Three-dimensional Magnetic Circuit Research Articles

An Improved Two-Dimensional Simplification Calculation Method for Axial Flux Permanent Magnet Synchronous Motor

The axial flux permanent magnet synchronous motor (APMSM) has the advantages of short axial size, high efficiency, and high power density. However, the three-dimensional magnetic circuit structure of this type of motor results in a longer calculation time, which is not conducive to rapid design and optimization. In order to quickly and accurately complete the preliminary calculation and optimization of axial flux permanent magnet synchronous motors, this paper proposes an improved equivalent calculation method for two-dimensional multi-layer linear motors. This method is based on the traditional two-dimensional multi-layer linear motor equivalent method, taking into account the complexity of geometric model establishment and simulation condition settings and applying the principle of analogy to achieve significant simplification of geometric modeling and simulation settings. The article elaborates on the correlation and differences between the proposed method and existing methods and verifies the calculation accuracy through finite element calculation. The results indicate that the improved two-dimensional multi-layer linear motor equivalent calculation method proposed in this article can significantly reduce calculation time while ensuring calculation accuracy and has good application prospects in preliminary design and parameter optimization processes.

Magnetic Field Analysis for the Permanent Magnet Spherical Motor With SMC Core

This paper presents a permanent magnet spherical motor (PMSM) with soft magnetic composite (SMC) core. The analytical model of the no-load air-gap magnetic field of the PMSM with SMC core is obtained based on the Laplace equation with the boundary conditions. When the SMC core is added to the stator teeth, a cogging effect occurs, which makes the three-dimensional magnetic circuit of the entire spherical surface uneven. When the spherical motor completes multi-degree-of-freedom motion, the air-gap magnetic field is severely distorted. In order to solve the above problems, this paper proposes for the first time the method of adding spherical shaped pole shoes to the stator teeth, which perfectly solves the problem of magnetic field distortion in this paper. The air-gap magnetic field distribution is improved by optimizing the structure of the stator tooth pole shoes. Finally, the static torque measurement platform was built to test the rotation energized output torque. The research results of this paper lay a theoretical foundation for the structural optimization design of the PMSM with SMC core.

Analysis and Performance Evaluation of a Novel Adjustable Speed Drive with a Homopolar-Type Rotor

The use of a magnetic adjustable speed drive is a popular choice in industrial settings due to its efficient operation, vibration isolation, low maintenance, and overload protection. Most conventional magnetic adjustable speed drives use various forms of the permanent magnets (PMs). Due to the PMs, this type of machine has continuous free-wheeling losses in the form of hysteresis and induced eddy currents. In recent years, the homopolar-type rotor has been widely used in high-speed machines, superconducting machines, and in the application of flywheel energy storage. This study proposes a new application of the homopolar-type rotor. A novel adjustable speed drive with a homopolar-type rotor (HTR-ASD), which has obvious advantages (no brush, no permanent magnet, and no mechanical flux regulation device), is designed and analyzed in this study. Its speed and torque can be adjusted only by adjusting the excitation current. Firstly, in this study, the structure, operation principles, and flux-modulated mechanism of the HTR-ASD are studied. The homopolar-type rotor has a special three-dimensional magnetic circuit structure with the same pole. The 3D-FEM is usually used to calculate its parameters, which is time consuming. In this study, an analytical method is developed to solve this issue. To analytically calculate the torque characteristics, the air gap magnetic flux density, and the winding inductance parameter, the equivalent circuit and the air gap permeance are researched to simplify the analysis. Then, the key parameters of the HTR-ASD are calculated. Finally, the performance of the HTR-ASD is comparatively studied using the analytical method and finite element method, and a comparison of the results is carried out. The comparison indicates that the analytical method is in good agreement with simulation results, and that it is very helpful for designing homopolar-type rotor machines. According to the analysis, the proposed adjustable speed drive displays a great performance in relation to the operating characteristics of a flexible mechanical speed drive.

Electromagnetic Design and Vibration Analysis of a Homopolar Linear Synchronous Motor

In this paper, the electromagnetic and mechanical characteristics of the improved homopolar linear synchronous motor (H-LSM) have been studied. Firstly, the influence of the ratio of the width and pitch of the rotor teeth is investigated on the magnetic field distribution and vibration traits. By establishing a simplified three-dimensional magnetic circuit model, the distribution of air gap flux density is attained. Secondly, the time and space distributions of the air gap flux density is decomposed, and the ratio of tooth width to tooth pitch with larger fundamental component is selected as the key index to design the H-LSM. Thirdly, through the modal analysis of the primary core, detailed investigation on the harmonics response is carried out, and the resonance frequency domain in the working process is clarified. Finally, 1-10th order frequency spectrum on the H-LSAM resonance is decomposed, which can provide a judgment for the fault diagnosis.

