Patent ID: 6700389
Filing Date: 2004-03-02
Classification: G01D,G01F

Abstract:
A method of compensating for the temperature dependence of the effective inductance of a magnetic core in an inductive coil sensor, the method comprising:charging the sensor to generate a voltage across the sensor; measuring the voltage across the sensor at the temperature of the sensor; measuring the voltage across the sensor at a reference temperature based upon the voltage measured across the sensor at the temperature of the sensor and the voltage measured across the sensor at the reference temperature, calculating the temperature of the sensor with respect to the reference temperature; determining the effective inductance of the sensor at the temperature of the sensor; calculating the temperature compensated effective inductance of the sensor at the reference temperature; wherein charging the sensor comprises alternately energizing and do-energizing the sensor with a voltage waveform; and maintaining the voltage waveform at one value of the voltage waveform; wherein measuring the voltage across the sensor at the temperature of the sensor comprises measuring the voltage across the sensor when the voltage across the sensor is at a substantially constant value; wherein measuring the voltage across the sensor at the reference temperature comprises measuring the voltage across the sensor when the voltage across the sensor is at a substantially constant value; and wherein calculating the temperature of the sensor with respect to the reference temperature comprises calculating the temperature of the sensor with respect to the reference temperature according to the equation Tcoil-T0=1Î±&af;[(VL&af;(Tcoil)VL&af;(T0))&it;(Vi&it;â€ƒ&it;n-VL&af;(T0)Vi&it;â€ƒ&it;n-VL&af;(Tcoil))-1]where Tcoil is the temperature of the sensor, T0 is the reference temperature, &agr; is the coefficient of resistance of the material of the sensor at the reference temperature, VL (Tcoil) is the voltage measured across the sensor at the temperature of the sensor, VL (T0) is voltage measured across the sensor at the reference temperature and Vin is a constant voltage.