Overview of PM/Reluctance Synchronous Machine Opportunities and Challenges

Abstract

The dramatic rise and fall of the price of rare-earth metals neodymium and dysprosium during the period between 2010 and 2014 has led to an energetic search for alternative machine topologies to replace high-performance PM synchronous machines using sintered NdFeB magnets. This chapter introduces the major alternative brushless synchronous machine configurations that are the subject of this book. These include PM synchronous machines that use either much smaller amounts of NdFeB magnets or alternative magnet materials such as ferrite magnets, as well as synchronous reluctance machines that require no magnets at all. A historical perspective is presented that introduces each of these machine alternatives in roughly chronological order in order to highlight the motivations and technical breakthroughs that both enabled and drove the new developments that continue to influence research efforts today. The chapter closes with summary comparisons of the strength and limitations of the major classes of brushless synchronous machines, providing a foundation for the detailed discussions of these alternative machine topologies that are presented in the following chapters.