A direct isolated bi-directional converter as a power electronic building block (PEBB)

A converter is described in this paper for use as a power electronics building block (PEBB). This PEBB can be utilized by itself or as a module in a larger converter. The converter utilizes a transformer, which adds isolation to the converter along with increasing the possible ways of configuring the modules. The PEBB is also bi-directional, which enables the PEBB to be suitable for a wider range of sources. The proposed PEBB is a direct converter. The direct conversion eliminates a capacitive filter, and when utilized with soft switching, increases the frequency of the voltage and current waveforms applied to the converter´s filters. These advantages result in fewer components, reduced cost, higher reliability, smaller size, and higher operating temperatures for switches. When the PEBB is utilized in the cascade configurations proposed herein, the direct conversion further increases the above advantages. The converter also utilizes a commutation method that short-circuits the transformer winding and results in soft switching under all load conditions, bi-directional power transfer capability, and substantially reduces the power rating of the clamping circuitry. These advantages are typically possible with no increase in conduction loss, VA ratings, or number of components when compared to a hard switching converter. Due to the advantages above, the proposed converter results in a PEBB with high performance, small size, low cost, and more possibilities for configuring the PEBBs.