Recent Trends in High-Performance and Resource-Efficient Motor Technologies for Electrification Systems

In recent years, efforts to address climate change and global warming have become increasingly important, and in Japan the movement toward electrification is accelerating with the aim of achieving carbon neutrality by 2050. Electric motors, which are key devices in electrification, play a major role in energy saving, and continuous research and development is being conducted to reduce losses and improve efficiency. However, the demand for rare-earth permanent magnets used in high-efficiency motors is expanding, raising concerns about cost increases and stable supply. This paper introduces examples of motor performance improvement and rare-earth saving, including: (i) system performance enhancement by integrating a boost reactor with a motor in a boost-type DC/DC converter, (ii) the development of motors using Sm-Fe-N bonded magnets that utilize surplus samarium (Sm), and (iii) efficiency improvement of rare-earth-free switched reluctance (SR) motors through a variable excitation-period single-pulse control method.