• Title/Summary/Keyword: nonlinear harmonic distortion

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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 Nonlinear Distortions OFDM Systems (OFDM 시스템의 비선형 왜곡 분석)

  • 전원기;조용수
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 1998.06a
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    • pp.165-170
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    • 1998
  • In this paper, the effect of nonlinear distortion, caused by a high-power amplifier (HPA) in an orthogonal frequency division multiplexing (OFDM) system, on the receiver part is analyzed. Since the HPA, which can be modeled by a memoryless Volterra system, distorts OFDM signals in a nonlinear fashion, the received signal at each subchannel includes the multiplicative distortion of 1-st order as well as additive nonlinear distortion of higher-order. The nonlinear distortion can be viewed as a nonlinear interchannel interference (NICI) since it consists of harmonic distortions and intermodulation distortions, produced by other subchannels affecting the subchannel of interest. In this paper, were analytically derive the variance of NICI in terms of average input power using the Volterra model for HPA, and then calculate the bit-error rate (BER) performance of an OFDM system. Also, we propose a simple method to compensate for the phase distortion in OFDM system amplified by HPA, and calculate its BER performance. Validity of the proposed approach is verified by computer simulations for an OFDM system employing 16-QAM constellation input.

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Identification of Nonlinear Parameters of Electrodynamic Direct-Radiator Loudspeaker with Output Noise (출력 소음을 고려한 직접방사형 라우드스피커의 비선형 매개변수 규명)

  • 박석태;홍석윤
    • Journal of KSNVE
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    • v.8 no.5
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    • pp.887-899
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    • 1998
  • It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

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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.

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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Analysis of Harmonic Currents Propagation on the Self-Excited Induction Generator with Nonlinear Loads

  • Nazir, Refdinal
    • Journal of Electrical Engineering and Technology
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    • v.9 no.6
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    • pp.1935-1943
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    • 2014
  • In recent years, the induction machines are increasingly being used as self-excited induction generators (SEIG). This generator is especially widely employed for small-scale power plants driven by renewable energy sources. The application of power electronic components in the induction generator control (IGC) and the loading of SEIG using nonlinear loads will generate harmonic currents. This paper analyzes the propogation of harmonic currents on the SEIG with nonlinear loads. Transfer function method in the frequency domain is used to calculate the gain and phase angle of each harmonic current component which are generated by a nonlinear loads. Through the superposition approach, this method has also been used to analyze the propagation of harmonic currents from nonlinear load to the stator windings. The simulation for the propagation of harmonic currents for a 4 pole, 1.5 kW, 50Hz, 3.5A, Y-connected, rotor-cage SEIG with energy-saving lamps, have provided results almost the same with the experiment. It can prove that the validity of the proposed models and methods. The study results showed that the propagation of harmonic currents on the stator windings rejects high order harmonics and attenuates low order harmonics, consequently THDI diminish significantly on the stator windings.

Analysis of nonlinear distortions in OFDM systems (OFDM 시스템의 비선형 왜곡 분석)

  • 전원기;조용수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.23 no.4
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    • pp.976-987
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    • 1998
  • In this paper, the effect of nonllinear distortion, caused by a high-power amplifier(HPA) in an orthogonal frequency division multiplexing (OFDM) system, on the receiver part is analyzed. Since the HPA, which can be modeled by a memeoryless Volterra system, distorts OFDM signals in a nonlinear fashion, the received signal at each subchannel includes the multiplicative distortion of 1-st order as well as additive nonlinear distortion of high-order. the nonlinear distortion can be viewed as a nonlinear interchannel interference (NICI) since it consists of harmonic distortions and intermodulation distortions, produced by oother subchannels affecting the subchannel of interest. In this paper, we analytically derive the variance of NICI in terms of average input power using the volterra model for HPA, and then calculate the bit-effor rate(BER) performance of an OFDM system. Also, we propose a simple method to compensate for the phase distortion in OFDM system amplified by HPA, OFDM system employing 16-QAM constellation input.

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Analysis on the Harmonics Characteristics Due to Increase & Decrease of Nonlinear Load (비선형 부하의 증감에 따른 고조파 특성 분석)

  • Kim, Jong-Gyeum;Lee, Eun-Woong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.52 no.3
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    • pp.100-106
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    • 2003
  • The increasing application of power electronic equipment in industrial field has led to a growing concern for harmonic distortion and the resulting impacts on system equipment and operations. Harmonic currents are generated by the operation of nonlinear loads and equipment on the power system. These are more increased by unbalance voltage of electrical distribution power systems. This paper describes harmonics characteristics generated by varying of nonlinear load at the PCC under the voltage unbalance.

A Study on the Series and Parallel Resonant Filters for Harmonic Currents Reduction of Nonlinear Loads (비선형부하의 고조파전류 저감을 위한 직렬 및 병렬 동조필터에 관한 연구)

  • 김경철;강윤모;백승현;김종욱
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.17 no.6
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    • pp.113-118
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    • 2003
  • This paper characterizes typical nonlinear loads into two types of harmonic sources, i.e., harmonic voltage source and harmonic current source. A series resonant filter is very effective in harmonic reduction for harmonic voltage source type of nonlinear loads such as personal computer loads with smoothing dc capacitors. A parallel resonant filter is suited for current source type of nonlinear loads such as ac drives with smoothing dc reactors. General compensation characteristics and comparison of series and parallel resonant filters are given analytically and experimentally. Compliance with IEC Std 1000-3-2 has been evaluated for limiting harmonic distortion.