Magnetomotive Force Research Articles

Torque improvement investigation of a double rotor permanent magnet motor based on effective utilization of magnetic field coupling

AbstractIn this paper, a torque improvement method is presented for a double rotor (DR) permanent magnet motor, where the key is to conduct the study based on effective utilization of magnetic field coupling. To facilitate systematic analysis, the magnetomotive force (MMF) and airgap flux density considering magnetic coupling effect are deduced and analysed. It contributes to building the relationships between the output torque caused by magnetic coupling and magnetic field harmonics. By introducing the coupling sensitivity coefficient, the coupling harmonics in the inner and outer airgap magnetic fields are obtained. Then, two coupling harmonic groups are further determined in terms of phase difference and torque contribution, where one of them is required to be enhanced and the other is needed to be reduced. On the basis of this, a comprehensive coupling factor is defined purposely to realise the design and evaluation of the characteristics of coupling harmonic groups. Some motor performances are analysed in details, including the torque, torque ripple, overload capability, and so on. Finally, a prototype motor is manufactured to verify the feasibility of the presented studies of the DR motor.

Improvement of electromagnetic torque of BLDC motor for electrical cutter application

As the advancement of brushless direct current (BLDC) motor is rising, it has been an advantage to use the motor for a wide range of applications. Its robustness and torque development have benefited small applications, such as the agriculture cutter. However, dropping performances of conventional BLDC are affected by the shape of the rotor that has unused magnetic flux. Therefore, this research aimed to analyze the electromagnetic torque by reducing the unused flux from an electromagnetic point of view. Two BLDC models with different slot-pole numbers and rotor types were modeled and simulated with equal permanent magnet volume, and magnetomotive force (MMF). Finite element method (FEM) software was used to compute back electromotive force (BEMF), cogging torque, electromagnetic torque, and magnetic flux density of the BLDC models. As a result, 9/8 slot-pole with zero ferromagnetic underneath the permanent magnet had the highest BEMF and torque produced compared to the conventional type, with a percentage difference of 27%. In conclusion, this research presents the motor that had an improvement of electromagnetic torque for electrical cutter application.

Toward a Novel Characterization of Transformer Interturn Faults Based on Arc-Induced Transients in Winding Magnetomotive Force

Toward a Novel Characterization of Transformer Interturn Faults Based on Arc-Induced Transients in Winding Magnetomotive Force

Torque Ripple Suppression With Compensation Control Method for Permanent Magnet Synchronous Motor With Asymmetric Magnetomotive Force

Torque Ripple Suppression With Compensation Control Method for Permanent Magnet Synchronous Motor With Asymmetric Magnetomotive Force

Pole-Changing Field Modulation Permanent Magnet Motor Based on Magnetomotive Force Offset

Pole-Changing Field Modulation Permanent Magnet Motor Based on Magnetomotive Force Offset

Low Vibration Research and Design of in-Wheel V-Shaped PM Motor From the Perspective of Winding Magnetomotive Force

Low Vibration Research and Design of in-Wheel V-Shaped PM Motor From the Perspective of Winding Magnetomotive Force

Effect of induced electric field parameters on physiochemical characteristics and microorganism of orange juice

