Research on rotor pole-arc of electrical dual-redundancy brushless DC motor

The effect of rotor pole-arc on the torque ripple is investigated in the electrical dual-redundancy BrushLess DC Motor (BLDCM), which redundancy structure is widely applied in the BLDCM. The pole-arc directly affects the flat top of the Electo Motive Force (EMF) of the electrical dual-redundancy BLDCM, and the waveform of EMF is clearly relevant to the torque ripple of BLDCM. Moreover, the pole-arc has an obvious influence on the cogging torque. First, the electromagnetic torque ripple due to nonideal EMF was analyzed in the paper. Then the effects of the pole-arc on both the EMF waveform and the cogging torque were calculated by Finite Element Analysis (FEA) in a typical electrical dual-redundancy structure, and the range of pole-arc tending to reduce the torque ripple was obtained. At last, the calculation and the analysis based on examples offered a useful reference for the design of electrical dual-redundancy BLDCM.