1. Department of Electricity and Electronics, Institute of Research and Development of Processes (IIDP), Faculty of Science and Technology, University of the Basque Country, Leioa (Bizkaia), P.O. Box 644, 48080 Bilbao, Spain
2. Department of Automatic Control and Systems Engineering, College of Industrial Technical Engineering (EUITI) Bilbao, University of the Basque Country, Bilbao (Bizkaia), Plaza de la Casilla 3, 48012 Bilbao, Spain
3. Department of Applied Mathematics, College of Industrial Technical Engineering (EUITI) Bilbao, University of the Basque Country, Bilbao (Bizkaia), Plaza de la Casilla 3, 48012 Bilbao, Spain