Yiheng Zhou

Levitation force control of maglev permanent synchronous planar motor based on multivariable feedback linearization method

The whole control system is a strong coupling, nonlinear and multivariable system because the motion of maglev permanent magnet synchronous planar motor has multi-degrees of freedom and the magnetic field produced by the permanent magnet decreases nonlinearly in the vertical direction. The decoupling and linearization of the levitation force is the key part for high-speed and high-precision control. The paper analyzes the mathematical model and the levitation force of the motor. After that, the paper designs a nonlinear controller, which achieves the goal of decoupling and linearizing the multivariable and nonlinear system, by using multivariable feedback linearization method. The simulation result in Matlab/Simulink shows that the whole control system has high-speed response to the given reference and good robustness under disturbance.

Modeling and Analysis of a Transverse-Flux Flux-Reversal Motor

Transverse flux motors are of great interest in the low-speed high-torque direct-drive applications. In this paper, a novel transverse-flux flux-reversal motor structure is presented, which is more suitable than conventional transverse-flux motors when cost and torque density are both considered. The basic structure and operating principle are introduced. The three-dimensional (3-D) equivalent magnetic circuit model is established to obtain the expression of electromagnetic torque. A 3-D finite element model is built to analyze the influence of structure parameters on the torque density. A prototype is designed and manufactured based on the analysis result of finite element method (FEM), the experiments of no-load back-electromotive force and load torque are carried out. The experimental results agree with the results of FEM, which verifies the accuracy of FEM analysis.

Modeling and analysis of a maglev vibration isolation unit using rectangle Halbach permanent magnet array

A maglev vibration isolation unit (MVIU) using rectangle Halbach permanent magnet array used for ultra-precision equipment and instruments vibration isolation is proposed in this paper. The structure and operation principle of this maglev vibration isolation unit are introduced. Analytical solutions to determine the field of the maglev vibration isolation unit are deduced. The correctness of the solutions is validated by comparison of the results obtained by analytic method and by finite element method. Based on the analytic solutions, the magnetic force and natural frequency of the maglev vibration isolation unit is also deduced in this paper.

Force characteristic analysis of a magnetic gravity compensator with annular magnet array for magnetic levitation positioning system

Magnetic levitation positioning system (MLPS) is considered to be the state of the art in inspection and manufacturing systems in vacuum. In this paper, a magnetic gravity compensator with annular magnet array (AMA-MGC) for MLPS is proposed. Benefiting from the double-layer annular Halbach magnet array on the stator, the proposed AMA-MGC possesses the advantages of symmetrical force, high force density and small force fluctuation. Firstly, the basic structure and operation principle of the AMA-MGC are introduced. Secondly, the basic characteristics of the AMA-MGC such as magnetic field distribution, levitation force, parasitic force and parasitic torque are analyzed by the three-dimensional finite element analysis (3-D FEA). Thirdly, the influence of structural parameters on force density and force fluctuation is investigated, which is conductive to the design and optimization of the AMA-MGC. Finally, a prototype of the AMA-MGC is constructed, and the experiment shows good agreement with the 3-D FEA results.Magnetic levitation positioning system (MLPS) is considered to be the state of the art in inspection and manufacturing systems in vacuum. In this paper, a magnetic gravity compensator with annular magnet array (AMA-MGC) for MLPS is proposed. Benefiting from the double-layer annular Halbach magnet array on the stator, the proposed AMA-MGC possesses the advantages of symmetrical force, high force density and small force fluctuation. Firstly, the basic structure and operation principle of the AMA-MGC are introduced. Secondly, the basic characteristics of the AMA-MGC such as magnetic field distribution, levitation force, parasitic force and parasitic torque are analyzed by the three-dimensional finite element analysis (3-D FEA). Thirdly, the influence of structural parameters on force density and force fluctuation is investigated, which is conductive to the design and optimization of the AMA-MGC. Finally, a prototype of the AMA-MGC is constructed, and the experiment shows good agreement with the 3-D FEA results.

