A Non-contact Inductive Position Sensor For Use In Micro Machines

Al need has arisen in research on micro machines for mi cro position sensors which are less affected by scaling laws than existing capacitive sensors. This paper de- scribes the development and operation of a non-contact inductive position sensor for use in micro magnetic bearings. As the sensor footprint area, in the micro machines being considered, will be less than I mm square the sensor coil inductances and impedance levels are small, and the parasitic and demodulator input capacitances begin to have a major influence on the transducer op- eration. To minimize the loading effect of these capac itances wideband current to voltage (I-V) converters have been introduced to match the output of the sen sor coils to the input of the signal conditioner circuit. Test results for these I-V converters are presented. Also overall test results of the position transducers showing transducer linearity and sensitivity for a range of sensor coils are presented.