A microwave photonic notch filter with a complex coefficient is proposed and demonstrated based on four wave mixing(FWM). FWM effect of two single-frequency laser beams occurs in a highly nonlinear fiber(HNLF), and mu...A microwave photonic notch filter with a complex coefficient is proposed and demonstrated based on four wave mixing(FWM). FWM effect of two single-frequency laser beams occurs in a highly nonlinear fiber(HNLF), and multi-wavelength optical signals are generated and used to generate the multi-tap of microwave photonic filter(MPF). The complex coefficient is generated by using a Fourier-domain optical processor(FD-OP) to control the amplitude and phase of the optical carrier and phase modulation sidebands. The results show that this filter can be changed from bandpass filter to notch filter by controlling the FD-OP. The center frequency of the notch filter can be continuously tuned from 5.853 GHz to 29.311 GHz with free spectral range(FSR) of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.展开更多
为实现在单相电网电压畸变条件下车网互联(V2G)系统的灵活直接功率控制,首先将复矢量引入电网谐波条件下的单相瞬时功率计算,分析了电网电压畸变时的单相有功功率与无功功率的成分。在建立单相V2G系统复矢量信号模型的基础上,设计复数...为实现在单相电网电压畸变条件下车网互联(V2G)系统的灵活直接功率控制,首先将复矢量引入电网谐波条件下的单相瞬时功率计算,分析了电网电压畸变时的单相有功功率与无功功率的成分。在建立单相V2G系统复矢量信号模型的基础上,设计复数控制器实现了功率稳定与并网电流谐波抑制2个独立目标的控制,并采取功率前馈控制改善了系统动态性能。最后,搭建了3.5 k V·A单相V2G系统的MATLAB/Simulink仿真模型与实验系统,仿真与实验结果验证了理论分析的正确性以及所提控制方案的有效性。展开更多
This paper analyses frequency tracking characteristics of a complex-coefficient adaptive infinite-impulse response (IIR) notch filter used for suppression of narrow-band interference (NBI) with a randomly-varying freq...This paper analyses frequency tracking characteristics of a complex-coefficient adaptive infinite-impulse response (IIR) notch filter used for suppression of narrow-band interference (NBI) with a randomly-varying frequency in a quadriphase shift keying (QPSK) modulated direct-sequence code-division multiple-access (DS-CDMA) communication system. The QPSK DS-CDMA signals are transmitted over a frequency non-selective Rayleigh fading channel. The analysis is based on a first-order real-coefficient difference equation with respect to steady-state instantaneous frequency tracking error from which a closed-form expression that relates frequency tracking mean square error (MSE) with number of DS-CDMA active users and NBI power is obtained. Closed-form expressions for optimum notch bandwidth coefficient and step size constant that minimize the frequency tracking MSE are also derived. Computer simulations are included to substantiate the accuracy of the analyses.展开更多
车内主动噪声控制中常使用的传统滤波-x最小均方(Filtered-x Least Mean Square,FxLMS)算法由于计算复杂度高,往往导致系统硬件算力不足,降噪效果不理想。文章提出一种基于改进局部次级通路建模方法的自适应陷波(Local-secondary-path F...车内主动噪声控制中常使用的传统滤波-x最小均方(Filtered-x Least Mean Square,FxLMS)算法由于计算复杂度高,往往导致系统硬件算力不足,降噪效果不理想。文章提出一种基于改进局部次级通路建模方法的自适应陷波(Local-secondary-path Filtered-x Least Mean Square,LFxLMS)算法及其相应的窄带主动噪声控制(LFxLMS-based Narrowband Active Noise Control,LFx-NANC)系统。所提出的改进局部次级通路建模方法具有更高的建模精度,且该系统相较于传统系统大大降低了计算复杂度。通过基于Matlab软件的仿真分析,验证了该系统对稳态及非稳态多谐波噪声的降噪性能。基于ADSP-21489控制器搭建车内双通道LFx-NANC系统,实现了在稳态工况下主驾位置处二、四、六阶降噪量分别达到34.67、21.41、10.29 dB(A);在加速工况下主驾位置处总声压级和二阶降噪量分别达到6.01 dB(A)和20.40 dB(A),同时在其他位置均有较好的降噪效果。文中提出的方法为主动噪声控制的工程应用提供了参考。展开更多
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2013AA014200)the National Natural Science Foundation of China(No.11444001)the Municipal Natural Science Foundation of Tianjin(No.14JCYBJC16500)
文摘A microwave photonic notch filter with a complex coefficient is proposed and demonstrated based on four wave mixing(FWM). FWM effect of two single-frequency laser beams occurs in a highly nonlinear fiber(HNLF), and multi-wavelength optical signals are generated and used to generate the multi-tap of microwave photonic filter(MPF). The complex coefficient is generated by using a Fourier-domain optical processor(FD-OP) to control the amplitude and phase of the optical carrier and phase modulation sidebands. The results show that this filter can be changed from bandpass filter to notch filter by controlling the FD-OP. The center frequency of the notch filter can be continuously tuned from 5.853 GHz to 29.311 GHz with free spectral range(FSR) of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.
文摘为实现在单相电网电压畸变条件下车网互联(V2G)系统的灵活直接功率控制,首先将复矢量引入电网谐波条件下的单相瞬时功率计算,分析了电网电压畸变时的单相有功功率与无功功率的成分。在建立单相V2G系统复矢量信号模型的基础上,设计复数控制器实现了功率稳定与并网电流谐波抑制2个独立目标的控制,并采取功率前馈控制改善了系统动态性能。最后,搭建了3.5 k V·A单相V2G系统的MATLAB/Simulink仿真模型与实验系统,仿真与实验结果验证了理论分析的正确性以及所提控制方案的有效性。
文摘This paper analyses frequency tracking characteristics of a complex-coefficient adaptive infinite-impulse response (IIR) notch filter used for suppression of narrow-band interference (NBI) with a randomly-varying frequency in a quadriphase shift keying (QPSK) modulated direct-sequence code-division multiple-access (DS-CDMA) communication system. The QPSK DS-CDMA signals are transmitted over a frequency non-selective Rayleigh fading channel. The analysis is based on a first-order real-coefficient difference equation with respect to steady-state instantaneous frequency tracking error from which a closed-form expression that relates frequency tracking mean square error (MSE) with number of DS-CDMA active users and NBI power is obtained. Closed-form expressions for optimum notch bandwidth coefficient and step size constant that minimize the frequency tracking MSE are also derived. Computer simulations are included to substantiate the accuracy of the analyses.
文摘车内主动噪声控制中常使用的传统滤波-x最小均方(Filtered-x Least Mean Square,FxLMS)算法由于计算复杂度高,往往导致系统硬件算力不足,降噪效果不理想。文章提出一种基于改进局部次级通路建模方法的自适应陷波(Local-secondary-path Filtered-x Least Mean Square,LFxLMS)算法及其相应的窄带主动噪声控制(LFxLMS-based Narrowband Active Noise Control,LFx-NANC)系统。所提出的改进局部次级通路建模方法具有更高的建模精度,且该系统相较于传统系统大大降低了计算复杂度。通过基于Matlab软件的仿真分析,验证了该系统对稳态及非稳态多谐波噪声的降噪性能。基于ADSP-21489控制器搭建车内双通道LFx-NANC系统,实现了在稳态工况下主驾位置处二、四、六阶降噪量分别达到34.67、21.41、10.29 dB(A);在加速工况下主驾位置处总声压级和二阶降噪量分别达到6.01 dB(A)和20.40 dB(A),同时在其他位置均有较好的降噪效果。文中提出的方法为主动噪声控制的工程应用提供了参考。
