• Title/Summary/Keyword: DC-link Voltage Ripple Compensation

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Performance Improvement of B4 Inverters by Adding Compensation Voltage (보상전압 첨가를 통한 B4 인버터 성능향상)

  • Lee, Dong-Myung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.1
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    • pp.110-116
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    • 2013
  • This paper proposes a current ripple reduction method to improve the control performance of B4 type inverter that is studied for cost-effective drive systems. B4 inverters employ only four switches and they have a center-tapped connection between the split dc-link capacitors and one phase of a three-phase motor or load. In the B4 topology, unbalanced three-phase voltages will be generated due to the dc-link voltage ripple. To solve this problem, this paper presents a voltage distortion compensation method that adjusts the voltage reference with the consideration of dc-link voltage ripple. The validity of the proposed method is verified by simulation and excremental results with an induction machine.

Compensation of Effects of DC-Link Ripple Voltages on Output Voltage of Two-Leg Three-Phase PWM Inverters (2-레그 3상 PWM 인버터의 출력전압에서 직류링크 리플전압의 영향 보상)

  • Kim Young-Sin;Lee Dong-Choon;Seok Jul-Ki
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.55 no.1
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    • pp.47-53
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    • 2006
  • In this paper, a simple scheme compensating for the effect of dc-link ripple voltages on output voltage of two-leg and three-phase PWM inverters is proposed, where single-phase half-bridge PWM convertor and two-leg inverter are used. The voltage at neutral point of the dc-link is controlled so that the upper-half of do-link voltage is equal to the lower-half voltage in average concept. However, the effect of the do-link ripple voltage results in the inverter output voltage and current distortion. This effect can be eliminated by introducing a compensation voltage in switching time calculation. Also, the inverter dead time should be compensated for sinusoidal output waveform. The proposed scheme has been verified by experimental results which were obtained from the V/F constant operation of the induction motor fed by two-leg inverter.

A Voltage Compensation Method to Improve the Control Performance for B4 Inverters (B4 인버터의 제어성능 향상을 위한 전압보상 기법)

  • 오재윤
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.317-320
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    • 2000
  • This paper proposes a voltage compensation method to improve the control performance of B4 inverter which is studied for low-cost drive systems. The B4 inverter employs only four switches and it has a center-tapped connection in the split dc-link capacitors to one phase of a three-phase motor. In the B4 topology unbalan-cd three-phase voltages will be generated by the dc link voltage ripple. To solve this problem we present a voltage compensation method which adjusts switching times considering dc link voltage ripple. The proposed method is verified by simulation results,

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DC-link Voltage Ripple Compensation Method for Single Phase 3-level PWM Converters (단상 3-레벨 PWM 컨버터를 위한 중성점 전압 변동 보상 기법)

  • Lee, Hee-Myun;Lee, Dong-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.4
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    • pp.8-15
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    • 2013
  • This paper proposes a DC-link voltage variation compensation method for a 3-level single phase converter for high-speed trains. Since 3-level NPC(Neutral Point Clamped) type converters have the split DC-link causing the inherent problem of voltage fluctuations in the upper and lower capacitors, reducing the voltage difference between the top and bottom capacitors is required. In this paper, compensation time proportional to the voltage difference is added to PWM switching time to solve the voltage variation. The compensation time is obtained by a PI controller. Simulation results demonstrate the validity of the proposed method.

Motor Control Method for Four-Switch Inverters with DC-link Voltage Ripple Compensation Algorithm (Four-Switch 인버터의 전압 변동 보상 기법을 통한 전동기 운전 기법)

  • Lee, Dong-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.7
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    • pp.59-66
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    • 2013
  • This paper proposes a new voltage reference generation method for Four-Switch Inverters(FSI) with compensation of the neutral DC-link voltage variation. Since FSIs have the split DC-link causing the inherent problem of voltage fluctuations in the upper and lower capacitors, it is required to take account the voltage difference between the top and bottom capacitors. In this paper, to reduce the effect by the voltage variation, reference voltages are modified by adding compensation voltages proportional to the voltage difference between upper and lower capacitors. Simulation results showing control performance of induction and permanent magnet motors demonstrate the validity of the proposed method.

