Research On Cascade Multilevel AC-AC Converter And Its Application

This paper cascades the level module of the high-frequency non-isolated three level AC-AC converters and proposes a family of multilevel cascade AC-AC converters. And it mainly researches four-level Boost AC-AC converter.Firstly, take three-level Boost AC-AC converter as an example, Find out the multilevel AC module. Analysising multilevel AC power supply module, proposes a family of multilevel cascade AC-AC converters on this basis.Secondly, studies four-level Boost AC converter input-output relations, the working principle and the advantages, disadvantages of two modes:not fully charge and discharge mode, fully charge and discharge mode. Use voltage instantaneous feedback control, analysis loop stability of closed loop control system, calculate control system parameters. On this basis, optimum design of converter including power circuit design, control circuit design, thermal design and printed circuit board (PCB) design.Operation principle and control strategy of the four-level Boost AC-AC converter are verified by simulation. Select not fully charge and discharge switch mode, prototype experimental research results show that multilevel converters have lower switching voltage stress and smaller output voltage ripple.Finally, researches multilevel cascade AC-AC converters'application in var compensation and Dynamic Voltage Restorer (DVR) multilevel cascade converter. Take four-level Boost AC-AC converter as an example, simulation and experimental results verify the correctness of the converter's application.