• Title, Summary, Keyword: Current distortion

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The Compensation of the Grid Current Distortion caused by the Grid Voltage Unbalance and Distortion for 3-Phase Bi-Directional DC to AC Inverter (3상 양방향 인버터의 계통전압 불평형 및 왜곡에 의한 계통전류 보상)

  • Yang, Seung-Dae;Kim, Seung-Min;Choi, Ju-Yeop;Choy, Ick;Song, Seung-Ho;Lee, Sang-Cheol;Lee, Dong-Ha
    • Journal of the Korean Solar Energy Society
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    • v.32 no.spc3
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    • pp.228-234
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    • 2012
  • This paper presents the algorithm of the compensation of the grid current distortion caused by the grid voltage unbalance and distortion in 3-phase bi-directional DC to AC inverter. Usually 3-phase grid system has unbalance and distortion because of connecting 1-phase and non-linear load with 3-phase load using same input node. Controlling 3-phase inverter by general method under the unbalanced and distorted grid voltage, the grid current has distortion. This distortion of the grid current cause the grid voltage distortion again. So, it need to control the grid current balanced and non-distorted, even the grid voltage gets unbalanced and distorted. There are some complex method to compensate the gird current distortion. it sugest simple method to solve the problem. PSIM simulation is used to validate the proposed algorithm.

A Compensation of the Grid Current Unbalance and Distortion caused by the Grid Voltage Unbalance and Distortion in 3-Phase Bi-Directional DC to AC Inverter (3상 양방향 인버터의 계통전압 불평형 및 왜곡에 의한 계통전류 불평형 및 왜곡 보상)

  • Yang, Seung-Dae;Kim, Seung-Min;Choi, Ju-Yeop;Choy, Ick;Song, Seung-Ho;Lee, Sang-Cheol;Lee, Dong-Ha
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.2
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    • pp.161-168
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    • 2013
  • This paper presents an algorithm of a compensation of the grid current distortion caused by the grid voltage unbalance and distortion in 3-phase bi-directional DC to AC inverter. Usually 3-phase grid system has unbalance and distortion because of connecting 1-phase and non-linear load with 3-phase load using same input node. Controlling 3-phase inverter by general method under the unbalanced and distorted grid voltage, the grid current has distortion. This distortion of the grid current cause the grid voltage distortion again. So, it need to control the grid current balanced and non-distorted, even the grid voltage gets unbalanced and distorted. There are some complex method to compensate the gird current distortion. it suggest simple method to solve the problem. Simulation and experiment is used to validate the proposed algorithm.

Scheme to Improve the Line Current Distortion of PFC Using a Predictive Control Algorithm

  • Kim, Dae Joong;Park, Jin-Hyuk;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1168-1177
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    • 2015
  • This paper presents a scheme to improve the line current distortion of power factor corrector (PFC) topology at the zero crossing point using a predictive control algorithm in both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM). The line current in single-phase PFC topology is distorted at the zero crossing point of the input AC voltage because of the characteristic of the general proportional integral (PI) current controller. This distortion degrades the line current quality, such as the total harmonic distortion (THD) and the power factor (PF). Given the optimal duty cycle calculated by estimating the next state current in both the CCM and DCM, the proposed predictive control algorithm has a fast dynamic response and accuracy unlike the conventional PI current control method. These advantages of the proposed algorithm lower the line current distortion of PFC topology. The proposed method is verified through PSIM simulations and experimental results with 1.5 kW bridgeless PFC (BLPFC) topology.

Suppression of Leakage Current and Distortion in Variable Capacitance Devices and their Application to AC Power Regulators

  • Katsuki, Akihiko;Oki, Takuya
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.66-73
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    • 2016
  • The quantity of alternating current (AC) leakage and the value of distortion factor in capacitor currents are discussed with regard to a new power component called variable capacitance device (VCD). This component has terminals for controlling its capacitance. Nonlinear dielectric characteristics are utilized in this device to vary the capacitance. When VCD operates in an AC circuit, the AC leakage from this device through direct current (DC) control voltage source increases according to the conditions of DC control voltage and so on. To solve this problem, we propose techniques for suppressing AC leakage. Although VCD has strong nonlinear characteristics, the current through the capacitor is not distorted significantly. The relations between AC leakage and the distortion in current waveforms are investigated. An application example for an AC power regulator is also introduced to evaluate the distortion in waveforms.

