Optimal Space Vector Modulation of a New Bidirectional Dual-Active-Bridge-Type Single-Stage Isolated Three-Phase Buck-Boost PFC Rectifier System

This article describes the optimization of a modulation scheme for the isolated Y-rectifier (iYR), a bidirectional three-phase power factor correction (PFC) rectifier with integrated galvanic isolation, with regard to minimum rms values of the transformer currents. The optimization is based on a numerical method, which utilizes space vector (SV) calculation to determine the steady-state waveforms of the iYR’s transformer currents with low computational effort. Compared with an existing modulation method, the optimization results show that, at part load operation, a substantial reduction of the transformer rms current is achieved. For example, the experimental results confirm that the optimization enables a reduction of the rms value of the transformer current SV over a grid period from 11.1 A to 8.8 A at a three-phase grid voltage of 400 V (rms and line-to-line), a dc output voltage of 400 V, and an output power of 1.2 kW (equal to 20% of the rated power of 6 kW). Owing to the generalized consideration of the iYR made possible by the SV-based description, the obtained optimization results can be applied directly also to other rectifier topologies presented in this article. This and further results and methods described in this article reveal the potential of SV calculation in connection with comprehensive analyses of complex three-phase isolated PFC rectifier systems.