Research And Equipment Development Of 10kV/750V Switched Capacitor ISOP DC Converter

With the depletion of traditional energy sources and the growing problem of environmental degradation,Developing green renewable energy has gradually become the trend of future energy strategy.Due to the limited capacity of self-consumption,the traditional grid structure is increasingly unable to meet the change of future energy structure.The DC grid and DC-DC conveter technology is an effective way to solve this problem.The input-series-output-parallel(ISOP)DC/DC converter has the characteristics of modularization,high reliability and scalability in system capacity,etc.So it is the outstanding choice for high-voltage input and high-current output applications.This paper focuses on the ISOP DC converter's topological structure,soft start process and power balance control strategy to sovle the remove faults,large startup current,and unbalanced power.The research focus and achievements are as follows:(1)Aiming at the shortcomings of traditional phase-shifted full-bridge ISOP DCDC converters such as fault removal,voltage matching and module redundancy,a switched capacitor type ISOP DC-DC converter who have the advantage of fault removal,voltage matching and module redundancy was studied.Firstly,the soft start process of the converter is analyzed in detail,and the soft start restriction condition of the converter is deduced.Then,the overall small-signal model of switched capacitor ISOP is established on the basis of Single switched capacitor sub-module small signal model,and the transfer function between each disturbance variable under the switching operation mode is deduced.(2)Aiming at the problems of input voltage sharing(IVS)and output current sharing(OCS)in switched-capacitor ISOP DC-DC converters,a decoupling control is proposed.Firstly,the anti-interference ability of IVS and OCS is analyzed.By introducing the coupling index,the coupling characteristics between input voltage balance control and output voltage control base on the IVS is analyzed.Furthermore,a voltage decoupling control method for switched capacitor ISOP DC-DC converter is proposed.The input voltage sharing loop and the output voltage loop is decoupled.The a detailed design of the controller was carried out for the input voltage balance closed loop and output voltage closed loop controller.Finally,a circuit simulation model was built.The simulation results verify the validity and correctness of the control strategy and parameters.For the 10kV/750 V Switched Capacitor ISOP converter,a detailed description of the main circuit parameters selection principles including DC-side capacitors,power devices,high-frequency transformers,output filter inductors and other main circuit parameter designis was performed.Then a 3-module ISOP experimental platform was built according to the parameters.And the hardware control circuit and software system of the experimental prototype were designed.Finally,the experimental results show the validity and correctness of the research results in this paper.