The Research Of Three Phase Voltage Source PWM Rectifier Based On Sliding Mode Control

In recent years, power electronics products are applied widely in production and life field, promoting an in-depth study of rectifiers and rectifying techniques. Traditional rectifiers of un-controlled diode and half-controlled thyristor inject a lot of harmonic and reactive into the power grid, causing serious power pollution, besides it exists many other serious drawbacks such as low power factor, AC input current serious distortion. Applying PWM control technology to control the rectifier circuit appropriately can make the input current and voltage of line-side to be sine wave which has same phase, realize unit power factor, and get a stable and controllable DC voltage-output, and even make the energy of line-side and DC side can be transmission with each other. The many advantages of the PWM rectifier make it widely used in various areas of power electronics and become a hot research topic.This paper first introduces the research and application of hot issues of the PWM rectifier, introduces the major typical topology, detailed analyze the principle of four-quadrant operation, and laborates the works of single-phase and three-phase voltage source PWM rectifier one by one. On the basis of introducing the works, we establish the mathematical model of three-phase PWM rectifier in the ABC three-phase and the αβ two-phase stationary coordinate system, as well as the mathematical model in dq two-phase synchronous rotating coordinate system which is based on switching function.Then, we introduce the basic theory and modeling of the sliding mode variable structure control, and analyze the reasons of the existence of the buffeting and give several weaken measures. After analyzing the applications and problems of the sliding-mode control for PWM rectifier, the three-phase PWM rectifier will be seen as a whole system, and establish the sliding surface computing unit based on the voltage and sliding-mode control law which is based current.Finally, we build a model of nonlinear control system in MATLAB, give the achievement method of space voltage vector control method and build the model to generate SVPWM wave. We through the voltage and current waveforms of line-side, as well as the DC voltage waveform to verify the characteristics of PWM rectifier that can make the input current sinusoidal, power factor, energy can flow in both directions and so on. We then compare the waveform of the conventional PI control and sliding mode control system, which have disturbance, and through the simulation wave to verify the feasibility and advantages of applying the sliding-mode control to PWM rectifier.