Study Of Energy Conversion Optimization Strategy For Thermoacoustic Power Generation System With Battery Load

Thermoacoustic power generation system is via the thermoacoustic engine draging thematching linear generator to do reciprocating motion, in order to realize the transformationbetween thermal energy and electrical energy. Thermoacoustic power generationtechnology has a series of advantages such as low costs, high reliability and less pollution.It can realize the collection and utilization of low quality heat energy, and it owns a largerdevelopment space in this day when the energy shortage and environmental pollutionbecoming increasingly serious day and day. However, this technology is still in theresearch stage, and the output electrical energy of it is so little that it needs to be stored inthe battery and use it in case of when you need. Therefore, how to control the battery loadto capture the maximum charging power from the thermoacoustic power generation systemthus improving the efficiency of the entire system becomes an issue requiring urgentsolution.This thesis carries out an analysis of the energy conversion characteristics between thethermoacoustic power generation system and the battery load. Based on this, the Buck-Boost chopper charging mode is proposed. It can overcome the disadvantage of the directcharging mode that the charge take place only when the output voltage is higher than thebattery terminal voltage. So that it can improve the charging electric power effectively.The Specific research contents are as follows:First, the armature current is limited to wave in a small range. At this time, theinduced electromotive force of the generator can be approximated as the standardsinusoidal voltage source. Let the Buck-Boost circuit work in the discontinuous currentmode, then set up and solving the system dynamic equation with the analytic method to getthe optimality switch state of the switch tube. Through the m function in the Matlab writeprograms to do the simulation about it, and the results show that the charging powerachieved by the battery load has been improved significantly. Second, cancel the limit to the size of armature current, then re-establish andre-solving the dynamic equations combined with the output thrust characteristics of thethermoacoustic engine as well as the motion characteristics of the linear generator to obtainthe new optimal switching state in the discontinuous current mode. The simulation resultsshow that the charging electric power has further significantly increase compared with thecurrent limiting case. In addition, the article also describes the thought that solving thedynamic equations with fourth-order Runge-Kutta method and solving the duty cycle withiterative method. This means is more conducive to the application in engineering practice,and it is tested to achieve good results through simulation.Finally, control the Buck-Boost circuit works in the current non-intermittent mode.Cancel some constraints in the discontinuous current mode, then the problem that thebattery load captures the maximum charging power converts to a multivariable nonlinearoptimization problem. Further more, this paper introduces the basic thoughts and theoptimization process of the simulated annealing algorithm, and apply it into the solving ofthe optimal duty cycle sequence. The simulation results show that, the charging power isfurther increased compared with discontinuous current mode.