Research On Multi-port Converter Control Based On Hybrid Energy Storage

With the increasing global energy consumption,environmental protection issues have become increasingly prominent.Therefore,the application of renewable energy has received extensive attention.Due to the intermittent,volatility and randomness of renewable energy,hybrid energy storage systems(HESS)are often needed to improve the power quality.The multi-port converter can realize the energy transfer between multiple energy sources,and has a good prospect connecting the HESS and the renewable power generation unit.Firstly,the overall structure of the HESS and its basic working principle are introduced.The battery,supercapacitor(SC)and photovoltaic are modeled and their basic working characteristics are analyzed.The main circuit parameters of the photovoltaic power generation device and the MPPT algorithm are designed and simulated in the MATLAB/Simulink to verify the correctness of the design.The power management strategy of the HESS is designed,including the power distribution scheme,the voltage control strategy of the SC and the protection strategy of the HESS.The power distribution strategy based on the first-order low-pass filter has been analyzed.In addition,a power distribution strategy based on the second-order low-pass filter is introduced to improve the cut-off characteristics at the handover frequency.At the same time,in view of the low utilization rate of SC in the traditional SC voltage control loop,the voltage band control strategy is introduced.By designing the charge and discharge protection strategy of the HESS,it is ensured that the HESS always works within the safe range.For the power coupling problem of three-port converter based on three-winding transformer,a three-port converter based on double transformer structure is adopted to realize the decoupling of power transmission.The state space averaging method is used to model the converter,and the current loop and voltage loop controller are designed.The correctness of the design is verified by simulation.The hardware experiment platform was built,and the sampling circuit and drive circuit were designed.The digital controller was designed by STM32F429.The correctness of the system design was verified by the experimental waveform.