Effects of Input Phase-Loss and Voltage Unbalance on Front end of Passive Low Harmonic Drive

Abstract

Input Phase-loss condition is one of the abnormal operations in Variable Frequency Drive (VFD) system. The Power conversion equipment unit (VFD) must be operational with one line disconnected at the input as defined in international standards. However, the operation under Phase-loss condition to be considered with respect to power density of the VFD. Generally, most of the VFDs are having power limiting functions under Phase-loss condition, considering the increased stresses faced by front end rectifier components, inverter control performance and the life time of the electrolytic capacitors. The Phase-loss condition is detected by measuring the DC link voltage measurements. But these parameters vary in their characteristics while connecting passive harmonic trap filters with the VFD; which will lead to failure of front end devices and will reduce the life time if the Phase-loss detection does not happen in the right instance. This work presents the analysis of this Phase-loss and the Voltage Unbalance condition of VFD with Passive trap filters and to gives the relationship between the ripple current and the load variation. The work also addresses the Lifetime variation of the DC Link capacitors and the DC Link Inductor loss variation with the passive trap filter connected.