Sensorless position control of electromagnetic linear actuator

Sensorless principles utilize the transducer characteristics of actuators during excitation. As the measured data are extracted directly from the actuator, an additional sensor is not required. The information on the armature position of a solenoid can be found in its impedance. With knowledge of the impedance's dependency on the position, an online analysis method can determine the current position and feed a position control system. On basis of a simplified solenoid model a method for position estimation and control with a pulse width modulated power supply is proposed.