Research on TMR Current Transducer With Temperature Compensation Based on Reference Magnetic Field

Abstract

TMR magnetoresistance sensors have advantages such as small size and low power consumption in the field of current measurement, but their sensitivity temperature dependence limits their application in the field of electric energy metering. A temperature compensation method based on reference magnetic field was proposed, which uses a constant current source and an iron core with an air gap to construct the reference magnetic field. The structures of the reference magnetic field channel and the measurement channel are the same, which the TMR sensors used are the same, and the signal processing circuits are the same. By analyzing the relationship between the air gap magnetic field and the primary current, a mathematical model was established between the input current and the sensor output voltage, thus providing support for the temperature compensation method of the TMR current sensor. The effectiveness of the temperature compensation method for TMR current transducer based on reference magnetic field is verified by the test data of the nonlinear characteristics and temperature characteristics. The results show that the temperature compensation method based on reference magnetic field reduces the temperature dependence of the sensor from -369ppm/℃ to -49ppm/℃. The proposed temperature compensation method does not require additional temperature sensors and does not require prior acquisition of TMR temperature characteristics, making it specific and universal.INDEX TERMS iron core, reference magnetic field, sensitivity temperature dependence, TMR current transducer

Characterization of Magnetoresistive Shunts and Its Sensitivity Temperature Compensation

“…The main results are summarized in Table 2, where TC wnc denotes the temperature coefficients obtained without compensation (Section 3.2) and TC wc with compensation (Table 2). A figure of merit that reflects the effectiveness of the thermal compensation performed is the percentage in reduction R experienced in the temperature coefficient before and after compensation, defined as: R(%) = 1 − TC wc TC wnc •100 (16) As summarized in Table 2, it was possible to reduce the initial temperature coefficients of the MR-shunt elements, achieving high reduction coefficients in all the cases tested, especially when the silicon-based temperature sensor was used.…”

“…Furthermore, MR sensors have sensitivity thermal dependence, which requires some type of thermal compensation (hardware or software). Thermal compensation strategies for MR sensors integrated in a WB structure can be found in [16][17][18][19].…”