Comparison of torque characteristic between two transverse flux motors with passive external rotor structure

An external rotor transverse flux motor has been proposed in our previous research, which has the advantages of low manufacturing cost and high torque density. In this paper, a novel transverse flux is introduced based on the foregoing motors structure. At first, the detail motor structures and working principle are introduced. Then, the three-dimensional model of proposed motor is built by finite element software, and the basic electromagnetic characteristics are analyzed by the finite element model. At last, the comparison of torque characteristic is done, the results show that the novel motor can provide 89.7% torque density of foregoing one by using 73.7% permanent magnet.

Force Characteristic Analysis of a Linear Magnetic Bearing With Rhombus Magnet Array for Magnetic Levitation Positioning System

Magnetic levitation positioning systems (MLPSs) are of great interest in high-precision applications in vacuum. In this paper, a linear magnetic bearing with rhombus magnet array (RMA-LMB) for MLPS is proposed. With the RMA, the proposed RMA-LMB possesses advantages of excellent force uniformity, high force density, and good manufacturability. First, the basic structure and operating principle of the proposed RMA-LMB are presented. Second, the expressions of magnetic field, static force and torque, and dynamic force and torque are obtained by an equivalent current model. Third, the 3-D finite-element analysis (3-D FEA) is employed to investigate the RMA-LMB, and the magnetic field distribution, the static force and torque, as well as the dynamic force and torque are analyzed. Finally, a prototype is constructed, and experiments show a good agreement with the FEA results.

An accurate real-time model of maglev planar motor based on compound Simpson numerical integration

To realize the high-speed and precise control of the maglev planar motor, a more accurate real-time electromagnetic model, which considers the influence of the coil corners, is proposed in this paper. Three coordinate systems for the stator, mover and corner coil are established. The coil is divided into two segments, the straight coil segment and the corner coil segment, in order to obtain a complete electromagnetic model. When only take the first harmonic of the flux density distribution of a Halbach magnet array into account, the integration method can be carried out towards the two segments according to Lorenz force law. The force and torque analysis formula of the straight coil segment can be derived directly from Newton-Leibniz formula, however, this is not applicable to the corner coil segment. Therefore, Compound Simpson numerical integration method is proposed in this paper to solve the corner segment. With the validation of simulation and experiment, the proposed model has high accuracy and can realize practical application easily.To realize the high-speed and precise control of the maglev planar motor, a more accurate real-time electromagnetic model, which considers the influence of the coil corners, is proposed in this paper. Three coordinate systems for the stator, mover and corner coil are established. The coil is divided into two segments, the straight coil segment and the corner coil segment, in order to obtain a complete electromagnetic model. When only take the first harmonic of the flux density distribution of a Halbach magnet array into account, the integration method can be carried out towards the two segments according to Lorenz force law. The force and torque analysis formula of the straight coil segment can be derived directly from Newton-Leibniz formula, however, this is not applicable to the corner coil segment. Therefore, Compound Simpson numerical integration method is proposed in this paper to solve the corner segment. With the validation of simulation and experiment, the proposed model has high accuracy and can ...

Electromagnetic and Mechanical Characteristics Analysis of a Flat-Type Vertical-Gap Passive Magnetic Levitation Vibration Isolator

In this paper, we describe a flat-type vertical-gap passive magnetic levitation vibration isolator (FVPMLVI) for active vibration isolation system (AVIS). A dual-stator scheme and a special stator magnet array are adopted in the proposed FVPMLVI, which has the effect of decreasing its natural frequency, and this enhances the vibration isolation capability of the FVPMLVI. The structure, operating principle, analytical model, and electromagnetic and mechanical characteristics of the FVPMLVI are investigated. The relationship between the force characteristics (levitation force, horizontal force, force ripple, and force density) and major structural parameters (width and thickness of stator and mover magnets) is analyzed by finite element method. The experiment result is in good agreement with the theoretical analysis.

Analysis and design of a low stiffness flat type vertical-gap passive maglev vibration isolation unit

In this paper, a flat type vertical-gap passive maglev vibration isolation unit(FTVPMVIU) with low stiffness is proposed. The magnetic field distribution is calculated semi-analytically by using equivalent current model. The expression of force is derived based on the equivalent current model and Lorentz force law. A method for electromagnetic design of the unit is also discussed. The natural frequency FTVPMVIU can be optimized to near 0, which is suitable for low frequency vibration isolation.