Research On Single-Stage Inverter Based On Bi-directional DC/DC Isolated Converter

The single-stage inverter could realize DC/AC function, voltage transformation and electrical isolation in one stage, has other merits as follows: small volume and low cost, and was suitable for using in small and medium power field. A single-stage inverter could be got by combination of two bi-directional converters because a bi-directional converter could work in two quadrants. So, the research on the single-stage inverter based on bi-directional isolated converter (Flyback, isolated Cuk and isolated Sepic-Zeta) was proposed in this paper.First, the operation principles and the working modes of the three converters under the complementary control were given in this paper. The feasibility of these converters outputting half-sinusoid was verified through the simulation, and the influnce of the output filter parameters to output wave was discussed. Based on these, the composition principles, working principles and control strategy were discussed. Then, the working principle, working modes and energy feedback of the single-stage flyback inverter were emphatically analyzied in this paper, and were confirmed with experiments. The relationship between the energy feedback and the circuit parameters was established through theoretical analysis. The correction of the analysis was proved by the Mathcad calculation and the Saber simulation. Meanwhile, design methods of the other inverters (Cuk inverter and Sepic-Zeta inverter) and the simulation results were also given in this paper.Based on experiments, the effects of ratio-transformer, absortion circuit, delay time and magnetic core to conversion efficiency of single-stage flyback inverter were discussed. Two prototypes, 27VDC/115V400Hz100VA and 270VDC/115V400Hz100VA, were made, the max efficiency of former prototype could reach 82.31%. Finally, the loss of the single-stage flyback inverter was analyzied in this paper. Finally, the results could be got as follows: the composition principles of the single-stage inverter were feasible, the design principles of single-stage flyback inverter circuit parameters were effective, and the single-stage flyback inverter was suitable for using in small and medium power filed.