Design And Predictive Control Research Of High Step-up Ratio DC/DC Converter For Fuel Cell

With the rapid development of the new energy industry,fuel cell have been applied in more and more occasions with the advantages of high efficiency and cleanliness.However,the performance of the existing non-isolated DC/DC converter,such as step-up ratio and response speed,has been unable to meet the higher and higher demand.Aiming at this problem,the main purpose of this thesis is to improve the step-up ratio and response speed of the DC/DC converter used in fuel cell.The research and design are carried out from the aspects of topological structure and control strategy.The specific contents are as follows:The topology of unisolated high step-up ratio DC/DC converter for fuel cell is designed.According to the output characteristics and applications of fuel cell,the demand analysis of DC/DC converter is carried out.On this basis,by comparing and analyzing the common topology,the topology of the non-isolated high step-up ratio fuel cell DC/DC converter is designed combining the two-phase staggered parallel structure with the voltage gain circuit,and the working modes and steady-state performance of the structure are analyzed.The characteristics of high step-up ratio,low voltage stress and low input current ripple are verified theoretically.The power circuit and control circuit of high step-up ratio fuel cell DC/DC converter are designed.The power circuit is designed according to the steady-state performance index of the converter,and the parameter calculation and selection of semiconductor devices,capacitors and inductors are completed.According to the control requirements of the converter,the control circuit is designed,including the main control circuit,sampling circuit,hardware protection circuit and driver circuit.The predictive controller of fuel cell DC/DC converter with high step-up ratio is designed.State space average method is adopted to establish the mathematical model of this topology,and the predictive model of input inductance current is obtained.After considering the desired control effects and hard constraints,the objective function of constrained model predictive control is designed.In order to solve the complex problem of predictive controller,the spider monkey optimization algorithm is introduced to design predictive controller,which is based on spider monkey optimization algorithm.The modular design idea is combined with dual-core DSP chip to complete the software design of control strategy and ensure the real-time performance of predictive controller.The simulation and experiment platform are set up to verify the design scheme.Based on the designed topology and predictive controller,a simulation platform of high step-up ratio fuel cell DC/DC converter is completed.The steady-state performance and dynamic performance are verified by simulation.According to the hardware circuit and control software of this thesis,the scheme is designed to build the experimental prototype of 6k W DC/DC converter and carry out the experimental research.The experimental result shows that the topological structure and control strategy designed in this thesis have high voltage step-up ratio and dynamic response speed.