Modulation Strategy for Resonant DC-Link Soft-Switching Inverter With Arbitrary Power Factor

In this article, an improved modulation strategy for resonant dc-link soft-switching inverter (RDCLSI) that applicable to any power factor angle is proposed. By minimizing the operating frequency of the auxiliary resonant circuit (ARC) and rearranging switching vectors, the proposed modulation resolves issues as the power factor angle increases. They are related to bidirectional energy flow between power supply and load, and restriction on setting dead time in the non-clamped phase. Under different power factors, according to the proposed modulation strategy, this article analyzes the working modes, compares the electrical performance of different modulation strategies, and optimizes the parameter design to reduce the ARC current stress. Finally, a 40 kHz/5 kVA prototype based on silicon carbide (SiC) MOSFET is constructed to validate the performance of different modulation strategies with power factor angles. The experimental results show that the proposed modulation strategy can maintain the efficiency above 98.05% in the full power factor range.