The Development And Design Of Inverter Used In5KW-Class Solid Oxide Fuel Cell Independent System

In the field of fuel cell power generation, compared with other fuel cell the advantageof solid oxide fuel cell (SOFC) system is its higher power density;the range of single fuelcell’s voltage is generally between0.6-0.8V. This thesis based on5KW SOFC stackwhich include about60series single battery that with80watts in power and the size of15cm*15cm. About the output electrical characteristics of SOFC,the range of outputvoltage is36V~50V, the range of output current is from20A to140A, which is a typicallow-voltage and high current DC power supply of a wide range of fluctuation instability.Obviously, such an unstable DC which is going to be transformed into practicalapplications220V/50Hz AC can not be applied to the actual and also it’s needed to ensurea high efficiency of the conversion for external load, so it is necessary to develop anddesign a power conversion unit for the KW-class SOFC systems.On the basis of the background of the study of solid oxide fuel cell power generationsystem, this thesis aimed to develop and design the set for5KW solid oxide fuel cellinverter.About the main work of this thesis, the first part is to design the DC/DC converteraccording the output characteristics of the solid oxide fuel cell system. This part using thepush-pull Isolated Boost Converter circuit topology is to transform a larger range of inputlow-voltage and high current power conversion into a high-voltage direct current. In orderto achieve the requirements of the conversion efficiency appropriation, this thesisdesigned an energy recovery circuit.After a pre-boost circuit, a single-phase full-bridge inverter circuit was designed.This part has applied the full-bridge topology，which connected the DC-side capacitors，which was designed for a voltage source inverter circuit.Inverter full-bridge drive signalusing a unipolar harmonic SPWM modulation， the equivalent multiplier, and thecorresponding all-digital and digital-analog combination of two modulation circuit. After the programs of the development and design，this thesis has completed thecircuit schematic design of each part and the drawing of PCB, also has completed thepreliminary work for the final prototype production. It has made a simple analysis on theoutput current and voltage waveforms after debugging the circuit.