Sliding Mode Control Of Boost Converter Based On Switching Model

Boost converters are widely used due to their advantages,such as simple topology,light weight,high efficiency,small size and high reliability.The traditional modeling method for Boost converter ignores characteristics of the device switches and obtains a linearized model with the small signal method,and designs the controller of the converter using linear control theory(frequency domain method).The problems of the traditional modeling and the control methods are: 1)The intrinsic nonlinear state of the converter can not be described with linearized models;2)The controller obtained based on a linearized model and linear control theory can only guarantee its performance near the operating point,and its performance deteriorates significantly when the system states deviate significantly from the operating point.The switching models of converters describe the change of state variables according to the different states of switches,which accurately reflect the operating state of the converter.But,the switching model of converter is a type of nonlinear(piecewise-linear)dynamic model,and the controller cannot be designed with the traditional method of the linear model.The controller of switching models can only be achieved based on Lyapunov theory for nonlinear system,but increases requirements for the designer and lacks general engineering method.The method of sliding-mode variable structure control is a discontinuous control method involving control variable switching near the sliding-mode surface,which has robustness performance and switching characteristics.Therefore,it is of great importance to combine the robust switching of the variable structure controller with the switching model of converters to realize robust switching control for converters.In this paper,the design of variable structure controller of the Boost converter based on the switching model is studied.By combining the switching dynamics model of converters with a certain sliding mode surface,the robust switching control of the Boost converter is constructed,which is robust to the uncertainty parameters of the converter and achieves better control performance.Motivated by the provided arguments,the traditional modeling and design approaches of the controller based on the Boost converter are presented in this paper,and the problems of the traditional methods are analyzed.The controller parameters of the traditional control method are optimized by genetic algorithm with multi-objective to obtain non-inferior solutions and achieve the “optimal” control pasrameters of PI,which can be used as a benchmark for the comparison of the provided methods.Then,the Boost converter control method based on variable structure control theory and switching model is investigated.The correctness and effectiveness of the provided method are compared with the traditional method.The detailed contents of this paper are shown as follows:(1)Firstly,the basic principles of the Boost converter are analyzed,and the mathematical model is set up with Kirchhoff’s law;the double-closed-loop PI control for the Boost converter is simulated and analyzed;The genetic algorithm is used to improve the control parameters of PI control performance.The simulation results show that the optimized PI controller with the genetic algorithm has better control performance than the traditional PI controller.(2)Secondly,the method of sliding-mode variable structure control is proposed for the switching model to improve the control performance of the system.The switching model(piecewise-linear model)is used to accurately describe the essential state of the Boost converter,and the variable structure switching controller is designed to improve robustness performance when the input voltage varied and the load abruptly changed.The simulation results show that the output voltage regulation time of the variable structure control strategy based on the switching model is shorter than that of the genetic algorithm optimized PI control algorithm when the input voltage varied.Additionally,the switching model-based variable structure control strategy exhibits better performance and stronger robustness than the genetic algorithm optimized PI control,when the load abruptly changed.The variable structure control strategy based on the switching model exhibits stronger robustness than the genetic algorithm optimized PI control algorithm,when the inductor parameters are uncertain.(3)Finally,in order to verify the proposed method in this paper,the hardware circuit of the Boost converter with TMS320F28335 as the core processor is designed,the experimental verification of the proposed method in this paper is conducted using the designed circuit.The experiment results demonstrate that the variable structure control method of the switching model provides better control performances.