• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.233-235
• /
• 2020

본 논문은 40 kV 나노초 펄스발생을 위한 모듈형 solid-state Marx modulator(SSMM) 설계에 대해 기술한다. 가속기 및 플라즈마 어플리케이션과 같은 다양한 응용분야에 요구되는 전압 및 전류 사양을 만족시키기 위해 10 kV(출력 전압), 50 ns(펄스폭), 20 ns(상승&하강 시간), 100 kHz(반복률)의 사양을 만족하는 단위모듈기반으로 모듈형 설계를 제안한다. 독립적인 제어가 가능한 4개의 단위모듈을 기반으로 제안된 SSMM은 임의의 출력 파워 및 임피던스를 만족시킬 수 있는 장점을 가지고 있다. 예를 들어, 모든 단위모듈의 위상을 같게 했을 때 출력전압을 증가시킬 수 있으며 각 모듈의 위상을 지연하였을 경우는 펄스의 반복률을 크게 높일 수 있다. 개발된 SSMM은 직렬 스택 MOSFET의 스위칭 성능을 향상시키기 위해 게이트 구동 회로는 동기 신호와 구동 전력을 제공하는 1 턴 변압기로 설계되었다. 출력 펄스의 폭과 하강시간을 최소화하기 위해 다이오드 대신 기생 커패시턴스에 저장된 에너지를 빠르게 방출하는 액티브 풀다운 회로가 적용되었다. 또한, 출력 펄스의 빠른 상승을 달성하기 위해 게이트의 라인 인덕턴스를 최소화하고 모든 게이트 신호의 동기화는 필수적이다. 개발된 ns급 펄스전원장치는 단위모듈을 기반으로 최대 펄스전압이 40 kV 까지 출력이 가능하며 이에 대한 상세설계 및 구현은 실험결과를 바탕으로 검증한다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.4
• /
• pp.291-299
• /
• 2007

To operate a permanent magnet synchronous motor (PMSM) at a maximum torque per ampere (MTPA) operation point, the exact values of machine parameters such as inductances and back-EMF constant, which are sensitive to motor phase currents and temperature respectively, should be blown. An adaptive estimation method for on-line estimation of the machine parameters is not suitable for practical applications since it has difficulties in estimating exact values and requires complex mathematical calculations. The purpose of this paper is to present a simple MTPA operation point tracking control strategy for vector controlled PMSM drives with slow dynamic loads. The proposed method searches MTPA operation points by modulating current phase angle and observing the variation in command power. The current angle modulation strategy is designed to sense the effect of load variations in the command power. Therefore, the proposed method can track the MTPA operation points of the PMSM regardless of load variations. Computer simulation and experimental study is also presented to show the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
• /
• 2000.11a
• /
• pp.55-57
• /
• 2000

This paper presents the measurement of phasor angle of power system using Synchronized Phasor Measurement System(SPMS). SPMS includes the GPS receiver, so it can add the exact time information to the data acquired from the power system by SPMS. Using that data, we can compare the difference of phasor angles of voltages currents acquired at the exactly same time, and monitor the RMS values of voltage and current. In this paper, we present the difference of voltage angles between 345kV Sinjechon S/S and 345kV Asan S/S, where two SPMS were installed separately, and prove their performance by comparing to simulation result of PSS/E.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2060-2062
• /
• 2001

전기를 에너지원으로 사용하는 각 종 부하는 가정, 공장 및 상가 등에 널리 분산되어 있고, 여기에 전기를 생산 공급하는 발전기도 지역적으로 분산되어 병렬운전이 되고 있다. 새로운 발전기가 병렬운전에 참여하기 위해서는 기존 운전되고 있는 전력계통과의 전압, 주파수, 상회전, 위상이 일치하여야 한다. 만약 이들 조건이 갖추어지지 않은 상태에서 임의 병렬 접속을 시도하게 되면 해당 발전기는 물론 전체 계통에 충격과 손상을 초래할 수 있다. 양측의 전압과 주파수 비교는 상용 계측기를 사용하여 비교적 쉽게 할 수 있느나, 상회전 방향과 위상차의 판별에는 세심한 주의가 필요하다. 최근의 발전기에는 병렬 운전 조건을 자동으로 조정, 확인을 하는 장치를 채용하고 있으며 구체적인 회로구성과 동작원리를 여기에서 살펴보았다. 병렬 접속이 이루어진 후 발전기 별 전력 분담과, 계통 주파수 변동에 따라 자동으로 발전기 출력 제어가 이루어지는 기능이 터빈 조속기 측에 설정되어 사용된다.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.331-333
• /
• 2007

