• Title/Summary/Keyword: voltage signal

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A Control Strategy Based on Small Signal Model for Three-Phase to Single-Phase Matrix Converters

  • Chen, Si;Ge, Hongjuan;Zhang, Wenbin;Lu, Song
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1456-1467
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    • 2015
  • This paper presents a novel close-loop control scheme based on small signal modeling and weighted composite voltage feedback for a three-phase input and single-phase output Matrix Converter (3-1MC). A small non-polar capacitor is employed as the decoupling unit. The composite voltage weighted by the load voltage and the decoupling unit voltage is used as the feedback value for the voltage controller. Together with the current loop, the dual-loop control is implemented in the 3-1MC. In this paper, the weighted composite voltage expression is derived based on the sinusoidal pulse-width modulation (SPWM) strategy. The switch functions of the 3-1MC are deduced, and the average signal model and small signal model are built. Furthermore, the stability and dynamic performance of the 3-1MC are studied, and simulation and experiment studies are executed. The results show that the control method is effective and feasible. They also show that the design is reasonable and that the operating performance of the 3-1MC is good.

Switching Signal Patterns to Prevent Short Circuit of AC Choppers (교류초퍼에서 단락사고 방지를 위한 스위칭 신호 패턴)

  • Jang, Do-Hyeon;Yeon, Jae-Eul
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.9
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    • pp.445-452
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    • 2001
  • Two switching signal patterns are proposed to prevent short circuit of PWM ac choppers. The voltage detection method and the current detection method are proposed to execute two switching signal patterns. In the voltage detection method, the dead-time has to be inserted to the switching signals after polarity of input voltage is checked by voltage transducer at input side. In the current detection method, the direction of load current is checked by current transducer at output side, and the dead-time delay is not considered. Controlling circuit built by current detection method is simple because the dead-time delay is considered. The experimental results are presented to prevent short circuit of ac chopper safely.

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Voltage disturbance detection method for HTS tape using electromagnetically coupled coils

  • Song, Seunghyun;Lee, Jiho;Lee, Woo Seung;Jin, Hongwoo;Hwang, Young Jin;Ko, Tae Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.16 no.1
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    • pp.23-26
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    • 2014
  • This paper represents the detection method of voltage disturbance for high temperature superconducting (HTS) tape using electromagnetically coupled coils. In order to detect the voltage as the superconductor transits from the superconducting state to the normal conduction state, voltage taps are widely used to get the voltage signal. And voltage taps are connected to data acquisition device via signal wires. However this new suggested method can detect the superconducting transition voltage without signal wires between voltage taps and data acquisition device by using electromagnetically coupled coils. This system consists of two electromagnetically coupled coils, the first coil to detect and transmit the voltage of HTS tape and the second coil to pick up the transmitted voltage from the first coil. By using this new suggested method, we can build the 'separated voltage-detection system'. HTS tape and first coil are located under liquid nitrogen vessel and the second coil is located under room temperature condition. In this paper, experiments are performed to verify the feasibility of the proposed method. As the result of the experiment, the separated voltage-detection system using electromagnetically coupled coils can successfully observe superconducting-normal transition of HTS tapes.

A Development of the Method Measuring from Signal Propagation Direction using Passive Electrical Properties in Human Body (인체에 있어서 수동적 전기특성을 이용한 신호전달방향 계측법 개발)

  • Park Hyung-Jun;Yoon Jae-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.55 no.8
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    • pp.378-385
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    • 2006
  • In this study, a method measuring signal propagation direction in human body was developed by using passive electrical properties of the body. The measured method of the signal propagation direction is to apply basic characteristic of electricity to the human body; when a voltage is set to a conducted medium, according to the polarity of the conducted voltage, the voltage rising or drop is generated. And using this concept, it is able to estimate the direction of electrical signal on the human body. The passive electrical properties were measured and the direction of signal propagation was estimated on the followings; between the flexor carpi radialis, between arms, between legs, between an arm and a leg, between the cervical vertebra and the upper limb, between the sacral vertebra and the leg, between the cervical vertebra and the tendon of triceps brachii, and between the sacral vertebra and the calcaneal tendon. As the result of experiments, the passive electrical properties were increased from l[Hz] to 50[kHz] of the inputted frequencies and showed at saturating tendency after that. And also, the estimated signal propagation directions using the developed method in this study agreed with the expected directions exactly at each part of the human body.

Implementation of multiple access bidirectional serial communications protocol using DC power line (직류 전원선을 이용한 다중 접속 양방향 직렬통신 프로토콜 구현)

  • Han, Kyong-Ho;Kim, Won-Il;Hwang, Ha-Yoon
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.332-338
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    • 2008
  • This paper handles, implementation of multiple access bidirectional serial communications protocol using two common DC power lines, whict are power supply and ground, connecting multiple devices. Communication between the host and the multiple clients are performed using unique packet data with device ID unique to each devices connected on the common power lines. Host initiates data communications by transmitting command packet to the designated client with the client's ID and the client responds by transmitting response packet to the host and in this way, multiple clients and host exchange the packet through the common power lines. The normal voltage of the power communication line maintains 24V corresponding to level 1 and the host drops the voltage to 12V on sending level 0 signal, also the clients normally keeps the line voltage to 24V use pull-down circuit to drop the voltage to 12V on sending level 1 signal. Power supply originates from the host, the host senses the voltage level of the power communication lines and when the clients activates pull down circuit to send level 0 signal and the voltage drops to 12V, the hosts switches power source from 24V to 12V. Also, when clients deactivate pull down circuit to send level 1 signal, the host senses the voltage increase and switches the power source from 12V to 24V. Experimental circuit is designed with one hosts and four clients and verified the power line voltage switching operation depending on the data signal levels on the power line. The proposed research result can be applied to two wire power communications system with one host and multiple low current consumption clients.

