Research On LCL-type Three-phase PWM Rectifier Control System Based On State Observer

Along with traditional energy sources dried up and the increasing environmental problems, the new energy power generation systems are widely used in modern industry application, such as wind and solar energy. Among them, the high frequency three-phase PWM rectifier as power transmission interface become the key technology of new energy generation systems. With the improvement of the power rating, the drawbacks of the traditional single L filter are began to stand out. LCL type three-phase PWM rectifier with its superior filtering characteristics, obtained the rapid promotion. However, LCL filter is a three order system,so more complex control designing, and its inherent resonant characteristics makes the system very easy instability. So this paper will research on control method and the damping technology of resonance of LCL system.This paper firstly to establish the mathematical model in the existing topology of three-phase PWM rectifier with LCL filter, the mathematical model is established in ABC stationary coordinate system and dq synchronous rotating coordinate system.Based on the mathematical model of the dq synchronous rotating coordinate system, take the d axis variables for analysis. Based on the four order model of discrete state space with a lag, analysing and designing about PI full state feedback control strategy.In view of the full state feedback control need more sensors, and there is not easy to detect every state, so the introduction of state observer. First of all, analysing and designing the traditional Luenberger state observer. Because of the observation error of the traditional state observer, put forward the proportional integral(PI) state observer. Through the introduction of the integral term, trying to eliminate the observation error. Finally, describes the principle and design method of Kalman filter, it has better performance in the noise environment.In order to verify the effectiveness of the full state feedback control strategy based on PI, the observation effect of the three kinds of state observer and the feasible of the full state feedback control strategy based on state observer, Three-phase source PWM rectifier with LCL filter is simulated in the MATLAB/SIMULINK environment.Finally, in order to verify the effectiveness and feasible of the full state feedback control strategy based on state observer, we have taken experiments in a three phase PWM rectifier experimental device.