A comparison of single and three phase DC/DC converter structures for battery charging

In order to obtain uninterrupted power in many critical applications such as control, protection, and communication; high current capacity battery groups are used as a replacement energy source. Charging the battery groups is made by DC/DC converters which are fed over power factor corrected rectifiers in a single or three-phase network according to their charging power level. Because of their high voltage conversion ratio, a single or three-phase inverter is used in conjunction with high-frequency transformers in the structure. Thus, the combination of electromagnetic knowledge and experiences with power electronics is concerned. It is known that FEM software brings the simulation opportunity of the power electronic circuits together with the magnetic circuit elements. This software is used in the fields of high-frequency application and provides more contribution to the design process. Also it makes the simulation more similar to the real environment. In this study, the performances of single-phase and three-phase DC/DC converters tested depending on their design values. In addition, the effects of three-phase three-limb core and five-limb core structures on the transformer losses and ripple have been analyzed. The saturation effects and the core losses were investigated by visualizing the AC and DC choke within the converter structure and flux distributions over transformers cores. The most suitable design and flux distribution has been investigated for the single and three phases, three and five limb transformer structures.