A reduced common-mode voltage space vector modulation method for current source converters

The common-mode voltage (CMV) produced from a converter system is a source of many problems. E.g. in the motor drive system, CMV might appear at the neutral point of the motor stator windings with respect to the ground and induce destructive bearing current. Reduced common-mode voltage space vector modulation (RCMV SVM) methods have been proposed in both voltage source converter (VSC) and current source converter (CSC) systems. The available RCMV SVMs reduce the CMV by avoiding the use of zero-state vectors. However, this will lead to some negative effects, such as shrink of modulation index range, increase of switching frequencies, and power quality performance deterioration, etc. In this paper, a RCMV SVM method for CSCs is proposed. It has almost the same harmonic performance compared to the conventional SVMs by allowing the use of zero-state vectors, but with much lower CMV. The effectiveness of the proposed RCMV SVM for CSCs is verified in an experimental prototype.