Feasibility of Noncontact Inductive Temperature Measurement Scheme Suitable for a Fixed or a Moving Conductive Target

The development of a new, noncontact, inductive-based temperature measurement scheme is presented in this article. Measurement of the temperature of a moving part is a challenging task when the line of sight is not available. This article presents a new, simple, and effective solution for this problem, for electrically conductive targets. The proposed approach is built by utilizing the temperature coefficient of resistance of the target material and its magnetic coupling to a sensing coil from which the measurement is made. The sensing coil is excited using a sinusoidal signal. As the temperature of the target changes, the resistance offered by the target to the eddy current path changes. The effective impedance of the sensing coil that is magnetically coupled to the moving target changes as the temperature of the target changes. In this work, it is shown that the real part of the impedance is correlated with the temperature of the target. As the sensing coil is also exposed to the change in temperature and due to the self-heating of the coil, coil resistance will change with the ambient temperature. A new but simple measurement mechanism is presented to resolve the resistive component due to the change in temperature of the target alone. Simultaneous measurement of temperature using a commercially available direct contact temperature sensor and the prototype of the proposed noncontact sensor showed a very good agreement. The worst case deviation observed from the test conducted over a temperature range of 40 °C–100 °C was less than ±2%.