Single Phase Full Bridge Inverter With Input Current Low Frequency Ripple Suppression

With the development of society and economy,the demand for energy is increasing,the problems caused by the energy crisis,environmental destruction have caused great annoyance to human beings,and the fuel cell,solar energy and wind energy and other new energy power generation system with renewable and cleanliness become a hot research topic in today’s society.In the small and medium power generation system,the new energy power generation system is mainly based on single phase inverter,while the full bridge inverter has a very wide applications in the area.As the single-phase inverter output side has the instantaneous pulse power,which pulsates at twice the output frequency,there will be current also pulsating at twice the output frequency in the input power source.This thesis discusses the generation mechanism and the harm of the second harmonic ripple,then analyzes and summarizes the development and current situation of the inverter input low frequency current ripple suppression technology at home and abroad,pointing out the advantages and disadvantages of various methods,and next a new method of low frequency ripple of input current of single phase full bridge inverter is proposed.This method is by breaking the output filter capacitor of the full bridge inverter into two,and a bridge arm is added to eliminate the two harmonic current in the input current by two additional harmonic voltages on the two output capacitors.This thesis analyzes the main circuit steady state characteristics and the ripple suppression mechanism,points out the impact on the power switch voltage and current stress after injecting second harmonic voltage,compares changes of second harmonic current flow path.Control strategy has also been discussed,it’s pointed out that the difference between PI controller and PR controller,the advantages of PR controller in suppressing ripple current are presented.The control diagram of the main circuit is described.Furthermore,the thesis establishes the mathematical model of the main circuit,discusses the static analysis and dynamic analysis,and gives the design criterion of the key circuit parameters.Finally,a 1kVA 450VDC/220V50HzAC full-bridge inverter with low frequency current ripple suppression is simulated and tested in the thesis,the ideal results are obtained.Simulation and experimental results confirm the correctness and feasibility of the proposed low frequency input current ripple suppression scheme.