Improving the Internal Electromagnetic Compatibility in Ac Drives

This paper deals with the analysis of the internal electromagnetic compatibility of ac drives fed by voltage source inverters. In particular, the optimum layout of the circuit configuration is designed on the base of the actual electromagnetic interference between the power and the control section of a power converter. Besides, further improvements can be achieved by means of an auto-tuning additional board, which scans all the possible converter switching frequencies and analyze the distortion on the control signals corresponding to each frequency. Its main task is to select as operating frequencies for the converter only the ones which produce low disturbances on the control signals. The combination of the internal EMI analysis and the auto-tuning system allows to achieve very efficient power converters.