Design and control of electric machines utilizing a field reconstruction method

Accurate assessment of the electro-magneto-mechanical energy conversion process usually requires a multi-physics Finite Element (FEA) analysis. Since FE analysis is a time consuming numerical process, lumped parameter models, simplified equivalent magnetic circuits, and separated field analysis are usually used for design and control of electric motor and generator drives. This computational burden is particularly visible in the design of generators for wind energy harvest and motors for propulsion of electric and plug-in hybrid electric vehicles where significant field statistics are often used in the design process. Field Reconstruction Method (FRM) is a technique in which a minimal set of fields analysis are used to establish basis functions for the magnetic flux densities in the machine. Once the basis functions are establish, the performance of the machine is predicted under arbitrary speed and excitation. It has been shown that the FRM can reduce the computational time by two or three orders of magnitude while maintaining the same level of precision that is usually accomplished in a two dimensional FE analysis. Due to its high computational efficiency, FRM has created new opportunity for health monitoring, fault tolerant operation, and multi-physics design of electric machines. Over the past 6 years, this technique has been successfully applied to permanent magnet, induction, and reluctance motor drives. In this tutorial, presenters will explain the fundamentals of the FRM in the context of permanent magnet synchronous machines (PMSM), induction machines, and switched reluctance machines. As part of the presentation, the impact and necessary modifications for inclusion of magnetic saturation will be discussed. Applications of the FRM in computation and elimination of acoustic noise and vibration in PMSM, maximum torque per ampere operation of induction motor drives, and elimination of system induced vibrations in doubly fed induction generators will be present- - ed to illustrate the potentials of this technique for optimal design and operation of electric machinery. Furthermore, highlights of recent ongoing research on magnetic flux estimation and fault tolerant operation of multi-phase permanent magnet motor drives will be shared with the audience. Finally, the potential impact of the FRM on the future generation of microcontrollers and integrated power electronic converters will be discussed. The tutorial will be summarized with a series of experimental results confirming the practicality of the FRM for future adjustable speed motor drive applications.