| Thermoacoustic power generation technology can convert the low quality heat such assolar energy, industrial waste heat and so on into electricity. It is a kind of new type powergeneration technology with the advantages of less pollution, reliable operation, lower cost etc.Thermoacoustic power generation technology converts heat energy to sound energy bythermoacoustic engine, and then sound energy to electrical energy by the linear generator.Although thermoacoustic power generation technology application prospect is good, thethermoacoustic energy conversion efficiency of power generation system is still very low;especially the system output power ability is weak. So it is improve to improve thethermoacoustic power generation system output power by the appropriate control strategy.Based on the thermoacoustic power generation system of electric load characteristic isanalyzed in this thesis, impedance matching load is designed applying to the thermoacousticpower generation system. When the thermoacoustic power generation system operates in thesteady state with the battery load, through control this circuit, it makes the generator operatingin the unit power factor, and the system output voltage is always higher than the batteryvoltage, that improves the energy conversion efficiency of the system and acoustic-electricconversion efficiency.The specific contents are as follows:Firstly, according to the impedance characteristics of the thermoacoustic powergeneration system, the mathematical model of permanent magnet linear generator in thesystem is built. Through the analysis, we concluded that the resonance circuit state in thethermoacoustic power generation system will improve the efficiency of acoustic-electricconversion. And the energy conversion efficiency and the output electric power ability are indifferent maximum respectively according to different electric load.Secondly, the impedance matching load is designed,which applying to thethermoacoustic power generation system. For the impedance of the load circuit, we useddouble closed loop direct current control strategy. The filter circuit which has been designedcan can offset the harmonic oscillation and maintain the output vlotage regulation whensystem is running.Thirdly, the simulation model of permanent magnet linear generator and impedance matching load circuit in thermoacoustic power generation system are built in the Matlab/simulink. We will simulate both the different load and different frequencies of driving forceconditions, then curve fitting the results. Through observed the variation concluded that theefficiency of acoustic-electric conversion in resonant circuit state is higher than non-resonantcircuit state. Both the thermoacoustic power generation system model of assuming theconstant of output voltage and the model of combine the permanent magnet linear generator isestablished. Simulation proof that the impedance matching load can make the system work inthe resonant circuit state and non-resonant circuit state with battery load.Both states canimprove the the efficiency of battery charging and the efficiency of the system.Finally, the experiment platform for the thermoacoustic power generation system isdesigned and the electrical energy storage circuit is built. PWM rectifier circuit is used forprocessing electrical energy. By unit power factor circuit operating, the feasibility andeffectiveness about the designed control strategy and the designed circuit are proved. |
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