A novel approach to analyze over-voltages due to PWM switching patterns in long cable PWM drive

Abstract

A novel theoretical analysis and a practical technique to model the reflected wave in PWM ASD-Motors is present. This technique could be used to evaluate the risk of motor insulation deterioration due to over-voltages in ASD system. It concerns especially lower or higher than 2pu over-voltages at motor terminals caused by the PWM switching patterns. It is shown that, theoretical peak voltage of 3pu and 5pu may be reached for some switching conditions with long motor leads. The simulation that PWM switching patterns result in lower or higher than 2pu over-voltages at motor terminals is validated by PSpice software.