Research On Predictive Current Control Technology Of Three-Port DC/DC Converter

The establishment of a reliable and stable microgrid energy storage system through the combination of renewable energy power generation equipment and energy storage devices is currently the main solution for the development and utilization of renewable energy.The structure of the microgrid energy storage system is divided into three parts: distributed generation system,energy storage system and load.As an important power electronic interface device in the microgrid energy storage system,the three-port DC-DC converter can conveniently and efficiently realize the flow and distribution of energy between the power generation system,the energy storage system and the load.It also bridges the micro-grid and even the two-way flow of energy between the grid and the energy storage components.Based on the basic working principle of three active bridge isolated three-port DC/DC converters,this paper analyzes the different operating modes of a switching cycle of a converter,and obtains the inductor current characteristics and power transmission characteristics of the converter,and derives the relationship between the transmission power and the phase-shifting,the inductance value,and the switching frequency.Aiming at the three-port converter in the microgrid energy storage system,the predictive current phase shift control technology of full-switching cycle sampling and half-switching cycle sampling is studied.In view of the shortcomings of the traditional predictive current control technology,the inductor current is sampled at the zero or midpoint of each switching cycle to avoid the high frequency inductor current generated at the moment of the switching tube from interfering with the sampling result.The predictive current phase shift control technique calculates the inductor current increment of the converter at different stages,and predicts the next rising edge shift and the next falling edge shift of the converter based on the sampled current value and the current reference value,updating the shift during each switching cycle makes the inductor current to reach a reference value.In this paper,the DC current elimination mechanism and circuit parameter sensitivity of the inductor current phase shift control technology in two different sampling modes are compared and analyzed.The sensitivity of the circuit parameters in the two sampling modes is verified by numerical simulation.A closed-loop control strategy for predictive current phase shift control technology of a three-port DC/DC converter is presented.Finally,the Matlab/Simulink simulation platform of three-port DC/DC converter is designed.The closed-loop control characteristics of the predictive current phase shift control technology in two sampling modes are compared and analyzed,The predictive current phase shift control technology of two different sampling modes are compared and verified from the multiple values of reference value mutation,inductance value mutation,input voltage fluctuation,load mutation and port switching.The output characteristics of the predictive current phase shift control technology in the two different sampling modes are completely analyzed.The output characteristics of the predictive current phase shift control technology in two different sampling modes are completely analyzed.