Equivalent electrical model of dual core fluxgate sensor and experiment verification

In order to realize closed loop interface circuit especially sigma-delta interface of fluxgate, an equivalent electrical model of dual core fluxgate sensor is established. Based on analysis of principle of the fluxgate sensor, constituent parts of the sensor model, consisted of voltage controlled current sources with different transfer functions, are established. To achieve this, the solenoid model is set up equivalent as the resource and testing loop combination with arctangent function to close B-H curves of core. Thereafter, a whole model of the sensor is presented by simulating the electromagnetic characteristics of the inside of probe on application of the circuit equation. When the exciting frequency is 1.145kHz, the deviation of frequency between simulative and experimental output is only 0.5%. The comparison between simulation and experimental shows the electrical model of the sensor accords with principle of fluxgate, and the results of simulation agree well with the experimental results. The electrical model can be simulated with interface circuit, which could accomplish not only the analysis of the entire performance of fluxgate and readout circuit, but also optimization of the closed loop testing circuit design.