Research On Optimized Control Methods For DC/DC Converters Based On Phase Trajectory

DC/DC converters have complex non-linear behaviors,while those behaviors is much related to dynamic and steady performances of system.Deeply understanding complicated related restriction characteristics and evolvement laws provides significant foundation to the optimization design.The phase trajectory have the simply and visual advantage in analysis,and the relation between system states is reflected clearly.So,it has important guiding meaning to the nonlinear control employing the phase trajectory.Aiming at the issue of DC/DC converter optimal control,this paper makes Buck converter as the research object and turn the optimal control into the design of optimal target trajectory.From the perspective of trajectory planning and control,this paper proposes a hybrid control method based on the trajectory planning and tracking,as well as a sliding-mode control method based on the trajectory constraint law.Make both methods can guide the practical trajectory,realizing the optimization of steady and dynamic processes.Main works of this paper are as follows:Firstly,the basic knowledge of phase trajectory is introduced,which is stated from aspects of dynamic system,movement law,phase trajectory and modeling method.This makes a foundation of this paper research.Secondly,in the aspect of the precious planning of trajectory,this paper makes buck converter as example.Employing non-ideal state space model,the stroboscopic map is used to describe the dynamic and steady behaviors.Aiming at the optimal time response,this paper proposed a time-optimal planning method in the cases of limited current and unconstraint current.The numerical solution of optimal-time trajectory is stated,and the stepping issue in load change process is analyzed.Thirdly,in the aspect of the constraint planning of trajectory,this paper make Buck-IPT as example.Base on resonant characteristics of the behind IPT circuit,builds a reduced-order state space model.In order to improve dynamic performances of Buck-IPT system,a planning method based on the constraint trajectory is presented.Then,this paper proposes a hybrid control method in the implementation of the precious trajectory control,which is a combination of dynamic tracking control based on two mode behaviors and a PI control based on the steady limited cycle.The detecting method and control strategy are analyzed.Simulation and experimental results have verified this hybrid control method.Finally,a sliding-mode control method is presented in the implement of constraint trajectory control,based on the exponential law.After that,simulation and experimental results have verified effectiveness.