Power-Dense Electrical Rotating Machines for Propulsion and Power Generation

The primary objective is to develop electric machine/drive topologies and power architectures that achieve the power densities required for 50% more power without the increase in weight or space requirements. In addition to PMSM-based designs, two new machine topologies will be considered. The first is a trapped flux coreless (TFC) machine that utilizes superconducting pucks made of YBCO to produce very high levels of magnetic flux density. The second machine topology that will be considered is a rotationally asymmetric permanent magnet synchronous machine (APMSM). In this topology, the rotor poles are tailored in such a way that torque production in one direction is improved by sacrificing torque production in the other direction. It has been shown that doing so enables an appreciable gain in the torque (power) density of machines [13] and is ideally suited for ship propulsion applications, since propellers are unidirectional. The potential advantage offered by the APMSM over the TFC is simplicity and reliability since there is no need for a cryogenic cooler. However, the APMSM does not have the capability to achieve the flux density levels of the TFC. Thus, it is likely the APMSM will utilize some ferromagnetic material to achieve reasonable flux densities.