A parallel three-phase converter system for ripple current compensation and passive filter reduction

In this paper a two-parallel inverter topology is introduced which combines the advantages of IGBT´s with the benefits of SiC-MOSFET´s to achieve an ideal output current. The common control algorithm which is implemented on a FPGA utilizes the IGBT inverter for carrying the major load current, while the SiC inverter is only used for ripple current compensation. In this configuration the system provides an active current harmonic canceling technique with the potential to save passive filter elements. This paper presents a mathematical model to characterize the circulating currents and to design an ideal controller that can be used to identify the theoretical limits of the system. A first practical implementation on test bench with corresponding measurement results demonstrate the feasibility and benefit of the proposed hybrid inverter structure.