Synchronous Permanent Magnet Planar Motor Research Articles

A magnetically levitated synchronous permanent magnet planar motor with concentric structure winding used for lithography machine

A novel magnetically levitated synchronous permanent magnet planar motor (MLSPMPM) with concentric structure winding, which can be used in lithography machine, is proposed in this paper. Topology and principle of the new MLSPMPM are introduced. The scalar magnetic potential is used to solve the magnetic system, and the differential equations are solved by the separation of variables method according to the boundary conditions. Characteristics, such as flux density, electromagnetic force, and back-EMF of the MLSPMPM, are obtained analytically. All of the results are validated by the finite element method. A prototype of the MLSPMPM is manufactured. Based on the prototype motor, some experiments are carried out. The measured results are used to showcase the validity of the analytical analysis.

Design and analysis of a 2-DOF synchronous planar drive for machine tools

This paper presents a synchronous planar motor prototype with a cross winding system for high dynamic motion in two feed axes. The approach uses a synchronous permanent magnet planar motor, where the magnets are located in the stationary part and the coils are mounted on one moving yoke. A cross winding technology with concentrated windings is implemented to realize a compact feed drive for machine tools. An experimental setup was used to obtain the characteristic behavior of the inductance and disturbance- and feed-force deviation of the drive. Disturbance-forces like cogging- and detent-forces occur due to parasitic effects between the permanent magnets and the iron based yoke. It is theoretically and experimentally shown, that both winding layers marginally interact. Based on the identified characteristics, two independent cascade control systems are developed. The disturbance-force is compensated by a feedforward control. The performance of this first prototype is finally shown in a circular milling setup.

Analysis and experiments of a novel synchronous PM planar motor with minimized cogging force

We deal with analysis and experiments of a novel moving-coil-type synchronous permanent magnet planar motor (SPMPM) with reduced cogging force. Our previous study assumed that the equation of magnetic flux existing between a permanent magnet (PM) and core was a second-order polynomial, and the minimum cogging force was theoretically and geometrically calculated without FE analysis. In this paper, the cogging force of SPMPM with an iron core is calculated exactly using geometrical factors, which are desired for determining the magnetic flux density. The analytical results of the cogging force using the factors agree well with those obtained by FE analysis and experiment. Several methods for reducing the cogging force of the SPMPM, such as separation and arrangement of the iron core, addition of an extra core, and addition of auxiliary core teeth, are introduced in this paper. Velocity control experiments of the SPMPM with modified and unmodified cores are carried out and the results are compared with each other. The velocity ripple of SPMPM with a modified core is much smaller than that of SPMPM with an unmodified core.

Modeling and Design of an Integrated Winding Synchronous Permanent Magnet Planar Motor

This paper presents a novel integrated winding synchronous permanent magnet planar motor (IWSPMPM), which is driven by composite currents. In this paper, the flux density distribution of a 2-D magnet array used for the IWSPMPM was obtained by solving the scalar magnetic potential. Expressions of the electromagnetic forces and back electromotive force of the IWSPMPM were derived. Based on this, the main dimension of the IWSPMPM was confirmed, and the expression was derived. The design of the coil and the permanent magnet was respectively studied, and the effects of the height of the coil and the thickness of the magnet on the electrical properties of the planar motor were analyzed. A prototype motor is manufactured, and some experiments were carried out with it. Both measurement and simulation coincide well.

Characteristic Analysis of a Long-Stroke Synchronous Permanent Magnet Planar Motor

This paper deals with the characteristic analysis of a long-stroke synchronous permanent magnet planar motor. The planar motor which employs a 2-D permanent magnet array for the stator, is suitable for the long-stroke applications since the moving coils can move freely. Operation principle and structure of this planar motor are introduced. Characteristics such as flux density, thrust and back-EMF are obtained analytically and compared with the finite element simulation results. A prototype motor is manufactured and successfully tested. The measured values are also in good agreement with the simulation ones.

Modeling and analysis of a magnetically levitated synchronous permanent magnet planar motor

In this paper, a new magnetically levitated synchronous permanent magnet planar motor (MLSPMPM) driven by composite-current is proposed, of which the mover is made of a copper coil array and the stator are magnets and magnetic conductor. The coil pitch τt and permanent magnet pole pitch τp satisfy the following relationship 3nτt = (3n ± 1)τp. Firstly, an analytical model of the planar motor is established, flux density distribution of the two-dimensional magnet array is obtained by solving the equations of the scalar magnetic potential. Secondly, the expressions of the electromagnetic forces induced by magnetic field and composite current are derived. To verify the analytical model and the electromagnetic forces, finite element method (FEM) is used for calculating the flux density and electromagnetic forces of the MLSPMPM. And the results from FEM are in good agreement with the results from the analytical equations. This indicates that the analytical model is reasonable.

A Study on the Characteristics of Planar Motor with Halbach Array

A synchronous permanent magnet planar motor (SPMPM) with Halbach array is proposed. The flux density distribution of Halbach array is obtained by analytical method; then, the characteristics of SPMPM with Halbach magnet array are evaluated. At last, the experiment results are used to verify the analysis propriety of this SPMPM. By comparison, it can be concluded that the analysis of SPMPM with Halbach magnet array is credible and feasible.

