Research On Control Parameter Impact On PWM Rectifier Performance

This dissertation takes the Grid Side Converter (GSC) of Wind Power Generation System as working background, studies the Space Vector Pulse Width Modulation (SVPWM) control method of three-phase voltage source rectifier. The impact of control parameters to PWM rectifier was mainly discussed and the theoretical analysis was validated by experiments and simulation based on Matlab/Simulink. The parameters include PI parameters, the limiter of regulator, dead time, switching frequency, modulation index and main circuit. This paper studies the concrete contents including the following aspects.The four-quadrant working principle, mathematical model, topological structure as well as feed-forward decoupling double-closed-loop control of PWM rectifier are analyzed. Then the vector control block diagram was given out, the principle and implementation procedure of SPVWM was analyzed in detail to build the foundation for later chapters.The PWM rectifier double-closed-loop transfer function's derivation and simplification procedures was analyzed concretely. The PI parameters'theoretical value of voltage loop and current loop were calculated in terms of transfer function. The effect of PI parameters to PWM rectifier's dynamic performance and the robustness of PI parameters to inductance was analyzed by simulations. This dissertation studied the effect of limitation of PI parameters to PWM rectifier's dynamic performance, then summarized the process of PI parameters tuning.The reason and effect to output voltage and grid side current of dead-time effect was researched in depth. By ignoring the switching delays as well as the resulting effects of dead time and the minimum pulse width, this dissertation discussed the influence of switching frequency and modulation index on the output voltage harmonic of PWM rectifier under SVPWM.The simulation models of PWM rectifier were built under Matlab/Simulink to analyze the impact of control parameters to PWM rectifier. These parameters include PI parameters, dead time, switching frequency, and modulation index.Design of the main circuit and selection of the parameters are given in detail to validate the impact of control parameters to PWM rectifier's performance. The experiment main circuit and the hardware design of control system of PWM rectifier were introduced. The DSP control system on the basis of DSP TMS3202812, which is appropriate for PWM control method were introduced. The software structure including main program interrupt subroutine flow chart was provided. This dissertation validated SVPWM of PWM rectifier on the flat of small power experiment and analyzed the impact of control parameters to PWM rectifier by accomplishing related experiments such as changing parameters of PI parameters, dead time, switching frequency, and modulation index.By virtue of the control parameters'impacts to the rectifier, these influence factors need to be taken into account when design PWM rectifiers. The rational design of PI parameters and other control parameters can benefit optimizing the rectifier's performance.