Improved hybrid method to calculate inductances of permanent magnet synchronous machines with skewed stators based on winding function theory

An improved hybrid method combining two dimensional (2D) finite element analysis (FEA) and the analytical method is put forward to calculate the stator winding inductance and synchronous inductance influenced by stator skewing technique. Based on winding function theory (WFT), the improved method proposes two factors to describe variable inductances along the stator skewing angles. Comprehensive simulations are then performed on three interior permanent magnet synchronous machines (IPMSMs), one normal and two skewed machines (half slot and one slot pitch skewing respectively). Extensive experiments are conducted on relevant prototypes with good correlation. Moreover, analysis and comparisons are made as to the influence of different skewing angles on the inductances and torque-speed curves. It is found that L
d
increases and L
q
decreases by skewing, leading to the reduction of the rotor saliency and maximal torque capability, but increase of the flux weakening capability.