Embedded Finite-Element Solver for Computation of Brushless Permanent-Magnet Motors

This paper describes the theory underlying the formulation of a "minimum set" of finite-element solutions to be used in the design and analysis of saturated brushless permanent- magnet motors. The choice of finite-element solutions is described in terms of key points on the flux-MMF diagram. When the diagram has a regular shape, a huge reduction in finite-element analysis is possible with no loss of accuracy. If the loop is irregular, many more solutions are needed. This paper describes an efficient technique in which a finite-element solver is associated with a classical d-q-axis circuit model in such a way that the number of finite-element solutions in one electrical half-cycle can be varied between 1 and 360. The finite-element process is used to determine not only the average torque but also the saturated inductances as the rotor rotates.