• Title/Summary/Keyword: Frequency drift

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Design of Active Disturbance Rejection Control for Inductive Power Transfer Systems

  • Wang, Yanan;Dong, Lei;Liao, Xiaozhong;Ju, Xinglong;Xiao, Furong
    • Journal of Power Electronics
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    • v.18 no.5
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    • pp.1434-1447
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    • 2018
  • The control design of inductive power transfer (IPT) systems has attracted a lot of attention in the field of wireless power transmission. Due to the high-order resonant networks and multiple loads in IPT systems, a simplified model of an IPT system is preferred for analysis and control design, and a controller with strong robustness is required. Hence, an active disturbance rejection control (ADRC) for IPT systems is proposed in this paper. To realize the employment of ADRC, firstly a small-signal model of an LC series-compensative IPT system is derived based on generalized state-space averaging (GSSA), then the ADRC is implemented in the designed IPT system. The ADRC not only provides superior robustness to unknown internal and external disturbances, but also requires few knowledge of the IPT system. Due to the convenient realization of ADRC, the designed IPT system retains its simple structure without any additional circuits. Finally, a frequency domain analysis and experimental results have validated the effectiveness of the employed ADRC, especially its robustness in the presence of frequency drifts and other common disturbances.

Study on Multi-Mode Monopulse Signal Processing System Providing Optimal Time Delay under High Doppler Condition (고속 도플러 편이 환경에서 최적 시간지연을 갖는 다중모드 모노펄스 신호처리에 관한 연구)

  • Lee, Jaemoon;Lim, Jaesung;Ahn, Huisoo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.5
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    • pp.582-589
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    • 2016
  • Multi-mode monopulse system is widely used for satellite terminal like UAV because of high tracking accuracy and low size/weight profile. In order to calculate tracking error, Multi-mode monopulse system utilizes high-order mode signal, and it should have enough C/N(carrier to noise) level therefore tracking system needs narrow band filtering of received satellite beacon signal as much as possible. However, UAV suffers for beacon frequency drift derived from Doppler effect due to satellite figure 8 movement and UAV maneuvering. Therefore wideband signal processing needs to be considered in advance for exact doppler compensation and consequent time delay. In this paper, we propose the multi-stage Digital Signal processing system for beacon signal, which could minimize the signal delay under high Doppler and low C/N condition.

Weighting Method to Identify Interharmonics based on Calculating the Bandwidth in Group-Harmonics

  • Vahedi, Hani;Kiapi, Alireza Alizadeh;Bina, Mohammad Tavakoli;Al-Haddad, Kamal
    • Journal of Power Electronics
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    • v.13 no.1
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    • pp.170-176
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    • 2013
  • Power converters produce a vast range of harmonics, subharmonics and interharmonics. Harmonics analyzing tools based on the Fast Fourier Transform (FFT) assume that only harmonics are present and the periodicity intervals are fixed, while these periodicity intervals are variable and long in the presence of interharmonics. Using FFT may lead to invalid and undesired results due to the above mentioned issues. They can also lead to problems such as frequency blending, spectral leakage and the picket-fence effect. In this paper, the group-harmonic weighting (GHW) approach has been presented to identify the interharmonics in a power system. Afterwards, a modified GHW has been introduced to calculate the proper bandwidth for analyzing the various values of interharmonics. Modifying this method leads to more precise results in the FFT of a waveform containing inter harmonics especially in power systems with a fundamental frequency drift or frequency interference. Numerical simulations have been performed to prove the efficiency of the presented algorithm in interharmonics detection and to increase the accuracy of the FFT and the GWH methods.

An Analysis and Design of RPV and AFD Method for Anti-Islanding of Single-Phase UIPV System under The Test Condition Recommended by IEEE 929-2000 (IEEE 929-2000 단독운전 시험조건 하에서 단상 계통연계형 PV 시스템의 Anti-Islanding을 위한 RPV 방식 및 AFD방식의 해석 및 설계)

  • Kim, Hong-Sung;Kim, Han-Goo;Choe, Gyu-Ha;Kim, Jae-Chul;Choi, Yung-Ho
    • The Transactions of the Korean Institute of Power Electronics
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    • v.12 no.1
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    • pp.37-49
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    • 2007
  • To detect islanding mode when the grid is being tripped is a major safety issue in utility interactive PV(UIPV) system. Widely used techniques among various active methods to detect islanding mode are Reactive power variation (RPV)method and Active frequency drift(AFD) method. In this paper, analytical design method is suggested for AFD and RPV method under IEEE recommended islanding test condition. And in order to show the validity of proposed method, EMTP based simulation was done for UIPV system with RPV method and AFD method. Results shows proposed method is very useful.

Novel islanding detection method for grid connected PV system (계통연계형 태양광발전시스템의 새로운 단독운전 검출기법)

  • Jung, Young-Seok;So, Jung-Hun;Yu, Byung-Gyu;Yu, Gwon-Jong;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • pp.1705-1707
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    • 2005
  • This paper proposes a novel active frequency drift(AFD) method for the islanding prevention of grid-connected photovoltaic inverter. To detect the islanding phenomenon of grid-connected photovoltaic(PV) inverters concerning about the safety hazards and the damage to other electric equipments, many kinds of anti-islanding methods have been presented. Among them, AFD method using chopping fraction(cf) enables the islanding detection to drift up(or down) the frequency of the voltage during the islanding situation. However, the performance of the conventional AFD methods, which have a certain value of cf only, is inefficient and difficult to design the appropriate cf value analytically to meet the limit of harmonics. In this paper, the periodic chopping fraction based on an AFD method is proposed. This proposed method shows the analytical design value of cf to meet the test procedure of IEEE Std. 929-2000 with the power quality and islanding detection time. To verify the validation of the proposed method, the islanding test results are presented. It is confirmed that the proposed method has not only less harmonic distortion but also good performance of islanding detection compare with the conventional AFD method.

