Research On Compound Iterative Control Strategy Of Three - Phase Voltage Source PWM Rectifier

With the rapid development of power electronics technology, there has been a wide range of deflectors. Rectifier as an interface between power grid and electrical equipment, has been researched hotly at present. But traditional rectifier device has low power factor, and its harmonic content is high, which cause great harm to the power system and users. In this paper, a kind of “proactive” solution is adopted to transform the device generating reactive power and harmonic.Three-phase voltage-type PWM rectifier can make DC output voltage to constant, the grid side current and voltage at the same phase, the flow of energy bi-directional and harmonic content low, which has been widely used in many areas. First, this paper introduces the background and significance of PWM Rectifier, and analyzes its research status mainly from the three aspects. Then several common topologies of rectifier is analyzed and three-phase half-bridge PWM Voltage Rectifier is selected as the object of study, whose mathematical models were constructed on the three-phase abc static coordinates and the two-phase dq synchronous rotating coordinates, which laid the foundation for the design of the controller.Secondly, the paper adopts the SVPWM direct current control strategy to study the system, which based on a fixed switching frequency. As for PI control cannot well balance dynamic and static performance of the system and waveform distortion caused by periodic disturbance of dead zones, etc. Put forward iterative learning control to the system control. A complex iterative learning control is designed, the convergence condition is given, and the convergence of the iterative learning law is verified. Among which, the voltage outer adopts composite iterative control strategy to get stable DC output voltage and restrain the influence caused by periodic disturbance. Current inner adopts traditional PI control, and achieves high power factor and low harmonic operation of rectifier according to current command outputted by the voltage outer. For sinusoidal pulse width modulation(SPWM) voltage utilization rate is low, dynamic response is slow and other issues, using the voltage space vector(SVPWM) modulation for rectifier control is raised and the detailed analysis of the specific implementation process is done.Finally, the feasibility and superiority of the multiple control strategy proposed by this paper are showed by simulation results.