3D Space Vector Modulation And Its Use For DC-Link Balancing And Common Mode Voltage Reduction In 3L-NPC Inverters

This paper introduces an innovative control strategy for three-level neutral point clamped inverters (3L-NPC), leveraging the concept of space vectors (SV) to effectively mitigate the common-mode voltage (CMV) and balance the neutral-point voltage (NPV). The key lies in considering the CMV of ambiguous two dimensional (2D) space vectors (SV) as the third dimension, leading to unambiguous SV. The dwell time (DT) of the ambiguous 2D SV is simultaneously used to minimize the error of the neutral point current, thereby balancing the NPV, while concurrently keeping the average CMV during a switching period to zero. This is possible due to a degree of freedom, which can be worked out by interpreting the DT as barycentric coordinates (BC). This paper discusses the analytical solutions of these ideas as well as the analysis of an exemplary algorithm. Notably, this method does not require the calculation of trigonometric functions, potentially enhancing performance in low computation power devices.