Effective magnetic decoupling control realization for rotary-linear switched reluctance motors utilized in drilling tools

Abstract

Rotary-linear motors which produce linear and rotary motions simultaneously have coupled magnetic paths. In this paper, coupling of a Rotary-Linear Switched Reluctance Motor (RLSRM) is studied and formulated. Then, an algorithm based on inductance profiles of the motor phases is proposed to decouple the motions – rotary and linear movements. This algorithm is developed from two excitation modes which produce the linear force and rotary torque, independently. Therefore, the control on the rotary and linear motions is realized by controlling the torque and force, respectively. Finite Element Analysis (FEA) is applied to the RLSRM model and the obtained results are utilized in the algorithm. A control flowchart is presented for applying the motion modes. The algorithm is implemented on a microcontroller and applied to a fabricated model. Experimental results are measured to verify effectiveness of the proposed control algorithm.