用脉冲整流器实现的电子模拟功率负载

对采用电压型脉冲整流器实现的电能反馈型电子模拟功率负载进行了设计研究 ,控制系统采用了性能优良的专门应用于实时控制领域的数字信号处理器TMS32 0F2 4 0 ,优良的控制方法使得所研制的功率负载在实现电能的再生并网时功率因数趋近于 1.0 ,且电压和电流谐波满足IEEE 519标准 .实验结果证实该方案能很好的解决直流电源出厂试验问题 .     

一种基于IPM的简化空间矢量PWM研究

基于智能功率模块（IPM）,提出了一种简化的以三相相电压的大小来判断具体扇区的空间矢量脉宽调制（SVPWM）算法,分析了算法原理,并给出了算法流程．在不同载波比N和调制度M下,用MATLAB软件对参考电压矢量各扇区分布、调制信号、直流电压利用率及输出电压谐波等进行了仿真研究,分析得出N影响到参考电压矢量扇区分布和谐波性能,M将影响到调制波形、直流电压利用率和谐波含量,合适的N和M有利于提高SVPWM总体性能．利用TMS320F2812DSP进行了实验,验证了算法的有效性。     

Exponential smoothing: The state of the art

This paper is a critical review of exponential smoothing since the original work by Brown and Holt in the 1950s. Exponential smoothing is based on a pragmatic approach to forecasting which is shared in this review. The aim is to develop state-of-the-art guidelines for application of the exponential smoothing methodology. The first part of the paper discusses the class of relatively simple models which rely on the Holt-Winters procedure for seasonal adjustment of the data. Next, we review general exponential smoothing (GES), which uses Fourier functions of time to model seasonality. The research is reviewed according to the following questions. What are the useful properties of these models? What parameters should be used? How should the models be initialized? After the review of model-building, we turn to problems in the maintenance of forecasting systems based on exponential smoothing. Topics in the maintenance area include the use of quality control models to detect bias in the forecast errors, adaptive parameters to improve the response to structural changes in the time series, and two-stage forecasting, whereby we use a model of the errors or some other model of the data to improve our initial forecasts. Some of the major conclusions: the parameter ranges and starting values typically used in practice are arbitrary and may detract from accuracy. The empirical evidence favours Holt's model for trends over that of Brown. A linear trend should be damped at long horizons. The empirical evidence favours the Holt-Winters approach to seasonal data over GES. It is difficult to justify GES in standard form–the equivalent ARIMA model is simpler and more efficient. The cumulative sum of the errors appears to be the most practical forecast monitoring device. There is no evidence that adaptive parameters improve forecast accuracy. In fact, the reverse may be true.     

非对称N次谐波凸轮的优化设计

讨论了非对称Ｎ次谐波凸轮的设计方法及其特点，并应用正交设计的方法初步确定凸轮型线的设计参数的变化区域．建立合理的优化模型进行求解，在国内首次应用非对称Ｎ次谐波理论设计凸轮．     

矿井提升机“可控硅—电动机”系统高次谐波的抑制

本文介绍了抑制矿井提升机“SCR—D”系统高次谐波的一种有效措施。经分析,其效果接近于24脉波整流电路,11、13、23、25等次谐波被显著地降低了。该方法结构简单、经济可行。     

确定饱和电机气隙磁场谐波的新方法

本文提出一种把分析气隙磁场的数值方法和解析方法结合起来以求解在饱和条件下电机气隙谐波磁场的方法。这种方法能求出在饱和条件下气隙谐波磁势及开槽等因素引起的谐波磁场,和由于饱和所出现的谐波磁场,这两种可以是同次而不同速的谐波磁场。根据这种新方法所给出的结果,可对电机性能进行准确合理的分析。本文所做的算例结果,证明了这种方法的正确性。     

超导体的谐波响应和磁通蠕动

Harmonic AC susceptibilities as a function of temperature (T) ,AC field frequency (f), amplitude (Bac) in DC fiedld (Bde) have been studied numerically. The numerical calculation is based on nonlinear vortex diffusion. The result shows that there exists seeond harmonic al-     

基于直接功率控制的钻机井场电网谐波抑制的研究

针对钻机自备电网的非线性负载产生的谐波,提出了基于直接功率控制的有源电力滤波方案.介绍了直接功率控制系统的控制方法、原理以及该系统的空间矢量调制控制策略,并进行了仿真实验.结果表明:基于直接功率控制的有源电力滤波器对井场电网有较好的谐波抑制和无功补偿的效果,可有效提高井场电网功率因数,减少谐波电流,改善输出电流波形.控制系统结构简单,易于实现工程化.     

病变语音信号的谐波噪声比分析

文章介绍了用噪音中谐波分量一噪声分量的比值来客观定量地评估桑音嘶哑程度的方法，并对提取谐波噪声比（ＨＮＲ）的具体算法做了分析讨论，实验和临床使用表明，这个声学参数能够很好地反映了病变语音的特性，具有重要的应用价值。