Novel Ultra-high Polarity and High-frequency Axial Flux Electric Machines and Wide Band Gap Power Electronic Drives

University Of Kentucky Research Foundation, Lexington KY

Investigators

Abstract

Electric motors account for more than 60% of the electricity consumed and electric machines and associated power electronic drives represent a multi-billion dollar industry. The research will develop fundamental knowledge and innovative concepts for high-efficiency and high-performance electric machines and drives through a synergetic combination of transformational designs, multiphysics analysis, and the latest developments in power electronics, including wide band gap devices. The project will train graduate and undergraduate research students, lead to engineering teaching and training curriculum development, publically disseminate the results, and support STEM middle and high school outreach activities and increased efforts to attract students, including women and minorities, to higher education in science and engineering. Raising the fundamental operating frequency for electrical machines results, in principle, in increased power density, provided that the typical challenges of higher losses, lower material utilization, and more complicated constructions, which are specific to conventional designs, can be overcome. The research will provide innovative solutions in this respect and study two novel axial flux permanent magnet machine topologies, which are best fitted for ultra-high number of poles and operation with high fundamental frequency, ensured through controlled supply from power electronics with wide band gap devices. One construction, suitable for high-speed operation, employs a coreless stator with an innovative continuous-wave phase winding arrangement in multiple layers. Another construction, suitable for low-speed direct drive operation, employs special rotors and innovative ferromagnetic-core stators with a winding pattern such that the stator coils and teeth are one order of magnitude lower than the number of rotor poles, a design feature that far exceeds the characteristics of known topologies. This machine also incorporates a torque magnification effect, which contributes to size reduction and efficiency increase for given power output. For two-phase machine designs, innovative hybrid H-bridge inverters comprising one leg with wide band gap devices and another leg with silicon devices are proposed for control and system integration. Computational studies include multi-physics analysis for electromagnetic, thermal, and mechanical stress, and differential evolutionary algorithms for mathematical optimization, and systematic comparison of thousands of candidate designs. Experimental studies include building prototype demonstrators and laboratory testing. The outcomes are ultra-high power density and efficient electric machine - drive systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.