Cost comparison of four-level NNPC converter with four-level FC and NPC converters

This paper focuses on the cost analysis of the four-level (4L) converters widely used in medium-voltage (MV) ac drive applications. Among the existing topologies, the flying capacitor (FC), neutral point clamped (NPC), and nested-NPC (NNPC) topology are common in MV drive applications. NNPC topology has been proposed in recent years as one of the promising solutions for a wide range of voltages (2.4–7.2kV) without the need for a series connection of power devices. But, so far, there is no study about cost comparison of NNPC with similar topologies. Hence, in this paper, a fair comparison is made based on the final price of FC, NPC, and NNPC topologies in a sample MV drive with ratings 6.9kV and 7.2MVA