Application Research For Direct Current Converter Based On Sliding Mode Variable Structure Algorithm

Nowadays, the accuracy and complication of industry equipments has achieved such a high degree that people can not control it effectively if only depends on human being. However, the computers are playing more and more important role in the industry field depending on their accuracy and pragmatically.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's 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.Due to the Buck converter has the nonlinear component, and the circuit has two kinds work statuses which are switching on and off, the status exists obviously switch characteristic. So the nonlinear arithmetic strategy for the Buck converter has been richly endowed by nature, especially the Sliding Mode Arithmetic (SMA). The present research methods apply the two dimension parameter to design the SMA controller, which is used for load voltage or current separately to create the sliding mode function. They can not reflect the system dynamic behaviors. In addition, the SMA algorithm produces flutter effect which is the main obstacle for the application of SMA controller in the practice.This thesis designs a three-dimensional sliding mode function; this function contains three parameters which are the difference of the load voltage, the difference alternative rates and the inductance currents. The purpose is to improve the nonlinear algorithm application performance on control Buck converter fields; at the same time, this method can reflect the system information and dynamic behavior. On account of the SMA has the self-chatter phenomenon, we can only try our best to restrain it but there is no way to avoid it. The thesis bases on the three-dimensional function, also separately use the Tendency Arithmetic (TA), Dynamic Sliding Mode Algorithm (DSMA) and the Fuzzy Algorithm (FA) to design and implement three relevant algorithm controllers to restrain the chatter.We have done the computer simulations for these three controllers on the Buck converter, and the results of the simulation testify that the three-dimensional sliding mode function designed in the thesis can control the converter effective. Furthermore, the restraining chatter, response velocity and the time of achieving stabilization status also have good effect.