M. E. Mosleh, M. R. Besmi,
Volume 8, Issue 1 (3-2012)
Abstract
This paper presents an approach to calculate the equivalent stray capacitance (SC) of n-turn of the helical flux compression generator (HFCG) coil with multi layer conductor wire filaments (MLCWF) in the form of rectangular cross-section. This approach is based on vespiary regular hexagonal (VRH) model. In this method, wire filaments of the generator coil are separated into many very small similar elementary cells. By the expanded explosion in the liner and move explosion to the end of the liner, the coil turns number will be reduced. So, the equivalent SC of the HFCG will increase. The results show that by progress of explosion and decrease of the turns’ number in the generator coil total capacitance of the generator increases until the explosion reaches to the second turn. When only one turn remains in the circuit, a decrease occurs in the total capacitance of the generator.
F. Tootoonchian, K. Abbaszadeh, M. Ardebili,
Volume 8, Issue 3 (9-2012)
Abstract
Resolvers are widely used in electric driven systems especially in high precision servomechanisms. Both encapsulated and pancake resolvers suffer from a major drawback: static eccentricity (SE). This drawback causes a significant increase in resolver output position error (RPE) which could not be corrected electronically. To reduce RPE, this paper proposes a novel structure with axial flux. Proposed topology, design guidelines, optimization procedure and several key features to improve the sensitivity of axial flux resolver (AFR) against SE are studied. Furthermore, to minimize RPE an optimized design is attained. The machines are investigated in detail by using d-q model and 3D time stepping finite-element analysis. The results of theses two methods are compared and both prototype machines (proposed and optimized) are built. In order to evaluate proposed topologies, an experimental test setup is devised. Finally, the experimental results of the prototype machines verified the analysis results.
A. Jabbari,
Volume 13, Issue 4 (12-2017)
Abstract
A 2D analytical method for magnetic vector potential calculation in inner rotor surface mounted and surface inset permanent magnet machines considering slotting effects, magnetization orientation and winding layout has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in quasi- Cartesian coordinate by using sub-domain method and hyperbolic functions. The developed method is applied on the performance computation of two prototypes surface mounted permanent magnet motors and two prototypes surface inset permanent magnet motors. A radial and a parallel magnetization orientation is considered for each type of motor. The results of these models are validated through FEM method.
A. Jabbari,
Volume 14, Issue 3 (9-2018)
Abstract
Brushless permanent magnet surface inset machines are interested in industrial applications due to their high efficiency and power density. Magnet segmentation is a common technique in order to mitigate cogging torque and electromagnetic torque components in these machines. An accurate computation of magnetic vector potential is necessary in order to compute cogging torque, electromagnetic torque, back electromotive force and self/mutual inductance. A 2D analytical method for magnetic vector potential calculation in inner rotor brushless segmented surface inset permanent magnet machines is proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in a quasi- Cartesian polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.
M. S. Hosseini, H. Javadi, S. Vaez-Zadeh,
Volume 16, Issue 1 (3-2020)
Abstract
Linear flux switching motors with simple passive segmented secondary, referred as Segmented Secondary Linear Flux Switching Motors (SSLFSMs), have low cost secondary and therefore are applicable to transportation systems like Maglev. However, it is shown that the SSLFSMs suffer from high thrust ripples. In this paper, minimizing SSLFSM thrust ripples besides maximizing its developed thrust are performed by considering the motor dimensions as design variables. Since the optimization of the motor is a high dimensional problem, a multi-level optimization method is employed to improve the machine performances and efficiency. According to the effects of the design variables on the optimization objectives, a sensitivity analysis is carried out to divide the design variables into two levels: mild-sensitive level and strong-sensitive level. Then, the two levels of design variables are optimized based on a mathematical model. Two different optimization methods as the Design of Experiment (DOE) and the Response Surface Method (RSM) are used in mild-sensitive level and the Genetic Algorithm (GA) is also used in strong-sensitive level. Based on FEM analysis, electromagnetic performance of the original motor and the optimal one are compared and the validity of the proposed optimization method is verified. Also, the effectiveness of the mathematical model used in thrust and thrust ripples calculations is evaluated and verified.
