Research Of Three-phase PWM Rectifier Key Technologies Based On SVPWM

According to the power semiconductor switching devices in the power electronic devices, the traditional diode uncontrolled rectifier and thyristor phase controlled rectifier in the operation process, there is a large amount of harmonic component in the network side current and DC side voltage and lower total power factor. PWM rectifier has the advantages of low harmonic pollution, AC side input current is sine wave, unit power factor control, DC side dynamic control response fast and four quadrant operation, make it widely used in all kinds of power electronic field. For the key technologies of PWM rectifier, which mainly includes the improvement of the system control strategy, the unbalanced situation of the power grid and the phase tracking problem, it is necessary to conduct in-depth research. This paper focuses on the study of three-phase voltage source PWM rectifier.This paper firstly introduces the background and significance of the research, and gives the research status and the main content of the PWM rectifier. Based on the main circuit topology of three-phase VSR, the mathematical model of three-phase VSR in the dq coordinate system is established. And the space voltage vector pulse width modulation technology is used to analyze and implement the two control strategies. One is based on the traditional PI double closed loop control strategy; the other is based on the EL model of the passive control algorithm. According to the EL mathematical model of three-phase dq in the VSR coordinate system, a passive controller with excellent performance is designed. The system output is stable, and the parameters of the AC inductance and the DC side capacitor are designed according to the dynamic and steady characteristics of the system.Secondly, in the case of unbalanced three-phase grid, the positive and negative sequence current in the grid has 2 harmonic problems, and a double current control strategy based on positive and negative sequence rotating coordinate system is proposed. Also in phase tracking precision, analyzes the working principle of the synchronous single and dual synchronous coordinate system software phase-locked loop, and the dual synchronous coordinate system software phase-locked loop is improved, so it can filter out the phase-locked loop input signal in the 2nd harmonic component, according to the three-phase electric network voltage fundamental positive sequence and negative sequence components, derived the mathematical relationship between the actual phase and the phase lock.Finally, on the premise of theoretical analysis, based on Matlab/Simulink, the simulation experimental platform, build the simulation model of three-phase VSR each function module, which mainly SVPWM modulation algorithm was verified. In addition, the good performance of three-phase VSR control system simulation model, and emphasis is given to the DC side voltage, the AC current in the three-phase grid voltage in simulation waveforms in balance and imbalance in these two cases, and analyze the results of the simulation waveform.