• Title/Summary/Keyword: Harmonic distortion

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On-line Harmonic Distortion Index for Power Quality Assessment (온라인 고조파 해석 지수의 개발)

  • Jang, Gil-Soo;Song, Hwa-Chang;Lee, Byong-Jun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.8
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    • pp.373-378
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    • 2001
  • This paper introduces a new online index to quantify the harmonic distortion. The proposed index based on VI product can represent the harmonic distortion of both voltage and current, and it includes the effect of interharmonic distortion. Also, the new index is suitable to online harmonic distortion evaluation since it only requires the r.m.s. (root mean square) value and fundamental frequency value of the signals. Case studies are presented to show the availability of the proposed index using the comparison with the THD (Total Harmonic Distortion).

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Harmonic Distortion Control for Electric Propulsion (전기 추진선을 위한 고조파 제어 사례 연구)

  • Kim, Ju-Wan;Lee, Choong-Yeol;Seo, Kun-Kyung
    • Special Issue of the Society of Naval Architects of Korea
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    • 2008.09a
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    • pp.38-45
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    • 2008
  • The application of the electric propulsion system to the vessels has recently become common due to the latest technology for controlling the electric motors with variable speed. However it has been found that harmonic distortion exists in the electric propulsion system, which consists of an electric motor, a converter and an inverter, and this harmonic distortion has a harmful effect on the system. In this paper, the definition of the harmonic distortion and problems caused by the harmonic distortion in the electric propulsion of the vessels are introduced and the practical solutions for the problems are investigated.

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The Control Technique of 3 Phase NPC PWM Inverter to control fixed Total Harmonic Distortion (종합 고조파 왜율 일정 제어를 위한 삼상 NPC PWM 인버어터의 제어 기법)

  • Song, Eon-Bin
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.565-567
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    • 1994
  • This paper presents a software based NPC PWM inverter control technique to eliminate the harmonics in the output waveforms of inverter. The proposed control technique is able to keep down total harmonic distortion and significantly improve the performance of the inverter. In the control node where the frequency ratio is 36 and the modulation index is $1.2\sim2.0$, the proposed inverter has been operated wi thin 5% Total Harmonic Distortion.

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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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    • 1997.07f
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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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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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Analysis of Total Harmonic Distortion in Microspeaker Considering Coupling Effect (연성 효과를 고려한 마이크로스피커 왜율분석)

  • Kwon, Joong-Hak;Kim, Kwang-Suk;Bang, Ki-Chang;Hwang, Sang-Moon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.4
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    • pp.473-479
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    • 2008
  • With the advent of mobile phone, digital multimedia broadcasting(DMB) service is to be realized for multimedia data communication. For an acoustic part, a smaller and lighter microspeaker is also soon to be realized as an MP3 song player and a speakerphone. Sound quality in the microspeaker is becoming more important in mobile phones. It is evaluated by total harmonic distortion(THD). THD is the proportion of higher order frequencies output response to sinusoidal input signal. It is affected by uneven magnetic distribution and nonlinear response of diaphragm. In this paper, harmonic distortion is analyzed by considering magnetic and mechanical coupling effects. Simulated results of THD are compared with experimental data. Results show that THD in lower frequency range is higher due to high displace on voice coil and high mechanical response of high order frequency.

Controller design for compensation of nonlinear harmonic distortion in direct-radiator loudspeakers (직접 방사형 스피커의 비선형 고조파 왜곡 보상 제어기의 설계)

  • 김윤선;박영진
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.399-402
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    • 1996
  • The electrodynamic loudspeakers should have a wide dynamic range to reproduce various sound levels. When the input signal is small, the radiated sound from the loudspeaker is not so much distorted. However, for large input signal with low frequency component the radiated sound is significantly distorted due to the nonlinearities of the loudspeaker. The suspension, damping, and magnetic flux of loudspeaker are the main sources of the nonlinearity. Such electromechanical parameters related to harmonic distortion have been represented by a polynomial model for diaphragm displacement, while each of the polynomial coefficient is evaluated by using the principle of harmonic balance experimentally. Based on the polynomial model, we designed a compensator for nonlinear harmonic distortion of direct radiator loudspeaker. Than observer is used to estimate the displacement of the loudspeaker diaphragm, which is rather difficult to measure directly in the conventional setting. The usefulness of the designed compensator is demonstrated by numerical simulations. Simulation results show about 30db decrease at the second and third higher harmonic distortions. We carry out an experiment on speaker to verify designed controller and nonlinear observer.

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Analysis of total harmonic distortion in microspeaker considering coupling effect (연성 효과를 고려한 마이크로스피커 왜율분석)

  • Kwon, Joong-Hak;Kim, Kwang-Suk;Bang, Ki-Chang;Hwang, Sang-Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.236-241
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    • 2008
  • With the advent of mobile phone, Digital multimedia broadcasting (DMB) service is to be realized for multimedia data communication. For an acoustic part, a smaller and lighter microspeaker is also soon to be realized as an MP3 song player and a speakerphone. Sound quality in the microspeaker is becoming more important in mobile phones. It is evaluated by total harmonic distortion (THD). THD is the proportion of higher order frequencies output response to sinusoidal input signal. It is affected by uneven magnetic distribution and nonlinear response of diaphragm. In this paper, harmonic distortion is analyzed by considering magnetic and mechanical coupling effects. Simulated results of THD are compared with experimental data. Results show that THD in lower frequency range is higher due to high displace on voice coil and high mechanical response of high order frequency.

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Enhanced Variable On-time Control of Critical Conduction Mode Boost Power Factor Correction Converters

  • Kim, Jung-Won;Yi, Je-Hyun;Cho, Bo-Hyung
    • Journal of Power Electronics
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    • v.14 no.5
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    • pp.890-898
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    • 2014
  • Critical conduction mode boost power factor correction converters operating at the boundary of continuous conduction mode and discontinuous conduction mode have been widely used for power applications lower than 300W. This paper proposes an enhanced variable on-time control method for the critical conduction mode boost PFC converter to improve the total harmonic distortion characteristic. The inductor current, which varies according to the input voltage, is analyzed in detail and the optimal on-time is obtained to minimize the total harmonic distortion with a digital controller using a TMS320F28335. The switch on-time varies according to the input voltage based on the computed optimal on-time. The performance of the proposed control method is verified by a 100W PFC converter. It is shown that the optimized on-time reduces the total harmonic distortion about 52% (from 10.48% to 5.5%) at 220V when compared to the variable on-time control method.

Carrier based SVPWM Method for Multi-Level System Considering Harmonic Distortion Factor

  • Lee, Yo-Han;Kim, Dong-Hyun;Hyun, Dong-Seok
    • Journal of Power Electronics
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    • v.1 no.1
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    • pp.26-35
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    • 2001
  • In most inverter/converter applications SVPWM method is a preferred approach since it shows good characteristics in linear modulation range and waveform quality. In this paper, we propose a new carrier based SVPWM method for multi-level system, First, we survey the conventional carrier based SVPWM method, and investigate the problem of the conventional one for the multi-level system with the focus on the switching frequency harmonic flux trajectories. Finally, we propose a new carrier based SVPWM method that can reduce harmonic distortion. Simulation and experimental results are given for verification of the proposed SVPWM method.

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