Research on inductance of PMSM with variable magnetic reluctance in exciting circuit

A permanent magnet synchronous motor (PMSM) with controllable exciting magnetic flux is presented which provides a new approach for solving the problem of flux weakening for PMSM. Air-gap flux weakening is accomplished by adjusting the field excitations magnetic reluctance with the rotor speed automatically. Magnetic flux distributions at different field excitations show that the permanent magnets, magnetic bridge and direct axis current (Id) and quadrature axis current (Iq) primarily influence on direct axis inductance (Ld) and quadrature axis inductance (Lq). Ld and Lq are calculated using the finite element method from the aspects of permanent magnet thickness, magnetic bridge dimension, current saturation, non-magnetic conductor and permanent magnet motion. Calculation results correspond with the inductance analysis and experiment results, which lay the foundation of the flux weakening analysis of this new PMSM.