Passive MEMS DC Electric Current Sensor: Part II - Experimental Verifications

This paper, the second part of two companion papers, reports experimental methodology and verification results based on the prototype device of the proposed passive MEMS dc current sensor in Part I. The relationship between output voltages and crucial factors, such as the relative position of the sensor to the two-wire appliance cord, different connection modes of the PZT partition plates, as well as the applied dc current has been characterized. The experimental methodology mainly includes those of how to position the sensor device, how to determine the measurement range for sensitivity characterization, and how to electrically connect the PZT partition plates in different modes. Sensitivity characteristics were studied in ac current from 8 to 400 mA and in dc current from 0.5 to 3 A, respectively. Two typical connection modes, i.e., in series and parallel, were investigated with ten PZT partition plates. In the case of dc current, the waveforms of the output voltage in the individual PZT plate were studied in detail. First, the initial peak voltages corresponding to ON-OFF switching of dc current can be clearly characterized with a higher amplitude (relatively lower frequency) for turning ON and a lower one (relatively higher frequency) for turning OFF. Second, the measured peak voltages are smaller than the analytical ones, but showing similar increasing tendency with the increasing of the dc current. In light of the above-mentioned experimental verifications, the proposed passive MEMS dc current sensor was proved to be applicable to direct measurements of the two-wire appliance cords without using cord separator. The proposed sensor devices are, therefore, more convenient than Hall-effect-based sensors in electricity end-use measuring and monitoring of dc power supply.