• Title/Summary/Keyword: zeros and poles

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Adjustable Phase, Discrete Time Sinewave Generator

  • Klunium, Sawitree;Praesombool, Sukunya;Hinjit, Watcharapong;Yimman, Surapun;Dejhan, Kobchai
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.277-281
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    • 2004
  • The following paper proposes the new design of digital sine wave generator which allows users to define the phase shift of the out put sinewave according to user's demands. This new sinewave generator will have 2 outputs, cos(${\omega}_0n$) and cos(${\omega}_0n$+${\phi}$) The design of the new system starts from the construction of discrete time system with impulse response as cos(${\omega}_0n$) in a pair of conjugate complex poles and a pair of zeros at the origin and the real axis. If users want to make a phase shift of sign wave, users can change the position of zero at the real axis. The results of the experiment have shown that the new design of sign wave generator has generated sine wave with the correct phase shift according to the theory.

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Design of active power factor control AC/DC converter having current control loop with no compensator (전류 제어 루프에 보상을 행하지 않는 능동 역률 제어 AC/DC 컴버터의 제어기 설계)

  • 이인호;김성환;유지윤;박귀태
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.2
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    • pp.216-223
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    • 1996
  • The active power factor control AC/DC converter needs a current loop compensator to obtain better dynamic characteristics and power factor performance, but the optimal design of a current loop compensator is difficult because the AC/DC converter is a nonlinear system having periodically varying poles and zeros. The predictive current control scheme generates a control input using the dynamic equations of the AC/DC converter so that the dynamic of the AC/DC converter is included in the controller and the necessary bandwidth and the gain characteristics of the current control loop are satisfied. And as a result, a compensator becomes unnecessary and the current loop shows the improved current loop characteristics. In this paper, a power factor controller without current loop compensator by adopting a predictive current control scheme is designed and the designed power factor controller is modelled by using a small signal perturbation modelling technique, and simulated to investigate its small signal characteristics. A 200 W power factor control AC/DC converter is built to verify the effectiveness of the proposed power factor controller.

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Modal Parameter Estimations of Wind-Excited Structures based on a Rational Polynomial Approximation Method (유리분수함수 근사법에 기반한 풍하중을 받는 구조물의 동특성 추정)

  • Kim, Sang-Bum;Lee, Wan-Soo;Yun, Chung-Bang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11a
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    • pp.287-292
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    • 2005
  • This paper presents a rational polynomial approximation method to estimate modal parameters of wind excited structures using incomplete noisy measurements of structural responses and partial measurements of wind velocities only. A stochastic model of the excitation wind force acting on the structure is estimated from partial measurements of wind velocities. Then the transfer functions of the structure are approximated as rational polynomial functions. From the poles and zeros of the estimated rational polynomial functions, the modal parameters, such as natural frequencies, damping ratios, and mode shapes are extracted. Since the frequency characteristics of wind forces acting on structures can be assumed as a smooth Gaussian process especially around the natural frequencies of the structures according to the central limit theorem (Brillinger, 1969; Yaglom, 1987), the estimated modal parameters are robust and reliable with respect to the assumed stochastic input models. To verify the proposed method, the modal parameters of a TV transmission tower excited by gust wind are estimated. Comparison study with the results of other researchers shows the efficacy of the suggested method.

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Design of pre-compensator and PD controller based the PI control system (PI제어계 기반 전치보상기 및 PD제어기의 설계)

  • Ha, Hong-Gon;Lee, Yong-Jae;Han, Dae-Hyun;Heo, Gyeong-Yong
    • Journal of the Institute of Convergence Signal Processing
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    • v.14 no.1
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    • pp.51-56
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    • 2013
  • PID control systems are significantly utilized in industrial fields because of its multiple advantages. Many researches about more effective PID controllers to enhance control system performances have been addressed so far. This paper proposes a novel PI-PD control system with a pre-compensator which is configured with a pre-compensator and PD controller in PIcontrol system. The normal method is applied to the proposed control system for obtaining a simple first-order controller from cancelation of poles and zeros. We design a pre-compensator and PD controller by using parameters of PI controller and the transfer function of a plant. Computer simulation is carried out to demonstrate effectiveness of the proposed control system.

