The Control Of Sliding Mode Variable Structure On Buck Converter

The Sliding Mode Control System (SMC) is a switching feedback control system with superior robustness; the Buck converter is also a switching control system essentially. Therefore, the application of the Buck converter sliding mode control can achieve better control performance. This paper works on sliding mode control theory applied to BUCK converter, seeks practical sliding mode observer design method, and designs and implements of sliding mode controller hardware circuit. It aims at improving the practicality and robustness of the sliding mode observer, and the dynamic characteristics of the BUCK converter. The main research work and conclusions are as follows:First of all, for the design problem of the state observer of the BUCK converter, the traditional sliding mode observer is analyzed. An adaptive sliding mode observer is designed based on the use of this equivalence principle of sliding mode, realized unknown state variables tracking of the BUCK converter. By comparison with the traditional sliding mode observer, it verified the new design of adaptive sliding mode observer has better steady state accuracy.Secondly, for the chatter problem of sliding mode observer, the idea of sliding mode controller to suppress the chatter using rate is extended to the design of sliding mode observer. Based on the merits of the integration reaching law and power frequency reaching law, power frequency integration reaching law and power frequency exponent integration reaching law sliding mode observers are designed. From the simulation results two new design methods, it shows that the sliding mode observer can achieve the design requirements, and play a good chattering restrained effect.Finally, combined with characteristics and engineering requirements of the BUCK circuit, proposed the application of BUCK converter technology based on the sliding mode control. The hardware circuit of sliding mode controller is realized by using operational amplifier. The experimental results show the validity and avaliability of the theory and technology of this paper.