Research On Multiple Bidirectional DC/DC Converter Used In Energy Storage Converter

Currently, the development of renewable energy power generation is in high speed,large scale energy storage system plays an important role in grid-connected renewablepower generation and restraining power fluctuations, the energy storage converter made upof AC/DC+DC/DC two stage structure has been widely used. The research object of thispaper is the bidirectional DC/DC converter in two-stage energy storage converter, theworking principle, multiple configuration, mathematical model and controller designing ofthe converter have been deeply researched and analyzed.The commonly used topology of bidirectional DC/DC converter has been introduced,the working principle of bidirectional half-bridge converter used in this paper has beenanalyzed, small-signal model of the converter was derived using the state-space averagingmethod, and the effect of reducing current ripple and volume of inductor by the multipleinterleaved structure used in this paper has been introduced.According to the requirement in battery charge and discharge controlling of energystorage converter, voltage and current double closed-loop control strategy was utilized inthis paper, Constant current charging and discharging ware achieved through currentclosed-loop control, constant voltage charging was achieved through voltage and currentdouble closed-loop control. The PI controllers of voltage loop and current loop waredesigned in frequency domain, the influence of control delay caused by digital control wasconsidered in designing. In order to verify the effect of controller, the simulation model wasestablished in matlab/Simulink. According to the multiple interleaved structure, based onanalyzing commonly used current-sharing method, digital current-sharing method was usedin current-sharing control, and the working state of circuit in the process of current-sharingcontrol was analyzed.A multiple bidirectional DC/DC converter experimental platform was build up, theparameters of main circuit ware calculated and the devices type have been selected.Experiments of constant current mode, constant voltage mode and switching betweenmodes ware accomplished, the results showed that the control strategy adopted in this papercould achieve precisely control of battery charging and discharging, it has excellent dynamic and steady performance, could be applied to two-stage energy storage converter.