Adjustable Field PMSM with Rotary Transformer Using Zero-Phase Current and Armature Coil-End

This paper describes a new adjustable field permanent magnet synchronous motor (PMSM). There are two types of synchronous motors: one is an electrically excited synchronous motor (EESM), and the other is the PMSM. The EESM can achieve an expansive driving range because the field energy can freely be controlled by brushes, slip rings, and field winding. On the other hand, the PMSM has advantages in efficiency and small motor volume because the recent PM has a high energy density. Against these, the proposed motor has both the field winding and the PM, enabling high-efficiency drive over a wide range. In addition, the proposed motor can receive the field energy wirelessly using special armature coil-ends and a zero-phase current. Therefore, mechanical contacts such as brushes or slip rings can be eliminated. This paper explains the proposed motor’s principles and essential operation characteristics through several computer simulations with a finite element method (FEM).