A. Jabbari, F. Dubas,
Volume 16, Issue 1 (3-2020)
Abstract
In this research work, an improved two-dimensional semi-analytical subdomain based method for performance computation in IPM machine considering infinite-/finite-magnetic material permeability in pseudo-Cartesian coordinates by using hyperbolic functions has been presented. In the developed technique, all subdomains are divided into periodic or non-periodic regions with homogeneous or non-homogeneous boundary conditions (BCs), respectively. Taking into account the appropriate interfaces conditions in the presented coordinates system, the machine performances including magnetic flux density, cogging/electromagnetic torque, back-EMF, and self-/mutual induction have been calculated for three distinct values of soft-magnetic material relative permeability (viz, 200, 800 and ∞). The semi-analytical results are compared and confirmed by the FEA results.
A. N. Patel, B. N. Suthar,
Volume 16, Issue 1 (3-2020)
Abstract
Cogging torque is the major limitation of axial flux permanent magnet motors. The reduction of cogging torque during the design process is highly desirable to enhance the overall performance of axial flux permanent magnet motors. This paper presents a double-layer magnet design technique for cogging torque reduction of axial flux permanent magnet motor. Initially, 250 W, 150 rpm axial flux brushless dc (BLDC) motor is designed for electric vehicle application. Initially designed reference axial flux BLDC motor is designed considering 48 stator slots and 16 rotor poles of NdFeb type single layer permanent magnet. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of reference motor. Additional layer of the permanent magnet is created keeping usage of permanent magnet same with an objective of cogging torque reduction. Three-dimensional finite element modeling and analysis have been performed to obtain cogging torque profile of improved axial flux BLDC motor with double layer permanent magnet design. It is analyzed that double-layer magnet design is an effective technique to reduce the cogging torque of axial flux BLDC motor.
H. Davari, Y. Alinejad-Beromi,
Volume 16, Issue 1 (3-2020)
Abstract
In this paper, at first, a 24/16 three-phase switched reluctance motor is designed, then the rotor poles shape tips corrected for reduction ripple of single-phase torque waveform. By doing this, the single-phase torque waveform has a flat surface and consequently, the single-phase torque ripple is reduced. Also, due to the commutation between the machine phases, the torque drops during this time, which are known as torque pits. To reduce the ripple torque at these points, which requires overlap between the two successive phases of the machine, the pulse width of the excitation of the machine phases is adjusted. Comparisons have been made between two types of direct current excitation and chopped current (with different pulse widths). The results show that for constant pulse width under chopped current, applying the arc and modifying the shape of the rotor poles can reduce the torque ripple by 3.4%. Also, by applying chopped current control, the torque ripple was reduced by 46.7% compared to its conventional design structure.
P. Vahedi, B. Ganji, E. Afjei,
Volume 16, Issue 4 (12-2020)
Abstract
Using ANSYS finite element (FE) package, a multi-physics simulation model based on finite element method (FEM) is introduced for the multi-layer switched reluctance motor (SRM) in the present paper. The simulation model is created totally in ANSYS parametric design language (APDL) as a parametric model usable for various conventional types of this motor and it is included electromagnetic, thermal, and structural analyses. The static characteristic of flux-linkage with a phase, phase current waveform, instantaneous torque, and electromagnetic losses are predicted using the developed electromagnetic model. Carrying out 3D FE thermal analysis, the temperature rise due to the calculated core and copper losses is predicted in the developed thermal model. The transient, modal and harmonic analyses are done in the introduced structural model to determine the mode shapes, natural frequencies, displacement, and sound pressure level (SPL) in both time and frequency domains. In order to evaluate the developed simulation model, it is applied to a typical multi-layer SRM, and simulation results related to all the above-mentioned analyses are presented.
