Research On Modular Balanced Control Of Input Series Output Parallel Inverter System

As an integrated system,input series output parallel(ISOP)inverter is suitable for ship power supply,urban rail transit and high-speed electrified railway.The key to ensure the stability of this kind of system is to achieve power balance.However,the remaining problems is that additional control rings are needed to implement the system.When the circuit parameters change,the system needs to be rebuilt,resulting in a long development period,which is not conducive to the rapid modular construction of the system.Aiming at this problem,this dissertation proposes a flexible scheme of IVS and OCS,carries out theoretical analysis,builds a prototype platform and carries out experimental research.In order to adapt to the input and output working conditions of the combined system,the submodule of the inverter is designed.The current inner loop controller is designed by using the virtual resistance,it can eliminate the resonant peak of the output filter which is based on the equivalent control block diagram of the inverter,.The voltage outer loop controller is designed to improve the steady output precision.The control loop of the sub-module of the inverter is realized by software,which is flexible and convenient for modular integration of the system.Compared with the market module,the control loop of the sub-module of the inverter in this project is realized by software,which can be secondary development.It is easier to realize the output flow sharing control and the combination of series and parallel,forming a distributed architecture with high flexibility and facilitating the modular integration of the systemA scheme of input voltage-sharing Model(VSM)combined with average current bus is designed to solve the problem of IVS and OCS in this system.The VSM module can be directly connected to the DC side of the ISOP system and the input side of the submodule,without the need to design a complex voltage equalization loop control circuit and the input voltage sampling circuit,and can be used for the series and parallel connection of different numbe r of modules according to the requirements.Saber simulation is used to verify the effectiveness of the scheme.In order to provide the parameter selection basis of VSM module for the system with different performance requirements,the influence of VSM module on systemstability and dynamic performance is further explored.Through the establishment of VSM module average switch model,the small signal model of the system is derived,furthermore,the transfer function of input voltage disturbance is obtained,and the parameter constraint condition that makes the system stabl e is obtained according to the Hurwitz criterion,and the influence of different parameter conditions on the dynamic performance of the system is studied by the analysis of input voltage disturbance.Saber simulation verifies the correctness of the stability constraint condition.In order to further verify the effectiveness of the proposed scheme,In this dissertation,an ISOP combined system composed of two inverter submodules is built.The experimental results show that the proposed scheme is effective.