Magnetoresistive sensors for angle, position, and electrical current measurement in demanding environments

Abstract

Nowadays, magnetoresistive (MR) sensors are used in a wide range of applications. In general, the MR-effect describes the change of the electrical resistance in an external magnetic field. MR sensors are not only used for measuring magnetic fields and rotational or linear motion, but also for non-contact switching applications and furthermore for highly dynamic current measurement. This is largely the result of increasingly complex demands on the sensors for e.g. high performance electrical drives. The sensors must not only be accurate and dynamic, but must also be robust under difficult operating conditions and exhibit very high reliability. Due to their physical working principle and their small size, MR sensors are especially suited to work in harsh environments like high or low temperature, radiation, pressure or mechanical shock. This paper describes the principle of operation, manufacturing process and benefits of MR sensors. This will be followed by a description of practical application examples from the automotive, oil and gas, renewable energy and space fields, where MR sensors are successfully applied in very small envelopes at very low /very high temperatures, under high pressure, high mechanical loading and under strong radiation.