A Main-Auxiliary Structured Resonant Galvanometer for Noninvasive Passive Dual-Frequency Detection

The urgent need for real-time monitoring and early warning for multifrequency currents in the same electronic device presents a great challenge to existing resonant current sensors. In this article, a main-auxiliary structured resonant or Wang galvanometer (MAS-RGM) is developed for achieving dual frequency current detections passively and non-invasively, as a solution to the above challenge. A dual-frequency current sensing theory is proposed with establishing a functional relationship between the applied current and the output voltage. A prototype, with a symmetrically main-auxiliary structure, is designed and fabricated to experimentally demonstrate the effectiveness of the developed MAS-RGM. Sensitivities of up to 70.65 and 33.59 mV/A are obtained in two frequency bands peaked at 50 and 60 Hz, respectively. Current detections with arbitrary dual frequency peaks can be accomplished by the geometrically adjustable design. High sensitivity is realized by matching the main-auxiliary structure's first two natural frequencies with the frequencies of currents. The proposed MAS-RGM is expected to have potential advantages for passive and noninvasive sensor nodes of wireless sensor networks in smart grids or intelligent factory.