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Expandable Flash-Type CMOS Analog-to-Digital Converter for Sensor Signal Processing

  • Oh, Chang-Woo;Choi, Byoung-Soo;Kim, JinTae;Seo, Sang-Ho;Shin, Jang-Kyoo;Choi, Pyung
    • Journal of Sensor Science and Technology
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    • v.26 no.3
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    • pp.155-159
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    • 2017
  • The analog-to-digital converter (ADC) is an important component in various fields of sensor signal processing. This paper presents an expandable flash analog-to-digital converter (E-flash ADC) for sensor signal processing using a comparator, a subtractor, and a multiplexer (MUX). The E-flash ADC was simulated and designed in $0.35-{\mu}m$ standard complementary metal-oxide semiconductor (CMOS) technology. For operating the E-flash ADC, input voltage is supplied to the inputs of the comparator and subtractor. When the input voltage is lower than the reference voltage, it is outputted through the MUX in its original form. When it is higher than the reference voltage, the reference voltage is subtracted from the input value and the resulting voltage is outputted through the MUX. Operation of the MUX is determined by the output of the comparator. Further, the output of the comparator is a digital code. The E-flash ADC can be expanded easily.

Development of Signal Coupler for Power Line Communication over Medium Voltage Distribution Line (고압 배전선로 전력선 통신 신호결합장치 개발)

  • Lee Jae-Jo;Park Young-Jin;Oh Hui-Myoung;Kim Kwan-Ho;Lee Dae-Young
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.6
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    • pp.409-416
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    • 2005
  • For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

Large Signal Determination of Non-Linear Output Capacitance of Gallium-Nitride Field Effect Transistors from Switch-Off Voltage Transients - A Numerical Method

  • Pentz, David;Joannou, Andrea
    • Journal of Power Electronics
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    • v.18 no.6
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    • pp.1912-1919
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    • 2018
  • The output capacitance of power semiconductor devices is important in determining the switching losses and in the operation of some resonant converter topologies. Thus, it is important to be able to accurately determine the output capacitance of a particular device operating at elevated power levels so that the contribution of the output capacitance discharge to switch-on losses can be determined under these conditions. Power semiconductor switch manufacturers usually measure device output capacitance using small-signal methods that may be insufficient for power switching applications. This paper shows how first principle methods are applied in a novel way to obtain more relevant large signal output capacitances of Gallium-Nitride (GaN) FETs using the drain-source voltage transient during device switch-off numerically. A non-linear capacitance for an increase in voltage is determined with good correlation. Simulations are verified using experimental results from two different devices. It is shown that the large signal output capacitance as a function of the drain-source voltage is higher than the small signal values published in the data sheets for each of the devices. It can also be seen that the loss contribution of the output capacitance discharging in the channel during switch-on correlates well with other methods proposed in the literature, which confirms that the proposed method has merit.

NEW ADAPTIVE METHOD FOR VOLTAGE SAG AND SWELL DETECTION

  • Mohamed, Mansour A.
    • Journal of the Korea Convergence Society
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    • v.4 no.1
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    • pp.33-41
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    • 2013
  • This paper presents an adaptive recursive least squares algorithm (ARLS) for detecting voltage sag and voltage swell events in power systems. Different methods have been developed to detect voltage sag and voltage swell. Some of them use window techniques, which are too slow when voltage sag or swell mitigation is required. Others depend on the extraction of a single non-stationary sinusoidal signal out of a given multi-components input signal, and therefore they don't consider the harmonic components in calculating the voltage root mean square value (rms). The method, proposed in this paper, is capable of estimating the voltage rms taking into account all harmonic components. The method is tested by applying it to different, simulated signals using ATP program, and compared with voltage sag detection algorithms.

Dynamic Response Improvement of Stand Alone Engine-Generator System using Double Voltage Detection Method (전압 이중 검출법에 의한 독립형 엔진-발전기 시스템 응답특성 개선)

  • Lee, Dong-Hee;Ahn, Jin-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.7
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    • pp.1195-1199
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    • 2008
  • In this paper, peak detector of generator's output voltage and variable gain controller are introduced for a fast dynamic response. The conventional r,m.s, signal detected has inherent time delay, and the dynamic response of generator using conventional PID controller has some problem in sudden load change. In this paper, the peak detector and signal selector with variable gain controller is used to overcome this problem. The main controller can check the voltage state from the peak detector. When a sudden load change, the over-voltage and under-voltage signal from peak detector change the controller's gain and exciter's current reference. The proposed scheme can improve the dynamic response, which is verified from experimental test of 200kW diesel engine-generator.