METHOD AND CONTROL SYSTEM FOR ZERO -SEQUENCE CURRENT COMPENSATION FOR GROUND CURRENT REDUCTION

摘要

A control system and methods for a multilevel power converter are provided. The converter includes a rectifier coupled to a DC link having a midpoint coupled to electrical ground that divides the DC link into two halves. The control system is configured to generate a reference current command for controlling an output of the rectifier, the reference current command generated based on a difference between a desired and measured DC link voltage value. The system is also configured to determine a zero-sequence current component of input current supplied to the multilevel power converter, wherein the zero-sequence current component is associated with nonlinearities in said multilevel power converter that cause ground current injection into the input current by the rectifier. The system is further configured to subtract the determined zero-sequence current component from the reference current command to reduce the ground current injected into the input current by the rectifier