Research On Deadbeat Control Based On The Three-level Gird-connected Inverter

With the change of the energy structure, the importance of new energy are increasing rapitly nowadays. As a key technology for efficient utilization of new energy, the grid connected power generation technology raise more and more attention. Because of lower harmonic, higher voltage level and less switching loss, the neutral point clamp three-level converter has been used widely in new energy grid connected power generation. In this paper, the study of deadbeat control is base on such converter.Firstly, the the background, development status of three-level inverter topology、 common-used control algorithms and deadbeat control are introduced separetely in this paper. Secondly, the switch and power transmission process of the neutral point clamp three-level converteris is introduced, and the mathematical model is established. To facilitate the design and performance analysis of deadbeat control system, both continuous and discrete mathematical model of the inverter are built, and then its complex vector model and control delay model are also built. According to the mathematical model of one-Sample Control Delay, the realization method of traditional deadbeat controland is introduced and then the performance of the control system is analyzed.Since traditional predictive algorithm of the reference current may cause large current overshoot or phase delay in different reference changes,a new predictive algorithm was introduced. To improve the robustness of deadbeat control,a control combining deadbeat control and Luenberger observer is introduced,and then the stability analysis is also given. To achieve zero steady-state current error,a Repetitive Control and an adaptive strategy are introduced in the paper. The ability to compatible with PWM modulation strategy is one of the advantages of deadbeat control. The modulation strategy is closely related to the performance of converter, such as Harmonics performance、switching losses、common-mode voltage etc. Then several PWM modulation strategy are studied in the ways of vectors and carriers method.At last, the simulation platform and experimental platform have been built, and simulation analysis and experimental verification of the deadbeat control and typical three-level PWM modulation strategy are both tested in these platgorm.