利用数字相敏检波器消除电容式传感器漏电产生的测量误差

Application of Digital Phase Detector to Elimination of Measuring Error Produced by the Current Leakage of Capacitive Sensor

在分析影响电容传感器测量精度各种因素的基础上,论述了由单片机构成的数字相敏检波器(DPSD)的工作原理以及采用这种DPSD实现的一种新型电容式传感器转换电路。在电路中运用了DPSD、高精度运算放大器和单片机,消除了传感器漏电所引起的测量误差,同时还有效地抑制了传感器引线电容及其他干扰信号对测量精度的影响。实验证明:这种转换电路具有很高的测量精度和可靠性,测量误差小于±1%,可以应用于航空航天等领域内的精密仪表中。

On the basis of the analysis of various factors affecting the precision of capacitive sensor,discusses the operating principle of digital phase detector （DPSD） based on single-chip microcomputer and a new measurement circuit of capacitive sensor is proposed. Due to the DPSD, the high precision operational amplifier and the microcomputer were adopted in this circuit, as a result, the measurement precision of capacitive sensor was no longer affected by the current leakage. The cable capacitance and the jamming signal was filtered effectively. It was proved that the measurement circuit of capacitive sensor has characteristics of high precision and high reliability, the measurement error less than ± 1%. It could be used in the aircraft and spacecraft instruments.