基于离散相位差检测的频率测量方法  

Frequency measurement method utilizing discrete phase delay detection

作　　者：汪正军 潘磊 纪国瑞 

机构地区：[1]国电联合动力技术有限公司,北京100039

出　　处：《仪器仪表学报》2013年第5期994-1000,共7页Chinese Journal of Scientific Instrument

基　　金：北京市产学研科研基金(1010013020105)资助项目

摘　　要：针对传统测周法进行频率测量时存在1个测量时钟周期的固有误差的问题,提出了离散相位差检测的频率测量方法。该方法首先对测量时钟的上升沿和下降沿进行计数,使误差降低到测量时钟的1/2,然后结合阻容延时存储的相位差信息,进行N段离散采样对比,从而获得测量时钟与被测信号的相位差。通过相位差的补偿,使测量误差降低到测量时钟的1/2N。理论分析和实验验证表明,该方法在测量时钟频率无法进一步提高时,通过增加离散分段数N,可以使测量不确定度和测量误差都得到大幅降低,有利于提高频率测量的精确度。Aiming at the problem that traditional frequency measurement with cycle test method has the inherent measure- ment error of 1 clock cycle ,a frequency measurement method based on discrete phase delay detection strategy is proposed. In this method ,the rising and falling edges of the measurement clock are both counted ,which makes the measurement error decreased down to a half of the clock cycle. Furthermore,the phase delay signal stored with the RC unit is sampled and compared with the N segment discrete reference values ,thus the phase delay between measurement clock and the measured signal is obtained ;and the error is reduced to 1/2N clock cycles through the compensation with the phase delay informa- tion. Theoretical analysis and experimental result show that when it is difficult to further increase clock frequency,increas- ing the number of the discrete segments N would decline both the measurement uncertainty and measurement error under the same clock frequency. The proposed novel scheme can enhance the frequency measurement precision.

关 键 词：频率测量 相位检测 延时信号 双沿计数法 测周法 

分 类 号：TM935[电气工程—电力电子与电力传动]