Research On Three Phase Pulse Rectifier Based On Space Voltage Vector Control

The conventional rectifier section widely consists of diode-rectifier circuit and phase-control thyristor rectifier, which injects large amounts of harmonics into the power networks and produces much contamination. The three-phase voltage-source PWM rectifier(VSR) have the characteristics of constant direct voltage, high power factor, small harmonic pollution, bidirectional power flow, so they have more and more application perspective in active filtering, reactive-load compensation and motor control systems.The principle of single-phase voltage-source PWM rectifier was introduced in details, constructing the high and low-frequency mathematical model based on the three-phase static coordinate system and the two-phase synchronous rotating coordinate system from the point of the topology of the main circuit, and select the three-phase voltage-source PWM rectifier as this major study. With the voltage space vectors pulsewidth modulation, we can get higher usage of the voltage, at the same time it can effectively reduce the current harmonics. In this paper, the principle of three-phase voltage space vector and the specific implementation were analyzed in details, choosing the vector sequencing strategy with relatively small harmonic content.As to the current control scheme, this paper propose a directly current control scheme, which with fixed switching frequency in dq rotation reference frame. And also, we introduce current decoupling input voltage feedback, which makes the system more stable and faster response, and through the closed loop system simulation to verify the feasibility of this current control scheme.In connection with shortage of conventional PI control, the improvement of PI control algorithm, which combine the characteristic of separate integral and change-velocity integral. In the case of not affecting the system's response speed, using improvement of PI control algorithm can slow down the rise speed and descent speed of DC voltage, and it can restrain output overshoot efficaciously. An analysis of the PLL how to affect the control system are took, and make a study and simulation on power frequency fluctuations. The designing method of the parameter of the main circuit is also described. The main circuit parameters on the dynamic characteristics and static characteristics have significant influence. The result of the simulation proves that analysis results are right and feasible.