• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1980-1990
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• 2017

A study on the multi-objective optimization of Interior Permanent-Magnet Synchronous Motors (IPMSMs) with 2, 3, 4 and 5 flux barriers per magnetic pole, based on Genetic Algorithm (GA) is presented by considering the aspect of irreversible demagnetization. Applying the 2004 Toyota Prius single-layer IPMSM as the reference machine, the asymmetrical two-, three-, four- and five-layer rotor models with the same amount of Permanent-Magnets (PMs) is presented to improve the torque characteristics, i.e., reducing the torque pulsation and increasing the average torque. A reduction of the torque pulsations is achieved by adopting different and asymmetrical flux barrier geometries in each magnetic pole of the rotor topology. The demagnetization performance in the PMs is considered as well as the motor performance; and analyzed by using finite element method (FEM) for verification of the optimal solutions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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• pp.2035-2042
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• 2011

In this paper, we proposed the outer-rotor type of FSPM motor for high speed operation and optimized motor shape. First of all, combinations of pole and slot numbers are examined for the optimal back-EMF and cogging torque, then optimizes the better shape design of the permanent magnet, rotor pole width. Further, The winding turns are obtained by circle of the voltage limit equation and motor parameters to minimize the current and to improve the efficiency. As a result, the performance of the designed model is satisfied, and it is verified through a two-dimensional finite element method (2D-FEA).

• Journal of Magnetics
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• v.21 no.2
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• pp.173-178
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• 2016

Six-step commutation control widely used in brushless DC (BLDC) motor can be applied to consequent pole permanent magnet (CPPM) belt starter generator (BSG) with trapezoidal back electromotive force (EMF) in the starter state. However, rotor position detection with three Hall sensors in BLDC motor can hardly be employed in CPPM BSG due to asymmetric flux distribution in each pole side of CPPM BSG. This paper presents a low-cost rotor position detection method for CPPM BSG in which six Hall sensors are proposed to be used based on the analysis of flux distribution by 3D FEA. In the method, the six Hall sensors are divided into three groups and two signals in each group are combined through performing logic operations. In addition, offset angle between back EMF and the related Hall signal can be compensated by moving the Hall sensors. Experiments of a 2 kW CPPM BSG prototype have also been performed to verify the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.106-114
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• 1998

Cogging torque is often a principal source of vibration and control difficulty in permanent magnet motors, especially at low speeds and loads. For example, reduction of cogging torque is an important specification for DC motors used for electric power stee- ring. This paper examines two motor design techniques, stator tooth notching and rotor pole skewing with magnet pole shaping, for reduction of cogging torque, and the effect of each method on the airgap flux, and the use of the Maxwell stress method and Fourier decomposition to calculate the periodic cogging torque. The analyses show that the cogging torque can be nearly eliminated by the suggested designs, with minimal scacrifice of output torque.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.375-383
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• 2008

This paper deals with reduction and analysis of cogging torque for permanent magnet synchronous generators with multi-pole rotor for wind power applications. Open-circuit field solutions are derived using a magnetic vector potential and a two-dimensional (2-d) polar coordinate systems. On the basis of derived open-circuit field solutions and 2-d permeance functions, we also derive open-circuit field solutions considering stator slotting effects. By using open-circuit field solutions considering stator slotting effects and energy variation methods, this paper analytically predicts the cogging torque considering skew effects. All analytical results are shown in good agreement with those obtained from finite element (FE) analyses. In order to reduce the cogging torque, by predicting the variation of the cogging torque according to pole arc/pitch ratio using analytical and FE methods, pole arc/pitch ratio which makes the cogging torque minimum are determined. However, we confirm that measured value for cogging torque of the PMG with determined pole arc/pitch ratio is twice higher than predicted value. Therefore, the reason for an error between measured and predicted cogging torque is discussed in terms of a shape of PMs and is proved experimentally.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.903-909
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• 2014

As a direct drive type washing machine requires two operating modes, washing and spinning modes, a design of the motor with high efficiency in each mode is not applicable to a conventional procedure. To achieve the requirements, a multi-pole outer rotor type switched reluctance motors are considered. To select a suitable motor type for the application, a static toque is compared based on the FEM analysis. The selected type is obtained for high and wide toque than other types of the motor. Further, the pole shape and arc are optimized to meet the required torque and torque ripple. To verify the proposed structure, the prototype is designed and manufactured. And the simulation and experimental results verify the validity of the proposed structure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6270-6275
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• 2014

The paper reports an improvement method on torque ripples of multi-pole interior permanent magnet synchronous motor (IPMSM) applied to a traction motor for hybrid electric vehicles. In the case of multi-pole IPMSM, the magnetic flux generated by a permanent magnet tends to leak through the bridge of the rotor without a link with stator windings. The slit design on the rotor surface was proposed to reduce torque rippling and increase the output power by reducing the leakage flux. Two design parameters for the slit are suggested for optimal design using the response surface method. As an analysis method, the 2D finite element method (FEM) was applied to consider magnetic saturation effect.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.926-930
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• 2004

This paper presents a comparison of the characteristics by two types of switched reluctance motor (SRM) drives using search coils, Exterior pole search coil and Interior central pole search coil, which are used for estimation of the rotor position. The advantages and disadvantages of the two types of drive methods are also described.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1065-1070
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• 2017

Magnetic gears are magnetically coupled to the input side and the output side of the rotary machine to transmit power without mechanical contact. The magnetic gear consists of an inner rotor, an outer rotor and pole pieces. Torque ripple occurs due to the difference in reluctance between the two rotors and the pole pieces during power transmission. Torque ripple is a cause of the noise and vibration of the rotary machine, so it is necessary to minimize it. In this paper, we propose a shape that cuts the corner of the pole piece and apply a fillet to reduce torque ripple. We used a two-dimensional finite element analysis method to compare and analyze the torque ripple of the magnetic gears according to the change of the fillet parameters and to find the pole piece shape with excellent torque ripple.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.682-684
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• 2015

A 12/14 bearingless switched reluctance motor (BLSRM) with hybrid stator poles has been proposed due to the outstanding decoupling characteristics between the torque and suspending force. However, the motor is a two-phase motor. The output torque of the motor has torque dead zone and high torque ripple. Hence, the motor cannot self-start at some rotor positions. To solve the self-starting problems and reduce the torque ripple, a stepped rotor is proposed in this paper. Then, the motor with the stepped rotor is optimally designed. In the new designed motor, the majority parameters are kept the same with those of original motor; only the torque pole arc and rotor pole shape are optimally designed. The characteristics of the redesigned motor, such as inductance, torque and suspending force, are analyzed and compared with those in the original motor. Finally, the effectiveness of the proposed method is verified by the simulation results.