EMI analysis in electrical drives when the grounding system is excited by a lightning strike using a suitable circuital model

In this paper an analysis of electromagnetic interferences (EMI) generated in a power drive system (PDS) when a lightning current flows in the grounding system is presented. High frequency (HF) model of a PDS and of two grounding systems have been developed adopting the network approach and have been implemented using power system blockset and Simulink toolboxes of MATLAB. The proposed HF model of the pds ac motor has been developed adopting the approach proposed by Metwally in (1999) for the simulation of the impulse response of the electrical motor while the grounding systems circuital models have been developed adopting the method described in Cecconi, V, et al (2005). The grounding system models have been validated comparing simulation results with the results obtained by Yaqing Liu et al. in (2001) and by Grcev in (1996 and 1997) using, respectively, the more rigorous methods of the transmission line method (TLM) and electromagnetic field method. The developed models are simpler than the models realized with the TLM and the electromagnetic field methods, require a shorter computational time and a minor cost because an on sale software for network simulation can be used. These characteristics permit to combined the grounding system models with the PDS HF model obtaining one model that permits to analyse EMI generated in the whole system giving as input only the waveform of the lightning current in time domain. In this work the implementation, using the software MATLAB, of the complete PDS and grounding systems models is presented and EMI in every section of the drive during a lightning strike are analysed