Fluxgate DC Earth Leakage Current Sensor

This paper describes results obtained from analysis and experiments done on a fluxgate dc earth leakage current sensor for electric vehicles and photovoltaic power generation systems. As fluxgate current sensors are extremely sensitive to room temperature, various applications need this characteristic. However, conventional fluxgate current sensors have a problem in that they can only measure a narrow range of currents. To address this issue, we propose that the turns of the excitation coil be optimized with a simulator. This new sensor consists of a coiled wire that is wound around a toroidal amorphous core and through a bus bar. The sensor detects variations in excitation current according to dc current. The sensor was analyzed with a simulator. The magnetic field simulator was used to calculate the excitation current, and the output voltage according to the excitation current was calculated with a circuit simulator. 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. As a result of analysis with the simulator, 35 turns of the excitation coil were used to achieve a wide range of measurements of ±600 mA.