Research On Bi-directional Power Converter For Ship Power Grid

With the development of modern power electronics technology,control theory technology,and other related technologies,marine integrated power systems have gradually become a hot topic for scholars in various countries,especially in the field of marine power distribution systems with energy storage units and mixed energy generation and supply-demand relationships in both directions.As a core device,the bidirectional power converter must not only achieve a reasonable regulation of energy flow,but also meet the requirements for maintaining the stability of the ship’s power grid.Therefore,this paper discusses the bidirectional power converter applied to the marine power grid as the research object.The bidirectional power converter applied to the marine power grid studied in this subject consists of a bidirectional AC/DC converter cascaded bidirectional DC/DC converter.The AC/DC link uses a three-phase reversible PWM rectifier topology based on LCL filtering,which reduces the filter volume while ensuring that the converter runs at the unit current of the power factor.The DC link uses a dual active bridge(DAB)DC/DC converter topology,which has the advantages of high power density,easy implementation of soft switching,high power bidirectional power transmission,and easy modular cascading.According to the overall control requirements of the system,the distributed control strategy is designed as the overall control scheme of the bidirectional power converter.That is to say,the AC/DC link at is designed as passive power control,and the DC/DC link at the is designed as active power control,which avoids the competition of power regulation by each controller,and also realizes the decoupling of control loops between each link;moreover,through the flexible switching of working mode,the coordinated distribution of energy among the ship’s power grid,DC bus and energy storage unit is realized,thus improving continuous power supply capacity and stability of ship power grid.In order to effectively damp the resonant peak of LCL filter,an active damping strategy based on band-pass filter(BPF-AD)method is designed in this paper.This method can not only guarantee the quality of incoming current,but also realize simply without increasing the control complexity.In addition,when the DAB converter is directly loaded,aiming at the problem of slow response of traditional closed-loop control to load sudden change,this paper proposes a state feedback dead beat control(SF-DBC)strategy,which effectively improves the dynamic performance of the system in the process of load change.Finally,a hardware experimental platform is constructed to comprehensively compare the simulation and experimental results,verifying the correctness and feasibility of the bidirectional power converter topology the distributed control strategy it uses for the ship’s power grid...