Combined current sensor and non-invasive displacement measurement for magnetic actuators

This study presents a novel design that combines the current sensor with a non-invasive displacement measurement that uses a single circuit for magnetic actuation systems (MAS). The combined sensor reduces the complexity obtains both displacement and dc current sensing with high resolution, fast response and minimum losses. This is achieved by adding a so-called sense inductance in series to the main actuator. The information of the dc current is obtained using a DCR current sensor and the displacement is estimated by the voltage developed across the sense inductance which is proportional to the displacement. The combined sensor has been verified experimentally on a single-axis levitator prototype of 2-2.5 mH inductance and 20 V input voltage. Results in displacement resolution of 100 mV/mm and current measurement of 160 mV/A are experimentally verified.