基于DSP的阻抗测量系统的研究

根据矢量电流电压法阻抗测量原理，以数字化测量思路，提出了一种基于DSP的阻抗测量系统。该系统以DDS信号源为测量激励，通过对标准电阻和待测阻抗元件两端的信号进行采样，将采样信号进行DFT，最终通过相关计算，实现待测信号的虚实分离，得出测量结果。系统通过设置采样频率和采样点数，有效避免了信号频谱泄漏现象而产生测量误差。通过测量试验验证，给出了几种主要测量误差引发的原因以及减小误差的有效方法，最终保证了±1%的相对误差。相比利用相敏检波器和时间数字转换器测量阻抗，该系统在保证测量精度的同时，大大简化了硬件电路和软件设计。

Research on impedance measurement system based on DSP

Based on the principle of impedance measurement of current voltage method and digital measurement thought, a kind of DSP impedance measurement system is proposed. This system takes DDS signal source as the measurement excitation, sampling the signals at both ends of standard resistance and measured impedance components, and then put the sampled signal into DFT. Finally, the measured signals are separated to false or true through relevant computation and the measurement result is gained. By setting the sample frequency and number, the measurement error caused by the frequency leakage of signal is effectively avoided in the system. Upon the measurement experiment, several reasons for main measurement error and effective method to reduce the error are put forward, and consequently the relative error is kept in ±1%. Compared with the method that applies phase sensitive detector and time to digital converter to measure the impedance, this system ensures the measurement accuracy and significantly simplifies the hardware circuit and software design.