A VCM (voice coil motor) is disclosed, the VCM including: a rotor including a cylindrical bobbin for accommodating a lens and protruded at a bottom end with a boss, and a coil block arranged at a periphery of the bobbin; a stator including a magnet facing the coil block and a yoke fixing the magnet; and an elastic member including a first elastic member formed with a through hole coupled to the boss of the bobbin and a second elastic member coupled to an upper end facing the bottom end of the bobbin; wherein the boss is formed with a disengagement prevention unit preventing the first elastic member from being disengaged from the boss, and the first elastic member is formed with a coupling unit contacting a joint where the disengagement prevention unit and the coupling unit meet.

Voice Coil Motor

This paper presents a novel design of six-degree-of-freedom (6-DOF) magnetically levitated (maglev) positioner, where its translator and stator are implemented by four groups of 1-D Halbach permanent-magnet (PM) arrays and a set of square coils, respectively. By controlling the eight-phase square coil array underneath the Halbach PM arrays, the translator can achieve 6-DOF motion. The merits of the proposed design are mainly threefold. First, this design is potential to deliver unlimited-stroke planar motion with high power efficiency if additional coil switching system is equipped. Second, multiple translators are allowed to operate simultaneously above the same square coil stator. Third, the proposed maglev system is less complex in regard to the commutation law and the phase number of coils. Furthermore, in this paper, an analytical modeling approach is established to accurately predict the Lorentz force generated by the square coil with the 1-D Halbach PM array by considering the corner region, and the proposed modeling approach can be extended easily to apply on other coil designs such as the circular coil, etc. The proposed force model is evaluated experimentally, and the results show that the approach is accurate in both single- and multiple-coil cases. Finally, a prototype of the proposed maglev positioner is fabricated to demonstrate its 6-DOF motion ability. Experimental results show that the root-mean-square error of the implemented maglev prototype is around 50 nm in planar motion, and its velocity can achieve up to 100 mm/s.

Design and Modeling of a Six-Degree-of-Freedom Magnetically Levitated Positioner Using Square Coils and 1-D Halbach Arrays

Analytical models have been demonstrated to be effective tools in the analysis of electromagnetic devices by providing fast, yet accurate solutions. In this paper, a comprehensive analytical framework for double-rotor radial-flux air-cored permanent-magnet (PM) machines is developed whereby the average as well as the torque ripples, back-electromotive force (EMF) waveforms, air-gap flux density distribution, and a number of other characteristics regarding the design of the machine are predicted. Also, closed-form expressions for inductances of the stator coils are analytically derived. All machine parameters and material properties including iron saturation are considered in the model. Moreover, an algorithm in order to optimally design the thicknesses of the rotor yokes based on the utilized steel is presented. Finally, genetic optimizations regarding the enhancement of the produced torque and back-EMF are performed. It is also shown that the results obtained from the proposed model match well with those issued from finite element method.

Analytical Design Framework for Torque and Back-EMF Optimization, and Inductance Calculation in Double-Rotor Radial-Flux Air-Cored Permanent-Magnet Synchronous Machines

Since a Halbach array exhibits a number of attractive features, it has been increasingly applied to different market sectors, including aerospace, industrial, domestic, renewable and healthcare and so on. The need of fast global optimisation, cost-effective design and physical understanding of the relationship between parameters and performance requires a powerful analytical model. Hence, this study develops a general analytical model which is capable of predicting the electromagnetic performance of slotted/slotless permanent magnet (PM) brushless machines with both even- and odd-segment Halbach array, having different magnet remanence, magnetisation angle and arc for each single magnet segment. The emphasis has been on the magnetisation which is the key in analytical modelling of PM machines having a segmented Halbach array and its investigation. The validity of proposed analytical model is extensively examined by finite-element analyses, together with its applications for global optimisation and comparative study.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-est.2012.0055

General analytical model for calculating electromagnetic performance of permanent magnet brushless machines having segmented Halbach array

This paper presents the modeling, optimization, and validation of a hollow plunger type solenoid for high speed On/Off valve. In the preliminary design, an accurate equivalent magnetic circuit model of the proposed solenoid is carried out, and the magnetic circuit is arranged in Kirchhoffs voltage law matrix form for the convenience of computer calculation. An iterative method is applied to obtain accurate permeability of the nonlinear magnetic material. To optimize the design parameters, a multiobjective optimization process is developed, and the multiobjective particle swarm optimization method is used to obtain the Pareto front of the desired objectives. An approved solution in Pareto front is selected by analytic hierarchy process and validated by the finite element analysis (FEA) method. A prototype based on the final optimized design is manufactured and tested. The experiment results verified the validation proposed design and optimization process.

