Research On Dual Phase Shift Control Of Dual Active Full-Bridge DC-DC Converter

With the development of human society,the issue of energy shortage has become the focus of attention of all countries.In this context,new energy power generation technology has developed rapidly.In view of the shortcomings of new energy power generation that are unstable and greatly affected by natural factors,energy storage links are usually set to ensure power quality.Dual Active Bridge(DAB)DC-DC converters are usually used as a bridge between the power grid and energy storage to ensure the stability of the system due to its bidirectional energy transmission,high power density,and easy realization of soft switching.This article first describes the basic principles and operating characteristics of dual active full-bridge DC-DC converters under single-phase-shift(SPS)control,and derives the transmission power,current stress and shifting characteristics under single-phase-shift control.Comparing the expressions between the phases,the direction of the transmission power can be changed by adjusting the phase-shifting,and the output voltage can be changed.The classic state space method is used for small-signal modeling and analysis,and the transfer function between the input and output voltages is derived.However,when the input and output voltages do not match,single-phase-shift control has problems such as large current stress and difficulty in achieving soft switching.Based on the shortcomings of single-phase-shift control,this paper analyzes the operating states of dual-active full-bridge DC-DC converters in a switching cycle under the extended phase-shift and dual-phase-shift control strategies,and derives the transmission power and current stress.The relationship between the combination and the shift.Through theoretical analysis,it is concluded that the use of extended phase shifting and dual phase shifting control can increase the adjustment range of the transmission power,the operation is more flexible,and the current stress is obviously reduced.After that,when the transmission power is the same under dual phase shift control,different shift phase combinations lead to different current stress.The dual phase shift control strategy is improved to reduce the current stress as the optimization goal,and find the most suitable shift.Compared with the combination,the minimum current stress control algorithm is proposed,and the optimal control strategy block diagram is drawn.The simulation of single phase shift control,extended phase shift control and double phase shift control is carried out by MATLAB/Simulink software,and the effectiveness of the minimum current stress control algorithm is verified by comparison.Finally,an experimental platform is set up,and the advantages of the proposed minimum current stress control algorithm in reducing current stress are verified by the experimental waveform.