Key Technology Of Multi-voltage Level DC/DC Power Converter For Hydrogen Fuel Cell

With the increasing global environmental problems,hydrogen has been widely used as a new secondary energy source.At present,new energy vehicles driven by hydrogen fuel are receiving increasing attention,and related multi-voltage level DC/DC power converters will also become the focus of research.Hydrogen fuel cell for new energy vehicles has a low voltage problem.In order to achieve the stable operation of the drive motor and other equipment in the hydrogen fuel cell vehicle,on the one hand,a boost converter is required to match the bus voltage level,and on the other hand,a buck converter is needed to supply power to other low-voltage electrical equipment in the car.The two form a multi-voltage level DC/DC power converter.In order to solve the problem of parallel current sharing control and performance optimization control of multi-voltage level DC/DC power converters,the main research contents are as follows.Firstly,according to the challenges encountered in DC/DC power converters,the topology,parallel current sharing control strategy and optimization control strategy of DC/DC power converter are studied and analyzed.and the appropriate topology of multi-voltage DC/DC power converter is selected.Secondly,the selected multi-voltage level DC/DC power converter topology is analyzed separately.Then,the formula of the multi-voltage level DC/DC power converter is derived to obtain the final average state-space model.In order to facilitate the subsequent research and analysis,the main circuit parameters of the system are designed.Thirdly,according to the shortcomings of traditional droop control methods,an improved algorithm is proposed to realize the current equalization and bus voltage compensation of parallel DC/DC power converters.The phase-shifted full-bridge converter and the three-phase interleaved parallel Boost power converter are simulated and verified,and the feasibility of the proposed control method is analyzed.Then,in order to solve the problem of poor control effect and unsatisfactory output performance of traditional double-closed-loop proportional integral(PI)control on complex control systems,non-singular terminal sliding mode dual closed-loop controllers are designed on the basis of phase-shifted full-bridge converter,three-phase interleaved parallel Boost power converter and three-phase interleaved parallel Buck power converter.The traditional dual-closed-loop PI control algorithm is optimized to improve the performance of the converter.A comparative simulation model is built to verify that the non-singular terminal sliding mode dual closed-loop control strategy has better dynamic performance and anti-interference ability.Finally,an experimental prototype is built for experimental verification.Experimental results show that the non-singular terminal sliding mode dual closed-loop control strategy can improve the dynamic performance and system efficiency of the three-phase interleaved parallel Boost power converter,prolong the service life of hydrogen fuel cells,and be suitable for the field of hydrogen fuel cell vehicles.