Research Of Single-phase Full-bridge Inverter Based On Hysteresis Control

Green energy such as solar, fuel cells and wind energy which have the advantage of no pollution, clean, etc, are gradually becoming the main source of mankind’s energy needs in future, the inverter plays an important role in the development and utilization process of these new energy. At present, the research of inverter focuses on circuit topology and control technical, good topology and control can not only optimize the performance of the inverter, but also improve energy efficiency, reduce cost at the same time.When single-phase full-bridge grid-connected inverter is the object of study, characteristics of L-type filter is analyzed as well as the switching frequency by using the traditional hysteresis control. A new hysteresis control is introduced after that, analysis of the inductor ripple current characteristic and the affect of the output inductance for the switching spectrum are researched, and then simulation and experiment are carried out to proof the analysis.The paper establishes the mathematical model of the SPWM inverter power supply, then the open-loop characteristics and output voltage waveform distortion of the single-phase full-bridge inverter are analyzed later. On the basis, the further analysis of the dual-loop method including voltage loop and inductor current inner-loop of the single-phase full-bridge inverter is done, and the closed-loop transfer of the inverter is derived and the equivalent model is proposed in order to study the closed-loop characteristics of the inverter. In the design of the dual-loop control systems, PSIM software is used to validate the theory and prove true. With proper parameters of the circuit and the control system, the inverter controlled by dual-loop control method has good stability and dynamic response.Based on the analysis of current hysteresis control, a improved control including hysteresis control is proposed, which retains the advantages of hysteresis control, but it will make the distortion rate of the inverter output voltage increase and will cause the switching frequency unfixed, the output filter design will be difficult too. For the above problems, this paper proposes corresponding improvement control methods. To decrease the output distortion rate, a three-states control method is proposed, and the switching operation modes are listed in the case of single-phase full-bridge. Through the analysis of the inverter switching frequency using hysteresis control, a varied hysteresis-band current control is introduced to replace the traditional hysteresis control. The proposed control retains the benefit of the hysteresis control having fast dynamic response and tackles the drawback of the standard hysteresis control having variable switching frequency. Simulation and experiment are carried out to proof the analysis.Finally, the above inverter and control are designed, including dead circuit, filter, switching selection, drive circuit and so on. On the basis, a complete experimental circuit is set up. At last, the paper analyzes the experimental results in order to verify the theoretical analysis.