Research On High Voltage Gain And Low Current Ripple DC/DC Conversion Technology

The output of the fuel cell is low voltage and large current,which is usually not used directly in the electrical system.It is necessary that there is a boost type DC/DC converter to connect to the output of the fuel cell.The DC/DC converter need to have a large and stable voltage gain and lower input current ripple in the wider input voltage range.In addition,in terms of the topology and system control,it is necessary to ensure that the fuel cell power generation system has good dynamic and static performance.The double coupled inductor interleaved Boost converter topology is proposed by analyzing the principle and the advantages of the interleaving technology,the switched capacitor and the coupled inductor.The converter can simultaneously achieve low input current ripple and high output voltage gain.On the basis of analyzing the working principle and steady state performance of the IPOS double coupled inductor Boost converter,taking the output power of 800 W as an example,the reasonable parameters of the coupled inductor,output capacitance,switched capacitor and diode are designed.In the aspect of system control,the state space average method and the small signal model analysis method are used to analyze the converter,and the open loop model of the system is established.The average current mode control network is adopted to design a suitable compensation network,so that the system can satisfy the stability of the closed-loop condition and have better dynamic and static characteristics.The stability of the closed-loop system is verified in Saber simulation environment.The driving circuit and voltage and current sampling circuit are designed.On the basis of the simulation verification,the hardware experimental platform with the output power of 800 W is set up for experiment.The theoretical design parameter are optimized and improved on the steady-state performance and dynamic characteristics of the converter.Through the simulation and experiment,it is proved that the double coupled inductor Boost converter can achieve low input current ripple and high gain of the output voltage under the good double closed loop control circuit,and can ensure the system has good dynamic and static characteristics at the same time.Therefore,the topology can satisfy the requirement of unidirectional boost DC/DC converter which is in series between the output of fuel cell and the load.