Thomas M. Jahns, University of Wisconsin
Interior permanent magnet (IPM) synchronous machines have experienced a surge of growing popularity during the past decade that began with the introduction of the Toyota Prius powertrain in 1997. However, IPM machines themselves have a much longer history that can be traced back many more years to the first half of the twentieth century. It is an instructive exercise to review some of the key milestones in this history in order to understand the intermingled impacts of the available magnet technology and the additional external factors that encouraged the early development of IPM machine technology.
Although IPM machine were limited to a relatively small number of specialized applications for many years, this presentation will highlight three separate factors that combined to spur the accelerated development and much-widened applications of today’s IPM machines. This factors include: 1) the development of high-strength NdFeB magnets made available at reduced prices; 2) advances in the theory and design of IPM machines; and 3) the development of advanced power electronics marked by major improvements in performance, size, and cost.
The discussion will conclude with a review of current factors, both positive and negative, that are influencing the current status of IPM machine technology and its future directions.