• Journal of Power Electronics
• /
• 제9권2호
• /
• pp.146-155
• /
• 2009

The static frequency converter (SFC) systems are used as a method of driving large synchronous machines in many power and industrial plants. In this paper, new control algorithms of SFC systems for starting gas turbo sets are proposed for a four quadrant operation: start-up at standstill; an acceleration up to the speed of the rated voltage; field weakening to reach the rated speed; synchronization to the main alternating current (AC) source; and dynamic braking to stop safely within the rating of the synchronous machine. Experimental results show that the proposed algorithms are proper and effective.

• 한국초전도ㆍ저온공학회논문지
• /
• 제7권3호
• /
• pp.21-28
• /
• 2005

Superconducting synchronous motors and generators have the field coil composed of superconductor with almost zero resistance at superconducting state. Therefore, copper loss at the conventional field coil is eliminated and the superconducting machine gets higher efficiency. The armature coil of the superconducting machine is composed of copper wire and supported by non-magnetic material such as FRP (Fiber Reinforced Plastic) This paper contains the design Procedure of a 1MW superconducting synchronous motor using high-temperature superconductor only for the field coil. Especially, the armature coil is designed by water-cooling in order to dissipate Joule heat easily. Moreover, 3-dimensional electromagnetic design is conducted to get a proper design result and reduce design errors from 2-dimensional approach.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제3권2호
• /
• pp.132-138
• /
• 2014

We investigated the harmonic voltages generated by a synchronous machine adding d-axis and q-axis harmonic field windings to reduce the harmonics in a power line. First, electronic circuits such as a frequency multiplier, band-pass filter, and phase shifter were newly designed and made to carry out the experiment. Next, an experimental circuit, for which an AC voltage of frequency 6f synchronized to the power line voltage of frequency f could be obtained, was constructed to examine the generation of harmonic voltage in more detail. Finally, an experiment involving the generation of harmonic voltage was performed using an experimental synchronous generator with harmonic windings in the d-axis and q-axis. In this paper, the power spectrum and the waveforms of the harmonic voltages in the armature winding are presented. Moreover, the values calculated from theoretical expressions of harmonic voltages in armature winding are compared with the values obtained by the experiment.

• 전력전자학회논문지
• /
• 제11권2호
• /
• pp.104-112
• /
• 2006

대용량 동기 발전 전동기 운전에는 주로 사이리스터를 이용한 정지형 주파수 변환장치(SFC static Frequency Converter)시스템이 널리 사용되고 있다. 본 논문에서는 기술적인 언급이 거의 되어있지 않은 회생 제동 시스템의 개선된 제어 알고리즘을 제시하였다. 기술적 언급이 없기 때문에 실제 구동되고 있는 양수 발전소의 실측 파형을 분석하여 알고리즘을 도출하였으며 이로 인해 기존의 회생제동 제어에서 사용되었던 전압센서가 필요 없게 되어 경제적인 절감 효과를 유발하고 또한 제어요소의 간략화로 제어의 강인성을 확보하였다. 그리고 실험을 통하여 실효성 및 타당성을 검증하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제9권3호
• /
• pp.32-36
• /
• 2007

On the contrary of a conventional motor with very narrow air-gap. it is difficult to calculate the accurate magnetic field distribution and the performance of an air-cored superconducting motor by 2 dimensional analysis. which does not use high permeability material except outer machine shield. This paper aims to do analysis of magnetic field and force distribution from the 3 dimensional modelling of a 1MW class superconducting synchronous motor. Especially. the field coil composed of Bi-2223 high-temperature superconductor and the outer machine shield are modelled by finite element analysis software according to their structures and the self-inductance and Lorentz force are calculated based on the 3 dimensional magnetic field calculation. Moreover. the influence of an important parameter, synchronous reactance, has been analyzed on the machine performances such as voltage variation and output power.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2009년도 추계학술대회 논문집
• /
• pp.19-20
• /
• 2009

• Journal of Electrical Engineering and Technology
• /
• 제2권1호
• /
• pp.61-67
• /
• 2007

In this article, a special kind of axial flux permanent magnet machine has proved to be suitable for high torque and low speed applications. An innovative design of the machine has been proposed in order to make the machine suitable for traction applications by means of field-weakening. The aim of this paper is to analyze, in general terms, the basic equations that describe the operating conditions of such machines. Optimal sizes for design can be obtained by calculating the power density and the air-gap flux density, etc.

• 전력전자학회논문지
• /
• 제18권5호
• /
• pp.437-442
• /
• 2013

For open-end permanent magnet synchronous machine(PMSM) with dual inverter system, where one inverter is connected to the source and the other is flying, the dc link voltage of the flying inverter can be boosted through the machine. For this reason, when compared with single inverter drive system, higher voltage can be applied to PMSM, and higher torque can be generated in the flux weakening region. In this case, however, active and reactive powers are separately supplied by each inverter to maintain the dc link voltage of flying inverter. Therefore, the required flux weakening control is different from the conventional method for a single inverter drive system. This paper proposes the novel flux weakening control method which maximizes the active voltage component in a dual inverter PMSM drive system. The proposed method was demonstrated and verified through experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1360-1361
• /
• 2011

본 논문은 Synchronous Machine을 기반으로 하여 250[kVA]의 용량을 가지는 플라이휠을 모델링하고 그 예를 수학적으로 해석함으로써 분산전원으로서의 신재생에너지와 연계하여 에너지를 저장/출력할 수 있는 타당성을 검토할 수 있도록 한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
• /
• pp.8-14
• /
• 2007

This paper deals with the electrical design and analysis of a 300HP, 60,000rpm permanent magnet synchronous motor for turbo machine. The design is performed by analytic method of magnetic field theory. And electrical losses of the motor driven by current with sinusoidal and harmonic form are analyzed by using FEM.