Mechanical Design of High-Speed, High-Frequency Air-Core Machine
MS student Yuanshan Chen with advisor K. Haran
A high power density electric machine (8 hp/lb) and integrated high-frequency drives were proposed by Professor Kiruba Haran in the NASA Fixed Wing Project. It is an unconventional inside-out permanent magnet motor with an advanced composite rotor structure. The motor’s cantilever design requires consideration for its mechanical integrity. This work includes the mechanical design of the proposed machine concept and the related finite element analysis (FEA) using computer-aided design software, Creo 2.0. Based on the FEA results, several motor structural parameters were optimized to meet the power density requirement of the project.
The first FEA was done to determine the thickness of the carbon-fiber retaining ring for the rotor by looking at the corresponding hoop stress and radial expansion when the rotor was in the 1.2X rated speed. Modal analysis was also performed on one of the stator designs. Possible vibration modes up to the machine maximum frequency were found and analyzed. To investigate the deflection due to gravity loading in the cantilever design, static studies were carried out to determine the vertical deflection of each structure. Various structural designs have been updated. Moving from the single mechanical bearing, then to the duplex bearing, the current bearing system design is implemented by two bearings in the stator, spaced across the active region, as shown in Figure 10.
This research is supported by NASA grant NNX14AL791 and the Grainger Center for Electric Machines and Electromechanics.