LQ-PID Controller Design for Speed Control of Induction Motor (유도전동기의 속도 제어를 위한 LQ-PID 제어기 설계)

  • 이충우;서병설
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.41 no.3
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    • pp.1-8
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    • 2004
  • This paper proposes an LQ-PID controller to reduce errors occurring between input and output speeds in braking or emergency braking and to solve delay of speed or the excessive overshoot problems occurring at the speed control of induction motor. The conventional LQ controller is a method that move the poles in locations that satisfy design specifications such as overshoot and settling time etc. by state-feedback. So it may not be able to satisfy the overshoot requirement in case of the existence of zero in the closed loop transfer function. To attack this zero-problem it is presented a new design methodology of LQ-PID controller by introducing an analytic technique to eliminate the effect of zeros on the closed loop transfer function.

Highly Linear Wideband LNA Design Using Inductive Shunt Feedback

  • Jeong, Nam Hwi;Cho, Choon Sik;Min, Seungwook
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.1
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    • pp.100-108
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    • 2014
  • Low noise amplifier (LNA) is an integral component of RF receiver and frequently required to operate at wide frequency bands for various wireless system applications. For wideband operation, important performance metrics such as voltage gain, return loss, noise figure and linearity have been carefully investigated and characterized for the proposed LNA. An inductive shunt feedback configuration is successfully employed in the input stage of the proposed LNA which incorporates cascaded networks with a peaking inductor in the buffer stage. Design equations for obtaining low and high impedance-matching frequencies are easily derived, leading to a relatively simple method for circuit implementation. Careful theoretical analysis explains that input impedance can be described in the form of second-order frequency response, where poles and zeros are characterized and utilized for realizing the wideband response. Linearity is significantly improved because the inductor located between the gate and the drain decreases the third-order harmonics at the output. Fabricated in $0.18{\mu}m$ CMOS process, the chip area of this wideband LNA is $0.202mm^2$, including pads. Measurement results illustrate that the input return loss shows less than -7 dB, voltage gain greater than 8 dB, and a little high noise figure around 6-8 dB over 1.5 - 13 GHz. In addition, good linearity (IIP3) of 2.5 dBm is achieved at 8 GHz and 14 mA of current is consumed from a 1.8 V supply.

Class-D Digital Audio Amplifier Using 1-bit 4th-order Delta-Sigma Modulation (1-비트 4차 델타-시그마 변조기법을 이용한 D급 디지털 오디오 증폭기)

  • Kang, Kyoung-Sik;Choi, Young-Kil;Roh, Hyung-Dong;Nam, Hyun-Seok;Roh, Jeong-Gin
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.3
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    • pp.44-53
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    • 2008
  • In this paper, we present the design of delta-sigma modulation-based class-D amplifier for driving headphones in portable audio applications. The presented class-D amplifier generates PWM(pulse width modulation) signals using a single-bit fourth-order high-performance delta-sigma modulator. To achieve a high SNR(signal-to-noise ratio) and ensure system stability, the locations of the modulator loop filter poles and zeros are optimized and thoroughly simulated. The test chip is fabricated using a standard $0.18{\mu}m$ CMOS process. The active area of the chip is $1.6mm^2$. It operates for the signal bandwidth from 20Hz to 20kHz. The measured THD+N(total harmonic distortion plus noise) at the $32{\Omega}$ load terminal is less than 0.03% from a 3V power supply.

