• 전력전자학회논문지
• /
• 제23권2호
• /
• pp.112-120
• /
• 2018

This work presents a hybrid generator, which is a combination of a permanent magnet (PM) and winding structure with a PM exciter. The field winding of the proposed hybrid generator is fed by the PM exciter and the embedded current controller, which is installed in the generator shaft. In the no-load condition, the output voltage of the generator is produced by the PM flux of the generator without any field winding current. The field winding current produces an insufficient flux to retain the output voltage of the generator when the load is injected. The total efficiency can be increased from the PM exciter and PM flux of the generator. The field current has to be controlled inside the proposed generator. The generated power from the PM exciter is used to excite the field flux of the generator. The embedded current controller is commanded by the external voltage controller using the infrared wireless method. The 10 kW prototype hybrid PM generator is designed and tested to verify the effectiveness of the proposed system. The experimental results are compared with those of the winding generator with PM exciter.

• Journal of Electrical Engineering and Technology
• /
• 제13권6호
• /
• pp.2268-2275
• /
• 2018

This paper presents a high-efficiency low-power permanent magnet (PM) generator for the power supply of the generator exciter. In the conventional generator system, the power for the exciter is fed by the generator output power or an emergency battery for the starting. The proposed low-power PM generator can generate the proper power and voltage to excite the exciter field winding. According to the starting of the generator, the designed PM generator can supply the constant voltage to the Automatic Voltage Regulator (AVR), then it can be used to control of exciter field current for the generator. Because of the designed PM generator which is placed inside the conventional generator system, the emergency battery and Potential Transducer(PT) for AVR can be removed. Thus, the total efficiency can be improved. The proposed generator system is tested in the practical system. And the efficiency characteristic is analyzed.

• 전기학회논문지
• /
• 제65권11호
• /
• pp.1827-1834
• /
• 2016

This paper presents a high efficient generator with PM(Permanent Magnet) exciter. The proposed PM exciter for the generator can produce a linear output voltage according to the engine speed. This output voltage is directly used to control the field current of the generator to adjust the generator output voltage. In the proposed generator system, since the field winding current can be supplied by the PM exciter, the generator can self-start without any battery or an external power supply due to the low residential flux. Furthermore, the operating efficiency of the generator is higher than a conventional winding exciter. The main problem of the proposed generator system, the field winding current controller has to be embedded inside the generator, and it rotates according to the generator shaft. In this paper, the proper embedded current controller is designed for the proposed generator system. Due to the embedded controller cannot be connected to the outside the generator controller, the measured instantaneous output voltage of the generator is transferred by the photo isolated communication using shaft aligned infrared transmitter and receiver to keep the constant generator output voltage. In this paper, 10kW, 380V engine generator with PM exciter and the embedded DAVR(Digital Automatic Voltage Regulator) are described. The proposed high efficiency generator is simulated and tested to verify the effectiveness.

• 핵의학기술
• /
• 제14권2호
• /
• pp.128-132
• /
• 2010

핵의학과 종합조작실은 방사선 관리구역으로 이곳에서 발생된 방사성오염물질은 방사성폐기물로 간주하여 일반쓰레기와 별도로 관리를 해야 한다. 본 실험은 우리가 미처 인식하지 못해 일반쓰레기로 처분되었던 방사성오염물질의 오염도를 측정하고 원인을 분석하여 보다 적극적인 방사성폐기물 관리 운영의 필요성을 제시하고자 함이다. 측정대상은 방사성의약품을 표지하기 위해 사용된 생리식염수와 $^{99}Mo$/$^{99m}Tc$ generator(국산 및 외산)에서 발생한 generator cap, saline needle cap, $^{99m}Tc$-needle cap, saline vial로 하였고, gamma survey meter를 이용하여 평균값과 표준 편차(mean${\pm}$SD)로 나타냈다. 측정대상물질의 오염유무를 알기 위해 방사선 관리구역에서 반출될 수 있는 물질의 표면오염도인 최대허용표면오염도의 1/10(43.2 cpm)을 기준값으로 정하였다. 각각의 표면오염도를 측정한 결과 방사성의약품 표지를 위해 사용된 생리식염수에서는 $14,429{\pm}26,378$ cpm으로 최대 허용표면오염도의 1/10을 초과하였다. 그리고 측정된 generator중 외산에서는 generator cap: $17{\pm}28$ cpm, saline needle cap: $35{\pm}66$ cpm, $^{99m}Tc$-needle cap: $9{\pm}21$ cpm, saline vial: $13{\pm}28$ cpm으로 최대허용표면오염도의 1/10를 초과하지 않았지만 국산에서는 generator cap: $22,852{\pm}52,545$ cpm, saline needle cap: $87,367{\pm}109,711$ cpm, $^{99m}Tc$-needle cap: $9,008{\pm}10,459$ cpm, saline vial: $186,416{\pm}158,196$ cpm으로 최대 허용표면오염도의 1/10를 초과하였다. 외산 generator에서 발생한 측정대상물질은 일반폐기물로 처분하고 국산 generator와 방사성의약품을 표지하기 위해 사용된 생리식염수는 반드시 방사성폐기물로 간주하여 처분해야 한다. 따라서 일반쓰레기 뿐만 아니라 종합조작실에서 반출되는 모든 물질에 대한 자체적인 방사선측정, 기록 및 비치와 방사성폐기물에 대한 지속적인 교육을 통해 방사성 폐기물이 일반쓰레기로 처분되어 나가는 것을 예방 할 수 있을 것이다.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2017년도 추계학술대회
• /
• pp.57-58
• /
• 2017

