Abstract

This study presents about various soft charging techniques used in variable frequency drives to limit the in-rush current into the dc-bus capacitors during pre-charging condition. The main objective of a pre-charging circuit is to charge the capacitor within possible allowed time and maximum converter current without any voltage overshoot. A capacitor pre-charging circuit needs to be robust and simple in control by limiting the dc link inductor and input ac current to any desired magnitude. In this study we will discuss about various soft charging topologies, techniques and their performance during different operating conditions such as partially pre-charged capacitors, input line voltage variation, ground faults and bus faults. In the final this study discusses also about a novel pre-charging circuit, technique and provides a comparison of proposed technique with the existing techniques.

Keywords:

Inrush current limiter, magnetic resistive-element, soft-charge circuits, variable frequency drives,

References

Competing interests

The authors have no competing interests.

Open Access Policy

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Copyright

The authors have no competing interests.