Numerical Study of Field-circuit Coupling and Output Response of TMR Current Sensor

Current sensors based on the tunneling magnetoresistance effect (TMR) have many advantages, such as small size, high sensitivity, wide measurement range, etc. In this paper, the output response of TMR current sensor under complex electromagnetic environments are numerically studied with finite element method. A prediction method for the operating characteristics of TMR sensor is developed with field-circuit coupling method, and the adaptability of TMR current sensor under different coil currents is also discussed. The results show that, the linear operating region of TMR current sensor is from6. 75mT to 6. 75mT. The variation of output voltage with the installation angle is in a cosine law. When the sensitivity axis of TMR current sensor is parallel to the magnetic field vector, the absolute value of its output voltage is the highest. Furthermore, when the Barker coil is applied with step, sinusoidal wave and harmonic currents, if the TMR current sensor works in the linear operating region, it can sensitively detect the magnetic field generated by different currents. The output voltage of TMR sensor changes with coil current waveform, amplitude and frequency, and shows good adaptability.