A non-intrusive voltage measurement scheme based on MEMS electric field sensors: Theoretical analysis and experimental verification of AC power lines.

A non-interference AC voltage measurement system based on a resonant electric field microsensor is proposed. The equivalent circuit of the proposed system is established, which shows that the frequency response function is only related to the capacitances of the system structure in the kHz low-frequency range. Furthermore, the sensitivity analysis and experiments demonstrate that the amplitude sensitivity is independent of the frequency of an unknown AC voltage. Therefore, this technique is very suitable for measuring arbitrary waveform voltage. A functional prototype was developed and tested to acquire AC power-line voltages. The prototype responded well to the transient waveform of the AC input signal, yet with a phase delay of 177.24°. The output of the system was linear in the range of 0-1000 Vrms at 50-Hz and the linearity was 0.54%, whereas the maximum relative deviation of the rms voltage measurements above 10 V was -0.83%. Finally, the shielding ability of the system against interference and noise was verified through the AC interference voltage measurement.