AbstractThe induced electric field (IEF) was produced via an oscillating magnetic field, for direct heating of orange juice within a winding coil. During the process, the applied magnetic field was at the range from 0.07 to 1.43 T with 50 kHz. Then, the numerical relationships between excitation voltage, magnetic field, IEF, induced current density, magnetomotive force and energy efficiency were investigated. Since a rectangular wave of excitation voltage was applied, the sawtooth waveform of induced voltage or IEF loaded on the juice was observed. As the magnetic field increased, outlet temperature and induced current density in the juice was improved, the maximum values were 99.5°C and 0.50 A/cm2, respectively, at a conductivity 4.53 mS/cm for the residence time of 4.5 min. However, the efficiency of the process exhibited a negative correlation with the escalation of excitation voltage. At initial colony count about 4.50 log colony‐forming units/mL, the IEF pasteurization reduced all the aerobic microorganisms, molds, and yeasts in the juice, which were evaluated at detectable limits below 1 log colony‐forming units/mL. Moreover, all treatments had no significant effects on pH, total soluble solids and titratable acidity of the juice (p > 0.05). In particular, there was also no significant change in color parameters after IEF pasteurization (p > 0.05). It indicated a significant decrease in vitamin C and total phenolic content of the control groups (p > 0.05), but no significant change in carotenoid content was observed in all treated juice (p > 0.05). heating technology using IEF has the potential to the pasteurization of fruit juice.Practical applicationsInduction electric field technology has progressed rapidly in the past 2 years, it can use oscillating alternating magnetic field to realize the direct heating of liquid food. The process has thermal and non‐thermal effects, at 65–70°C, within 15–30 s to achieve the commercial asepsis of acidic liquid food. After the pasteurization, it can better maintain the color and flavor of the juice. We have assembled a laboratory prototype for testing in the early stage, the processing capacity is at the range of 0–10 L/h. Currently, the system has been able to reach the pilot production scale with the processing capacity of 100–500 L/h. Through the use of highly permeable magnetic materials, the energy consumption per ton of juice processing is controlled at 120 k·Wh level for the pasteurization and is expected to achieve a larger processing capacity in the future.

Retraction Notice: Analysis of Suspension and Guidance System of EDS Maglev Based on a Novel Magnetomotive Force Model

Retraction Notice: Analysis of Suspension and Guidance System of EDS Maglev Based on a Novel Magnetomotive Force Model

Analytical modeling of cylindrical eddy current brakes and multi-objective optimization based on game theory

With the research and development of eddy current brake (ECB), today ECBs have been applied in a variety of fields including vibration control and braking of strong impact loads.The application of a new cylindrical structure eddy current brake (ECB) for strong impact braking of large machinery has been discussed recently. Its high-speed and high-kinetic-energy braking conditions require different analytical and optimization design models and methods from what has been addressed in previous studies. For subsequent more engineering-oriented research and optimization, modeling methods are needed, as well as analysis and optimization studies for braking forces and critical speeds of interest. In this work, a magnetic equivalent circuit model is established, and the influence of eddy current induced during application is taken into account by considering it as a magnetomotive force in the model. The braking force is calculated with the MEC model and an approximate electric field cross-section method. A small prototype experiment is carried out and proves the correctness of the proposed model. Using the proposed and FEM model, parameters of the ECB are analyzed. Then, aiming at design objectives of the ECB that are somewhat competitive under this special braking condition, a multi-objective optimization model is established using the Stackelberg game strategy. An FEM model is built and assessed based on optimization results. The results indicate that the multi-objective optimization model based on the Stackelberg game is effective for the design of this ECB structure.

Improved design-oriented analytical modelling of flux switching PM machines

Purpose This paper aims at the analytical formulation of the electromagnetic features of flux switching permanent magnet (PM) machines with emphasis on the PM air gap flux density and armature magnetic reaction. Design/methodology/approach The PM air gap flux density is formulated considering three different analytical models. These differ by the incorporation of the air gap magnetic saliency level from the stator side. In addition, the armature magnetic reaction is investigated based on a simplified magnetic reluctance circuit that considers the flux switching permanent magnet machines magnetic circuit geometry specification. Then, the no- and on-load torque is predicted based on the two air gap flux densities. Findings It has been found that the PM air gap flux density considering the stator saliencies with trapezoidal magnetomotive force waveform presents the highest accuracy. Despite the simplicity of the magnetic equivalent circuit-based approach, the predicted air gap armature magnetic reaction is in good agreement with the finite element analysis (FEA) one. These lead to the analytical predictions of the no- and on-load torque which is characterized by an acceptable accuracy. Research limitations/implications This work should be extended to experimental validation of the FEA results regarding the torque production generation. Originality/value The paper proposes an improved design-oriented analytical approach with emphasis on the PM air gap flux density and the armature magnetic reaction of flux switching PM machines.

