A linear switched reluctance motor: converter and control

The converter topology with a minimum number of power devices and control implementations to facilitate the pulsation free force control of linear switched reluctance machines are investigated for the first time in this paper. The minimisation of the devices offers cost reduction, compact packaging and enhanced overall reliability. With that in view, a topology with 3N_sc+3 devices is chosen where N_sc is the number of sectors in the linear machine. The propulsion force with conventional control of single phase excitation has high commutation torque pulsation and it is overcome with a multiphase excitation strategy proposed in this paper. Further, the proposed control strategy reduces the normal force pulsation. A systematic step by step design procedure of the switching strategy for the converter known as unipolar switching strategy, proportional plus integral current controller and gating control strategy of a long linear switched reluctance machine are presented. Experimental correlation of the proposed converter arrangement and control strategy is presented with a 4.8 m long linear switched reluctance machine in achieving the stated objectives