Operation Control Strategy And Research Of The DC-DC Converter With A Wide Input Range And High Voltage Gain For Fuel Cell Vehicles

As one of the most important carrier in the process of transportation,automobiles have been invented for more than 130 years.Up to now,fossil fuel is still the main energy source of traditional vehicles.With more and more automobiles in the world,a large amount of fossil fuel is consumed every year,which aggravates environme nta l pollution,energy crisis and other issues.In order to alleviate these issues and adapt to the trend of energy revolution,the development of new energy vehicles has attracted wide attention all over the world.As an important component of new energy vehicle,fuel cell vehicles have low dependence on fossil fuel.Therefore,fuel cell vehicles have a broad prospects for development.In order to achieve good speed regulation performance,the voltage level of DC bus is high,so the dc-dc boost converter with a wide input range and high voltage gain is needed to act as the required power interface between the fuel cell source and DC bus.As an on-board energy source,the output voltage of fuel cell decreases rapidly with the increase of output current,which makes it difficult to promptly respond to the sudden changes in load power.Therefore,the super capacitor that cooperate with wide voltage gain bi-directional dc-dc converters is essential for coordinated operation control and quick response to load power shortage.Therefore,a new non-isolated high ratio step-up dc-dc converter with switchedcapacitor structure on the fuel cell side is proposed in this paper,which has the following features: high voltage gain and wide input voltage range,low voltage stress across the power devices,common ground between the input and output sides.In this paper,the theoretical analysis and dynamic modeling of the topology are introduced,and the closed-loop voltage and current control strategy of the converter is designed to accomplish the prototype experiments.Then a bidirectional dc-dc converter with coupled inductor on the fuel cell side is proposed to realize the advantages of high voltage gain,low voltage stress and common ground between the high and low voltage sides,which effectively decreases the current ripple of high and low voltage interfaces.In this paper,the theoretical analysis of the topology is presented,as well as the bidirectional closed-loop current control strategy of the converter is designed to complete the prototype experiments.Finally,Based on the experimental platform built in the laboratory,this paper studies the power coordinated control strategy of the two dc-dc converters above in the hybrid energy sources system of fuel cell vehicles,as well as the feasibility and effectiveness of the coordinated control strategy is verified by the simulation and experimental results.