Effect of Inductor Placement on DC Bus Capacitor of Adjustable Speed Drives

TLDR: In this paper, the difference in the DC bus capacitor ripple current values between the two topologies for a given grid disturbance condition was identified, and it was found that the DC choke topology is better in terms of the stress on DC bus capacitance under balanced, unbalanced, and distorted grid conditions, considering the practical field data.

Abstract: Commonly available adjustable speed drives with diode bridge front end usually employ an inductor either in the AC side (line choke) or in the DC side (DC choke). While both the topologies are commercially popular, the difference between their performances under grid disturbances is of interest. It is identified that there exists a difference in the DC bus capacitor ripple current values between these topologies, for a given grid disturbance condition. However, both the topologies result, approximately, in the same amount of ripple in the torque for most of the cases, irrespective of the grid disturbances (up to the level of disturbance considered). It is found that the DC choke topology is better in terms of the stress on the DC bus capacitor under balanced, unbalanced, and distorted grid conditions, considering the practical field data.