A DITC Method With Copper loss Minimum During Commutation Region of Bearingless Switched Reluctance Motor

In the paper, a control strategy based on direct instantaneous torque control (DITC) is proposed to suppress the torque ripple and reduce the copper loss of bearingless switched reluctance motor (BSRM) during commutation region. A sharing suspension windings bearingless switched reluctance motor (SSWBSRM) is taken as research objective in the paper. The mathematical model of SSW-BSRM in non-overlapped region between stator pole and rotor pole is derived, which better reveals the characteristics of torque and suspension force during commutation region. The correctness of the proposed model is verified by comparing with the finite element analysis results. According to the difference in torque and suspension force generated by the currents of outgoing phase and incoming phase during commutation region, both the currents of torque winding and suspension winding are modulated. With the optimization objective of minimizing the square of the current (copper loss), each current is optimized based on the Lagrange multiplier method. The simulation on a three-phase 12/8 SSW-BSRM by comparing with current chopping control (CCC) validate the performance of the proposed control strategy. The simulation results show that the proposed control strategy can suppress the torque ripple and reduce the copper loss of BSRM.