Bidirectional Three-Phase DC–AC Converter With Embedded DC–DC Converter and Carrier-Based PWM Strategy for Wide Voltage Range Applications

A bidirectional three-phase dc-ac converter with embedded dc-dc converter for bidirectional storage interface is proposed in this paper. With the help of the embedded dc-dc converter, the voltage of the storage battery can vary in a wide range. To minimize the power rating and power losses of the embedded dc-dc converter, a simple carrier-based pulsewidth modulation (PWM) strategy with zero-sequence injection is proposed. By adopting the proposed PWM strategy, only a small ratio of total power needs to be processed by the embedded dc-dc converter, while most of the power is only processed by the three-phase dc-ac stage within a single conversion stage. As a result, quasi single-stage power conversion is achieved to improve the conversion efficiency of the overall dc-ac power system. Principles, characteristics, and implementations of the proposed three-phase dc-ac converter and its PWM strategy are analyzed in detail. The feasibility and effectiveness of the proposed solutions are verified with experimental results.