高圧IGBTを2直列3並列接続した高圧大容量DC/DC変換器

抄録

In the last decade, many projects on offshore wind farms have been planned and conducted to be compliant with government policies, especially in Europe. Some projects adopt HVDC transmission using a long-distance submarine cable from offshore to onshore. However, medium-voltage (MV) collection grids use AC, not DC. Moreover, the MW rating of wind turbines have been increasing over the years. The increase in the MW rating has led to higher currents in the MV collection grid and longer distances between wind turbines. Thus, the MVDC collector grid is expected, and an HV DC/DC converter is required to step up the MVDC to HVDC.

This paper introduces a circuit configuration of a high-voltage DC/DC converter with two-series, three-parallel connected IGBTs (2S3P-IGBT) to convert MVDC to HVDC and the switching test results of 2S3P-IGBTs. Further, this paper discusses a design method of a snubber capacitor for voltage sharing and the zero-voltage switching operation in series-connected IGBTs. A bus-bur construction is also discussed to reduce current mismatch in parallel-connected IGBTs. Experimental results show less than 10% voltage imbalance and current mismatch.