谐振高压传感器信号的高精度测量

High Precision Measurement of Resonant High Voltage Sensor Signal

差分谐振式高电压传感器的测量精度与后续频率测量电路的性能密切相关,而传统的谐振式传感器频率测量电路普遍存在精度和分辨率不高、响应速度慢以及携带不便等问题,针对这些问题,设计了一种基于现场可编程门阵列(FPGA)的高精度测频电路。该测频电路主体基于脉冲计数原理,同时利用XilinxFPGA内的CARRY4延时单元构造TDC(时间数字转换器)电路测量闸门边界与基准时钟边沿之间的微小时间间隔,克服了传统频率计中脉冲计数多记、漏记一个脉冲的问题,大大提高了频率测量的分辨率和精度。此外,为保证TDC电路工作稳定可靠,专门设计了校准电路对TDC延时链中的每个CARRY4单元定时进行在线校准。经实验测试表明,该测频方案技术指标足以满足谐振传感器的使用需求,具有较好的应用前景。

Difference of resonant type high voltage sensor measurement accuracy is closely related to the subsequent frequency measurement circuit performance, and the traditional frequency resonant sensor measurement circuit are widespread and resolution is not high precision, response speed slow and cumbersome problem, to solve these problems, we design a based on field programmable gate array(FPGA) of high precision frequency measuring circuit.The main body of the frequency measuring circuit is based on the principle of pulse counting.Meanwhile, the CARRY4 delay unit in Xilinx FPGA is used to build the TDC(time digital converter) circuit to measure the tiny time interval between the gate boundary and the edge of the reference clock, which overcomes the problem that the traditional frequency meter counts multiple pulses or misses one pulse.The resolution and precision of frequency measurement are greatly improved.In addition, in order to ensure the stable and reliable operation of TDC circuit, a calibration circuit is specially designed to conduct timed online calibration for each CARRY4 unit in the TDC delay chain.The experimental results show that the technical index of the frequency measurement scheme is enough to meet the demand of resonance sensor and has a good application prospect.