• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.67-69
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• 2004

This paper describes an approach to design a interior permanent magnet motor(IPM motor) for the reduction of cogging torque. The magnitude of the torque ripple and cogging torque in a interior permanent magnet motor(IPM motor) are generally dependent on several major factors: the shape of stator tooth tip, slot opening width, air gap length, the shape of barrier preventing flux leakage of magnets, magnet configuration and magnetization distribution or magnet poles. In this paper, the IPM BLDC motor is designed considering a saturated leakag flux between the barriers on the rotor for increasing the efficiency and decreasing the magnitude of the cogging torque. Analytical model is developed for the IPM BLDC motor with a concentrated winding stator. The results verifies that the proposed design approach is very efficient and effective in reducing the cogging torque and the torque ripple of the IPM BLDC motor to be used in an electric vehicle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1895-1898
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• 2017

This paper discusses methods for the torque ripple and noise reduction of DC motors for automotive air-conditioning based on electromagnetic field analysis. The target of the motor is a blower motor, and to reduce cogging torque and the torque ripple, the optimum model was selected by deforming the brush or commutator shape. In addition, to reduce the cogging torque, the model design was carried out by applying the skew method and the magnetization method of a magnet to the rotor. For optimization, the shape, material, and drive system of the motor were selected using an electromagnetic field as the analysis tool, and the method of reducing the cogging torque was applied to 4-pole, 12- and 13-slot motors considering the mechanical part. Lastly, this paper confirmed thatthemethod, which proposed how much noise, cogging torque, and vibration are reduced, improves through practical analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.2
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• pp.71-77
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• 2012

The cogging torque is important to the cut-in wind speed. And, it causes the acoustic noise and the vibration on the machine. This paper presents a 3D FEA(Finite Element Analysis) to evaluate the effect of magnet skew and stator displacement on cogging torque reduction, for double core AFPM(Axial Flux Permanent Magnet) generator. As a result, the magnet skew and the stator side displacement are proved excellent techniques to reduce the cogging torque.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.6
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• pp.287-291
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• 2006

Recently, various applications of permanent-magnet(PM) electric motor have been more increased. Compared with the other electric motors, PM electric motor has cogging torque which results from the interaction between PM of rotor and slot-teeth structure of stator. Audible noise and vibration is caused by this cogging torque. So, the reduction of cogging torque is main designing goal of PM electric motor. The purpose of this paper is to realize the decrease of cogging torque using new experimental design and response surface analysis which is one of the statistical methodologies.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1111-1112
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• 2011

This paper investigated application of fractional-slot concentrated-winding axial flux permanent magnet machines for wind turbines. Design criteria of cogging torque and voltage regulation was firstly proposed for this kind of application. Fractional winding has small cogging torque which is highlight for wind turbines, but slot leakage inductance would increase voltage regulation, which is an important performance index of generators. By varying slot opening, cogging torque and slot leakage inductance could be adjusted. In this paper, cogging torque and inductances were calculated by both analytical and finite element methods. Voltage regulation was studied by two-axis model under unity-power-factor load and verified by transient finite element analysis.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.21-23
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• 1997

The analysis of the permanent type synchronous motor is performed by using the finite element method (FEM). The optimal design of the permanent magnet is presented for minimizing cogging torque in this paper. The cogging torque is expressed in terms of scalar potential computed by the virtual work formula. The minimization of cogging torque is achieved by using the ( ${\mu}$ + ${\lambda}$ ) Evolution Strategy (ES) and the selected flux densities are used to a constraint.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1986-1991
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• 2016

The vibration soucre of motor has a electromagnetic and mechanical causes. The most widely known, electromagnetic reasons are cogging torque and RMF(Radial magnetic force). Recently, analysis of the cogging torque has been made actively. but analysis of the RMF was not filled. So, in this paper, analyzed RMF. the vibration test were performed for the basic and reduced model of cogging torque and RMF. And it analyzed for the effect of each factor on the vibration. Finally, the vibration was formulated for stator's weight and RMF. To this end, natural, cogging torque and RMF of frequency were analyzed and these relationships were considered.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.864-866
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• 2000

In the slotted motor, cogging torque is generated due to the interaction between the rotor magnets and the slots on the stator. It is well known that cogging torque produces vibration and noise which may be detrimental to the performance of position and speed control system. Hence, the prediction of cogging torque is very important at the design stage of BLDC motor. In this paper, permanent magnets with different arc an91e of inner and outer radius is proposed. The cogging torque of proposed model and conventional one is analyzed by 2-D FEM and compared.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.18-23
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• 2005

Ships have been propelled and maneuvered by electrical drives since trle late seventies. Recently, rare earth PMs allow the design of brushless motors with very high efficiency over a wide speed range. This is the most important factor in ship propulsion technology. Several types PM motors have been developing for ship propulsion system. However these have disadvantage such as cogging torque. It causes an undesired effect that contributes to output ripple, vibration, and noise of machine. Therefore several techniques may be adopted in designing PM motor in order to reduce the cogging torque. This paper describes cogging torque receding methods such as adjusting arigap length, magnet arc, and magnet thickness. That are analysed by using the finite element method(FEM) and the maxwell stress tensor method.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.243-250
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• 2015

This paper proposes a novel skewed-type iron slot wedge that can improve both the cogging torque and the output power of a permanent magnet synchronous generator (PMSG). Generally the open slot structure is adopted in a PMSG due to its convenient winding work, but the high cogging torque is undesired. Firstly, an iron slot wedge was utilized to reduce the cogging torque of an open slot type PMSG. However, the output power of the machine decreased rapidly with this method. Thus, a proposed skewed type iron slot wedge is presented to improve the output power as well as the cogging torque as compared to the open slot type. Shape optimization of the skewed-type iron slot wedge is performed to simultaneously maximize the output power and reduce the cogging torque. The Kriging model based on the Halton sequence method and a genetic algorithm are used to optimize the design.