Multiport Converter With Enhanced Port Utilization Using Multitasking Dual Inverters

Abstract

With the development of renewable energy and electric vehicle technologies, a need for multiport DC/DC/AC converters with high power density and reliability has arisen. A dual inverter based bidirectional multiport converter with two dissimilar voltage DC ports and an AC port is presented. The converter is capable of processing up to 1.67, 1.41, and 1 p.u. of power through its main DC, auxiliary DC and AC ports respectively, while only using the semiconductor and magnetics effort of a DC/AC converter rated for 1 p.u. Analysis reveals that this is more than thrice and twice the power limits of the main and auxiliary DC ports respectively, compared to using two independent inverters with a three-winding transformer. Furthermore, the proposed converter is more efficient than the latter option. These benefits are due to the multitasking of inverters and the existence of single stage DC/DC and DC/AC power transfer mechanisms enabled by the use of a center tapped transformer. A control strategy using these two mechanisms, capable of independently controlling the power flows between ports is also presented. Independent inverter control is also possible, allowing power flow between the main DC and AC ports during the failure of a single inverter. These claims are verified through thorough analysis, extensive simulation and experimental results using a 3 kW prototype.

Keywords

• Bidirectional DC/DC/AC conversion
• center-tapped transformer
• DC/DC/AC multiport converter
• dual inverters