Error estimation of magnetic flux measurement of the permanent magnet materials in an open magnetic circuit

Electromagnetic modelling of electrical machines through finite element analysis is an important design tool for detailed studies of high resolution. Through the usage of finite element analysis, one can study the electromagnetic fields for information that is often difficult to acquire in an experimental test bench. The requirement for accurate result is that the magnetic circuit is modelled in a correct way, which may be more difficult to maintain for rare earth free permanent magnets with an operating range that is more likely to be close to non-linear regions for the relation between magnetic flux density and magnetic field strength. In this paper, the inclination angles of the magnetic flux density, magnetic field strength and magnetization are studied and means to reduce the inclination angles are investigated. Both rotating and linear machines are investigated in this paper, with different current densities induced in the stator windings. By proper design of the pole shoes, one can reduce the inclination angles of the fields in the permanent magnet. By controlling the inclination angles, one can both enhance the performance of the magnetic circuit and increase the accuracy of simpler models for permanent magnet modelling.

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Theoretical research on magnetization and demagnetization process of electrohydraulic servo valve with permanent magnet torque motor

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220961126 ◽

2020 ◽

pp. 095440622096112

Author(s):

Minghao Tai ◽

Yulei Jiang ◽

Long Chen ◽

Yuchuan Zhu

Keyword(s):

Mathematical Model ◽

Magnetic Flux ◽

Permanent Magnet ◽

Magnetic Circuit ◽

Theoretical Research ◽

Magnetic Flux Density ◽

Magnetomotive Force ◽

Static State ◽

Servo Valve ◽

Magnetic Steel

The magnetization and demagnetization process of electrohydraulic servo valve with permanent magnet torque motor is the last manufacturing process of electrohydraulic servo valve before its service, which has a significant effect on the output characteristics and magnetic stability of both torque motor and electrohydraulic servo valve. However, the previous studies mainly focus on the static state of the magnetic circuit instead of the changes of the magnetic steel’s states while operating magnetization and demagnetization process of torque motor, which causes many issues such as the unpredictability and inaccuracy of magnetization and demagnetization process. In this paper, a set of theoretical models are proposed to describe this entire magnetization and demagnetization process more accurately aiming at this issue. Firstly, a detailed magnetic circuit mathematical model of permanent magnet torque motor before demagnetization is established according to two kinds of magnetic circuits. Secondly, different from the existing research, in this paper, taking the variety of internal reluctance and magnetomotive force of magnetic steel into consideration, an equivalent method is presented by dividing the B-H curve of the magnetization and demagnetization process into several segments. Finally, the finite element method is used to verify the accuracy of the proposed mathematical model. The research results show the proposed model can accurately calculate the magnetic flux density of magnetic steel at any time and even the air gap’s magnetic flux and the output torque after the magnetization and demagnetization process. This research can help to design the magnetization and demagnetization process such as demagnetizing current to make sure the toque motor meets the requirements, which has an important guiding significance to design and conduct the magnetization and demagnetization process of electrohydraulic servo valve with permanent magnet torque motor.

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Study of Magnetic Circuit to Estimate Air Gap Magnetic Flux Density and Output Torque in Spoke Type Permanent Magnet Vernier Machine

2020 23rd International Conference on Electrical Machines and Systems (ICEMS) ◽

10.23919/icems50442.2020.9291161 ◽

2020 ◽

Author(s):

Hiroshi Takahashi ◽

Shoji Shimomura

Keyword(s):

Magnetic Flux ◽

Permanent Magnet ◽

Flux Density ◽

Magnetic Circuit ◽

Air Gap ◽

Magnetic Flux Density ◽

Output Torque

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A NEW MODEL OF PERMANENT MAGNET MATERIALS FOR COMPUTER AIDED DESIGN

Le Journal de Physique Colloques ◽

10.1051/jphyscol:19888309 ◽

1988 ◽

Vol 49 (C8) ◽

pp. C8-679-C8-680 ◽

Cited By ~ 1

Author(s):

J. Chavanne ◽

P. Tenaud

Keyword(s):

Permanent Magnet ◽

Computer Aided Design ◽

New Model ◽

Computer Aided ◽

Permanent Magnet Materials ◽

Aided Design

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Effects of contact gap on nondestructive evaluation using magnetic measurement for ferromagnetic steel

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209411 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 969-975

Author(s):

Hiroaki Kikuchi ◽

Yuki Sato

Keyword(s):

Magnetic Flux ◽

Nondestructive Evaluation ◽

Effective Permeability ◽

Magnetic Circuit ◽

Magnetic Measurement ◽

Air Gap ◽

Motive Force ◽

Hysteresis Curve ◽

Evaluation Technique ◽

Ferromagnetic Steel

We investigated effects of contact gap on magnetic nondestructive evaluation technique using a magnetic single-yoke probe. Firstly, we evaluated hysteresis curves and impedance related to permeability of the material measured by a single-yoke probe, when an air gap length between the probe and specimens changes. The hysteresis curve gradually inclines to the axis of the magneto-motive force and magneto-motive force at which the magnetic flux is 0 decreases with increasing the gap length. The effective permeability also decreases with increasing the gap thickness. The incremental of gap thickness increases the reluctance inside the magnetic circuit composed of the yoke, specimen and gap, which results in the reduction of flux applying to specimen.

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Analysis of structure factors affecting suspension force of permanent magnet system with variable magnetic flux path control

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209470 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 1495-1504

Author(s):

Fangchao Xu ◽

Yongquan Guo ◽

Ran Zhou ◽

Junjie Jin ◽

Chuan Zhao ◽

...

Keyword(s):

Magnetic Flux ◽

Permanent Magnet ◽

System Structure ◽

Magnet System ◽

Load Torque ◽

Factors Affecting ◽

Annular Gap ◽

Path Control ◽

Structure Factors ◽

Flux Path

To solve the problem of reduction of suspension force of permanent magnet system with variable magnetic flux path control, according to the structure of the system, suspension principle of the permanent magnet system with variable magnetic flux path control and the generation principle of the load torque, the influence of the mechanical structure of the system on the suspension force is analyzed by changing part of parameters of the system structure. The results show that the existence of magnetic isolation plate is the main reason for the decrease of suspension force, the permanent magnet ring can be thickened to 11.91 mm, the annular gap can be reduced to 1 mm, thickness of the “F” shaped magnetizer can be increased to 9 mm to increase the suspension force.

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Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209452 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 1337-1345

Author(s):

Chuan Zhao ◽

Feng Sun ◽

Junjie Jin ◽

Mingwei Bo ◽

Fangchao Xu ◽

...

Keyword(s):

Finite Element ◽

Permanent Magnet ◽

Dynamic Characteristic ◽

Driving Force ◽

Magnetic Circuit ◽

Response Speed ◽

Computation Method ◽

Element Analysis ◽

Element Simulation ◽

The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

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