Study On Repetitive Control Theory For CVCF Inverters

The repetitive control (RC) theory is a new theory based on internal model (IM) principle. It is an effective method to overcome the periodic disturbance. In AC power system, nonlinear loads are major sources of total harmonic distortion (THD). This built the motivation for this dissertation. Therefore, research works have been done through simulation and experiment on RC characteristics, basic controller design principle and RC application in AC power system.Firstly, the relationship between IM, compensator and plant has been studied from the viewpoint of poles placement, according to which, the relevant explicit expression has been deduced. And from it, optimal compensator can been obtained. Secondly, the characteristics of RC have been studied profoundly when disturbance is stochastic. Thirdly, dynamic characteristic of RC has been analyzed. The factors that can improve the performance of transient response have been discussed.Two new design methods of repetitive controller have been proposed based on designing of prototype repetitive controller. First, we present a method to get optimal controller by assigning all poles of system on a given radius. Compared with old method, new method can get explicit parameter of controller, which can guarantee best performance for system. In addition, another method has been proposed for plant that has unstable zeros. The ideal effects have been obtained in steady error and rate of error convergence.By studying the parameter shift of component, a new method that build inverter's model by circuit's topology and parameters has been applied in RC system. According to plant model, modified design method based on partly cancellation is adopted for AC power system. Because new controller has strong stability, RC system doesn't need high accurate mathematics model. Furthermore, the stability can be improved by using special function in IM and compensator.A novel controller design method is proposed for inverter. A repetitive controller can be obtained by designing a zero phase shift low pass filter. With the help of digital signal processing and software tools, it is easy to design a satisfactory controller. The performance of system has been improved remarkably. It is a good method to design repetitive controller for inverter.