• Title/Summary/Keyword: Current Shaping

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Comparison of Performance of Brushless DC Drives under Direct Torque Control and PWM Current Control

  • Zhu Z. Q.;Liu Yong;Howe David
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.4
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    • pp.337-342
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    • 2005
  • Direct torque control (DTC) was originally developed for induction machine drives, and, more recently has been applied to permanent magnet brushless AC (BLAC) drives. In this paper, the performance of DTC controlled brushless DC (BLDC) drives is compared with that of PWM current controlled BLDC drives, both with and without current shaping. Both simulation and experimental results are presented, as well as the analysis of the resulting torque waveforms. It is shown that, in addition to exhibiting a fast torque response, a DTC controlled BLDC drive has a significantly lower low-frequency torque ripple than the PWM current controlled BLDC drive without current shaping, and that it is easier to implement than PWM current control with current shaping.

Accuracy Enhancement of Parameter Estimation and Sensorless Algorithms Based on Current Shaping

  • Kim, Jin-Woong;Ha, Jung-Ik
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.1-8
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    • 2016
  • Dead time is typically incorporated in voltage source inverter systems to prevent short circuit cases. However, dead time causes an error between the output voltage and reference voltage. Hence, voltage equation-based algorithms, such as motor parameter estimation and back electromotive force (EMF)-based sensorless algorithms, are prone to estimation errors. Several dead-time compensation methods have been developed to reduce output voltage errors. However, voltage errors are still common in zero current crossing areas, and an effect of the error is much worse in a low speed region. Therefore, employing voltage equation-based algorithms in low speed regions is difficult. This study analyzes the conventional dead-time compensation method and output voltage errors in low speed operation areas. A current shaping method that can reduce output voltage errors is also proposed. Experimental results prove that the proposed method reduces voltage errors and improves the accuracy of the parameter estimation method and the performance of the back EMF-based sensorless algorithm.

Digital Switching Control Method for Current shaping of Single Phase Flyback Inverter for Photovoltaic AC Modules (PV-AC 모듈형 단상 플라이백 인버터의 출력 전류 품질 보정을 위한 디지털 스위칭 제어기법)

  • Noh, Yong-Su;Lim, Sung-Bum;Ji, Young-Hyok;Jung, Doo-Yong;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.47-48
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    • 2012
  • In generally, grid connected single-phase flyback inverter is operated as boundary or discontinuous conduction mode. However, the flyback inverter can be operated in continuous conduction mode (CCM) due to its operating conditions in spite of it is designed to operate under boundary or discontinuous conduction mode. This situation causes unintended distortion to output current. In this paper, a current shaping method on unfolding bridge to reduce the output current distortion.

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Low Voltage CMOS LC VCO with Switched Self-Biasing

  • Min, Byung-Hun;Hyun, Seok-Bong;Yu, Hyun-Kyu
    • ETRI Journal
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    • v.31 no.6
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    • pp.755-764
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    • 2009
  • This paper presents a switched self-biasing and a tail current-shaping technique to suppress the 1/f noise from a tail current source in differential cross-coupled inductance-capacitance (LC) voltage-controlled oscillators (VCOs). The proposed LC VCO has an amplitude control characteristic due to the creation of negative feedback for the oscillation waveform amplitude. It is fabricated using a 0.13 ${\mu}m$ CMOS process. The measured phase noise is -117 dBc/Hz at a 1 MHz offset from a 4.85 GHz carrier frequency, while it draws 6.5 mA from a 0.6 V supply voltage. For frequency tuning, process variation, and temperature change, the amplitude change rate of the oscillation waveform in the proposed VCO is 2.1 to 3.2 times smaller than that of an existing VCO with a fixed bias. The measured amplitude change rate of the oscillation waveform for frequency tuning from 4.55 GHz to 5.04 GHz is 131 pV/Hz.

Analysis of Acceleration Characteristics of a Railgun (레일건 가속특성 분석)

  • Lee, Young-Hyun;Kim, Seong-Ho;Lee, Byung-Ha
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.5
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    • pp.511-518
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    • 2021
  • To accelerate a launch mass with a low level of pressure as possible in a railgun, it is required to hold supplied current nearly constant during launch phase. We obtained the discharging conditions for required current shaping by modeling and analysis of circuit equations coupled to acceleration equation of the launch mass. The acceleration characteristics of the railgun in the conditions were analyzed by comparing experimental and theoretical results.

