• Journal of Power Electronics
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• 제16권1호
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• pp.142-152
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• 2016

Common mode voltage (CMV) generation is a major problem in switching power converter fed induction motor drive systems. CMV is the zero sequence voltage generated due to the switching action of power converters. Even a small magnitude of CMV with a high rate of change may circulate large bearing currents which may damage a machine's bearings and shorten its life. There are several methods of controlling CMV. This paper presents 3-level sinusoidal pulse width modulation based techniques to control the magnitude and rate of change of CMV in multilevel AC-DC-AC drive systems. Simulation and experimental investigations have been presented to validate the performance of proposed technique to control CMV in 3-level neutral point clamped inverter based AC-DC-AC system.

• 한국생산제조학회지
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• 제19권5호
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• pp.678-683
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• 2010

The drum cam with rotational follower is used to apply the ATC and index table of machine tools and it has the merit of minimizing the backlash. In general, to machine the drum cam with rotational follower, 5-axis CNC machine must be used and its kinematic principle must be included in modeling on CAM. So, the commercialized CAM software can't be applied to this machining of drum cam. Though some special software for machining drum cam was developed, it could be applied to special 5-axis CNC machine tools and the finish machining module was not applied. To solve this problem, this study includes the induction of the post processing algorithm for the rough machining of drum cam on several 5-axis CNC machine tools, type AC, AB and Be. The finish machining software will be treated in next study. A sample drum cam was machined on 5-axis CNC machine tool of AC type. The designed geometric profile of drum cam consist to the measured profile after machining well. This post processing algorithm for rough machining of the drum cam was clearly verified.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권6호
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• pp.431-440
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• 2000

This paper analyses the dynamic performance of HVDC System connected to a weak AC system for various exciter characteristics of synchronous machines connected at the converter bus. Conventionally capacitors are used to supply reactive power requirement at a strong converter bus. But the installation of synchronous machine is essential in a isolated weak network to re-start after a shutdown of HVDC and to increase system strength. The dynamic performance of a synchronous machine depends on the characteristics depends of its exciter. In this paper, several exciter types are used to investigate their effect on the dynamic performance of the HVDC system and modifications to standard exciter topologies are suggested to mitigate observed problems.

• 전기학회논문지
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• 제61권11호
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• pp.1601-1605
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• 2012

Three-phase voltage and current is applied to the three-phase alternating current motors which are commonly used in industry. Three phase variables of a, b, c are converted into d, q, 0 axis and the AC machines are modeled and analyzed. Basically the coordinate transformation or d-q transformation is used for convenience, a few steps are needed to analyze the motor performances - separating d and q components, establishing each equivalent circuit, and solving the differential equations of the circuits. In this study, a modeling technique of induction motor using complex vector is proposed and it can explain the induction motor physically. This method does not need the separating process of d and q components. With this technique, the model becomes simple, is easy to understand in physical, and can get the same results with those from the other models. These simulation results of the proposed model are compared with them for the conformation of the proposed method.

• 전력전자학회논문지
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• 제7권3호
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• pp.244-252
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• 2002

본 논문에서는 가변속 교류 전동기 구동에 많이 사용되는 3상 ac/dc/ac PWM 컨버터 시스템에서의 직류링크 리플전류를 주파수 영역에서 해석하고자 한다. 고조파 전류는 컨버터의 스위칭함수와 지수함수 형태의 퓨리에 급수 전개를 이용하여 분석된다. 전원측 컨버터와 부하측 인버터의 스위칭 주기간의 변위각과 비동기 PW이 리플전류에 미치는 영향도 고찰된다. 해석 결과가 PSIM을 이용한 시뮬레이션으로부터 나온 고조파 스펙트럼과 잘 일치함을 확인한다 제시된 해석기법은 PWM의 원리에 대한 이해를 돕고, 해석 결과는 직류링크 커패시터의 고주파 등가 모델링에 이용된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.822-824
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• 2000

To apply HTS to AC devices, it is necessary that study theoretically and experimentally to analyze the AC losses. It should be investigated the theoretical mechanisms precede the actual experiments. Because the AC losses cause some complicated troubles in AC machines, we can design the machines properly. In this study, firstly we analyze the basic cause of AC losses by investigating the several loss factors, secondly measure the AC losses of HTS by using Magnetization. Technique and this results show that AC losses of HTS is tenuous than those of general materials used in power system. Consequently we can compare the actual results with the theoretical results. And we find that AC losses of HTS are related to the amplitude of external magnetic field and the frequency. Through this study, we find that it is possible to apply the results by Magnetization. Technique to the AC power system, to the design of AC machine, to design of HTS proper to the foretold AC losses.

• 한국생산제조학회지
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• 제19권5호
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• pp.684-690
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• 2010

A drum cam with rotational follower has a cam mechanism and it is mainly used in its application such as index table and ATC of machine tool. Also its use can reduce the backlash in its kinematic movement. To machine the drum cam with rotational follower, 5-axis CNC machine tool is generally used and its kinematic principle is included in it's design. Until now, the commercialized CAM software can't cover the application of the drum cam machining. Even if, some special software was developed for machining a drum cam, the post processing method for finish machining was not developed yet. And to overcome the problem, the form tool is still used on the tool path of rough machining. This study includes the induction of the post processing technique for the finish machining of drum cam on three 5-axis CNC machine tools, type AC, AB and BC. To prove the finishing geometric profile, the result was clearly verified through inspection and geometric measurement after direct machining of the drum cam in AC type 5-axis machine tool in this study.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.605-609
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• 2000

This paper presents a development of the Pulse Width Modulation ASIC for control of the AC servo or spindle motor in machine tools. The ASIC is designed two PWM functions for simultaneous control of a converter and an inverter. Also the device includes additionally two UART functions for interfacing the RS232C with PC or other devices. The device is connected to the microprocessor of Intel or Motorola by bus interface. The required output voltage and frequency for the motor control is programmed to the PWM block and the corresponding switching signals are calculated and generated with regard to the programmed value.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.529-533
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• 2000

This paper present a new sort of multilayer piezoelectric ceramic transformer for AC-adapt. This piezoelectric transformer operates n the second thickness extensional vibration mode. The output voltage of the multilayer piezoelectric transformer was simulated using ANSYS. As results, the maximum stress appeared at the two points where one is the middle of input and the other is middle of output side in Second thickness extensional vibration mode. And output voltage was inversely decreased by increasing number of output layers.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1998-2008
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• 2020

Solenoid operated valves (SOV) play important roles in industrial process to control the flow of fluids. Solenoid valves can be found in so many industries as well as the nuclear plant. The ability to be able to detect the presence of faults and predicting the remaining useful life (RUL) of the SOV is important in maintenance planning and also prevent unexpected interruptions in the flow of process fluids. This paper proposes a fault diagnosis method for the alternating current (AC) powered SOV. Previous research work have been focused on direct current (DC) powered SOV where the current waveform or vibrations are monitored. There are many features hidden in the AC waveform that require further signal analysis. The analysis of the AC powered SOV waveform was done in the time and frequency domain. A total of sixteen features were obtained and these were used to classify the different operating modes of the SOV by applying a machine learning technique for classification. Also, a deep neural network (DNN) was developed for the prediction of RUL based on the failure modes of the SOV. The results of this paper can be used to improve on the condition based monitoring of the SOV.