Research On The Buck-Boost Converter Based On AC-Link Series Resonance

Power supply is the basic component of power electronic equipment.With the decrease of the appearance size of electrical equipment,high efficiency and high power density has become the hotspot and trend of power technology research and development.The traditional AC-DC converter has a combination of rectification and direct transformation.A DC energy storage structure exists in the process of power transformation.AC-Link technology dose not have dc energy storage,which effectively improves the power density of switching power supply.The advantages of the converter with AC-Link technology and the development of this technology at home and abroad are described in this thesis.In order to improve the working stability of the converter in the non-ideal input state,the phase-locked loop technology is investigated.Based on AC-Link technology,a new type of buck-boost converter topology is proposed based on the existing series resonant converter.Respectively for the Buck and the Boost converter under two kinds of working mode of the working condition is analyzed,given the typical drive mode of the switch tube and determine the switch by a frequency converter cycle and driving waveform corresponding relation.Using the Simulink module of Matlab software,the simulation model of this new circuit structure is established.The results of the converter in two working modes show that it meets the design expectation target.The principle of the single/double synchronous coordinate system is analyzed and the flow chart of the system is established.The simulation model of the two is established,and the simulation is compared with the input state of frequency offset,voltage mutation,three-phase unbalance and the existence of harmonics.The phase detection part of the three-phase detection module is selected as the software phase lock loop with better performance.Combined with the former is build based on AC-Link series resonance Buck-Boost converter of the simulation model of converter under non-ideal input state in work conditions are simulated,the results show that after using the phase lock loop,the working stability of the converter has been enhanced.The hardware test platform of three-phase detection is tested.The results show that the three-phase detection module can accurately extract the phase and voltage information to provide accurate working interval information for system.The converter's control program is written,which laid the foundation for the subsequent experimental verification work.