Research On Control Technology Of ISOP DC-DC Converter For Electrical Energy Router

With energy shortages and environmental pollution issues becoming increasingly prominent,large-scale new energy power generation and energy storage systems have been rapidly developed and applied.In this context,the energy internet,which can widely connect new energy power generation systems to the power grid,and is easy to realize the transformation of energy consumption structure and the intelligent control of electric energy,has emerged as the times require.As one of the core equipment of the energy internet,the electrical energy router(EER)has many advantages such as high and low voltage side electrical isolation,two-way power transmission,multi-voltage level interfaces,and easy access to new energy and energy storage equipment.Therefore,this paper takes EER as the application background,and takes the input-series output-parallel dual-active-bridge(ISOP-DAB)DC-DC converter as one of its core components,mainly carry out relevant control optimization technology research in the aspects of working principle,backflow power and dynamic performance.Firstly,the working principle and power characteristics of the ISOP-DAB converter under single-phase-shift(SPS)and extended-phase-shift(EPS)are analyzed.On the basis of working modal analysis,the mathematical models of the inductor current under the control of SPS and EPS are established respectively,the expression of transmission power under the control of SPS and EPS is derived and compared.The analysis shows that EPS has increased the freedom and flexibility of system control compared with SPS control,and increased the power transmission range to a certain extent.Then,based on the aforementioned analysis of SPS control,a hybrid model predictive control strategy is proposed to solve the problems of input capacitor voltage balance,output voltage stability and slow dynamic response.The mathematical model of the ISOP-DAB converter under SPS control is established,and the input capacitor voltage and output voltage state space averaging equations are derived.On this basis,the output voltage and input capacitor voltage objective functions are constructed,and their corresponding predictive control models are solved respectively,furthermore,a hybrid model predictive control strategy based on the ISOP-DAB converter is obtained,and the feasibility of the proposed control strategy is verified through simulation results.Subsequently,aiming at the backflow power problem of ISOP-DAB converter under SPS control,this paper proposes a multi-objective optimization control strategy based on EPS.And established a state space averaging equation based on EPS control,and compared the current stress and backflow power under EPS with SPS control.At the same time,with dynamic performance and backflow power optimization as the control goal,a multi-objective optimization control strategy based on input capacitor voltage balance and output voltage stability model predictive control and gradient descent algorithm to achieve backflow power optimization is introduced.Then the simulation verifies the effectiveness of the ISOP-DAB converter multi-objective optimization control strategy based on EPS.Finally,this paper builds an ISOP-DAB converter experimental platform,introduces the overall electrical framework of the experimental platform,and then validates the above-mentioned theoretical analysis and optimized control strategy.The experimental results prove the correctness of the theoretical analysis and the proposed optimal control.