1. Department of Electrical, Electronics and Telecommunications Engineering (DEET), Balzay Campus, University of Cuenca, Cuenca 010107, Ecuador
2. Department of Electrical Engineering, E.T.S.I. Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
3. Department of Electrical Engineering, University of Jaen, EPS Linares, 23700 Jaen, Spain