A modular three-phase AC-AC converter with small number of film capacitors for highvoltage high-current applications

摘要

High-voltage and high-current power converters are essential in numerous applications, including shipboard power systems and industrial motor drives. Most of the existing topologies are based on dc-link converters, and use dc-dc or dc-ac power cells to realize a multilevel power converter. Therefore, they require a large number of capacitors with high capacitances. This paper proposes a new modular three-phase ac-ac converter, the power cells of which are formed by a new class of three-phase ac-ac converters. In the proposed modular converter, the input and output terminals of the power cells can be connected in series or in parallel. This paper studies the Input-Series Output-Parallel (ISOP) structure. The proposed modular converter requires a small number of power cells, and consequently a small number of capacitors. Moreover, the capacitance of each capacitor in a power cell is very small. This eliminates the need for electrolytic capacitors, which have high failure rates. This paper presents the principles of the operation of the proposed modular converter. The proposed ISOP modular configuration is evaluated in this paper, and the results verify its promising features for the high power applications.