Application Of Sliding-Mode Variable Structure Control In Power Electronic Switching Converters

This paper is devoted to studies of power electronic switching converters using Sliding Mode Variable Structure Control (SMVSC) theory. Since the "on-off operation mode is the only admissible one for power converters, it does not cause any difficulties when they are controlled by SMVSC which implies high frequency switching in implementation. The main advantage over the classical control schemes (e.g. PWM control) is its robustness for plant parameter variations, which leads to invariant dynamics and steady-state . response in the ideal case. Some literature states that sliding mode control has been presented as a good alternative to the control of switching power converters. SMVSC is firstly applied to H-model bridge DC-DC converter, three-phase rectifier and three-phase inverter in this paper.On the basis of the mathematical descriptions of power converters in which load, filter and switching matrix are taken into account together, such as DC-DC converter, three-phase rectifier and inverter, the sliding mode controllers with double closed-loop structures of current and voltage loop are designed to improve the robust and dynamics of power electronic switching converters.The chatting problem is the main obstacle to use the variable structure sliding mode control widely. In order to alleviate this phenomenon, the reasons that lead to the chatting and several alleviating chattering methods are discussed and analyzed in detail, and a new chattering alleviation method, a Fuzzy Sliding Mode Variable Structure Controller (FSMVSC), is proposed in this paper. FSMVSC combine the advantages of both fuzzy control and sliding mode variable structure control.The proposed algorithms are verified by simulation. The results show that SMVSC for power converters is rather simple and yet quite efficient, and that the advantages of FSMVSC are obvious in comparison with traditionalSMVSC.