Research on Closed-Loop TMR Current Sensor with Temperature Compensation Based on Reference Magnetic Field

The construction of the DC distribution grid puts forward new requirements for the performance of the current sensor. The tunnel magnetic resistance (TMR) current sensor has the advantages of high sensitivity and low power consumption. However, while the magnetic tunnel has improved its sensitivity, it inevitably leads to serious temperature drift problems. This paper proposes a closed-loop TMR DC current sensor temperature compensation method based on the reference magnetic field. The constant current source circuit and the iron core generate a reference magnetic field, which acts on TMR sensor chips of the same model and batch as the measurement channel. This chip output and the measurement channel have the compensation voltage of the same dynamic temperature characteristics. Test data of non-linearity and temperature characteristics verify the effectiveness of the design method of a closed-loop TMR DC current sensor based on the reference magnetic field dynamic compensation. The results show that the temperature dependence of the sensor is reduced from -369 ppm/°C to -81 ppm/°C by the temperature compensation method based on the reference magnetic field.