The Research And Design On Three-phase Voltage Source Pwm Rectifier

Compared with diode uncontrollable rectifier and phased thyristor rectifier, PWM rectifier has the advantage of symmetrical sinusoidal AC current, unity power factor operation and two-way flow of energy. In this paper, the soft-ware of three-phase voltage source PWM rectifier which has been tested is designed both in the condition of power balance and the condition of power imbalance.In this paper, the obtain and synchronization of the phase of network voltage is achieved by three-phase software PLL. The method is using the correspondence between PI regulator output error of the angular frequency and the 2812 the timer counts to Generate periodic interrupt timer and add a fixed angel during the interruption process, by which it would achieve the purpose of phase-locked. The experimental result proves the scheme is feasible. By increasing the current limiting resistor and software programming, it overcomes the start-up problem of PWM rectifier in hardware and software. In the condition of balance power voltage, the steady state and dynamic state performance test is conducted. The results show that the three-phase voltage source PWM rectifier achieve the symmetrical sinusoidal AC current, DC voltage following a given constant value, unity power factor operating condition and energy flowing in both directions.This paper deeply studied the relationship of three-phase voltage source PWM rectifier's positive and negative sequence of electric parameters, the mathematical model of three-phase voltage source PWM rectifier and the control strategy of three-phase voltage source PWM rectifier under condition of unbalanced network voltage. On this basis, the model of dual current control system based on the positive and negative sequence current rotating coordinate is established by using MATLAB simulation tools. The results firstly show that the control strategy of inhibiting the negative sequence imbalance current of network could improves the current waveform of three phase voltage source PWM rectifier that makes the three phase current Symmetry. Secondly, the results show that the control strategy of inhibiting the harmonic of DC side eliminate the second harmonic of DC voltage in three-phase voltage source PWM rectifier.It completes the part of three-phase voltage source PWM rectifier's experiment under the condition of imbalance network voltage. Achieve the separation of the imbalance voltage which establishes basis for the experiment of PWM rectifier under the condition of unbalance voltage.It is true that controlling independently using double coordinate system is better in restraining DC voltage harmonic than using identical system. Thus, realizing non-convalesce error, reducing harmonic and energy loss caused by the twice harmonic in asymmetry power system, obtaining quickly following performance and high resistive performance.