Magnetoresistance and Magnetocapacitance Effect in Magnetic Tunnel Junction with Perpendicular Anisotropy of Magnetic Electrodes Tb22−δCo5Fe73/Pr6O11/Tb19−δCo5Fe76

This paper presents the results of studies of the effects of magnetoresistance and magnetocapacitance in magnetic tunnel junctions [Formula: see text]Co5[Formula: see text]/Pr6[Formula: see text]/[Formula: see text]Co5[Formula: see text] with perpendicular anisotropy of magnetic electrodes and a paramagnetic barrier layer. Experimentally measured values of tunnel magnetic resistance and tunnel magnetic capacitance in such contacts exceed 100% at room temperature. The paper analyzes the effect of magnetization reversal of one of the electrodes on the conductivity of magnetic tunnel junctions with electrodes that have perpendicular anisotropy. It is shown that significant changes in tunnel magnetic resistance and tunnel magnetic capacity in such contacts can be explained by the separation of electrons with major and minor spin polarization in the inverse nanolayer in the interface region. The separation of polarized electrons is caused by the magnetomotive force acting on the electron spin in a strongly gradient magnetic field. Such a magnetomotive force occurs with antiparallel magnetization of the magnetic electrodes and it has opposite directions for major and minor polarized electrons. As a result of the spatial separation of polarized electrons in the inversion layer, an inhomogeneous distribution of the electron density along the direction of magnetization of the magnetic contacts occurs. As a result, an additional Coulomb barrier between the magnetic electrodes and the dielectric nanolayer appears in the tunnel contacts and an additional spin capacitance appears.

Vector magnetic circuit analysis of silicon steel sheet parameters under different frequencies for electrical machines

AbstractSilicon steel sheets (SSSs), serving as the principal constituent of the magnetic circuit in electric machines, necessitates precise modelling and accurate computation using magnetic circuit theory as a prerequisite for analysing the characteristics of electric machines. Nevertheless, the conventional magnetic circuit theory, limited to a single reluctance component, fails to address the phase relationship between magnetomotive force and magnetic flux, and inadequately represents the magnetic flux distribution observed under high‐frequency conditions. Consequently, the existing magnetic circuit model for SSSs remains imperfect in its current state. Fortuitously, the advent of magductance has effectively addressed these challenges. Building upon magductance, this study deduces the fundamental laws and theorem within the vector magnetic circuit theory. Subsequently, a distributed parameter vector magnetic circuit model for the SSSs is constructed, accompanied by the derivation of expressions pertaining to its reluctance and magductance. The authors propose the transfer function composed of reluctance and magductance parameters, successfully resolving the phase between the magnetic circuit vectors, the magnetic flux distribution, and the magnetic circuit loss under different frequencies for SSSs. Finally, experimental findings affirm the efficacy and validity of the distributed parameter vector magnetic circuit model for SSSs. The proposal of vector magnetic circuit theory opens a whole new door for the analysis, computation, and optimisation of electric machines.

Thermal analysis of sinusoidal doubly salient Electro-Magnetic Machine with distributed magnetomotive forces considering complex heat distribution and material thermal characteristics

Sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces has DC excitation and AC armature windings in the same stator slot, which leads to the complicated distribution of heat sources and thermal resistances. One of the keys to design this motor is to estimate the temperature rise accurately. In this paper, the thermal performance of the motor materials at different temperatures was tested. According to the complex structure characteristics, the layered and sub-regional equivalent model of the stator slot is proposed. The model not only uses the material thermal data obtained from experiments, but also considers the complex thermal resistances and AC/DC losses distribution in the slots, as well as the influence of winding and insulation processes on the temperature rise of the motor, which is conducive to obtaining the highest point of the motor temperature and ensuring the calculation accuracy. The 3-D global steady-state temperature distribution of sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces is studied, and the temperature rise of each part under different current densities is also analyzed. Finally, the temperature experiment of the prototype is carried out. The experiments show that the accurate loss calculation and thermal parameters make the maximum error between the simulation model and the actual measurement is 3.8 °C. The results not only guide the selection of reasonable armature and excitation winding current density of sinusoidal doubly salient electro-magnetic machine with distributed magnetomotive forces, but also provide data and experience support for temperature estimation of motors with complex winding distribution.

