Modularized high frequency high power 3-level neutral point clamped PEBB cell for renewable energy system

This paper presents a modularized high frequency high power 3-level neutral point clamped power electronics building block (PEBB) for renewable energy system. Three-level diode neutral point clamped (NPC) and 3-level active NPC are most popular topologies used in industrial applications based on modularized building block. However, since the single 3-level diode NPC or active NPC cell is unable to form a 3-level DC-DC chopper, the applications of PEBB cells based on these two circuits are limited where a DC-DC chopper is needed. In this paper, loss analysis for the 3-level chopper built by two 3-level diode NPC cells or active NPC cells are conducted. Switching loops in PEBB cells are identified, and double pulse tests are conducted for turn on and turn off transient of the switching loops. Based on double pulse tests, the switching losses will be quantified for different switching loops. Two 3-level bi-directional chopper circuits based on the active NPC PEBB cells are presented and compared. Then the modified PEBB cell derived from single active NPC cell is proposed for 3-level bi-directional chopper. Based on a common active NPC PEBB cell, the power converter can be built with modularized structure to achieve high frequency, high efficiency and low cost.