Start and smooth torque analysis for the two-pole skewed-stator brushless DC motor using equivalent magnetic vector potential model

The start and smooth torque analysis of the two-pole skewed-stator brushless DC motor using the equivalent magnetic vector potential (EMVP) model with finite-element calculation is presented. From the magnetic flux distribution through the stator leg, the reluctance values are obtained to help select the required auxiliary torque, i.e., the reluctance torque, for compensating the nulls of the electromagnetic torque. The EMVP model for the anisotropic ring permanent magnet rotor, with irregular magnetic flux distribution on the inner rim of the rotor, is proved to be superior to the equivalent current sheet model traditionally used for isotropic permanent magnets. The numerically obtained results are in excellent agreement with the corresponding test results.