| Uncontrolled rectifying with diodes and phase-controlled rectifying with thyristors usually appeared in early rectifiers, which fill the grid with a large number of harmonic components and reactive power. PWM rectifier solves the problem. Controllable power factor, low distortion of AC-side current and bi-directional flow of power are three advantages of PWM rectifier. In recent years, LCL filter, which is suitable for middle-power and high-power systems, was proposed by some researchers to replace the conventional L filter on the AC-side.In this paper, main circuit theory and control algorithm were analyzed first. The mathematical model of three-phase voltage source PWM rectifier was derivated. The characteristics of LCL filter was analyzed. The result shows resonance potential of LCL filter. So no damping or under damping may lead to unstability. A new design method for LCL filter was proposed. Based on the current harmonic restriction of IEEE-519 standard, the parameters of LCL filter were calculated by iterative algorithm by the harmonic voltage of SVPWM. The VOC(Voltage-oriented control) algorithm was also introduced. And the active damping methods for resonance elimination were derivated. Their essence is improved algorithm instead of damping resistor to suppress the resonance.Then simulation was carried out using the Matlab/Simulink software. Based on the theoretical analysis and simulation validation, a 500kW/600V prototype was developed. Its software and hardware implementation were introduced in detail. At last the prototype system was tested comprehensively. Then experiments with various loads and under different working modes were conducted and the waveforms were shown. Experiment results show fast dynamic response and good steady-state performance, validating the theoretical analysis and algorithm simulation.
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