This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis.
I E E E Transactions on Power Electronics, 2013, Vol 28, Issue 1, p. 314-324
DC/DC Converter; DC grid; full-bridge three-level; Wind Turbines