[1] Univ Calif Santa Cruz, Dept Elect Engn, Santa Cruz, CA 95064 USA
[2] Clemson Univ, Zucker Grad Educ Ctr, N Charleston, SC 29405 USA
[3] Penn State Univ, Dept Elect Engn, State Coll, PA 16801 USA
[4] Univ Andres Bello, Fac Engn, Santiago, Chile
[5] Aalborg Univ, Dept Energy Technol, DK-9220 Aalborg, Denmark