Graphical Analysis of a DC-DC Converter Effect on a Fuel Cell: D-transformation

In practical cases, the use of a renewable energy device with a DC-DC converter is preferred to a single device alone for the purpose of compensating unstable output power and intrinsic limitations of the device. However there has not been fundamental understanding how to transform the device internal properties not only the output current and voltage. Therefore, a fundamental understanding of the DC-DC converter is urgently required. In this study, we investigate the fundamental role of a DC-DC converter when connected with renewable devices. We use a graphical and mathematical method for qualitative and quantitative analysis. The analysis is model-based and done for boost, buck and buck-boost converters, respectively. We find that the essential role of the DC-DC converter is to transform the fundamental electrical properties of a device to suitable properties for the load.