Experimental characterisation of linear permanent magnet actuator with gas springs

This paper mainly describes the experimental characterisation of linear permanent magnet actuator which has been developed for produce strong vibrations for drilling applications. To improve the energy conversion ratio in actuator, gas springs are added to store more mechanical energy at the end of the stroke on both sides of the piston (rotor). The gas springs allow the piston to oscillate at high frequency and with a long stroke length, in spite of the pistons large weight. The movement of the piston between the gas springs allows considerable vibrations in housing (stator). These stator vibrations effectively utilized in many industrial applications like drilling applications and wire line jar applications. For the best integration of gas springs with linear machine, tubular structure is selected. The machine is hermetically sealed to avoid the leakage of the gas and to avoid contact of mud fluid in drilling applications. The completely sealed rotor structure makes more promising for instrumentation to determine the dynamic parameters. The instrumentation and experimental methods used for determination of dynamic parameters like position and velocity of both piston and housing, electrical force and electrical parameters like resistance and inductance are described. The experimental results are compared with simulations.