Research On Single-Stage Flyback Inverter

The Single-Stage isolated inverters can fulfill all the functions of two-stage inverters in one stage,including DC/AC inverter, voltage adjustment and electrical isolation. Thus, the circuit structure and the control schemes can be simplified, with resultant high reliability and reduced cost. Therefore, it becomes an interest of research in low power DC/AC applications. In this dissertation, three novel single-stage isolated inverter topologies were proposed. Both of them are composed by two basic bi-directional DC-DC converters, and the input ports of the two converters are parallel, the output ports are connected in series.The flyback inverter that features simplest structure was researched in this dissertation. Based on the analysis of the basic flyback converter and bi-directional flyback converter, the basic operation principles of the flyback inverter were presented. And then two control strategies were given, including difference control strategy and unilateral control strategy. The later strategy was proposed to eliminate the power circulation that exists in the inverter under the former control strategy.The unilateral control strategies can be classified into two basic control modes: un- alternate switching mode and synchronous rectification (SR) mode. The theoretical analysis and simulations of these two control modes were given in detail, also with the experimental verification. And the design guideline of the circuit parameters in both the discontinuous current mode (DCM) and continuous current mode (CCM) were given respectively.Based on the above research, a 100VA prototype was developed. Experimental results certify that the proposed flyback inverter features small THD in the output sinusoid voltage, small size, light weight and fast dynamic response. Compare to the operation under the DCM mode, the power switches of the inverter under the CCM mode has lower peak current and rms current, so the efficiency can be improved. As the synchronous rectification strategy can reduce the conduction losses of the rectifier, and also due to the ZVS realization of all synchronous rectifiers, the...