Using energy more efficiently provides major economic advantages, reduces our consumption of limited resources, and mitigates climate change. About 45% of all energy is used through electric motors and a majority of world's energy is generated using electric generators. Permanent magnet motors and generators play a critical role for energy conversion and are used in many applications including appliances, industrial, automotive, aerospace, oil and gas, and medical equipment. Permanent magnet generators are used in renewable energy applications including wind and ocean wave derived power. Because of their relatively high efficiency, permanent magnet electric machines play a key role compared to other electric machines. One developed machine class, the flux switching permanent magnet (FSPM), has gained significant interest in the scientific community because of its inherent advantages in terms of high efficiency, high power density, and high-speed capability; however, it has yet to become commercially viable. The main challenge of this machine is the requirement of very high fundamental frequency, especially in medium to high-speed machines, as current power electronics are unable to provide such frequency. In addition, high fundamental frequency causes additional losses in the motor, reducing its efficiency. This university-industry research collaboration proposes a novel flux switching permanent magnet machine topology to mitigate this issue and reduce the frequency requirement by 60%, to increase efficiency, and to promote further research on FSPM machines and applications. The research will focus on developing theory as well as designing and testing an experimental machine prototype. In addition, this project aims to provide continuing education for practicing engineers. Research results will be incorporated into future short courses and seminars, with dissemination to practicing engineers. Through this and with enhanced classes for undergraduate and graduate students, the workforce skill set will be prepared to develop more efficient electric machines. Also, demonstrations will be created to promote engineering and efficient energy practices for pre-college students, including underrepresented groups, during campus visits. These programs will aim to inspire current and future engineers to continue to further sustainable engineering practices.
The flux switching permanent magnet machine has a very simple rotor structure, which is a promising candidate for low cost and high-speed operation. It provides an excellent opportunity to achieve higher power density and improved efficiency. The current FSPM machine being extensively studied is the 12 stator slot / 10 rotor pole (12/10) topology. This relatively high number of poles, in addition to high-speed applications, is the primary cause of the high fundamental frequency requirement. It has long been thought that the 12/10 has the smallest number of poles needed to create sinusoidal back-EMF and acceptable torque characteristics. However, this research proposes the study and development of a novel 6/4 FSPM topology, utilizing a dual stator structure. The reduced number of rotor poles results in a 60% reduction in fundamental frequency requirements, which reduces the core and permanent magnet losses, improving efficiency in these areas by 33% for the same rotor speed. These improvements result in more efficient and higher power density machines. Thus, the development of the novel 6/4 topology will aim to enable other permanent magnet machines to replace current low efficiency machines in various applications. Through the course of this project, sizing equations and other scientific techniques will be developed to quantify the benefits of the proposed machine compared to current technology. A proof of concept machine and a higher power prototype will be developed to validate the theoretical results.