Theoretical Analysis of Second Harmonic Distortion for Threshold Current in DH Laser Diode (DH Laser Diode의 Threshold Current에 대한 2차 고조파 왜곡의 이론적 해석)

  • 김성일;박한규
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.17 no.2
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    • pp.10-14
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    • 1980
  • In this paper, the second harmonic distortion of the DH L.D. is analyzed using dynamic and static rate equations. In this analysis the modulation current Jm is changed by varang the iinjection current with the relation of where m stands for modulation index. It is showed that relative harmonic distortion ( ) has a peak exactly at the threshold current. It is also confirmed that this method is simople and more accurate than previously reported methods in the decision of the threshold current.

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Letters Current Quality Improvement for a Vienna Rectifier with High-Switching Frequency (높은 스위칭 주파수를 가지는 비엔나 정류기의 전류 품질 개선)

  • Yang, Songhee;Park, Jin-Hyuk;Lee, Kyo-Beum
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.2
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    • pp.181-184
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    • 2017
  • This study analyzes the turn-on and turn-off transients of a metal-oxide-semiconductor field-effect transistor (MOSFET) with high-switching frequency systems. In these systems, the voltage distortion becomes serious at the output terminal of a Vienna rectifier by the turn-off delay of the MOSFET. The current has low-order harmonics through this voltage distortion. This paper describes the transient of the turn-off that causes the voltage distortion. The algorithm for reducing the sixth harmonic using a proportional-resonance controller is proposed to improve the current distortion without complex calculation for compensation. The reduction of the current distortion by high-switching frequency is verified by experiment with the 2.5-kW prototype Vienna rectifier.

A study on the CFT error reduction of switched-current system (전류 스위칭 시스템의 CFT 오차 감소에 관한 연구)

  • 최경진;이해길;신홍규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.21 no.5
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    • pp.1325-1331
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    • 1996
  • In this paper, a new current-memory circuit is proposed that reduces the clock feedthrough(CFT) error voltage causing total harmonic distortion(THD) increment in switched-current(SI) systems. Using PMOS transistor in CMOS complementary, the proposed one reduces output distortion current due to the CFT errorvoltage. A proposed current-memory is designed using a 1.2.mu.m CMOS process anda 1MHz sinusoidal signal having a 68.mu.A amplitude current is applied as input (sampling frequency:20MHz). It hasbeen shown from the simulation that the output distortion current effected by the CFT error voltage is reduced by approximately 10 times the error voltage of conventional one, THD is -57dB in case ofappling 1kHz frequency input signalwith 0.5 peak signal-to-bias current ratio.

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Reducing Current Distortion in Indirect Matrix Converters Operating in Boost Mode under Unbalanced Input Conditions

  • Choi, Dongho;Bak, Yeongsu;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1142-1152
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    • 2019
  • This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method.

Harmonics Analysis of Leakage Current Waveforms and Surface Discharge for EPDM Polymer Insulator (EPDM 고분자 애자에 대한 표면방전 및 누설전류파형의 고조파분석)

  • 박재준;양태규
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.9
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    • pp.1013-1021
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    • 2004
  • This paper presents the results of spectrum analysis of leakage current waveforms on contaminated polymer insulators under fog conditions. This is a basic study on development of a monitoring for aging degree and surface pollution state using distortion rate(%) of 3rd and 5th harmonics according fundamental frequency[60Hz] under environment conditions. Arcing on the surface was always associated with distortion in the leakage current ; hence the low frequency components of the leakage current can be used as a means to evaluate the surface degradation. The results indicate that the distortion rate by spectrum analysis is available for the monitoring of contamination condition of EPDM Polymer insulators.

REDUCTION OF VOLTAGE STRESS AND INPUT CURRENT HARMONIC DISTORTION IN SINGLE STAGE PFC CONVERTER BY SELECTIVE VARIABLE FREQUENCY CONTROL (선택적 주파수 변환방식에 의한 단상 역률보상회로의 캐패시터전압 및 입력전류 고조파왜곡의 감소)

  • Choi, Hang-Seok;Lee, Kyu-Chan;Cho, Bo-Hyung
    • Proceedings of the KIEE Conference
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    • pp.1999-2001
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    • 1997
  • The main two drawbacks of the Sin91e Stage PFC (SS-PFC) converters employing a DCM Boost PFC cell are relatively high voltage stress on the bulk capacitor and the input current harmonic distortion. The high voltage stress on bulk capacitor makes the SS-PFC converter impractical in a universal input application and the input current harmonic distortion lowers power factor. In this paper a selective variable frequency control that reduces the voltage stress on the bulk capacitor and the input current harmonic distortion is proposed. Computer simulation results of the proposed control method are presented.

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