HIGHLY FAILURE TOLERANT TEMPERATURE ACQUISITION FOR THERMOCOUPLE APPLICATIONS

摘要

The invention relates to a method for a thermo voltage acquisition from a thermocouple element (1), comprising: a first measurement (Al) measuring the voltage (V_TC) at the thermocouple element (1) for a first bias voltage (V_BIAS), a second measurement (B1) measuring the voltage (V_TC) at the thermocouple element (1) for a second bias voltage (V_BIAS), a third measurement (A2) measuring the voltage at a probe resistor (2) for the first bias voltage (V_BIAS), and a fourth measurement (B2) measuring the voltage at the probe resistor (2) for the second bias voltage (V_BIAS), wherein during the first and second measurement (A1, B1) the bias voltage (V_BIAS) is applied to one terminal (3) of the thermocouple element (1) to set the working point of the thermocouple element (1) to two different levels, and wherein the probe resistor (2) is connected in series between the bias voltage source (4) and the terminal (3) of the thermocouple element (1), and wherein during the third and fourth measurement (A2, B2) the bias voltage (V_BIAS) is applied to the probe resistor (2), and further comprising the steps of: calculating a first difference (Dl) between the first measurement (Al) and the second measurement (Bl) by subtracting the second measurement (B1) from the first measurement (A1), calculating a second difference (D2) between the third measurement (A2) and the fourth measurement (B2) by subtracting the fourth measurement (B2) from the third measurement (A2), calculating a correction factor (CORR) by multiplying the first difference (D1) with the fraction of the third measurement (A2) to the second difference (D2), and calculating the corrected thermo voltage (V_TC) of the thermocouple element (1) by subtracting the correction factor (CORR) from the first measurement (Al). The invention further relates to a thermo voltage acquisition circuit (7), for acquiring a thermo voltage (V_TC) from a thermocouple element (1).