[IEEE 2011 8th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives - (SDEMPED 2011) - Bologna, Italy (2011.09.5-2011.09.8)] 8th IEEE Symposium on Diagnostics for Electrical Machines, Power Electronics & Drives - Study of cardioid-shaped loop current space vector trajectories for rotor eccentricity detection in power synchronous machines