• The Transactions of the Korean Institute of Electrical Engineers B
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• 제55권9호
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• pp.459-464
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• 2006

The detent force by end-effect has an undesired influence on moving coil type Permanent Magnet Linear Synchronous Motor(PMLSM). So, the reduction of detent force by end-effect is especially required for the improvement of thrust characteristics. In this paper, in order to reduce detent force by end-effect, the auxiliary-teeth is installed at the end part of mover. It is also analyzed by Finite Element Analysis(FEA) and optimized by using neural network. By comparison, the detent force is reduced about 41.4[%] comparing to that of basic model.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제57권3호
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• pp.390-397
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• 2008

Permanent Magnet Linear Synchronous Motor (PMLSM) has high efficiency, high energy density, and high control-ability. But, the detent force always is produced by the structure of slot-teeth. There are the disadvantages such as noise and vibration of the apparatuses are induced and the control ability is curtailed because detent force acts as thrust ripple. Therefore, the detent force reduction is an essential requirement in PMLSM. Generally, the method, skewing permanent magnet or slot-teeth, is used to reduce the detent force. But the thrust is decreased at the same time. If permanent magnet is skewed, the lateral force which operates as the perpendicular direction of skew direction is generated in linear guide of PMLSM. So, V-skew model is proposed for the reduction of lateral force. The lateral force acts as braking force in linear motion guide, and it has bad influence to the characteristics of PMLSM. However, these problems will not be solved by 2-dimensional Finite Element Analysis (FEA). So, in this paper 3-dimensional FEA is applied to analyze the PMLSM where permanent magnet is skewed and has overhang. The detent force and thrust characteristics considering skew and overhang effects of permanent magnet are analyzed by 3-dimensional FEA and the results are compared with experimental values to verify the propriety of analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제55권4호
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• pp.209-215
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• 2006

Recently Permanent Magnet Linear Synchronous Motors(PMLSMs) are widely used for many linear transportation applications. The PMLSM has many advantages such as simple structure, high speed and thrust. However, especially in short primary type PMLSM, there exists very large detent force, which makes the thrust force ripple, undesired vibration and noise. The detent force is composed of the Cogging force and the End force. The Cogging force comes from the interaction between the permanent magnets and interior teeth of the stator. And the End force acts on the exterior teeth of the stator by the permanent magnets. Usually End force is larger than Cogging force, so the detent force is drasically reduced only by reducing the End force. This paper shows the End force is minimized by optimizing the stator length and chamfering the shape of the exterior teeth of the stator.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제49권3호
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• pp.138-144
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• 2000

The detent force caused by the interaction of magnets with the teeth of a armature core deteriorates the driving performance of a permanent magnet linear synchronous motor. In this paper, we analyze the fields and forces of a linear synchronous motor with segmented or skewed magnet arrangement according to lateral overhang length of permanent magnets. For the analysis, the 3-dimensional equivalent magnetic circuit network method is used. The detent force and the static thrust are analyzed according to the segmented or skewed angle and the overhang length of permanent magnets, and the optimal angles that the detent force is minimized are found out in each case. The analysis results are compared with the experimental ones and shown a reasonable agreement.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.1-6
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• 2002

The severe problem in improving the positioning precision of a permanent magnet linear synchronous motor (PMLSM) is the large detent farce caused by the permanent magnet arrangement. It is generally an undesired effect that contributes to the torque ripple, vibration and noise of machine. The detent force is arisen from the difference of the position of a permanent magnet end and a tooth position. In this paper, the four methods to reduce detent force were studied and analyzed. The methods are adjusting the width of permanent magnet, varying the shape of armature teeth, relocating the permanent magnet, and adjusting the width of permanent magnet and relocating the permanent magnet at the same time. To analyze the detent farce according to flour methods, a two-dimensional Finite Element Analysis [FEA] was used and we compared with the ratio of reduction of the detent farce according to the flour methods.

• Journal of Power Electronics
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• 제6권4호
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• pp.290-297
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• 2006

Various methods have been discussed to reduce detent force in a tubular permanent magnet type linear single phase AC generator. In particular, the proposed methods depend on variations of the permanent magnet construction. These methods include two approaches in the form of sloped magnets, and conical magnets in addition to the conventional method of optimizing the magnet length. The undesired detent force ripples were calculated by a two dimensional Finite Element Method (FEM). Moreover, the generated electromotive force in the stator coils was calculated for each configuration of the permanent magnet. The experimental results agreed well with those obtained from the FEM-based simulations. Sufficient reduction in the detent force was achieved over the range of 40% while the root mean square of the output voltage was maintained. It was found that sloping the permanent magnet decreased the detent force and at the same time increased the generated rms voltage of the AC generator. The performance of the designed linear AC generator was evaluated in terms of its efficiency, total weight, losses, and power to weight ratio.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제54권10호
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• pp.477-482
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• 2005

In this paper, detent force is minimized using notch and slot-aputure width adjustment in a slotted PMLSM. This time, the moving model node technique has used to reduce the time and the effort for calculation according to changing design parameters. As the result, the detent force of proposed model is decreased from 9.44[N] to 0.97[N] compare with it of basic model greatly. The thrust Is decreased 1.3[$\%$] from 342.07[N] to 337.48[N] a little. The notch is applied to PMLSM simply, the detent force is reduced greatly.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제52권7호
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• pp.320-326
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• 2003

Slotless Permanent Magnet Linear Synchronous Motor (PMLSM) has good control ability but thrust density is low. So, this paper proposes inserted core type of slotless PMLSM to improve its thrust density. Inserting the core between windings of each phase, detent force is generated by the difference of magnetic resistance in an air gap. To minimize detent force, this paper applies the neural network to inserted core type of slotless PMLSM. The, Magnetic pole ratio, the width of the inserted core and the width of the coil are selected as a design parameter to minimize detent force. In comparison with inserted core type one, thrust ripple greatly decreases by minimizing detent force and also thrust increases in this optimal model.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.757-759
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• 2000

The problem in improving the positioning precision of a permanent magnet linear synchronous motor(PMLSM) is the large detent force caused by the permanent magnet. The detent force is thought to arise from the difference of the position of a permanent magnet end and a tooth position. In this paper, Three methods of reducing detent force is presented The first method is adjusting the width of permanent magnet. The second method is varying the shape of armature teeth. The third method is the arrangement of the permanent magnet end. This paper compares with the ratio of reducing the detent force according to the three methods.

• The Transactions of the Korean Institute of Electrical Engineers B
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• 제49권11호
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• pp.749-756
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• 2000

Detent force develops generally undesirable effect that contributes to the output ripple of machine, vibration and noise. This paper proposes detent force minimization techniques for a Permanent Magnet Linear Synchronous Motor (PMLSM). In addition, thrust according to each minimization technique is estimated to observe the change of machine performance. A two-dimensional Finite Element Method is used to predict detent force and thrust due to structural factors and non-linearity. And moving node technique for geometric models is proposed to reduce modeling time and efforts.