1. INTRODUCTION
MO DELS are required in order to analyze and design an electrical machine. Machine models are typically
developed using one of two methods. The first method
involves the generalized electrical machine theory, from
which an equivalent circuit can be constructed [I]. The
second method involves numerical calculations, from
which the field distribution can be obtained [2]. In an
equivalent circuit or analytical model, the machine is represented
by lumped parameters such as inductances and
resistances derived based on simplifying assumptions.
These assumptions generally include linear magnetic materials,
simplified toothislot and rotor/stator geometry,
and idealized geometry and distribution of machine windings.
The analytical model for a permanent magnet synchronous
machine (PMSM) shown in Fig. 1 includes
d-axis and q-axis inductances [3]. This paper uses a
PMSM as the ellectrical machine example because it contains
typical features of conventional machines such as
saturation and saliency, and also has special magnetic material
(permanent magnets). Nonetheless, all discussions
in this paper, including those involving the improved FE
inductance calculation method, can be applied to other
types of electrical machines.
Analytical models often are used for machine perfor-