抄録
This paper describes an ac / dc earth leakage current sensor using fluxgate magnetic sensor with self-excitation circuit for dc distribution system of photovoltaic power generation systems, data center systems, electric vehicles, and etc. The self-excitation circuit could be used in fluxgate current sensor to achieve a high sensitivity about ten times higher than conventional separate excitation circuit. The sensor achieves to detect a small ac / dc current of 10mA. Two kinds of detection by pulse width and pulse frequency could be used in this system to achieve a wide measurement range of 1:1000. Equivalent circuit analysis could be used in the fluxgate sensor to achieve optimized fluxgate current sensors characteristics of the sensitivity and a quiescent current. The sensor achieves a low quiescent current of 15mA and less. We found that the results from simulations almost corresponded to those from measurements, and were able to verify the validity of the basic analytical model. These concepts are realized by the simple configuration and low cost sensor, which a toroidal core based on thin-film nanocrystalline soft magnetic material, an excitation coil, and electric circuits.