A. Jabbari,
Volume 17, Issue 1 (3-2021)
Abstract
In this paper, we present a semi-analytical model for determining the magnetic and electromagnetic characteristics of spoke-type permanent magnet (STPM) machine considering magnet segmentation and finite soft-material relative permeability. The proposed model is based on the resolution of the Laplace’s and Poisson’s equations in a Cartesian pseudo-coordinate system with respect to the relative permeability effect of iron core in a subdomain model. Two different magnet-segmented STPM machine was studied analytically and numerically. The effect of the iron core relative permeability on the STPM machine performances was investigated at no-load and on-load conditions with respect to certain values of iron core relative permeability by comparing cogging torque, electromagnetic torque ripple, and reluctance torque ripple waveforms. In order to validate the results of the proposed analytical model, the analytical and numerical results were compared. It can be seen that the analytical modeling results are consistent with the results of numerical analysis.
A. Jabbari, F. Dubas,
Volume 17, Issue 2 (6-2021)
Abstract
In this paper, we present a mathematical model for determining the optimal radius of the iron pole shape in spoke-type permanent-magnet (PM) machines (STPMM) in order to minimize the pulsating torque components. The proposed method is based on the formal resolution of the Laplace’s and Poisson’s equations in a Cartesian pseudo-coordinate system with respect to the relative permeability effect of iron core in a subdomain model. The effect of PM width on the optimal radius of the iron pole has been investigated. In addition, for initial and optimal machines, the effect of the iron core relative permeability on the STPMM performances was studied at no-load and on-load conditions considering three certain PM widths. Moreover, the effect of iron pole shape on pulsating torque components with respect to certain values of iron core relative permeability was studied by comparing cogging torque, ripple and reluctance torque waveforms. In order to validate the results of the proposed analytical model, three motors with different PM widths were considered as case studies and their performance results were compared analytically and numerically. Two prototype spoke-type machines were fabricated and the experimental results were compared to analytical results. It can be seen that the analytical modeling results are consistent with the numerical analysis and experimental results.
J. Sepaseh, N. Rostami, M. R. Feyzi,
Volume 17, Issue 4 (12-2021)
Abstract
A new axial magnetic gear (AMG) with enhanced torque density and reduced cogging torque is proposed in this paper. In the new structure, the direction and width of permanent magnets in high-speed rotor are changed and permanent magnets are removed from the modulator while the low-speed rotor remains unchanged. The torque density of the proposed magnetic gear is enhanced by using an appropriate direction and pole pitch for permanent magnets of high-speed rotor. The proposed AMG is compared with recent structures in the literature with the highest torque density. Three-dimensional (3D) finite element analyses are employed to obtain the cogging torque and torque density. The results of the analysis indicate that not only torque density increases but also cogging torque decreases dramatically.
S. Hasanzadeh, M. Yazdanian, S. M. Salehi,
Volume 18, Issue 3 (9-2022)
Abstract
Over the past four decades of developing superconducting machines, many topologies have been suggested. The most successful topology of high-power superconducting (HPS) machines is an air-cored radial flux synchronous machine. There are two possible topologies for this type of machine, rotational field, and stationary field. In this paper, the relative advantages and disadvantages of these topologies are compared in detail. Analytical study of these topologies shows that the inversed machine topology leads to more efficient high-temperature superconductor (HTS) wire utilization and hence more economical production. In order to confirm the result obtained by analytical calculations, 2-D finite element model (FEM) of the machine is utilized.
F. Tootoonchian, M. Amiri,
Volume 19, Issue 1 (3-2023)
Abstract
Multi-Speed resolvers are desirable position sensors for high performance closed-loop control of inverter driven machines due to their high accuracy. However, developing a winding with high number of poles with limited number of slots is a main challenge in achieving multi-speed function. Therefore, in this paper different winding configuration are proposed to achieve 5-X performance of a disk type wound-rotor resolver. Then, the best winding is chosen for experimental verification. In addition to the accuracy of the sensor, the optimal winding selection index is defined considering copper usage, number of winding layers (overlapping or non-overlapping configurations), the number of turns for each coil of the winding (variable or constant turn configurations), and the amplitude of the fundamental harmonic. An objective function is defined involving all the mentioned indices with different weights determined based on the importance of each index. Finally, a prototype of the sensor with the best winding is built and tested. The experimental measurements verify the results of the simulations that are obtained using 3-D time setting finite element analysis.
