A dynamic temperature compensation method for micro electromagnetic force load cell

The temperature drift problem of micro electromagnetic force weighing sensors mainly stems from the thermal expansion and contraction of the mechanical structure, the temperature drift of circuit components, and the change in the magnetic induction intensity of the permanent magnet. For a sensor with a range of 200g and a graduation value of 0.1mg, the study analyzed the temperature drift characteristics of the mechanical lever transmission ratio, the voltage reference of the driving circuit, the sampling resistor, and the permanent magnet through mathematical modeling. The main influencing factors and the installation position of the temperature-compensated sensor were determined. Through a linear heating test (record the indication drift every 10°C), a temperature drift compensation function was established using quadratic fitting, and a dynamic compensation method based on the zero reference point, the half-scale reference point, and proportional following the maximum scale reference point in the interval was proposed. This method enables the influence of the mechanical and circuit parts to simultaneously affect the starting reference point of the sensor in the software, ensuring that the length of the sensor’s measurement range interval is precisely symmetrical with the real-time temperature. In addition, the concept of dynamic compensation sensitivity was introduced, and the matching relationship between the compensation amount and the graduation value was adjusted in real time to improve the compensation accuracy. Experiments show that this method achieves dynamic temperature compensation within the range of 5°C to 35°C, with the absolute value of the compensation error being less than 0.5mg, significantly improving the sensor’s adaptability in environments with large temperature fluctuations.