Adaptive Sliding Mode Control Of Three-phase PWN Power Converter

With the development of semiconductor integration technology and power electronic components,power electronic equipment plays an increasingly important role in people's daily lives,and power converters are also used in various occasions.The traditional uncontrolled rectifier and phase-controlled rectifier inject a lot of harmonics and reactive power into the power grid during operation,which not only reduces the efficiency of energy transmission from the power grid to the electrical equipment,but also causes extreme safety questions and electricity quality problems.The three-phase pulse width modulation(Pulse Width Modulation,PWM)power converter solves the current harmonic problem from the source,and has the advantages of operating at unit power factor,continuously adjustable DC output voltage,and fast dynamic response speed.It makes up for the defects of traditional rectifier equipment.The research of three-phase PWM power converter is increasing day by day.The following research and work on the control technology of three-phase voltage-source PWM power converter has been carried out:Significance and background of the three-phase PWM power converter,the current status of topology research,the current status of mathematical modeling research and the research status of control strategy are first described.The three-phase voltage-source PWM power converter is selected as the research object.Based on the topology of the three-phase voltage-source PWM power converter,its working principle is analyzed,and its switching state and working mode are elaborated.The mathematical model of the three-phase voltage PWM power converter in the two-phase stationary coordinate system is established under ideal circumstances.The mathematical model is converted to a two-phase rotating coordinate system by coordinate conversion.The AC currents and voltages are converted into DC,which provides convenience for the design of the subsequent controller.According to the mathematical model of the three-phase voltage-source PWM power converter in the two-phase rotating coordinate system,the parameters of the main circuit components are selected by analyzing the control performance of the converter.The performance indices of the three-phase voltage PWM power converter are proposed,the voltage and current double closed-loop control strategy is adopted,and the proportional integral(PI)controller is used to design both the current inner loop and the voltage outer loop.Based on the voltage and current double closed-loop control strategy,the outer voltage loops all adopt sliding mode variable structure controller,and the inner current loops adopt sliding mode controller,adaptive first-order sliding mode controller and adaptive second-order sliding mode controller respectively.Stability analysis are conducted separately.Simulink simulation models are built and simulation experiments are carried out.Experimental results show that in three-phase voltage-type PWM power The proposed adaptive second-order sliding mode control algorithm has better effects than first-order sliding mode control algorithm,the start-up time is reduced by 31.3%,the output voltage ripple peak-to-peak value is reduced by 7.6%,the voltage drop during sudden load is reduced by 12.1%,and the harmonic content is reduced by 22.6%;sliding mode control has a comprehensive effect improvement over PI control.The proposed adaptive first-order sliding mode control algorithm has better effects than sliding mode control algorithm,the peak-to-peak value of output voltage ripple is reduced by 40.0%,the voltage drop of the load mutation is reduced by 6.5%,and the harmonic content is reduced by 14.9%.