Multiobjective Optimization of a Hollow Plunger Type Solenoid for High Speed On/Off Valve

This paper presents a new 2-D permanent-magnet array for a planar motor, in which the angle between the magnetization directions of any two adjacent magnets is 45°. The harmonic model for flux density distribution of the array is solved by the scalar magnetic potential equation and validated by the finite-element method. An analytical model for real-time control is derived by taking the first harmonic of the magnetic flux density distribution. The ignored higher harmonics in z-component of the magnetic flux density distribution is minimized by the genetic algorithm such that the analytical model becomes more accurate. Compared with the well-known Halbach magnet array, the proposed magnet array has lower higher harmonic components and higher z -component of the magnetic flux density, which will reduce the force ripples of the planar motor.

Analysis and Optimization of a New 2-D Magnet Array for Planar Motor

This paper presents an optimization of voice coil motor (VCM) used in ultra-precision motion stages based on an improved magnetic equivalent circuit (MEC) model. The modified MEC model takes into consideration the nonlinear saturation effect of ferromagnetic material by segmentation, and estimates the magnetic flux density in air gap of VCM in a more precise way. The results of experiment, finite-element analysis, and MEC model are compared to validate the correctness of the improved MEC method. A new optimization criterion is used to measure dynamic response and heat dissipation of VCM simultaneously. The geometric parameters of VCM are optimized, and the resulting VCM is proved to have a better dynamic response and lower heat dissipation.

Optimization of Voice Coil Motor to Enhance Dynamic Response Based on an Improved Magnetic Equivalent Circuit Model

The invention discloses a voice coil motor relating to an ultraprecise motion positioning device and comprising an upper permanent magnet assembly, a lower permanent magnet assembly and one or two winding assemblies arranged between the upper and the lower permanent magnet assemblies. The voice coil motor is technically characterized in that the degree of freedom of the voice coil motor moving along the Y-axis direction is increased; when a motor rotor moves along the Y-axis direction, the effective coil area between the permanent magnet assemblies is unchangeable, and the motor rotor has a Lorentz resultant force of zero along the Y-axis direction and an unchangeable Lorentz force along the X-axis direction. The invention meets the motion requirements that the rotor of the voice coil motor finely moves in the X direction and the motor rotor can move for a long stroke along the Y-axis direction, increases working space of the motor, and solves the problem of limited motion of the rotor along the Y-axis direction in the traditional voice coil motor structure.

Voice coil motor

The invention discloses a 6 freedom degree micromotion bench in ultra precise processing and testing device technical domain, which is characterized by the following: possessing three groups of electromagnetic driving units; arranging in horizontal plane; driving the micromotion bench to X, Y, theta z3 freedom degree move in horizontal plane; arranging three electromagnetic driving units along vertical direction; driving the micromotion bench to Z, theta x and theta y3 freedom degree move This invention possesses simple structure and higher displacement distinguishability, which can be used to realize 6 freedom degree motions for ultra precise process and check

6 freedom degree micromotion operating platform

This paper presents novel overlapping ironless windings for permanent magnet planar motors, which have high winding factors and make full use of the magnetic field of the magnet array in the planar motor. A simple analytical model of the planar motors is developed and validated by finite-element method first. Then the winding factors of the ironless windings are derived and used to simplify the analytical model. Furthermore, the design rules of the ironless windings for the planar motor are obtained from the analytical model with winding factors and the ironless windings are optimized for maximum steepness of the planar motor. Compared with the nonoverlapping ironless windings, the novel overlapping ironless windings have a much (up to 25%) larger force with the same copper loss and nearly the same size when the coils of the windings have a large length/width ratio.

Ming Zhang

Papers

Analysis and Optimization of a New 2-D Magnet Array for Planar Motor

Optimization of Voice Coil Motor to Enhance Dynamic Response Based on an Improved Magnetic Equivalent Circuit Model

Voice coil motor

6 freedom degree micromotion operating platform

Analysis and Design of Novel Overlapping Ironless Windings for Planar Motors