| High-power frequency converter rapid feedback control system has a wide range of applications in the field of transmission system. In ac-dc-ac voltage frequency Control System, dual PWM rectifier and inverter adopt PWM technology to control rectifier bridge with sine PWM, making the input current nearly approach sine wave current and phase controllable, so its input current Only contain high harmonics with switching frequency, these high-frequency harmonics, easily filtered out, but also the power factor close to 1, to reduce the power grid hazards.In steady-state condition, the working principle of voltage source type PWM rectifier has been analyzed here, the key for which has been found to be ac-side current control. Based on the mathematical model under reference frame (a,b,c), the mathematical model under reference frame d-q is deduced by introducing the idea of rotating reference frame. After analyzing and comparing two kinds of direct and indirect current control methods of three-phase VSR, the author employs the latter as main control scheme by using dual closed-loop control scheme, through sampling instantaneous current of phase a and b and converting them by 3s/2r to get active component and reactive component of ac-side current ,directly control the phase and amplitude of current.On the basis of theoretic analysis, reconstruct the diode VSR ac-dc-ac rectifier, modify and design the procedure and control strategy that is SVPWM technology. Adopted MATLAB / Simulink to simulate three-phase VSR and analyze simulation results. In this experiment, we presented the relevant test waveform, and analyzed the experimental results. |
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