Design of the DC leakage current sensor with magnetic modulation-based scheme

Currently, the DC leakage current sensor is mainly used in the MRT DC substation to prevent cable insulation failure and monitor security on each DC cable leakage current to ensure the quality of power supplies. In this paper, the magnetic modulation DC leakage current sensor with rapid demagnetization will be investigated. In terms of circuit design, the signal originates from a square wave generator and is then sent to a third-order low-pass filter for signal demodulation. The modulated signals pass through the offset compensation circuit and will be integrated to achieve the balance of the core flux. The characteristics of the system will be analyzed with the aids of the core magnetization curve and the sensing circuit measurements of the micro-current, rated current and high current response. FPGA-based platform will also be employed to design the demagnetization and calibration control circuits such that the automatic DC leakage current monitoring system can be implemented. Finally, the proposed DC leakage sensing system will be simulated by the tool Multisim to validate the accuracy of the measurement system and verify the functions of the design requirements.