• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2057-2061
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• 2015

This paper describes analysis and experimental characterization of low speed direct drive fractional slot concentrated winding (FSCW) surface permanent magnet synchronous motor (SPMSM) with consequent pole (CP) rotor, for which studies have been recently performed. The proposed motor, which consists of 30 poles and 36 slots, is analyzed and characterized by extensive 2D finite element analysis (FEA) and together with 3D FEA for an appropriate PM overhang length design. The validity of the analysis is confirmed by the corresponding experiments which fully characterize the proposed motor with excellent agreement between the FEA and the experiments. Thermal stability is also experimentally examined to determine continuous operating points and instantaneous operating points of the proposed motor. It is highly expected that the proposed motor is applicable for low speed direct drive applications.

• 조명전기설비학회논문지
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• 제29권5호
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• pp.41-49
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• 2015

In this paper, we studied an optimal design and efficiency improvement of the BLCD motor used in home electronic appliance. The number of stator slots is chosen depending on the rotor poles, phase number, and the winding configuration. In general, a fractional slots/pole design is preferred to minimize cogging torque. To reduce the winding resistance, we reduced the coil length and we improved the coil space factor. We proposed three types of stator slot shape design for the optimal BLDC motor design. One of them, U-type slot shape is a best optimal design, it proved by the simulated and tested. Optimal design of essential parameters aiming at high winding factor are presented to create for a high-quality system implementation. Design analysis is verified by testing and building a prototype motor.

• Journal of Magnetics
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• 제19권1호
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• pp.84-89
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• 2014

This paper presents an analytical prediction and experimental verification of the electromagnetic performance of a parallel magnetized surface-mounted permanent magnet (SPM) motor having a fractional number of slots per pole combination. On the basis of a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for flux density produced by the permanent magnets (PMs) and stator windings are derived. Then, analytical solutions for back-electromotive force (emf) and electromagnetic torque are derived from these field solutions. The analytical results are thoroughly validated with 2-D nonlinear finite element (FE) analysis results. Finally, the experimental back-emf and electromagnetic torque measurements are presented to test the validity of the analysis.

• 한국전자파학회논문지
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• 제24권6호
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• pp.581-585
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• 2013

마이크로스트립 패치 안테나의 대역폭을 확장하기 위한 방안을 제시하였다. 이 안테나는 사각형의 슬롯을 가진 접지판 위에 변형된 T-자 모양의 마이크로스트립 라인으로 급전되는 구조를 갖는다. 제시된 마이크로스트 립 패치 안테나는 슬롯과 변형된 T-자 모양의 급전 라인의 크기와 위치를 최적화시킴으로써 광대역 특성을 구현 하였다. 컴퓨터 모의실험 결과에 의하면 VSWR 2:1 기준에서 127.8 %(0.65~2.95 GHz)의 대역폭을 얻을 수 있었다.

• Journal of Magnetics
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• 제18권3호
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• pp.268-275
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• 2013

This paper shows the characteristics of performance for interior permanent magnet machine (IPM) considering driving conditions such as maximum torque per ampere (MTPA) and flux-weakening control especially in terms of harmonic loss. In particular, based on finite element analysis (FEA), permanent magnet (PM) eddycurrent loss and the harmonic iron loss have been computed where the models have been intentionally designed to identify the effects of pole-slot combinations on the loss while maintaining the required power for electric vehicle. From the analysis results, it was shown that the rotor iron loss and PM eddy-current loss of machine employing fractional slot winding are extremely large at load condition. Furthermore, it was revealed that the harmonic iron loss at high-speed operation is mainly distributed over stator teeth and rotor surface, which may aggravate cooling system of the rotor structure in the vehicle.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.216-224
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• 2013

This paper describes dual inverter drive for a fractional-slot concentrated winding permanent magnet synchronous machine (PMSM). PMSMs are widely used in many applications from small servo motors to few megawatts generators thanks to its high efficiency and torque density. Especially, fractional-slot concentrated winding PMSM is very popular in the applications where wide operation range is required because it shows very wide constant power speed ratios. High speed operation, however, requires lots of negative daxis current for reducing back-EMF regardless of output torque. Field weakening current does not contribute to the torque generation in surface mounted PMSM case and causes inverter and copper loss. To reduce the losses from field weakening current, this paper proposes PMSM with split stator and parallel dual inverter drive. Proposed parallel dual inverter drive reduces back-EMF and enables efficient drive at high speed and light load situation. Control strategy of proposed dual inverter system is established through loss analysis and simulation. Proposed concept is verified with practical experiment.

• 한국통신학회논문지
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• 제28권11A호
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• pp.912-920
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• 2003

본 논문에서는 UWB용 소형 안테나를 설계하기 위해 폭이 넓은 안테나의 슬롯면내에 구형 루프를 추가하고 이중급전 방법을 사용한 슬롯루프 안테나를 제안하였다. 이 안테나는 3개의 기하학적인 공진 구조에 의해 다중 공진 모드를 발생시키는 새로운 구조이며, 각각의 공진 주파수에 따른 임피던스 정합은 이중 급진점의 오프셋 길이를 변화하여 얻을 수 있다. 제작된 안테나는 중심 주파수가 6.755 ㎓이며, 슬롯의 크기는 12.5mm${\times}$50mm이고 슬롯 내의 구형 루프의 크기는 10.5mm${\times}$27.5mm이다. 실험 결과 슬롯루프 안테나의 비대역폭은 VSWR 2:1 기준으로 63.21 %로 측정되었으며 이는 이론 값과 5% 범위 이내에서 일치하였다. 또한 안테나의 최대 이득은 7.42 ㏈i로 측정되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.50-52
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• 2008

In this paper, we investigated the iron losses in the rotor core of interior permanent magnet synchronous machine (IPMSM), which have distributed armature windings. From the analysis results, we can conclude that iron losses of rotor are definitely large at load condition if the number of slots per pole is fractional. Since the slot-pole combination may induce excessive heating, particular care should be necessary in design of PMSM for a high power rating application such as electric vehicles.

• 한국전자파학회논문지
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• 제27권1호
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• pp.14-19
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• 2016

본 논문에서는 물결모양 구조를 갖는 광대역 슬롯 안테나를 제안하였다. 제안된 안테나는 물결모양 슬롯 구조를 가지는 접지면과 마이크로스트립 급전선으로 이루어져 있다. $70{\times}70{\times}1.6mm$의 한정된 크기에서 제안된 안테나는 물결모양 슬롯 구조를 통해 전류의 경로를 길게 하여 보다 동작주파수를 낮추었으며, 광대역의 대역폭을 갖는다. 안테나의 측정된 10 dB 반사손실 대역폭은 2,180 MHz(2.5~4.68 GHz)이며, 중심주파수 3.59 GHz에서 비대역폭 60.7 %를 가진다. 제안된 안테나는 전방향성 방사 패턴을 가지며, 측정된 이득과 평균효율은 3.48~5.83 dBi, 81.55 %의 값을 갖는다.

• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1526-1526
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• 2016