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Synchronous reluctance machines are very appealing for high-speed traction applications due to their robustness, simple structure, absence of magnets, and simple control. The absence of magnets means that synchronous reluctance machines are not susceptible to price variability and sustainability of rare-earth materials. Also, there are no concerns about demagnetization or uncontrolled generation mode. However, the challenge of achieving a good constant power to speed ratio is dependent on the mechanical aspects of the design. Conventional synchronous reluctance designs perform poorly compared to permanent magnet machines due to the presence of bridges and/or center posts that provide a path for performance-robbing leakage flux and the absence of permanent magnets that help saturate the bridges and/or center posts. Elimination or reduction of these features presents a challenge for rotor mechanical retention due to the reduction in radial stiffness that these members provide mainly for high-speed applications. A carbon-fiber sleeve on the rotor will provide the needed mechanical strength to enable a reduction of bridges and/or center posts. This paper will present the design details, analysis, manufacturing, and test results of a proof-of-concept carbon-fiber-wrapped synchronous reluctance machine targeting traction applications. [ABSTRACT FROM AUTHOR]

Electric drive systems, which include electric machines and power electronics, are a key enabling technology for advanced vehicle propulsion systems that reduce the petroleum dependence of the ground transportation sector. To have significant effect, electric drive technologies must be economical in terms of cost, weight, and size while meeting performance and reliability expectations. This paper will provide details of the design, analysis, and testing of an advanced interior permanent magnet (PM) machine that was developed to meet the FreedomCAR 2020 specifications. The 12-slot/10-pole machine has segmented stator structure equipped with fractional-slot nonoverlapping concentrated windings. The rotor has a novel spoke structure/assembly. Several prototypes with different thermal management schemes have been built and tested. This paper will cover the test results for all these prototypes and highlight the tradeoffs between the various schemes. Due to the high machine frequency ( $\sim$1.2 kHz at the top speed), detailed analysis of various loss components and ways to reduce them will be presented. In addition, due to the high coolant inlet temperature and the fact that the machine is designed to continuously operate at 180 ^\circ\C, detailed PM demagnetization analysis will be presented. The key novelty in this paper is the advanced rotor structure and the thermal management schemes. [ABSTRACT FROM AUTHOR]