Buck变换器导通模式转换滑模PI混合控制策略

Hybrid control strategy with sliding mode and PI controller for Buck converter considering conduction mode

为了满足Buck变换器由待机或轻载向较大负载状态快速转换的需求,基于对传统平均电流控制Buck变换器的动态性能分析,提出了一种改进的适用于断续导通模式/连续导通模式过程的滑模PI混合控制策略。该策略电压外环依据系统状态和导通模式分别采用PI控制器和滑模控制器,其中稳态工况应用PI控制器,负载增大动态工况根据导通模式转换为滑模控制器,并通过统一校正的平均电感电流实现导通模式的准确判断。该混合控制策略可以有效结合PI控制与滑模控制各自的稳态与动态性能优势。仿真和实验结果表明,相比于传统平均电流控制,本策略动态响应时间缩短约65%,电压跌落减小35%以上。

To meet the demand for fast conversion of Buck converter from standby or light load to large load state,based on the dynamic performance of the Buck converter with the traditional average current control method,the improved hybrid control strategy with sliding mode controller and PI controller suitable for DCM/CCM process is proposed.According to the system state and conduction mode,the PI controller or the sliding mode controller is utilized in the voltage outer loop.In addition,the PI controller is used in the steady-state condition,which is then converted to the sliding mode controller according to the conduction mode in the dynamic condition of the load increase.Furthermore,the accurate judgment of the conduction mode is realized by the unified corrected average inductance current.Thus,the proposed hybrid control strategy can effectively combine the steady-state and dynamic performance advantages of PI control and sliding mode control.The simulation and experimental results show that,compared with that of the traditional average current control,the dynamic response time of this strategy is reduced by about 65% and the voltage drop is reduced by more than 35%.