This paper proposes a high efficiency hybrid generator which has a winding and PM(Permanent Magent) field together. The PM field can supply the enough flux to generate the no-load output voltage, and the field winding current can supply the flux to compensate the voltage drop from the load. Furthermore, the PM exciter can supply the enough power for the field of the generator. The detailed design and the FEM analysis are presented to verify the proposed hybrid generator. Then the experimental results shows the effectiveness of the proposed system.

• 한국기계가공학회지
• /
• 제15권4호
• /
• pp.141-147
• /
• 2016

A direct PM generator has the effect of reducing the mechanical noise and ease of maintenance by eliminating a number of power transmission components. In addition, wind turbines operating at low speed with the advantages of high output, high efficiency, and small size. The generator was designed as a small direct-drive PM generator that can be applied to a kite even at low wind speeds. The RPM (Revolutions Per Minute) of the reel was measured in two ways using a cadence/speedometer sensor and a tachometer while the actual kite. The RPM derived from the experiment was applied to the simulation on the designed generator. The no-load characteristic analysis for the magnetic fields produced for the permanent magnet generator by a permanent magnet and stator winding currents is achieved using a 2D coordinate system. A commercial electromagnetic analysis program, ANSYS Maxwell, was used to model the electromagnetic dynamics.

• 전기학회논문지
• /
• 제61권12호
• /
• pp.1820-1827
• /
• 2012

This paper is to present a new method of cogging torque reduction for axial flux PM machines of multiple rotor surface mounted magnets. In order to start softly and to run a power generator even the case of weak wind power, reduction of cogging torque is one of the most important issues for a small wind turbine, Cogging torque is an inherent characteristic of PM machines and is caused by the geometry shape of the machine. Several methods have been already applied for reducing the cogging torque of conventional radial flux PM machines. Even though some of these techniques can be also applied to axial flux machines, manufacturing cost is especially higher due to the unique construction of the axial flux machine stator. Consequently, a simpler and low cost method is proposed to apply on axial flux PM machines. This new method is actually applied to a generator of 1.0kW, 16-poles axial flux surface magnet disc type machine with double-rotor-single-stator for small wind turbine. Design optimization of the adjacent magnet pole-arc which results in minimum cogging torque as well as assessment of the effect on the maximum available torque using 3D Finite Element Analysis (FEA) is investigated in this design. Although the design improvement is intended for small wind turbines, it is also applicable to larger wind turbines.

• Journal of Magnetics
• /
• 제20권4호
• /
• pp.405-412
• /
• 2015

In this study, we describe the effects of changing the magnet shape of permanent magnets (PMs) in a rotor Halbach-array PM generator for reciprocating free piston generator applications. More specifically, the rectangular-shaped magnets were replaced by the trapezoidal-shaped magnets. The initial design, an analytical magnetic field solution of rectangular shaped magnets, is presented and air-gap magnetic flux density and thrust force were estimated. The results were compared to the finite element analysis (FEA) showing excellent agreement. Using FEA, the effect of the shape of the magnets on the flux density and thrust force waveforms is analyzed. Moreover, the proportion of the Halbach array in the machine was optimized by the means of a parametric search. The results obtained from the analytical calculations and FEA were validated by comparing to those of Radial-array PM generator.

• 전기학회논문지
• /
• 제61권3호
• /
• pp.380-383
• /
• 2012

Small permanent magnet generator can be used not only as an emergency power source but also an exciting power source of generator for small generating systems because it does not need the external exciting power source. Especially the air-gap flux density of the buried PM synchronous generator can be increased more than that of the permanent magnet. In this study, the analysis of the small buried type PM synchronous generator is performed. From the phasor diagram considering armature resistance for exact analysis, analytic equations are induced and the efficiency, developed voltage, load current are calculated. The experimental results are compared with the calculated results for the appropriateness.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.3-5
• /
• 2006

In this paper, annual energy production(AEP) of the wind generator system is analogized considering the regions of a variable wind speed and it is applied to optimal design of the PM wind generator for capturing maximum energy in the operating regions. In addition, internet parallel computing is used to loose excessive calculation times through optimization of the finite element analysis(FEA).