• Title/Summary/Keyword: Ripple current

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Decision of Modulation Index of Current-Source TPWM Inverter for Minimization of Speed Ripple and Position Error (속도맥동 및 위치오차를 최소로 하는 전류원 TPWM 인버터의 변조도 결정)

  • 구본호;권우현;김수중
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.11
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    • pp.1819-1828
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    • 1989
  • In this paper, we determined the modulation index for minimization of speed ripple and position error using maximum speed ripple (SRF) and maximum position error(PEF) in current source TPWM inverter. Through computer simulation, we compared with total current harmonic distortion, SRF and PEF for square wave modulation method and TPWM method. As a result, it turns out that square wave modulation method is superior to TPWM method of 3 pulses per half cycle in speed ripple and position error contents. And TPWM is better than square wave method when pulse number is more than 5. Also, in these pulse numbers, moduladtion index of minimum speed ripple and munimum position error is 0.91.

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A Study for Torque Ripple Reduction with PWM Pattern on Brushless DC Motor During Commutation (BLDC 전동기에서 PWM 방식에 따른 토크리플 저감에 관한 연구)

  • Kim, Sang-Hoon;Kwon, Kyeong-Jun
    • Journal of Industrial Technology
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    • v.24 no.A
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    • pp.109-117
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    • 2004
  • This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

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Input Current Ripple Improvement on Interleaved Boost Power Factor Corrector Operating in Discontinuous Current Mode (불연속 전류모드로 동작하는 Interleaved 승압형 역률보상 컨버터의 입력전류 리플개선)

  • 허태원;박지호;노태균;김동완;박한석;우정인
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.17 no.1
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    • pp.116-123
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    • 2003
  • In this paper, interleaved boost converter is applied as a pre-regulator in switched mode power supply. The pre-regulator plays a role to improve power factor. Interleaved Boost Power Factor Corrector(IBPFC) can reduce input current ripple as a single voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. Each converter cell is also operated in discontinuous current mode and inductor current of each converter is discontinuous. Total input current which is composed by each converter cell is continuous current. Thus, IBPFC is able to improve input current ripple. IBPFC operating in discontinuous current mode can be classified as six modes from switching state and be carried out state space averaging small signal modeling. A control transfer function is obtained according to the modeling. Single voltage control loop is also constructed by the control transfer function. From experimental result, improvement of power factor and input current ripple are verified.

A Current Control Strategy for Torque Ripple Reduction on Brushless DC Motor during Commutation (Brushless DC Motor에서 토크리플 저감을 위한 전환 구간에서의 전류제어 기법)

  • 권경준;김상훈
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.3
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    • pp.195-202
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    • 2004
  • This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor during con)mutation. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage during commutation, the torque ripple can be reduced. The simulation md experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

An Improved Torque Ripple Minimization of Brushless DC Motor (개선된 Brushless DC Motor의 토크리플 최소화)

  • Chung, Jin-Hwa;Chung, Sun-Tae
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.298-302
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    • 1994
  • Brushless DC motors have a trapezoidal back EMF wave form and are fed with rectangular stator currents. Under these conditions, the torque produced is theoretcally constant. However, in practice, torque ripple may exist, one major cause of which conies from phase current commutation. In this paper we propose an improved method of reducing the torque ripple due to phase current commutation of indirectly restricting the uncommutated current through control of the other phase currents. Simulation results are present.

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Filter Design for Grid-Connected Single-Phase Inverters

  • Kim, Hyo-Sung
    • Journal of Power Electronics
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    • v.9 no.4
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    • pp.623-630
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    • 2009
  • This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

Photovoltaic Multi-string PCS with a Grid-connection (계통연계형 멀티스트링 태양광 발전 시스템)

  • Kwon, Jung-Min;Kim, Eung-Ho;Nam, Kwang-Hee;Kwon, Bong-Hwan
    • New & Renewable Energy
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    • v.3 no.4
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    • pp.69-76
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    • 2007
  • In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

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Photovoltaic Multi-string PCS with a Grid-connection (계통연계형 멀티스트링 태양광 발전 시스템)

  • Kwon, Jung-Min;Kim, Eung-Ho;Kwon, Bong-Hwan
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.11a
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    • pp.255-258
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    • 2007
  • In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

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A Current Control Algorithm for Torque Ripple Reduction of Four-Switch Three-Phase Brushless DC Motors (4스위치 3상 BLDC 전동기의 토크 리플 저감을 위한 전류제어 알고리즘)

  • 박상현;김태성;이병국;현동석
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.2
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    • pp.126-133
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    • 2004
  • In this paper, a new current control algorithm is proposed for four-switch three-phase brushless DC(BLDC) motor drives, which are suitable for low cost applications. A current reference generation scheme is developed and implemented to obtain high performance characteristics in the four-switch system, such as small torque ripple and fast dynamic speed/torque response. Especially, the proposed scheme can successfully reduce the torque ripple during commutations, so that it can be expected that the four-switch system can be much more practically applied for the industrial application areas.

Low-ripple coarse-fine digital low-dropout regulator without ringing in the transient state

  • Woo, Ki-Chan;Yang, Byung-Do
    • ETRI Journal
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    • v.42 no.5
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    • pp.790-798
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    • 2020
  • Herein, a low-ripple coarse-fine digital low-dropout regulator (D-LDO) without ringing in the transient state is proposed. Conventional D-LDO suffers from a ringing problem when settling the output voltage at a large load transition, which increases the settling time. The proposed D-LDO removes the ringing and reduces the settling time using an auxiliary power stage which adjusts its output current to a load current in the transient state. It also achieves a low output ripple voltage using a comparator with a complete comparison signal. The proposed D-LDO was fabricated using a 65-nm CMOS process with an area of 0.0056 μ㎡. The undershoot and overshoot were 47 mV and 23 mV, respectively, when the load current was changed from 10 mA to 100 mA within an edge time of 20 ns. The settling time decreased from 2.1 ㎲ to 130 ns and the ripple voltage was 3 mV with a quiescent current of 75 ㎂.