1. Department of Electrical, Electronic and Computer Engineering, University of Catania, Catania, Italy
2. Politecnico di Torino, Dipartimento Energia ‘G. Ferraris’, Torino, Italy
3. Department of Electrical and Computer Engineering, Baylor University, Waco, TX, USA
4. Department of Astronautical, Electrical and Energy Engineering, Sapienza University of Rome, Rome, Italy