The Research And Implementation Of Switching Converter’s Sliding Mode Control Technique

Switching converter is the core part in all kinds of electric energy conversion devices, its application is more and more wide. The control system has an important influence on the performance of the switching converter and is associated with a number of technical indicators. The traditional control method is a linear control based on the converter’s small signal model. When there is a large transient change, the behaviors of the converter cannot be fully reflected, it will probably make the system to be unstable. The sliding mode control is a new control technology, belongs to the category of nonlinear control. It is especially suitable for the circuit with “switch” characteristic like the switching converter. It has the characteristic that can make the system stable when the input or the load changes in a large range.In this paper the sliding mode control of switching converter technology is researched. Based on the summary of various converter control technology, analyze the basic principle of the traditional voltage control and current control and point out their limitations in the control. Focus on the new control technique—sliding mode control, analyze its basic concept and mathematical description, associate with the switching converter and summarize the universal design method of the sliding mode control switching converter.A direct sliding mode control switching converter was designed based on hysteresis modulation. Combined with the three basic principle of sliding mode control, derived the design formulas and provided the detailed calculation process of the control parameters, analyzed the influence of different parameters to the system performance. A control model was established by MATLAB/Simulink to simulate the transient response of the system under the external disturbances and the different performances in different design parameters. In order to solve the problem that the switching frequency is unset when the input or load changes and realize the fixed frequency control, equivalent control principle was used to convert the direct sliding mode control to indirect. Also discussed the principle of design, parameter selection and system simulation in detail.In the aspect of circuit implementation, the hardware circuit was structured by universal electronic components according to the existing design parameters. Simulated the main circuit module and tested the designed system in actual, verified the theory on design.