Research On The Equilibrium Control Strategy Of Electric Vehicle Charger’s Input Series Output Parallel DC-DC Converter Module

As the economy develops,the increasing number of motor vehicles has made energy and environmental issues increasingly prominent.The power system of electric vehicles(EV)is mainly based on new energy,with the advantages of green environmental protection and no pollution.It is an important way to solve environmental pollution problems.As an important charging device for electric vehicles,on-board chargers directly affect the energy source of electric vehicles.At the same time,the rapidly developing electric vehicle industry also puts forward higher requirements for chargers.In order to improve the power level of the car charger and reduce the voltage stress of the power tube,input-series output-parallel(ISOP)DC-DC converters can be used,but there is a problem of unbalanced sub-modules.Therefore,based on the design of the dual active bridge(DAB)DC-DC converter of the sub-module unit,this paper studies the charger ISOP DC-DC converter and its control strategy to solve the problem of module power.Equilibrium issues,which enable it to run stably,play a key role in improving the overall performance of the charger.Firstly,the topology structure of the DAB converter of the ISOP submodule is analyzed,its working principle is explained,and the transmission power of the DAB converter and the implementation of soft switching when using single phase shift control are deduced.Based on this,the DAB component parameters were selected,and the Matlab/Simulink simulation model was built to verify the rationality of the theoretical analysis and design.Secondly,the current main charging methods of electric vehicle power batteries are compared and analyzed,and the two-stage charging method with better effect is selected.Based on the DAB theoretical analysis,the small signal model of the ISOP-DAB converter is studied,and the control relationship between the transmission power and the phase shift amount is derived.In order to realize the balanced control of the ISOP converter,the relationship between the input and output of the ISOP DC-DC converter is studied,and the stability analysis of its corresponding control is carried out.stable.A module equilibrium control strategy based on sliding mode controller is proposed to achieve equilibrium control among modules and improve the degree of modularity.Based on the above theoretical analysis,Matlab/Simulink simulation software is used to simulate and verify the ISOP DC-DC combined converter.The simulation results verify the feasibility and effectiveness of the control strategy.Finally,a 2.4kW two-module ISOP DC-DC converter experimental platform based on dSPACE control of a semi-physical simulation system was built.The control principle of dSPACE is introduced,and the hardware circuit is designed,including the control,driving,sampling,protection and other aspects of the circuit.The working condition and balance effect of the sub-module are tested.The experimental results verify the rationality of the hardware parameter design and the effectiveness of the control strategy to meet the design requirements of electric vehicle chargers.