Research On Topology Of AC-AC Converter Based On Magnetic Coupling Impedance Source Network

With the increasing stress of major energy sources such as oil,coal and natural gas,the development and utilization of new energy sources are particularly important.High gain AC-AC voltage converter has attracted more and more attention of scholars at home and abroad.Compared with traditional indirect AC-AC converter and matrix converter,chopper type AC-AC converter has the advantages of simple control,small device size,high transmission efficiency and large voltage gain.In a chopper type AC-AC converter,a converter with a magnetic coupling inductance unit has the advantage of reducing switching stress and achieving higher voltage conversion ratio.In order to reduce the topology limitation and the power device limitation of the converter,a series of AC-AC chopper with magnetic coupling inductance structure is proposed.These topologies can achieve higher voltage gain,and each of them has its own unique advantages and characteristics.In this paper,the magnetic coupling traditional AC-AC converter as the research object,summed up the traditional AC-AC converter topology group,and the topological group theory analysis,finally,through Pspice simulation and experimental verification to prove the correctness and advantage of the circuit theory analysis.Secondly,in order to further improve the voltage gain,reduce the input voltage harmonic,and improve the power factor of the input voltage.In this paper,the topology groups of these converters are improved,and two types of quasi Z source topology groups are proposed.The two topological groups are theoretically analyzed and verified by PSPICE simulation.Finally,the I quasi Z source magnetic coupling converter and the II quasi Z source magnetic coupling converter are experimentally verified,and the voltage gain is proved to be high.Then,in order to reduce the voltage stress and reduce the size of the converter,the aforementioned quasi Z source converter is optimized and improved,and an improved topology group without output filter is proposed.The circuit switches the output switch forward,which sufficiently relieves the switching stress of the switch.Finally,PSpice simulation and experimental verification show that the improved quasi Z source topology has the advantages of increasing voltage gain and reducing switching voltage stress.Finally,in order to further improve the voltage gain and retain the advantages of the above converter,such as reducing the voltage stress of the switching tube and the continuous input current,this paper introduces the TL type capacitor clamping unit.Instead of a single capacitor structure of the converter with TL capacitor clamp unit,finally proposed the enhanced AC-AC AC chopper,through theoretical analysis shows that the converter has low voltage stress,high transmission efficiency,low input current harmonics and high input power factor,voltage transfer ratio advantage.Finally,the correctness of the theoretical analysis and the advantages and characteristics of the converter are proved by Pspice simulation and experimental verification.A series of single-phase AC-AC converters proposed in this paper can also be applied to three-phase AC-AC converters,which is of important guiding significance for three-phase AC-AC converters to achieve high gain voltage transmission.