Research And Implementation Of Voltage Source PWM Rectifier Based On Sliding Mode Variable Structure Control

With the development of power electronics, microelectronics and computer, the power conversion apparatus based on the PWM (Pulse Width Modulation) technique is gaining more and more application. PWM rectifiers have the characteristics of large power factor, small harmonic pollution, bidirectional power flow, small capacity power storage segment and constant direct voltage, so they have more and more application perspective in active filtering,reactive load compensation, tide control, solar electrical energy generation and motor control systems.The PWM rectifier is a multivariable, nonlinear and strongly coupled time-variant parameter system. For obtaining a high-performance control system of the PWM rectifier, modern control theories and advanced control strategies must be applied so that the system has strong robustness to overcome the influence of parameter variance, load variance and nonlinear factors on systemic performance. Sliding-mode variable structure control is a strong robustness control method, has low requirements for the accuracy of a systemic mathematical model, and has the advantages of rapid response, insensitiveness to parameter variation and external disturbance variation, no need of systemic online identification, easy implementation, suitability for computer implementation, etc.Therefore, the sliding-mode variable structure control is very suitable for thehigh-performance PWM control system.This paper selects the three-phase voltage source rectifier as a research object researching the designing goal and the designing method and the invariance of the VSC. The theory and the structure of PWM rectifier are analysed in details, construct the mathematical model under three phase stationary reference frame, two phase stationary reference frame and two revolvi-ng reference frame. And the connection among DC voltage, AC current, source voltage and switching mode of rectifier is also included. On the basis of the theory analysis, this paper constructs the simulation experiment for the design scheme based on MATLAB/Simulink, and compares the design scheme proposed Abstract in this paper with the traditional PI control scheme.Finally according to the simulation of the system a main circuit and a control circuit are built. For the main circuit, its main task is setting and calculating the parameters of the AC-side inductance, the DC-side capacitor and the IGBT based on control algorithm and the performance of the system. The control section is based on TMS320F2812that a DSP chip product of TI Company, including voltage and current detection-conversion module, the power switch driver module, PWM output module. It is introduced in this paper that the ideas of modular design and the process of working in details. Then debugging and analyzing are implemented according to the requirement of the system and the performance of DSP chip. The experimental results show that the system can response rapidly and achieve the stable value in a short time...