A New Relieving-DC-Saturation Hybrid Excitation Vernier Machine for HEV Starter Generator Application

Benefiting from flexible flux control and short-circuit withstand ability, the hybrid excitation machine is an emerging starter generator solution for hybrid electric vehicle propulsion. However, to realize a brushless hybrid design in conventional permanent magnet machines, a three-dimensional magnetic circuit is usually adopted, leading to complicated mechanical structure and torque density sacrifice. To address this issue, a new relieving-dc-saturation hybrid excitation Vernier machine is proposed in this article, which integrates good torque density and bidirectional flux control within a simple and brushless structure. The key is to artificially construct reluctance effect in a consequent-pole Vernier permanent magnet machine (CP-VPMM) by introducing extra dc field excitation equipped with the relieving-dc-saturation ability. In this way, the advantages of bidirectional flux control in stator-dc-excited reluctance machine and good torque density in CP-VPMM are well combined in this topology, making it especially suitable for multimode starter generator application. In this article, the machine structure and its design mechanism are introduced, with its electromagnetic performance evaluated by the finite-element simulation. A prototype is manufactured and tested. Experiment results verify the feasibility of this new topology.

Electromagnetic Characteristic of a Novel Linear Flux Switching Machine With Three-Dimensional Magnetic Circuit

The novel linear flux switching permanent magnet machine with a three-dimensional magnetic circuit is proposed in this paper, which is suitable for aerospace, missile launch, and other fields, benefiting from high thrust force and low cost. First, the basic structure and working principle of the machine are introduced. Second, the equivalent magnetic circuit model considering the variable reluctance is established and the equations are put forward for magnetic analysis. Third, the simplified finite element model is performed to calculate the field distribution, the air-gap flux density, the flux linkage of winding, and the back electromotive force. Finally, a prototype is constructed and experiments show a good agreement with analysis.

可変界磁機能を有する3次元磁気回路モータの提案

可変界磁機能を有する3次元磁気回路モータの提案

New Motor Having a Simple Structure with Three-Dimensional Magnetic Circuit and Loop Windings

New Motor Having a Simple Structure with Three-Dimensional Magnetic Circuit and Loop Windings

Evaluation of DC Brush-Less Motors Using Powder Magnetic Cores

A high-speed motor and a DC brush-less motor for factory automation (FA) were made to investigate the applicability of the powder magnetic core to motor application. The performances of these motors were compared with the similar motors having conventional electromagnetic steel core. Although the permeability and saturated magnetization of powder magnetic core were less than those of electromagnetic steel core, the output performances of each core motor were almost the same. The FA motor with powder magnetic core using three-dimensional magnetic circuit showed higher torque than the electromagnetic steel core motor with the same volume.

三次元磁気回路に基づく田磁路型可変インダクタの動作解析

Since an EIE-core variable inductor is constructed from cores and windings, it has good features for an electric power apparatus, such as simple construction and high reliability. The variable inductor does not need any gaps for harmonic current reduction and has a suitable structure for a larger capacity. For optimum design, a quantitative analysis method for the variable inductor is important. In a previous paper, we derived a two-dimensional nonlinear magnetic circuit model of the EIE-core and found operating characteristics of the variable inductor. Although the calculation value and actual measurement showed good coincidence, in the large domain of the control current, a tendency was shown to expand quantitive error, and further improvement in calculation accuracy became a subject. In this paper, we present a three-dimensional magnetic circuit to improve analysis accuracy, and compared calculated results with actual measurements.

One method for calculating flux-MMF relationship of orthogonal-core

One method for calculating flux-MMF relationship of an orthogonal core is described. The calculation is based on a three-dimensional magnetic circuit model of the orthogonal core. The model is derived by dividing the orthogonal core, inclusive of the surrounding region, into elements comprising a three-dimensional magnetic circuit. Using this model, the flux-MMF relationship of the orthogonal core with arbitrary dimensions can be calculated from the B-H characteristic of the core material. The calculation method presented is useful for optimum design of devices using an orthogonal core. >

Three-dimensional analysis of magnetodynamic fields in electromagnetic devices taken into account the dynamic hysteresis loops

A new magnetic field equation exhibiting dynamic hysteresis loops is proposed. Based on this magnetic field equation, a system of two-dimensional magnetic circuit equations taken into account the dynamic hysteresis loops is derived by the method of magnetic circuits. By means of magnetic power invariant transformation, a system of two-dimensional magnetic circuit equations is transformed into a system of three-dimensional magnetic circuit equations. This system of three-dimensional magnetic circuit equations is discretized in time by a finite difference method. A system of three-dimensional magnetic circuit equations discretized in time is solved by a simple iteration method, using a relaxation parameter. As an example, a system of three-dimensional magnetic circuit equations of a simple saturable reactor is derived. Also, the numerical solutions of dynamic hysteresis loops in a saturable reactor are presented together with those of experimental results.