Research On Disturbance Rejection Control Methods For Buck Converter

With the rapid development of power electronics technology,the application of DC converters in various fields is increasing,and the performance requirements of DC converters are correspondingly higher.Therefore,improving the performance of the DC converter and obtaining a high-quality output waveform have become the goals pursued by the DC converter.The quality of the output waveform of the DC converter is mainly considered from three aspects: one is dynamic performance,the other is steady-state accuracy,and the third is anti-interference ability.In order to achieve the desired control effect,the research of nonlinear control theory has become an important direction in the research field of DC converter control.Buck converter is used as the research object of control algorithm.The main work includes:In the system modeling,the system parameters such as resistance,inductance and capacitance in the Buck converter may be affected by uncertain factors,and the change of these parameters is regarded as a concentrated disturbance amount.The concentrated disturbance can be divided into mismatched disturbances and matched disturbances in one channel according to whether or not with the control signal.For the mismatched disturbance,if the sliding mode control method can not solve the problem,the observer-based sliding mode compound control method is designed.The disturbance value is estimated by the observer and the feedforward compensation is directly performed to cancel the influence of the disturbance amount on the final output voltage,thereby improving the robustness and anti-disturbance of the Buck converter system.In view of the deficiency of fast response of traditional observer based sliding-mode control methods,A finite-time exact observer is proposed and a corresponding non-singular terminal sliding mode controller is designed to ensure that the controller does not have singular value problems and can make the Buck converter system converge in a limited time.In addition,for the sliding mode control,the power-exponential approach law is designed to cause the chattering phenomenon,which reduces the chattering phenomenon of the Buck converter output voltage.Applying this control method enables the system to have faster convergence speedand stronger anti-disturbance ability.Finally,the DSP is taken as the core component of the control algorithm,and the hardware experiment platform is built.The software design of the sliding mode control method based on the unknown input observer is completed.The experimental results show that the proposed control method has strong resistance to load changes.