• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.321-326
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• 2013

This paper investigates the magnetic excitation force of a surface-mounted permanent magnet (SPM) motor according to the change of pole/slot combination. The characteristics of magnetic flux and radial magnetic force (RMF) due to pole/slot combination were analyzed by using magnetic circuit analysis. Also, the RMF of motors with the variable pole/slot combination was numerically simulated by using the finite element analysis to verify the result of the magnetic circuit analysis. This research shows that RMF ripple is reduced when the number of pole is smaller than the number of slot.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.527-533
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• 2005

The linear hybrid stepping motors (LHSM) has been widely used due to its simple structure and low cost control. Despite of its attractive features, the conventional LHSM has the multiples of 4th times harmonic reluctance force from excitation current and cogging force from space harmonic of permeance. This paper propose a new LHSM, which the mechanical and electrical phase difference are $45^{\circ}$. The proposed motor shows a unique ability to deliver low detent force and we propose a closed-loop control scheme to attack the ripple force for high performance applications. An analytical and experimental comparison between conventional and proposed LHSM is evaluated to confirm the effectiveness of the proposed modeling and control scheme.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.2
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• pp.447-452
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• 2017

The stator phase winding of a linear pulse motor, which is a new type of linear motor, is comprised of two phases and is structurally characterized by a stacking method in which the winding of one phase is laid on top of the winding of another phase. Such a structural characteristic induces a difference in the flux linkage resulting from the flux of each stator phase winding in the same condition. The difference in the induced flux linkage acts as a kind of thrust ripple component in terms of the generated thrust. Thus, in order to maintain consistent thrust force, a method is required to solve the problem caused by the structural singularity. Hence, in this study, we present a technique for reducing the thrust force ripple generated by the stacking of the stator phase windings of a linear pulse motor through the generation of a compensating current reference value of the current controller in order to keep the torque constant. The proposed compensating algorithm is validated by simulations and experimental results.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.208-215
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• 2007

The significant drawback of the permanent magnet linear synchronous motor (PMLSM) is force ripples, which are generated by the distortion of the stator flux linkage distributions, cogging forces caused by the interaction of the permanent magnet and the iron core and the end effects. This will deteriorate the performance of the drive system in high precision applications. The PMLSM and its parasitic effects are analyzed and modeled using the complex state-variable approach. To minimize the force ripple and realize the high precision control, the components of force ripples are extracted first and then compensated by injecting the instantaneous current to counteract the force ripples. And this method of the PMLSM system is realized by the field oriented control method. In order to verify the validity of this proposed method, the system simulations are carried out and the results are analyzed. The effectiveness of the proposed force ripples reduction method can be seen according to the comparison between the compensation and non-compensation cases.

• Journal of Magnetics
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• v.17 no.2
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• pp.109-114
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• 2012

The torque characteristics of a surface-mounted permanent magnet synchronous motor (SPMSM) are analyzed in this study. The harmonics of the back electromotive force (EMF) and cogging torque are analyzed by the finite element method to study their effects on the torque ripple. Although low cogging torque can be achieved by varying geometric parameters such as the permanent magnet (PM) offset and notch depth on the stator teeth, the torque ripple is increased in some cases. The analysis results show that the ripple of the generated torque is determined by not only the amplitudes but also the phases of harmonics for the back EMF and cogging torque.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.39-46
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• 1998

For permanent magnet brushless DC motors used for high speed fuel pumps, torque ripple is an important origin of vibration, acoustic noise and speed fluctuation. In this paper, the output torque profile of a PM motor with one phase energized is decomposed into the commutation torque, the reluctance torque and the armature reaction torque according to their source origins. It verifies that the output torque profile is qualitatively equivalent to the BEMF profile for low reluctance motors. This paper discusses the effect of magnet pole shaping and magnet arc length on the output torque and torque ripple. A magnet edge shaping is proposed to design a trapezoidal BEMF motor without torque ripple, with minimal sacrifice of the maximum output torque.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.788_789
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• 2009

The cogging force of a permanent-magnet linear motor is a major component of the detent force, but unfortunately makes a ripple in the thrust force and induces undesired vibration and acoustic noise. In this paper, Coupling Particles Swarm Optimization is applied to optimization the shape of permanent magnet linear motor by minimizing the undesired vibration and acoustic noise in the thrust force and also considering the maximum thrust force. The result shows that the 9-pole 10-slot PMLM removes almost of the cogging force while giving a big thrust force.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.9
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• pp.525-531
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• 2004

This paper proposes inserted core type of slotless Permanent Magnet Linear Synchronous Motor(PMLSM) to improve its low thrust density. However, by inserting the core between windings of each phase, detent force is generated and it acts as thrust ripple. Furthermore, linear motors generate end effect making thrust ripple. So, this paper applies the neural network to minimize detent force and to maximize thrust. Also, sub-poles is placed at the end parts of the mover to compensate end effect. To confirm of calculation method's validity, the calculated results are compared with experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1353-1356
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• 2009

As a method obtaining linear thrust force for the magnet wheel producing a strong traction torque, the concept of magnetic shield is suggested and compared with the existing approaches. Specially, as the magnet wheel, in which the permanent magnets rotate mechanically instead of ac driving to make traveling field, is physically similar with the rotary induction motor, there is a periodical force ripple in tangential direction as well as normal direction. But, the force ripple can be suppressed from a shape change of the shield plate. Namely, the change brings out a change of entry and exit effect of the circumferential field for the magnet wheel. The feasibility of the shield concept is verified from simulation and experiment.

• Journal of the Korean Society of Industry Convergence
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• v.18 no.1
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• pp.53-60
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• 2015

For high-accuracy position control of a linear motor, it has been proposed a nonlinear controller including a synchronization algorithm. Linear motors are easily affected by force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbances. Synchronization error is also caused by skew motion, model uncertainties, and force disturbance on each axis. Nonlinear effects such as friction and ripple force are estimated and compensated for. The synchronization algorithm is used to reduce the synchronous error of the two side pillars. The performance of the controller is evaluated by computer simulations.