Novel mathematical formulas for incident and reflected waves for differential mode analysis in long cable ASDs with experimental validations

Abstract

This work presents a new computation technique for incident and reflected waves as well as their associated over-voltages and Differential Mode (DM) currents along the Adjustable speed drive (ASD) cable. This method is based on developed mathematical formulas ready for numerical computations. Moreover, it allows simulation of the pulse voltage transients and their DM currents not only at the motor terminals but also at any point along the cable.The developed technique is highly recommended for the investigation of the over-voltage and the conducted EMI, due to the cable length. An approach for measuring required characteristics of the system has also been presented. It has been applied to an industrial 5 kVA ASD prototype using a 4-wire shielded long cable. The paper includes simulation results and experimental validations of the proposed technique.Index Terms-Cables, electromagnetic interference (EMI), electromagnetic transient propagation, overvoltage, insulated gate bipolar transistors, pulse width modulation, variable speed drives.