| With the rapid development of the global economy,the existing energy system is facing great challenges.The development and use of new energy has begun to attract people’s attention and research.In the development and utilization of new energy,the DC microgrid has played an important role and has been It is a research hotspot of scholars at home and abroad.In the DC microgrid,in order to solve the intermittent and randomness of renewable energy due to environmental factors,energy storage links can be added,and bidirectional DC converters are used to control the bidirectional energy transmission between the energy storage links and the DC bus.In order to provide stable and continuous electrical energy for the DC microgrid,and at the same time maximize the use of renewable energy.The dual active full-bridge bidirectional DC-DC converter has the advantages of low voltage and current stress of the switch tube and easy implementation of soft switching,and is suitable for medium and high power occasions.In this paper,the optimal control strategy of the dual active full-bridge bidirectional DC-DC converter is studied to improve the transient and steady-state characteristics of the converter,ensure the safe operation of the DC microgrid and the efficient charge and discharge of the energy storage link.Analyze the working principle of single-phase shift control,aiming at the problems faced by the converter during the transient process of starting and switching loads,etc.,on the basis of single-phase shift control,study the transient characteristics to optimize the control strategy,and use the output side in the starting phase The optimized start-up control strategy of blocking is used to suppress the current shock during the start-up phase of the converter;the single-phase shift control strategy based on power prediction and the optimized modulation method are used during the load switching phase to suppress the voltage overshoot and current shock during this phase.Aiming at the problem of large steady-state current stress of the converter under single-phase shift control,the working principle of the extended phase shift control is analyzed,and the factors that affect the current stress of the converter when the same power is transmitted under the extended phase shift control are obtained to obtain the optimal The combination of phase-shift angles can minimize the current stress of the converter,and a current stress optimization control strategy based on extended phase shift is further obtained.For the converter,the current stress optimization control strategy based on extended phase shifting is adopted,and there is a problem of large power circulation under light load.The working principle of double phase shift control is analyzed,and the current stress optimization control strategy based on double phase shifting is further explored.Suppress the power circulation of the converter under light load.Comparing the optimization effects of the current stress optimization control strategy based on extended phase shifting and the current stress optimization control strategy based on dual phase shifting under different loads,a dual-mode switching optimization control strategy is proposed to make the converter light-load and heavyload states There are better optimization effects in the following.At the same time,the influence of the dual-mode switching optimization control strategy on the soft switching of the switching tube and the conduction loss of the switching tube is analyzed to discuss the effect of the dual-mode switching optimization control strategy on the charging and discharging efficiency of the energy storage link. |