A Simplified Torque Ripple Reduction using the Current Shaping of the Flux Switched Reluctance Motor

  • Lee, Heon-Hyeong;Wang, Qi;Kim, Se-Joo;Choi, Woong-Chul;Lee, Geun-Ho
    • Journal of Magnetics
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    • v.17 no.3
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    • pp.200-205
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    • 2012
  • Recently, applications of the reluctance torque motor have been quite limited due to their inherent limitation of noise and vibration and thus, researches on the reluctance motor have been limited as well. However, with the tremendous increase in the cost of rare earth material magnets, studies of the reluctance torque motor are being conducted more and more. In principle, reluctance torque is generated when the inductance is changed. Therefore, in order to generate continuous torque in the switched reluctance motor, it is necessary to figure out the exact inductance level corresponding to the rotor position and the current level to be applied in that rotor position, respectively. If the current level or the rotor position is not accurately determined, then the generated reluctance torque becomes unstable and undesirable torque ripples prevail to eventually cause noise and vibrations. In this research, a flux switched reluctance motor (FSRM), which is classified into the switched reluctance motor (SRM), was studied. A methodology using the current shaping control according to the rotor position was proposed. Based on the proposed methodology, the optimal current waveform and the torque distribution function for the FSRM to minimize torque ripple was established and demonstrated in this paper.

Diffractive Optical Element for Noise-reduced Beam Shaping of Multi-array Point Light Source

  • Lee, Jonghyun;Hahn, Joonku;Kim, Hwi
    • Current Optics and Photonics
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    • v.5 no.5
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    • pp.506-513
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    • 2021
  • An arrayed diffractive optical element design for the beam-shaping of a multi-array light source is proposed. This is an essential device for recent optical security and face recognition applications. In practice, we devise a DC noise reduction technique featuring high fabrication error tolerance regarding the multi-array light source diffractive optical elements, as a necessary part of the proposed design method. The spherical diverging illumination leads to DC-conjugate noise spreading. The main idea is tested experimentally, and the multi-array light source diffraction pattern is investigated numerically.

Method of Reducing Residual Vibration at the LCD Transfer Robot (디스플레이 반송로봇 잔류진동 저감방안)

  • Moon, Sung Bae;Rim, Kyung-Hwa
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.2
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    • pp.98-105
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    • 2017
  • In the display industry, the residual vibration of the transfer robot can increase the process time and cause the breakage of the glass substrate, which is critical to productivity of display manufacturing. In this paper, the natural frequencies of transfer robot are analyzed by finite element method. On the basis of the analyzed data, we investigated the response characteristics of input shaping control with or without the glass presence on the hand of the transfer robot using MATLAB program, and compared with the current response characteristics of input shaping control applied to the industry. Based on this, we suggest an optimal residual vibration control method for the practical application in display industry.

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Functionally Graded Properties Induced by Direct Laser Melting of Compositionally Selected Metallic Powders (레이저 직접 용융 시 금속분말의 함량조정을 통한 경사물성 부여)

  • Han, S.W.;Ji, W.J.;Lee, C.H.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.23 no.5
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    • pp.303-310
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    • 2014
  • Functionally graded properties are characterized by the gradual variation in composition and structure through the volume of the material, resulting in corresponding gradation in properties of the material. Direct laser melting (DLM) is a prototyping process whereby a 3-D part is built layer-wise by melting metal powder with laser scanning. Studies have been performed on the functionally graded properties induced by direct laser melting of compositionally selected metallic powders. For the current study, quadrangle structures were fabricated by DLM using Fe-Ni-Cr powders having variable compositions. Hardness and EDX analysis were conducted on cross-sections of the fabricated structure to characterize the properties. From the analysis, it is shown that functionally graded properties can be successfully obtained by DLM of selected metallic powders with varying compositions.

Controller Design of BLDC Motor Fin Position Servo System by Employing H-infinity Loop Shaping Method (H-infinity Loop Shaping 방법을 이용한 BLDC 전동기 핀 위치제어시스템 제어기 설계)

  • Zhu, He-Lin;Mok, Hyung-Soo;Lee, Hyeong-Geun;Han, Soo-Hee;Seo, Hyeon-Uk
    • The Transactions of the Korean Institute of Power Electronics
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    • v.24 no.1
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    • pp.49-55
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    • 2019
  • This study proposes a robust control of a fin position servo system using the H-infinity loop-shaping method. The fin position control system has a proportional (P) position controller and a proportional-integral (PI) controller. In this work, the position control loop requires a wide bandwidth. No current control loop exists due to the compact design of the system. Hence, the controller parameters are difficult to determine using the traditional cascade design method. The $H_{\infty}$ controller design method is used to design the controller's gain to achieve good performance and robustness. First, the transfer function of the system, which can be divided into tunable and fixed parts, is derived. The tunable part includes the position P controller and speed PI controller. The fixed part includes the rest of the system. Second, the optimized controller parameters are calculated using Matlab $H_{\infty}$ controller design program. Finally, the system with optimized controller is tested by simulation and experiment. The control performance is satisfactory, and the $H_{\infty}$ controller design method is proven to be valid.