전동기의 동손 및 철손을 포함한 손실이 최소가 되는 운전 점을 추적함으로써, 전동기의 제정수 변동에 무관하게 항상 최대 효율점에서 영구자석 동기전동기를 운전할 수 있는 새로운 최대 효율 제어 알고리즘을 제안한다. 제안된 최대 효율점 추적 제어 알고리즘은 전류의 위상각 변동에 따른 가변속 구동장치의 입력 전력 변화로부터 부하 변동에 의한 영향을 제거함으로써 정상 상태에서 부하변동에 무관하게 최대 효율점으로 수렴이 가능하고, 그 구성이 단순하기 때문에 산업계에 널리 적용될 수 있다. 실험을 통해 제안된 알고리즘의 효용성을 입증한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.2
• /
• pp.97-102
• /
• 2019

The GNSS(Global Navigation Satellite System) provides important information such as Position and Navigation, Timing(PNT) to various weapon systems in the military. as a result, applications that employ satellite navigation systems are increasing. therefore, a number of studies have been conducted to deceive the weapon systems that employ GNSS. GNSS spoofing denotes the transmission of counterfeit GNSS-like signals with the intention to produce a false position and time within the victim receiver. In order to deceive the victim receiver, spoofing signal should be synchronized with GNSS signal in doppler frequency and code phase, etc. In this paper, Civilian GPS L1 C/A spoofing signals have been evaluated and analyzed by SDR receiver.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.4
• /
• pp.43-54
• /
• 2004

A visualization study was carried out to investigate the effects of phase difference qualitatively by examining wake pattern on the phase difference of a dragonfly type wing model. The model was built with scaled-up, flapping wings composed of a paired wing with fore- and hind-wings in tandem that mimick the wing form of a dragonfly. The present study was conducted by using the smoke-wire technique and an electronic device below the tandem wings was mounted to find the exact wing position angles. Uncertainties in wing position angle are about $\pm$$1.0^{\cire}$ and instantaneous wing positional angle varies from $-16.5^{\cire}$ to $+22.8^{\cire}$. The tests were made at phase differences between the fore-wing and hind-wing at $0^{\cire}$, $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$. The results show that Karman vortex structures were produced at phase differences of $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$, but Karman vortex structures were not observed at the phase difference of $0^{\cire}$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.2
• /
• pp.141-154
• /
• 2013

The technology of precise time-synchronization between signal receive devices for separation distance operation can be a key point for the technology with TDoA-based system. We propose a new method for the higher accuracy of system's time-synchronization in this paper, which uses OCXO and DPLL with high accuracy to achieve phase synchronization at 1 pps (pulse per second) of signal. And the method receive time value from a GPS satellite. Essentially, the performance of GPS with high accuracy refers to long-term frequency stability for its reliability. As per the characteristic, as the GPS timing signals are synchronized continuously, the accuracy of time-synchronization gets improved proportionally. Therefore, if the time synchronization is accomplished, the accuracy of the synchronization can be up to 0.001 ppb (part per billion). Through the improved accuracy of the time-synchronization, the measurement error of TDOA-based location detection technology is evaluated. Consequently, we verify that TDoA-based location measurement error can be greatly improved via using the improved method for time-synchronization error.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.5
• /
• pp.951-958
• /
• 2019

For the power grid-connection of distributed generation, the output voltage of the distributed generation must be synchronized with the grid voltage before the grid-connection. In this paper, a vector control based synchronization algorithm was developed for grid linkage of three-phase inverters. A three-phase voltage inverter was designed and fabricated to verify the effectiveness of the developed algorithm. The main controller of the three-phase inverter was developed based on DSP, and the electrical level of the system was set to an electrical level that can be tested in the laboratory. Throughout the experiments, it was confirmed that the proposed algorithm could be used as a synchronization algorithm for grid-connection by showing that the output voltage of the three-phase inverter is synchronized with the grid voltage.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.2
• /
• pp.179-184
• /
• 2016

The electrical load testing system developed from this study was designed to control rated-capacity-testing or variable-load-testing in an active and precise manner and save electric energy during testing, and also to convert the saved electric energy through the electrical load testing system to grid line. As for the device under testing, it was designed to be applied to not only transformer, rectifier, voltage regulator, inverter which require grid voltage source but, also applied to electric power, aerogenerator, photovoltaic, hybrid generator, battery, etc. which do not require grid voltage source. The system was designed to return the power consumed during the testing to the grid line by connecting the synchronizing pwm inverter circuit to the grid voltage source, and was also made to enable the being-tested system from disuse of approximately 93.4% energy when compared to the conventional load testing system which has used the passive resistor.