Design and Control of a High-Power Low-Loss DC–DC Converter for Mining Applications

This paper proposes a new design procedure for a bidirectional dc/dc LCL converter for potential megawatt range applications, including mobile mining equipment. This type of dc/dc converters employ two dc/ac converters and a passive LCL filter instead of a traditional high-frequency transformer. The exclusion of the transformer eliminates the core losses, while the switching losses are minimized by using soft switching operation. The proposed design method is different from previous publications as it ensures zero reactive power circulation, minimizes the size of the biggest capacitor, ensures stable and robust operation, and offers a good tradeoff between the capacitor size and the fault current in the converter under a dc fault condition. In addition to the proposed design, a simple and effective control strategy is proposed, which is based on single phase pq theory. The converter design and control have been evaluated by a digital simulation in EMTP-RV software environment for a 100 MW 300 kV/20 kV converter. Experimental validation has been carried out on a laboratory 200W 100V/20V prototype converter.