Non-Saliency of Interior Permanent Magnet Hybrid Excitation Machine

It is a general perception that the interior permanent magnet machines will have different values of inductances along d-axis and q-axis and hence they are salient pole machines. Though it is true in most of the cases, some interior permanent magnet machines may turn out to be non salient pole machines. Hence an accurate modeling of magnetic equivalent circuit is very much required in order to estimate the inductance values along d-axis and q-axis. A hybrid excitation machine with an interior configuration of permanent magnets and field winding is proposed in the literature. Though it appears to be a salient pole machine from rotor configuration view point, the actual analytical inductance analysis on this machine proves that it is a non-salient pole machine. A simpler analytical approach is carried out through approximate linear magnetic equivalent circuit. The analytical analysis is validated with analysis carried out through FEM software.