Research On Nonlinear Control In Switching Dc-dc Power Converters

In recent years, due to the development of power electronics technology, switching power converters has been applied in various fields deeply. Among those applications we require switching power converters with high-quality output waveform, whose quality includes following two aspects:good dynamic performance and high steady-state accuracy. So the study of simple control strategy on switching power converters with excellent dynamic and static performance has always been the power electronics and automation researching hot issues.Considering the physical characteristics of DC-DC power converters system, we give the average state-space model according to their'on'and'off'stage. In order to obtaining the high-performance power converters, we apply nonlinear control method to design several new types of controllers based on the average state-space model.Firstly, according to the variable structure of DC-DC power converters, we design sliding mode controller. At the same time we take into account inner links of two sliding surface. Sliding mode control has the strongpoint of fast response and strong robustness of system parameters and external disturbs. And the disadvantage is the chattering problems in practical sliding mode.Secondly, this thesis combines the Backstepping, sliding mode, adaptive methods to design the controller of DC-DC power converters. Simulation results show that: These methods can eliminate sliding chattering in certain extent, but the system response time is a little longer than only sliding controller.In the ending, considering the rapidness of the sliding mode control and good stability of the Backstepping sliding mode control, we use the controllers switching strategy to make two controllers switch to get the fast system response, and eliminate the chattering. A large number of simulation results showed that under the designed controllers the system has good tracking performance, goodish steady state and dynamic performance. It means that the control strategy we propose can meet the requirements of DC-DC power converters, further more the controllers are simple and have strong robustness.