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Research On The Soft-Switching Three-phase PWM Inverter Technique

Posted on:2006-12-04Degree:DoctorType:Dissertation
Country:ChinaCandidate:C Y XuFull Text:PDF
GTID:1102360155460309Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
Based on analysis and evaluation of the existing study of inverter soft-switching topology circuit, a novel three-phase soft-switching PWM inverter topology has been further investigated in this dissertation. As a part of National Nature Science Foundation of China (No:59977012), the study mainly focuses on the topology of main circuit and control strategy about soft-switching three-phase PWM inverter, which is to explore a practical soft-switching three-phase PWM inverter topology and in order to provide for industry a feasible soft-switching three-phase PWM inverter scheme, its operation mechanism is investigated.A novel assistant resonant soft-switching three-phase PWM inverter topology circuit is proposed which contains such characteristics as simple structure, convenient control, low cost and high density, capable of realizing the soft-switching action of all the inverter power switch devices. In this paper, author has investigated the soft-switching operation mechanism of the circuit topology, analyzed the soft-switching action pattern of the main circuit about soft-switching three-phase PWM inverter, established mathematical model and control strategy of the inverter soft-switching action process and completed computer simulation, so that the theory base has been established for the experimental research.Carrier wave forms are studied to fit three-phase PWM inverter soft-switching operation. It is pointed out that sawtooth carrier wave with positive or negative slope has to be selected respectively according to the polarity of inverter output current, which is a necessary condition to realize soft-switching operation. Also, optimized SAPWM modulation wave has been utilized, improving the utility ratio of DC voltage and restraining effectively the output harmonic current of inverter.Flux linkage locus of soft-switching three-phase PWM inverter is analyzed, and it is declared that under the soft-switching PWM pattern, space voltage vectors vary greatly, sometimes even no zero space vectors exists. The rotating speed of flux linkage locus is adjusted by the non-zero space vectors, so the speed of flux linkage locus still equal to that of hard-switching PWM pattern. The reason of soft-switching PWM inverter's current wave distortion has been discussed also, two corresponding compensation methods are proposed, effectively improving the output current waveform of the inverter. The reason of resonant slot abnormity in the experiment has been discussed and the relationship between PWM gating signals of soft-switching inverter and resonant timing has also been demonstrated, so the normal realization of soft-switching action is guaranteed.Experimental investigation has been carried out for the assistant resonant soft-switching three-phase PWM inverter, establishing experimental system, optimizing...
Keywords/Search Tags:Soft-Switching, Inverter, SAPWM, Resonant, Flux Linkage Locus
PDF Full Text Request
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