• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.1
• /
• pp.46-52
• /
• 1998

This paper describes a current-shaping method for the production of constant torque of SRM under the nonlinear magnetic saturation condition. A current detection technique in the inductance increasing region and an approximation technique for modeling of nonlinear inductance profile are adopted. In the proposed system, a single switching angle control and voltage control is used to shape the current waveform for the generation of flat torque at any given load condition. Finally the validity of the proposed method was verified using a constructed 3HP 6/4 SRM.

• Proceedings of the KIPE Conference
• /
• 2017.07a
• /
• pp.86-87
• /
• 2017

본 논문에서는 3상 22kW급 전기자동차 탑재형 충전기를 위한 단일단 AC-DC 컨버터를 제안한다. 제안하는 3상 단일단 AC-DC 컨버터는 제안하는 인터리빙 회로와 스위칭 기법으로 입력필터가 작고 넓은 전압 및 부하영역에서 소프트스위칭을 성취하여 높은 효율을 성취할 수 있으며 전해커패시터를 제거하고 필름커패시터를 사용하여 높은 수명 및 전력밀도를 기대할 수 있다. 또한 제안하는 컨버터는 단상 단일단 AC-DC 컨버터를 모듈구조로 구성하여 출력전류에 포함된 120Hz 맥동전류를 출력에서 상쇄시켜 저주파 성분이 없는 직류전류로 충전이 가능하다. 제안하는 3상 단일단 AC-DC 컨버터의 동작원리를 제시하고 시작품을 통해 본 논문의 타당성을 검증하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.9
• /
• pp.937-942
• /
• 2008

This paper presents a case history on failures of impeller and shaft due to pressure pulsation at single stage feed water pumps in 700 MW nuclear power plant during commissioning operation. The pumps had been service and had run for approximately $40{\sim}50$ hours. For the most part, the failures of impeller occurred with the presence of a number of fatigue cracks. All cracks were associated with the deleterious surface layer of impeller by visual and metallurgical examination. On-site testing and analytical approach was performed on the systems to diagnose the problem and develop a solution to reduce the effect of exciting sources. A major concern at high-energy centrifugal pump is the pressure pulsation created from trailing edge of the Impeller blade, flow separation and recirculation at centrifugal pumps of partial load. Pressure pulsation due to the interaction generating between impeller and casing coincided with natural frequencies of the impeller and shaft system during 1ow load operation. It was identified that dynamic stress exceeding the fatigue strength of the material at the thin shroud section due to the hydraulic instability at running condition below BEP.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.17 no.1
• /
• pp.83-88
• /
• 2011

There are various environmental conditions under which ship may navigate over ocean or in harbor. Ship's torque and speed change frequently under the voyage conditions. In this case, harmonics is created in the electrical power systems. The major adverse impacts of voltage and current harmonics in the electrical power systems on generator, transformer, converter, inverter and propulsion motor lead to the increase of machine heating caused by iron and copper losses which are dependent on frequency. In this paper, an analysis of THD(total harmonic distortion) for currents and voltages in the propulsion equipment was carried out. The THD and torque ripple in the input currents of the propulsion motor have been confirmed by the simulation results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.4
• /
• pp.399-406
• /
• 1998

This paper proposes an instantaneous torque control method for the high performance SRM drive. In first, we e establish SRM model with the characte1istics of the torque. phase current and rotor position which were measured in t the experimental SRM. Based on this model. the reference torque waveform to minimize torque ripple is obtained by t the control of resultant torque considering phase torque overlap according to the variation of load and speed. And the r reference current waveform for the tracking of reference torque are decided. The control method for tracking the r reference current is used the delta modulation technique. The proposed method is validated by the comparing with S simulation and experimental results.

• JOURNAL OF ELECTRICAL WORLD
• /
• s.315
• /
• pp.74-79
• /
• 2003

지구온난화 방지 등 환경보전을 목적으로 전기기기 및 설비의 전력소비를 저감시키기 위한 성에너지관련법이 일부에서 시행되어 각 방면에서 그에 대한 대책이 이루어지고 있다. 전기기기 중에서도 공조기는 일반가정의 소비전력에서 차지하고 있는 비율이 $24\%$로 상당히 큰 편이다 최근 공조기는 소비전력을 저감시키기 위해 기간부품의 효율 개선을 도모하여 왔으나, 이 효율 개선에는 전력소비가 큰 압축기(탑재)모터와 이것을 구동하는 인버터의 손실 저감도 반드시 필요하다. 또 효율개선 외에 공조기 운전시의 쾌적성 향상의 관점에서 저진동화 및 저소음화를 도모할 필요가 있어 구조명과 함께 인버터 제어면에서의 대책을 시행하여 왔다. 압축기 중에서도 성능개선이 두드러진 룸에어컨은 압축기에 고효율의 브러시레스 DC모터를 탑재하여 정현파구동방식을 이용한 인버터에 의해 고효율화를 실현하였다. 이 정현파구동방식은 독자적인 과(過)변조 PWM(Pulse-Width Modulation) 방식을 적용하여 효율 개선에 크게 기여하고 있다. 또 인버터는 압축기 특유의 맥동(脈動)부하에 기인하는 진동을 제어$\cdot$억제하여 저진동화를 실현하였다. 또한 패키지에어컨에서는 인버터 캐리어주파수에 기인하는 캐리어음(音)을 인버터제어로 억제하여 저소음화를 실현하였다. 본고에서는 공조기를 대상으로 특히 에너지 소비가 큰 압축기용 모터와 이것을 구동하는 인버터의 효율개선 기술과 저진동화 및 저소음화를 도모하기 위한 인버터 응용기술에 관하여 기술한다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.4 no.3
• /
• pp.55-60
• /
• 2003

In the controller design of position or velocity control system, the flexibility of the mechanical system is always the limiting factor to the higher performance. Most mechanical systems coupled with rotary shaft are 2-Inertia systems which are consist of motor and load inertia. These inertias make a torsion In rotary shaft and cause torsional vibration. To suppress vibration, various control strategies have been proposed mainly for controlling 2-inertia system. In this paper, a speed controller design for a 2-inertia system composed of voltage controlled DC motor and load inertia is made by using CDM(coefficient diagram method). First, the 2-inertia system model is derived. Then the CDM is used to design the proper controller. A validity of this approach is confirmed by simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.2
• /
• pp.132-140
• /
• 2001

A universal motor is a small dc series machine motor that is designed to operate from an ac machine. The characteristics of universal motors are high no-load and staring torque. Because of the high operating speed, the size of these motors for a given hp rating is typically smaller that other fractional hp ac machine, making it ideal for hand-held tools and appliances where weight, compactness, and speed are importance factors. A phase-angle control with AC drive system gains a high popularity due to their simple implementation, but contains the disadvantage of their poor input power factor, subharmonic current. Pulse width modulation control with DC drive systems increase the power factor as without delay phase angle. This paper analyzed the subharmonic characteristics of the phase angle control system that is controlled by zero voltage crossing similar to traditional method, and the dc chopper system that is used PWM.