Performance Improvement in Single-Phase Electric Spring Control

  • Wang, Qingsong;Zuo, Wujian;Cheng, Ming;Deng, Fujin;Buja, Giuseppe
    • Journal of Power Electronics
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    • v.19 no.3
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    • pp.784-793
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    • 2019
  • Two objectives can be pursued simultaneously with the ${\delta}$ control of a single-phase electric spring (ES). These objectives are the stabilization of the voltage across the critical load (CL) of a power system, and the achievement of a specific functionality similar to the pure compensation of reactive power or the correction of the power factor. However, existing control systems implementing the ${\delta}$ control do not cope with non-ideal operating conditions, such as line voltage distortions, and exhibit a somewhat sluggish regulation of the CL voltage. In an effort to improve both the steady-state and transient performances of an ES power system, this paper proposes implementing the ${\delta}$ control by means of a control system built up on the repetitive control and assisted by state feedback with pole assignment. This paper starts by analyzing the dynamics of an ES power system in terms of its poles and zeros. After that, a reduced second-order model of the dynamics is formulated to avoid a notch filter in the pole assignment. A repetitive control for an ES power system is then designed to meet the two above mentioned objectives. Experimental tests carried out on a laboratory setup demonstrate the effectiveness of the proposed control system in significantly improving the ES power system performance, while reaching the two objectives. In particular, the tests outline the large mitigation of harmonics in the CL voltage under line voltage distortions and its fast stabilization action.

Highly Linear Wideband LNA Design Using Inductive Shunt Feedback (Inductive Shunt 피드백을 이용한 고선형성 광대역 저잡음 증폭기)

  • Jeonng, Nam Hwi;Cho, Choon Sik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.11
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    • pp.1055-1063
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    • 2013
  • Low noise amplifiers(LNAs) are an integral component of RF receivers and are frequently required to operate at wide frequency bands for various wireless systems. For wideband operation, important performance metrics such as voltage gain, return loss, noise figures and linearity have been carefully investigated and characterized for the proposed LNA. An inductive shunt feedback configuration is successfully employed in the input stage of the proposed LNA which incorporates cascaded networks with a peaking inductor in the buffer stage. Design equations for obtaining low and high input matching frequencies are easily derived, leading to a relatively simple method for circuit implementation. Careful theoretical analysis explains that poles and zeros are characterized and utilized for realizing the wideband response. Linearity is significantly improved because the inductor between gate and drain decreases the third-order harmonics at the output. Fabricated in $0.18{\mu}m$ CMOS process, the chip area of this LNA is $0.202mm^2$, including pads. Measurement results illustrate that input return loss shows less than -7 dB, voltage gain greater than 8 dB, and a little high noise figure around 7~8 dB over 1.5~13 GHz. In addition, good linearity(IIP3) of 2.5 dBm is achieved at 8 GHz and 14 mA of current is consumed from a 1.8 V supply.

UWB Bandpass Filter Using Capacitive Coupling with Cross Resonator ("+"자 공진기와 용량성 결합을 이용한 초광대역 대역 통과 여파기)

  • Dong, Thai Hoa;Lee, Jae-Young;Kim, Ihn-Seok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.5
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    • pp.486-493
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    • 2010
  • This article introduces a novel ultra wideband(UWB) bandpass filter(BPF) with sharp roll-off characteristics in stripline structure. The UWB characteristic is basically obtained from capacitive coupled cross resonator. The resonator has ${\lambda}/2$ length. And at the center of the resonator, two stubs are loaded, one is a ${\lambda}/8$ short-circuited stub and the other is a ${\lambda}/8$ open-circuited stub. The two stubs provide two attenuation poles at lower and upper cutoff frequencies. For input and output lines, two identical capacitively coupled lines have been installed to suppress the unwanted signals in the lower and upper stopbands. The filter has been designed for the U.S. UWB band(3.1~10.6 GHz) with two transmission zeros at 2.4 and 11.1 GHz. The filter has been realized with Low Temperature Core-fired Ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results. Insertion loss less than 0.7 dB and return loss better than 14 dB in the pass band have been measured. The group delay in the center frequency is 0.27 ns and the group delay variation within pass band is less than 0.5 ns. The size of the filter is $6{\times}18{\times}0.6\;mm^3$.