Electrical Machine Winding Performance Optimization by Multi-Objective Particle Swarm Algorithm

The present work aims to optimize the magnetomotive force and the end-winding leakage inductance from a discrete distribution of conductors in electrical machines through multi-objective particle swarm heuristics. From the development of an application capable of generating the conductor distribution for different machine configurations (single or poly-phase, single or double layer, integral or fractional slots, full or shortened pitch, with the presence of empty slots, etc.) the curves of magnetomotive force and the end-winding leakage inductance associated with the winding are computed. Taking as an optimal winding the one that presents, simultaneously, less harmonic distortion of the magnetomotive force and less leakage inductance, optimization by multi-objective particle swarm was used to obtain the optimal electrical machine configuration and the results are presented.

Analysis, Design and Effectuation of a Tapped Inductor Current Converter with Fractional Output for Current Source Systems

This article proposes a new connection method of tapped inductors that works in the current source, which enables the current-mode power converter circuit to have a new topological relationship. Usually, in a switched-inductor circuit, a stable output multiple is obtained through the connection of the inductor and the switching devices. This is because the tapped point on the inductor varies, and the magnetomotive force (mmf) of inductance is adjusted. Thereby, the output current is controlled by the states of switching devices within a certain range. This optimized circuit structure can adjust the output current according to load changes in practical applications without changing the input power supply. The proposed method has been verified for its feasibility through detailed analysis and hardware work. The principal analysis based on the flux linkage and the PSIM simulation confirms that the theoretical circuit can be implemented. Finally, a hardware circuit is built to obtain real and feasible conclusions, and it is verified that the circuit can achieve a stable output and variable current within a specific range. The proposed work presents an alternative power conversion methodology using the active switching of mmf, and it is a stable and simple power conversion technique.

Analysis and multi-objective optimization design of sinusoidal DSEM with two different excitation modes based on Gray-Fuzzy-Taguchi method

The nonlinearity of sinusoidal doubly salient electro-magnetic machine (SDSEM) leads to the fuzzy optimization range of its design parameters. And there is a conflict problem in multiple optimization objectives. Therefore, the multi-objective optimization of SDSEM with two different excitation modes is carried out based on the Gray-Fuzzy-Taguchi method. Firstly, the proposed sinusoidal method of square wave back electromotive force (EMF) phase modulation is introduced. And the key parameters to improve the symmetry and sinusoidal degree of the back EMF waveform are pointed out. Then, the sensitivity of key parameters is analyzed and the signal-to-noise (S/N) ratio is calculated by Taguchi orthogonal test. Secondly, the S/N ratio is linearly normalized by grey correlation analysis. Then, fuzzy reasoning is used to synthesize multiple performance indexes of the motor into a multiple performance characteristics index (MPCI) value, and the optimal scheme is obtained. Finally, the optimized SDSEM with concentrated magneto-motive forces (SDSEM-CF) and SDSEM with distributed magneto-motive forces (SDSEM-DF) are simulated and compared. The SDSEM-DF prototype is developed and verified by experiments. The results show that the no-load back EMF of the prototype has a good sinusoidal degree. Based on vector control, the sinusoidal drive of DSEM is realized without increasing the control complexity, which greatly reduces the torque ripple of the flux reluctance motor.

Effect of stator winding chording on the performance of five phase synchronous reluctance motor

The effect of winding chording on five-phase synchronous reluctance motor (SRM) modelled in phase variables is presented. The stator winding configuration is shifted a pole pitch from a full-pitch configuration to a 54 degrees over-full-pitched configuration incorporating the effect of 3rd harmonic of the air-gap magneto-motive force in the inductance equations. The models are monitored on starting, synchronism, loading, faults and loss of synchronism. These are considered simultaneously with vector potential, rotor speed, air-gap flux linkage and winding current. The phase variable (analytical) models have been simulated by using MATLAB/Simulink software while ANSYS Maxwell software has been used to simulate the finite element model (FEM) of the motor for corresponding chording ranges for comparison on direct online starting (DOL). Under all conditions considered in the work, the detailed results are presented and very close similarity is observed between the analytical and the nearly ideal FEM model for all chording ranges and the similarity is enhanced with increase in chording angle.