Ali Jabbari, Ali Badran,
Volume 19, Issue 3 (9-2023)
Abstract
Cost reduction, increased efficiency and reliability, extended service life, reduced noise and vibration, and environmental friendliness are critical for new generation wind turbines and electric vehicles. Segmented Hybrid Permanent Magnet (SHPM) machines, on the other hand, which are primarily segmented PMs combined with different materials, dimensions, and magnetization directions, offer a way to meet these needs. In this study, we present nine topologies of segmented PM-rotor SHPM generators based on the Taguchi experimental design method, while presenting a simple and accurate model based on subdomain method for estimating the magnetic performance characteristics of SHPM machines. An analytical model is provided. Magnetic partial differential equations (MPDEs) are represented in a pseudo-Cartesian coordinate system, and with appropriate boundary conditions (BC) and interface conditions (IC), the general solution and its Fourier coefficients are extracted using a variable separation approach. The performance characteristics of nine of the SHPM machines studied were compared semi-analytically and numerically. Two prototype SHPM machines were manufactured and semi-analytical modeling results were compared with finite element analysis (FEA) methods and experimental testing (load mode) on a generator. The FEA simulation and experimental test results have a maximum error rate of about 3, confirming the high accuracy of the provided semi-analytical model. We compare the induced voltage, torque ripple and magnetic torque among the investigated topologies.
Ali Jabbari, Hassan Moradzadeh, Rasul Lotfi,
Volume 19, Issue 4 (12-2023)
Abstract
Along with the development of hybrid electric vehicles, researchers are trying to reduce existing limitations such as noise and environmental concerns and improve the efficiency and reliability of these systems. The use of magnetic gear technology is one of the solutions that have been recently proposed to remove these limitations and achieve higher benefits. In this paper, a mechanically coupled magnetic geared (MCMG) machine has been introduced. An accurate analytical model based on the subdomain method is presented to calculate the magnetic machine performance. To do this, first, a pseudo-Cartesian coordinate system is specified, and then the constitutive equations, i.e. Laplace’s and Poisson’s equations are rewritten for different regions of the machine. The separation of variables method was used to determine the general solution of the equations. Then by applying appropriate interface and boundary conditions, the Fourier coefficients of the equations were determined. To verify the analytical results, the performance of the proposed magnetic machine is numerically simulated using the finite element method in commercial software, and then a prototype is built and tested in three distinct modes. By comparing the analysis results with numerical simulation results and experimental tests, the high accuracy of the proposed analytical model can be confirmed.
Reza Mirzahosseini, Elham Rahimi Namaghi,
Volume 19, Issue 4 (12-2023)
Abstract
In this paper, a new topology of fractional slot concentrated winding double rotor axial flux permanent magnet synchronous motor (FSCW-DRAFPMSM) is introduced. The desired structure consists of a nonslotted stator core and two rotor discs. The pole number of the two rotors is different and these two rotors rotate at different speeds in opposite directions. A sample motor with an output power of 200 Watts is designed with the proposed structure. The two rotors of this sample motor rotate with speeds of 1200 and 857 rpm. The Finite Element Method (FEM) is employed to evaluate the performance of the proposed structure. Some performance characteristics of the case study machine, such as the Back EMF, input power, and electromagnetic torques of two rotors are presented to confirm the correctness of the operation of the proposed structure. In addition, the shifting technique is used to improve the Back EMF waveform of the machine. An analytical formula is proposed for calculating the fundamental component of the Back EMF waveform. The accuracy of the formula is approved by FEM.
Fateme Zare, Farid Tootoonchian,
Volume 20, Issue 2 (6-2024)
Abstract
The Recent development of 2-DOF electrical machines leads to increasing need for 2-DOF position sensors. Using a planar sensor instead of two linear ones decreases the complexity, and cost of the employed drive. Therefore, in this paper a new slotless configuration is proposed for the planar resolver, that simplifies the manufacturing of the sensor. Then, the optimal combination of the stator/mover number of coils is determined based on the proposed analytical model. Finally, to reduce the number of integrated parts of the proposed resolver, a new configuration with skewed coils is proposed. The success of the developed model and the presented configuration is validated using three-dimensional finite element analysis.
