High Speed, High Frequency Air-Core Machine and Drive
PhD student Digvijay Deswal with adviser K. Haran
The need to produce very high power density machines requires the use of maximum current density along with high-frequency currents. Specially tailored Litz machine windings are being developed. Manufacturing trials (arrived through software simulation and theoretical calculations) were done to mitigate the risk of the machine winding not matching the required dimension.
A set of fixtures (figured out through trial and error) was made, as shown in Figure 1, to obtain the required dimensions within certain tolerance levels. A completed winding is shown in Figure 2. Modifications to the manufacturing process are ongoing.
At the system level, a separate study was carried out on the electro-magnetic model of the high power density machine to investigate the effect of real-case voltage waveforms (multi-level voltage waveform) on power output and magnet losses. This work includes finding the optimum number of levels in the input voltage waveform, so that the control complexity of the power electronics circuit and current harmonics are manageable.
This research is funded by NASA and the Grainger Center for Electric Machinery and Electromechanics.