The past, present, and future of power electronics integration technology in motor drives

The physical integration of power electronics and electric machines to form integrated motor drives (IMDs) eliminates the need for special enclosures and connecting cables in order to achieve mass, volume, and cost savings. The objective of this paper is to examine the future of integrated motor drive technology by first reviewing the history of IMD products from the 1960s to today, highlighting both the reasons for their success as well the significant technical obstacles that they had to overcome. Special attention is directed to the application of IMD technology to electric vehicle traction motor drives during the past 15 years. A long-term vision for IMDs is presented that calls for embedding the drive electronics directly inside the machine enclosure. In keeping with this vision, wide-bandgap (WBG) power semiconductor switches (SiC and GaN) offer exciting prospects for shrinking the size of power converters and simplifying their cooling requirements. New concepts for applying this WBG technology to IMDs are introduced, including revived interest in PWM current-source inverters. In the concluding section, a variety of other promising technologies are introduced that will be critical to realizing the full potential of integrated motor drives.