| Popis: |
The controlled-type soft-switching technology based on critical conduction mode (CRM) is an effective way to achieve zero voltage switching (ZVS) of switches. However, the high reverse inductor current of the conventional constant boundary conduction mode (CBCM) method leads to high conduction losses. In this paper, the single-phase three-level neutral point clamped (3L-NPC) inverter is taken as an example for analysis, and a minimum reverse inductor current control is proposed. Firstly, the requirement for achieving ZVS of switches is quantitatively analyzed, and the model of the equivalent resonance circuit is built. Accordingly, the theoretical minimum reverse inductor current for achieving ZVS in the fundamental period is derived, which lowers the conduction losses of switches. Then, by establishing the power losses analysis model of the 3L-NPC inverter, the power losses of the proposed scheme and the conventional CBCM method are calculated and compared in detail. Finally, a 1 kW single-phase 3L-NPC inverter prototype is built, and experimental results verify that the proposed method features lower conduction losses than that of the CBCM method. The maximum efficiency of the 3L-NPC inverter is increased by 0.5 percentage point. |
