On Sliding Mode Control For Buck Converter

The Buck converter is the base of all kinds of electrical power ones. It is usually used for the power parts in the machine, and the quality of the converter affects the machines' performance, so the requirement for the Buck converter output precision degree is also higher and higher. The most control algorithms for the Buck converters are linearity control especially in the actual application. Linearity control methods have obvious disadvantages which have higher hypersensitive for system parameters and the robustness is not good. So when the system parameters changed slightly or perturbation, the control output will be quite different and the equipment will be damaged.The sliding mode control technique as a nonlinear control approach has been widely used in power electronic systems and realizes its advantages of good dynamic response,.high robustuess, wide-range signal stability and simple control implementation etc. But its disadvantages of big steady-state error and chattering restrict its application range. Application of sliding mode control theory to the Buck converter and design of practical sliding mode controller are studied in this thesis. The main contributions are as follows.The basic theory of Buck converter is analysed and the mathematical model is given. The Integral sliding mode controller is desigened for the Buck converter to eliminate the output steady-state error. When the upper of the load disturbance is unkowned, the above controller is invalid. Then, adaptive integral sliding mode controller is desigened to solve the problem. An improved integral sliding mode controller is desigened to lower the chattering phenomenon and it also can lower the system stable error by adjusting some controller parameters.The chattering of sliding mode algorithm can't be avoided completely. In order to reduce chattering effects, dynamic sliding mode controller is desigened. But the robustness of Buck converter with the controller is weakened obviously. After analysis of cause, the adaptive dynamic sliding mode controller is desigened to resolve the issue above.At last, the conclusions are drawn, and the further research directions are presented.