Modeling And Control Of Fuel Cell DC-DC Converter

With increasing environmental pollution and energy crisis, the development of new green energy attracts more and more international academic and engineering attentions. The fuel cell has an advantage of non-polluting, zero emission and purifying. Fuel cell power generation depends on the supplement of fuel which often leads to instability or even large-scale fluctuations in the output voltage of the fuel cell, so the design of a safe, reliable, efficient DC-DC converter is essential.This paper aims to design a DC-DC converter capable of converting fuel cell energy efficiently, do its theoretical analysis and research, and use embedded chip to ensure that DC-DC converter achieve efficient and reliable power conversion. The article summarizes the work completed as follows.(1) A push-pull Buck DC-DC converter and push-pull Boost DC-DC converter topologies are proposed. Analyze their working principle and characteristics respectively. Establish their large-signal system model with state-space average modeling method, as linear controller is always designed based on a linear model, so the nonlinear model is linearized between the steady-state values to obtain a linear small signal model, supporting the design of linear controller.(2) Finish the push-pull Buck DC-DC converter hardware design. Then combine the small-signal circuits and circuit model parameters have been designed to perform frequency domain analysis, pointed out the problem of insufficient dynamic response, then design compensation feedback controller, the simulation shows that the control effect is remarkable, which provides theoretical support for the actual hardware circuit control. Finally, use the DSP to control the DC-DC circuit, the experimental results show that the DC-DC converter output voltage can tracking the design voltage quickly, has a good response of step change and load variation.(3) Control the forward DC-DC converter with fast model predictive control algorithm. Analyze the advantages compared with traditional model predictive control algorithm. Establish the small-signal model and discrete-time hybrid model of forward DC-DC converters, and then propose fast model predictive control performance function and constraints, modify the set voltage to solve the problem of model mismatch may exists. Finally, compared with traditional compensation feedback controller, the situation is much better in step response than compensating feedback controller, the fast model predictive controller is effective.