Analysis and Comparison of Even-Order Back EMF Harmonics of Fractional-Slot Concentrated-Winding Consequent Pole Permanent Magnet Vernier Machines

Fractional-slot concentrated-winding (FSCW) consequent pole (CP) permanent magnet vernier (PMV) machines have received increasing attention due to their less magnet consumption but larger torque capability. However, the PM magnetomotive force (MMF) distribution is asymmetric in the CP structure. Thus, even-order air-gap flux density and back-electromotive force (back-EMF) harmonics are generated, which increases torque ripples. In this paper, to eliminate the even-order back-EMF harmonics and the resulting torque ripples, a comprehensive investigation on even-order flux density and back-EMF harmonics of five-phase FSCW CP PMV machines was presented, and then the general design rules without even-order back-EMF harmonics were summarized. Firstly, considering single- and double-layer windings, the effects of slot/pole number combination and flux modulator distribution on even-order flux density and back-EMF harmonics were analyzed. Secondly, the optimal slot/pole number combinations were selected, and then the rules for eliminating even-order back-EMF harmonics of CP PMV machines were summarized. As an extension, it was revealed that the harmonic elimination mechanism of CP PMV machines is applicable to CP-Halbach PMV machines. According to the summarized general design rules, the five-phase CP and CP-Halbach PMV machines with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> =20/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> =21/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z_f</i> =10 were proposed. Their detailed performance has been comparatively analyzed and then the optimal one was selected for prototyping. Both finite element analysis (FEA) and experiments were carried out to validate theoretical analyses.

Armature MMF Reconfiguration Method of Six-Phase Integral-Slot PMSMs for Zero-Order Vibration Reduction Under Open-Circuit Faults

It is well known that the vibration performance of the permanent magnet synchronous machines (PMSMs) will deteriorate under the open-circuit fault operation. However, the cause of the vibration deterioration and corresponding methods to reduce the vibration are still unclear. This paper reveals the reason of the zero-order vibration deterioration for integral-slot six-phase PMSMs open-circuit fault operation. Furthermore, a magnetomotive force (MMF) reconfiguration method is proposed to suppress the fault-resulted zero-order vibration. The key is to eliminate the fundamental backward-rotating MMF, which contributes to the fault-resulted zero-order radial force under the open-circuit fault operation. With the aid of the response surface method, the analytical expressions of the optimal reconfigured current are derived considering all four open-circuit fault types. Compared with the conventional method, the fault-resulted zero-order radial force is greatly weakened by adopting the proposed method. Finally, the prototype of a six-phase 72-slot/12-pole PMSM is manufactured. The current and vibration tests are carried out to validate the theoretical analysis.

Cogging Torque Reduction of Axial-Modular Flux Switching Permanent Magnet Machine by Module Combination Technique

Flux switching permanent magnet machine exhibits high cogging torque due to the doubly salient topology and high air gap flux density. This paper proposes a new axial-modular flux switching permanent magnet (AM-FSPM) machine, which has an improved torque capability and the potential of cogging torque suppression by module combination technique. The cogging torque analytical expression of the machine with axial-modular topology is derived based on a magnetomotive force-permeance model. Then, the AM-FSPM machines are divided into two types by the combinations of stator-slot and rotor-pole, named fundamental harmonic offset naturally and fundamental harmonic offset manually. In addition, four approaches are investigated to reduce cogging torque by changing modular magnetomotive force and changing modular permeance. It can be concluded that the modular rotor tooth combination method has the most attractive torque performances among the four methods. Finally, the effectiveness of the proposed approaches is verified by the 3D finite element analysis and experimental results.