Thick-Film Radial Position Sensor for High Temperature Active Magnetic Bearings

This paper presents the development of radial eddy-current position sensors for high temperature active magnetic bearing (AMB) applications. Thick-film technology was used to realize silver coils printed on ceramic substrates. Long term measurements showed a good stability of this technology at high temperature. However, silver migration was observed between the wire connections and countered with the use of dielectric pastes. An AC current source at 900 kHz and high impedance amplifiers enabled the sensor temperature compensation. The sensor response was measured from room temperature up to 600°C.