1. CEFET-MG,Department of Electrical Engineering,Belo Horizonte,Brazil
2. Universidde Federal de Minas Gerais,Department of Electrical Engineering,Belo Horizonte,Brazil
3. Universidade Federal do Recôncavo da Bahia,Department of Electrical Engineering,Cruz das Almas,Brazil
4. Universidade Federal de Juiz de Fora,Department of Electrical Energy,Juiz de Fora,Brazil
5. Universidade Federal de Viçosa,Department of Electrical Engineering,Viçosa,Brazil