A Wideband Closed-Loop Residual Current Sensor Based on Self-Oscillating Fluxgate

The increasing switching frequency of inverters in new electric power technology causes leakage currents at tens or even hundreds of kHz, exceeding the measurement frequency range of conventional AC residual current sensors. In addition, the cost of residual current sensors developed specifically for DC is high, limiting further application promotion. Hence, this paper focuses on designing a wideband closed-loop residual current sensor based on self-excited oscillation fluxgate, which outperforms ordinary measurement methods. The sensor is developed through the optimization of demodulation circuits, and the increase of AC windings and the construction of excitation voltage regulating circuits. The DC residual current measurement accuracy of the sensor is better than ±0.2%. The standard deviation of zero-point change is 0.00046 mA. The adoption of this innovative sensor not only enables precise and stable measurement of residual currents but also facilitates current monitoring in high-frequency applications. It can be fully applied in the field of power technology and will promote the development of efficient and reliable power systems.