analysis to obtain a high torque density. It has several governing characteristics, including a Halbach permanent magnet arrangement, slotless stator windings, an outer rotor, lower reactance and a high current density. Since the current density of this design is high, the existence of circulating currents should be considered for safe operation under different levels of manufacturing tolerances. In particular, the low reactance of the motor and the slotless structure greatly contribute to increase the circulating current. Therefore, this paper analyzes various factors affecting the circulating current such as eccentricity and imbalanced windings. Finally, an analytical model is used to calculate magnetic and electric loading, and non-linear finite element analysis are applied and compared to obtain the machine performance. [ABSTRACT FROM AUTHOR]

This paper investigates a new method for the demagnetization fault recognition and classification in double-sided permanent magnet synchronous linear motors that are used in linear motion applications. This method is based on time–time-transform (TT) coupled with extreme learning machine (ELM), which are especially suitable for the industrial occasions such as motor batch demagnetization inspection before delivery and periodic maintenance. First, a finite element analysis model with demagnetization faults is built to extract three lines (up-line, center-line, and down-line) magnetic flux density signals. Second, TT is first applied to conduct magnetic signals waveform transformation, and digital picture processing technology is innovatively used to extract the pixel rate of its diagonal elements contour surfaces as the fault feature. Then, machine learning algorithm called ELM is utilized as a classifier to obtain the unique fault labels that can represent the demagnetization occurred positions, sides, and severity types in detail. The validity and superiority of ELM is verified through comparison with back propagation neural network, and probabilistic neural network. Finally, prototype motor experimental platform is designed to confirm the correctness and effectiveness of this proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a detailed analysis of the electromagnetic force and vibration behavior of an axial flux permanent magnet synchronous machine (AFPMSM). First, the AFPMSM configuration and two types of dual three-phase winding are introduced. Subsequently, the electromagnetic force of the double-stator inner-rotor AFPMSM is investigated. Its spatial and temporal characteristics are derived analytically and validated through two-dimensional Fourier decomposition. A multiphysics model is established to calculate the vibration of the AFPMSM, which includes control, electromagnetic, structural, and vibration model. The accuracy of this multiphysics model is verified by the modal and vibration test. Furthermore, the vibration of the AFPMSM with three winding types considering current harmonics are calculated based on the multiphysics model. The vibration performance of the AFPMSM with three different winding types are compared and the mechanism of vibration is discussed. It was concluded that the novel detached winding could mitigate the vibration of dual three-phase AFPMSMs. Finally, the vibration test is carried out to validate the theoretical analysis and the experimental results agree well-with the simulation results. This paper provides an effective method for double-stator permanent magnet synchronous machine (PMSMs) to reduce vibration. [ABSTRACT FROM AUTHOR]

This paper improves the position sensorless drive by sensing actual machine phase voltages. A high-bandwidth phase voltage measurement is developed for pulsewidth modulation (PWM) voltage inverters. On the basis, the actual phase voltage is obtained based on the digital integration of PWM voltage using the capture modulator in existing drive microcontrollers (MCU's). Comparing to existing phase voltage measurement, no separated A/D converter and communication hardware are required because PWM pulses are directly measured using MCUs. However, for standard machines without neutral points, only line-to-line ac PWM voltages can be measured for the phase voltage reconstruction. Since the capture based on transistor-transistor logic (TTL) logics receives only digital signals, a preprocess circuit to convert ac PWM line voltages to equivalent digital signals is proposed. This paper clearly explains the voltage sensing hardware using MCU capture modulator. According to experimental results, a 150-MHz sampling rate for phase voltage measurement is achieved based on the proposed capture-based voltage measurement. Although the physical limitation of back electromotive force estimation still appears, the proposed phase voltage measurement substantially enhances the sensorless drive performance at low speed. [ABSTRACT FROM AUTHOR]

This paper analyzes different stator windings configurations for permanent-magnet synchronous machines during the presence of a stator turn fault. Due to the inverter pulsewidth modulation, the fault commonly occurs in variable-frequency permanent-magnet machine drives. In this paper, two types of windings are compared to identify key machine topologies that can achieve the reduced influence of the turn fault. When the machine is operated in real time, the windings with separated neutral points reduce the torque ripple caused by fault-reflected flux harmonics. Analytical models based on equivalent circuits are developed to predict the machine flux and torque waveform during the presence of the turn fault. All developed analytical models are verified by the finite-element analysis and experimental results on a 750-W surface permanent-magnet machine prototype. [ABSTRACT FROM AUTHOR]

The 3-D modeling technique presented in this paper, predicts, with high accuracy, electromagnetic fields and corresponding dynamic effects in conducting regions for rotating machines with slotless windings, e.g., self-supporting windings. The presented modeling approach can be applied to a wide variety of slotless winding configurations, including skewing and/or different winding shapes. It is capable to account for induced eddy currents in the conductive rotor parts, e.g., permanent-magnet (PM) eddy-current losses, albeit not iron, and winding ac losses. The specific focus of this paper is to provide the reader with the complete implementation and assumptions details of such a 3-D semianalytical approach, which allows model validations with relatively short calculation times. This model can be used to improve future design optimizations for machines with 3-D slotless windings. It has been applied, in this paper, to calculate fixed parameter Faulhaber, rhombic, and diamond slotless PM machines to illustrate accuracy and applicability. [ABSTRACT FROM PUBLISHER]