Theoretical Analysis and Its Applications of a PM Synchronous Motor With Minimized Cogging Force

This paper deals with theoretical analysis and design of permanent magnet (PM) synchronous motors (PMSMs) with minimized cogging force. Recently, many optimal designs for the PMSMs have been done by finite element (FE) analysis, but such analysis generally is time consuming. In this study, the equation of magnetic flux lines existing between PMs and iron cores is expressed geometrically and the cogging force is calculated theoretically without FE analysis. The form of equation is assumed to be the second-order polynomial and the virtual core is used to express the cogging force in analytical model. The cogging force can be calculated by applying the solved flux line equation and the flux density equation to the Lorentz force equation by using the Maxwell stress tensor. The theoretical analysis of minimized cogging force is applied to several prototypes such as synchronous PM planar motor (SPMPM), 2-DOF PMSM with screw motion, and axial flux PM (AFPM) brushless dc motor in this paper, and the analytical results are validated by FE analyses and experiments.

Electromagnetic Forces Acting on the Planar Armature of a Core-Type Synchronous Permanent-Magnet Planar Motor

The core-type synchronous permanent-magnet planar motor (SPMPM) discussed in this paper includes one or more planar armatures each of which contains two sets of three-phase windings named x-winding and y-winding. For each planar armature, a magnetic field energy equation is established first. This equation describes the mechanism of the coupling between the permanent-magnet array, the x-winding and the y-winding in the core-type SPMPM. By using virtual work principle, x-direction thrust force, y -direction thrust force and vertical force acting on the planar armature are modeling analytically. For eliminating the coupling in these force models, the excitation flux linkages and phase currents are all transformed into d-q synchronous reference frame. From the decoupling force equations, some characteristics of the vertical component of force on the planar armature are obtained. The electromagnetic force model is helpful for the design of the contactless planar bearing and the servo control system of the SPMPM.

Modeling the Static Vertical Force of the Core-Type Permanent-Magnet Planar Motor

The vertical electromagnetic force affects the design of the air bearing or magnetic bearing of a synchronous permanent-magnet planar motor (SPMPM), whereas the static vertical electromagnetic force is one of the important components of the vertical electromagnetic force. This paper discusses the problem of modeling the static vertical force of the SPMPM analytically. First, we obtain an analytical model of the scalar potential and the equations for calculating the magnetic field energies (MFE) in the magnet array and in the air gap. Since the MFE in the yokes is small enough to be neglected, we obtain the overall MFE equation by summing both the air-gap MFE equation and the magnet array MFE equation. Second, using the virtual work principle, we establish an analytical model of the static vertical force. Using this analytical model, we discuss the characteristics of the static vertical force. To verify the usability of the vertical force model, we analyze a magnet array by the analytical method proposed in this paper and by the finite-element method (FEM). The results show that the vertical force model proposed in this paper is approximately equal to the result from the FEM. This indicates that the vertical force model can be used for estimating the value of the static vertical force in a core-type SPMPM. Furthermore, the analytical model produces continuous results in shorter calculation time.

Minimization Design of Normal Force in Synchronous Permanent Magnet Planar Motor With Halbach Array

This paper deals with the characteristics analysis and the normal force minimization of a synchronous permanent magnet planar motor (SPMPM) with a Halbach magnet array. The characteristics such as flux density, back-EMF and thrust are evaluated and compared with experimental values. The measured values of back-EMF are in good agreement with the simulation ones, but the experimental results of thrust are much smaller than those of simulation due to the friction force generated by the normal force. The normal force is minimized by using a genetic algorithm, and it is greatly decreased from 672.83 N to 144.24 N.

Design and Experimental Validation of Performance for a Maglev Moving-Magnet-Type Synchronous PM Planar Motor

In this paper, a novel maglev moving-magnet-type synchronous permanent magnet planar motor (SPMPM) is proposed. A stator is composed of several printed circuit boards instead of copper windings. The proposed SPMPM shows the important characteristic that propulsion planar forces have structural independence of each other so it can be easy to control the motion of the SPMPM. The magnetic field distribution, propulsion force, and suspension force equations are solved analytically and verified using the experimental works

A novel synchronous permanent magnet planar motor and its model for control applications

A novel synchronous permanent magnet planar motor (SPMPM) with iron core is proposed. It has higher continuous force compared to the coreless SPMPM. In the novel SPMPM, two sets of windings for generating x-direction thrust and y-direction thrust are perpendicularly fixed in the x-direction slots and y-direction slots of a mover core, respectively. For control system development applications, an electromagnetic model is derived and the analytical method for calculating the model parameters is also reported. The model describes an important characteristic of the novel SPMPM that the x-direction thrust and y-direction thrust are independent of each other. To verify the model and the parameter calculation method, the finite element method (FEM) is used for calculating the phase inductances and electromagnetic forces of an example SPMPM. The results from FEM are in good agreement with the results from the analytical equations. It demonstrates the feasibility and credibility of the proposed model and parameter calculation method to a certain extent.

Characteristic analysis of planar motor using the volume integral equation method

The characteristics of a three-phase synchronous permanent magnet planar motor (SPMPM) are analyzed numerically using a volume integral equation method (VIEM). The mover dimensions are optimized to minimize the detent force. The back-EMF waveform is calculated and the coil dimensions are optimized to set the back-EMF constant to a constant value regardless of mover positions. All simulation results are verified by a comparison with experimental results.

Analysis and design of synchronous permanent-magnet planar motors

The force equation of a synchronous permanent-magnet planar motor (SPMPM) was investigated. The flux density distribution of a two-dimensional (2-D) magnet array for a SPMPM was obtained by solving the equations of the scalar magnetic potential. The expressions of the force and back-EMF constant were derived and examined. Using these expressions, the conditions for normal operation of the SPMPM were found and the optimal design was determined in order to maximize the force of the SPMPM.