磁调制DCCT调制噪声及测量方法研究

Study on Modulation Noise and Its Measurement Method of DCCT with Magnetic Modulation

硬X射线自由电子激光装置要求电源输出电流分辨率优于2.5×10^-6,因此,直流电流互感器(DCCT)的分辨率也必须高于以上指标,而降低DCCT调制噪声是提高其分辨率的重要方法。为降低调制噪声,本文提出了一种调制噪声的数学模型,导出了磁调制噪声的近似表达式,分析了调制噪声与相关因素的关系。同时提出了一种调制噪声的评估方法,该方法利用Matlab的periodogram命令获得噪声功率谱。利用数学模型和评估方法分析了Sinap-DCCT产品的噪声特征,结果表明,调制噪声与相关因素的关系符合数学模型的推论。据此,给出了降低DCCT调制噪声的解决方向。

The hard X-ray free electron laser device demands that the current resolution of power supply is better than 2.5×10^-6.Therefore,the resolution of the direct current transformer(DCCT)must be higher than the above index,and reducing the modulation noise of DCCT is an important method to improve its resolution.In order to reduce the DCCT’s modulation noise,a mathematic model of modulation noise was proposed,an approximate expression of magnetic modulation noise was derived,and the relationship between modulation noise and related factor was analyzed in this paper.A method to evaluate the modulation noise was presented,which used the periodogram command of Matlab to obtain the noise power spectrum.The noise characteristics of Sinap-DCCT product were analyzed by using the mathematic model and evaluation method.The result shows that the relationship between modulation noise and related factor is consistent with mathematic model.According to this,the solution of reducing DCCT modulation noise was given.