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A Temperature Difference-to-Frequency Converter Using Resistance Temperature Detectors. (측온저항체온도센서를 이용한 온도차-주파수변환기)

  • Chung, W.S.;Kim, H.B.;Lee, J.S.;Lee, K.M.;Kim, H.S.;Shin, H.J.
    • Proceedings of the KIEE Conference
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    • pp.1163-1165
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    • 1987
  • A novel temperature difference-to-frequency converter using two resistance temperature detectors (RTDs) has been developed. The resistance difference of two RTDs is converted into its equivalent inductance to form the resonant circuit of the Colpitts oscillator. The conversion sensitivity of $16\;Hz/^{\circ}C$ and the residual nonlinearity less than 2.15% over the temperature difference range from $35^{\circ}C$ to $155^{\circ}C$ are obtained by the prototype converter. The frequency drift of oscillator itself is ${\pm}0.5\;Hz$. Thus, the minimum detectable temperature difference is estimated to be ${\pm}0.013^{\circ}C$. The proposed converter, except for two RTDs, can be fabricated in monolithic IC form.

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Design of Mooring Lines of a Floating Offshore Wind Turbine in South Offshore Area of Jeju (제주 해양환경에 적합한 부유식 해상풍력발전기 계류선 설계)

  • Choung, Joonmo;Kim, Hyungjun;Jeon, Gi-Young
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.4
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    • pp.300-310
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    • 2014
  • This paper presents a mooring design procedure of a floating offshore wind turbine. The environment data of south offshore area of Jeju collected from Korea Hydrographic and Oceanographic Administration(KHOA) are used for hydrodynamic analyses as environmental conditions. We considered a semi-submersible type floating wind turbine based on Offshore Code Comparison Collaborative Continuation(OC4) DeepCWind platform and National Renewable Energy Laboratory(NREL) 5 MW class wind turbine. Catenary mooring with studless chain is chosen as the mooring system. Important design decisions such as how large the nomial sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. Considering ultimate limit state and fatigue limit state based on 100-year return period and 50-year design life, respectively, longterm predictions of breaking strength and fatigue are proposed.

A Temperature Difference-to-Frequency Converter Using Resistence Temperature Detectors (측온 저항체 온도센서를 이용한 온도차-주파수 변환기)

  • Chung, Won-Sup;Kim, Hong-Bae
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.11
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    • pp.1282-1285
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    • 1988
  • A novel temperature difference-to-frequency converter using two resistance temperature detectors (RTD) has been developed. The resistance difference of two RTD is converted into its equivalent inductance to form the resonant circuit of the Colpitts oscillator. The conversion sensitivity of 16 Hz/$^{\circ}C$ and the residual nonlinearity less than 2.15% over the temperature difference range from 35$^{\circ}C$ to 155$^{\circ}C$ are obtained by the prototype converter. The frequency drift of oscillator itself is $\pm$ 0.5Hz. Thus, the minimum detectable temperature difference is estimated to be $\pm$ 0.013$^{\circ}C$. The proposed coverter, except for two RTD, can be fabricated in monolithic IC form.

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A 32nm and 0.9V CMOS Phase-Locked Loop with Leakage Current and Power Supply Noise Compensation

  • Kim, Kyung-Ki;Kim, Yong-Bin
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.7 no.1
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    • pp.11-19
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    • 2007
  • This paper presents two novel compensation circuits for leakage current and power supply noise (PSN) in phase locked loop (PLL) using a nanometer CMOS technology. The leakage compensation circuit reduces the leakage current of the charge pump circuit which becomes more serious problem due to the thin gate oxide and small threshold voltage in nanometer CMOS technology and the PSN compensation circuit decreases the effect of power supply variation on the output frequency of VCO. The PLL design is based on a 32nm predictive CMOS technology and uses a 0.9V power supply voltage. The simulation results show that the proposed PLL achieves a 88% jitter reduction at 440MHz output frequency compared to the PLL without leakage compensator and its output frequency drift is little to 20% power supply voltage variations. The PLL has an output frequency range of $40M{\sim}725MHz$ with a multiplication range of 11023, and the RMS and peak-to-peak jitter are 5ps and 42.7ps, respectively.

Design of the Voltage-Controlled Sinusoidal Oscillator Using an OTA-C Simulated Inductor

  • Park, Ji-Mann;Chung, Won-Sup;Park, Young-Soo;Jun, Sung-Ik;Chung, Kyo-Il
    • Proceedings of the IEEK Conference
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    • pp.770-773
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    • 2002
  • Two sinusoidal voltage-controlled oscillators using linear operational transconductance amplifiers are presented in this paper: One is based on the positive-feedback bandpass oscillator model and the other on the negative-feedback Colpitts model. The bandpass VCO consists of a noninverting amplifier and a current-controlled LC-tuned circuit which is realized by two linear OTA's and two grounded capacitors, while the Colpitts VCO consists of an inverting amplifier and a current-controlled LC-tuned circuit realized by three linear OTA's and three grounded capacitors. Prototype circuits have been built with discrete components. The experimental results have shown that the Colpitts VCO has a linearity error of less than 5 percent, a temperature coefficient of less than rm 100 ppm/$^{circ}C$, and a $pm1.5 Hz $frequency drift over an oscillation frequency range from 712Hz to 6.3kHz. A total harmonic distortion of 0.3 percent has been measured for a 3.3kHz oscillation and the corresponding peak-to-peak amplitude was 1V. The experimental results for bandpass VCO are also presented.

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