Mitigation of Low Frequency AC Ripple in Single-Phase Photovoltaic Power Conditioning Systems

  • Lee, Sang-Hoey;An, Tae-Pung;Cha, Han-Ju
    • Journal of Power Electronics
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    • v.10 no.3
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    • pp.328-333
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    • 2010
  • A photovoltaic power conditioning system (PV PCS) that contains single-phase dc/ac inverters tends to draw an ac ripple current at twice the output frequency. Such a ripple current perturbs the operating points of solar cells continuously and it may reduce the efficiency of the current based maximum power point tracking technique (CMPPT). In this paper, the ripple current generation in a dc link and boost inductor is analyzed using the ac equivalent circuit of a dc/dc boost converter. A new feed-forward ripple current compensation method to incorporate a current control loop into a dc/dc converter for ripple reduction is proposed. The proposed feed-forward compensation method is verified by simulation and experimental results. These results show a 41.8 % reduction in the peak-to peak ac ripple. In addition, the dc/ac inverter control system uses an automatic voltage regulation (AVR) function to mitigate the ac ripple voltage effect in the dc link. A 3kW PV PCS prototype has been built and its experimental results are given to verify the effectiveness of the proposed method.

A Feedforward Compensation Method for 120Hz Output Voltage Ripple Reduction of LLC Resonant Converter (LLC 공진 컨버터의 120Hz 출력전압 리플 저감을 위한 전향보상 방법)

  • Yoon, Jong-Tae;Lee, Kui-Jun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.26 no.1
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    • pp.46-52
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    • 2021
  • This study proposes a feedforward compensation control method to reduce 120 Hz output voltage ripple in a single-phase AC/DC rectifier system composed of PFC and LLC resonant converters. The proposed method compensates for the voltage ripple of the DC-link by using the AC input and DC output power difference, and then reduces the final output voltage ripple component of 120 Hz through feedforward compensation based on the linearized frequency gain curve of the LLC resonant converter. Through simulation and experimental results, the validity of the ripple reduction performance was verified by comparing the conventional PI controller and the proposed feedforward compensation method.

Compensation of Effects of DC-Link Ripple Voltages on Output Voltage of Two-leg Three-Phase PWM Inverters (2-leg 3상 PWM 인버터의 출력전압에서 직류링크 리플 전압의 영향 보상)

  • Kim, Young-Sin;Lee, Dong-Choon;Seok, Jul-Ki
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.572-574
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    • 2005
  • In this paper, a compensation scheme for the effect of dc-link ripple voltages on output voltage of two-leg and three-phase PWM inverters is proposed, without which compensation scheme the three-phase output voltage and current are much distorted. The proposed scheme has been verified by experimental results.

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A Novel High-Performance Strategy for A Sensorless AC Motor Drive

  • Lee, Dong-Hee;Kwon, Young-Ahn
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.3
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    • pp.81-89
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    • 2002
  • The sensorless AC motor drive is a popular topic of study due to the cost and reliability of speed and position sensors. Most sensorless algorithms are based on the mathematical modeling of motors including electrical variables such as phase current and voltage. Therefore, the accuracy of such variables largely affects the performance of the sensorless AC motor drive. However, the output voltage of the SVPWM-VSI, which is widely used in sensorless AC motor drives, has considerable errors. In particular, the SVPWM-VSI is error-prone in the low speed range because the constant DC link voltage causes poor resolution in a low output voltage command and the output voltage is distorted due to dead time and voltage drop. This paper investigates a novel high-performance strategy for overcoming these problems in a sensorless ac motor drive. In this paper, a variation of the DC link voltage and a direct compensation for dead time and voltage drop are proposed. The variable DC link voltage leads to an improved resolution of the inverter output voltage, especially in the motor's low speed range. The direct compensation for dead time and voltage drop directly calculates the duration of the switching voltage vector without the modification of the reference voltage and needs no additional circuits. In addition, the proposed strategy reduces a current ripple, which deteriorates the accuracy of a monitored current and causes torque ripple and additional loss. Simulation and experimentation have been performed to verify the proposed strategy.

C-link Ripple Voltage Compensation Algorithm for Integrated ESS and UPS System with PV Generation (태양광 발전을 갖는 통합 ESS 및 UPS 시스템의 직류 링크 맥동전압 보상 알고리즘)

  • Kim, Min-Gi;Choi, Bong-Yeon;Kang, Jin-Wook;Kim, Jun-Gu;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.443-444
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    • 2014
  • Using the ESS(Energy Storage System) as a UPS(Uninterruptible Power Supply) is being studied recently. When the system is operating at UPS mode in integrated ESS and UPS system, the grid supplying power is disconnected and power from PV generation and battery are supplying to load. Operating in UPS mode, when PV generation power is diminished by partial or total clouded situation, DC-link voltage fluctuates. The fluctuation of DC-link voltage influences the load and system as sensitive loads may malfunction. This paper suggests the DC-link ripple voltage compensation algorithm in bi-directional converter. The algorithm stabilize the DC-link and load voltage.

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