High speed permanent magnet (PM) machines are used in microturbine applications due to their compactness, robust construction, and high efficiency characteristics. These machines are integrated with the turbines and rotate at the same speeds. This paper discusses in detail the losses in high speed PM machines. A typical PM machine designed for microturbine application is presented with its detailed loss calculations. Various loss verification methods are also discussed.

High speed permanent magnet (PM) machines are used in microturbine applications due to their compactness, robust construction and high efficiency characteristics. These machines are integrated with the turbines and rotate at same speeds. This paper discusses in details losses in high speed PM machines. A typical PM machine designed for microturbine application is presented with its detailed loss calculations. Various loss verification methods are also discussed.

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This paper gives the analysis and test of a surface mounted axial flux permanent magnet synchronous motor (PMSM) for a high-speed centrifugal compressor drive. Both analytical analysis and 3-D electromagnetic finite element method (FEM) are used to calculate flux density in the airgap, rotor back iron, and stator iron. 3-D FEM is used to simulate the electromotive force (back EMF) and torque. The motor has been tested up to 87,000 rpm using an open-loop controller. The advantages and disadvantages of this kind of structure are analyzed, and some improvements of this design are also considered and partially verified by experiments.

The long-term storage of liquid hydrogen for space missions is of considerable interest to NASA. To this end, the Reverse Turbo-Brayton Cryocooler (RTBC) is considerably lighter than conventional designs and a potentially viable and attractive solution for NASA's long-term Zero-Boil-off (ZBO) hydrogen storage system for future space missions. We present the systems design, fabrication, and performance evaluation of the Permanent Magnet Synchronous Motor (PMSM) powering a cryocooler capable of removing 20 W of heat at 18 K with a COP of 0.005 and driven by two 2-kW permanent magnet synchronous motors operating at 200 000 rpm and at room temperature and 77 K. Structural, thermal, and rotordynamic aspects of system design are considered.