Study And Design Of Three-phase Voltage Source PWM Rectifiers

The21st century is the era of science and technology, and the era of information. The innovation of science and technology to people’s all aspects of production and life brought great convenience. People have higher dependence and require of electronic products, especially in harmonic suppression and reducing reactive power of the negative impact of power grid. Compared with conventional diode non-controlled rectifier and thyristor phase-controlled rectifier, three-phase voltage pulse width modulation (PWM) rectifier with many virtues, such as sinusoidal line current of grid side, high power factor, power can be two-way transmission, etc., in line with the "green energy "requirements, which are widely used in static var generator (SVG), high-voltage direct current (HVDC) transmission, superconducting magnetic energy storage (SMES), active power filter (APF) and other areas. Now widely used by bicyclic PI control strategy in rotating coordinate system. But the PWM control strategy have many defects that does not meet certain requirements such as the nonlinear characteristics, a small input current distortion and unity power factor, although the PI regulator is easy to implement. Sliding mode variable structure control with self-adaptive, fast dynamic response, fast and stable range of advantages, especially for switching control of power electronic systems.Three-phase PWM Rectifier is a time-varying nonlinear, strong coupling system, and a complex control system. The paper use the current inner loop feed-forward and voltage outer ring sliding mode control decoupling strategy. The paper is given the system hardware and software program design on the basis of principle analysis. Finally dose simulation experiment by MATLAB and verified the feasibility and superiority of this control strategy. First, this paper summarized several common topology structure of PWM rectifier, analyzed the general number model and mathematical model of two phase rotating coordinate system and establishing the model, and introduced the conversion relationship between the two,which is on the basis of the analysis of the working principle of three-phase voltage source PWM rectifie.,finally the paper introduces the current inner loop feedforward decoupling control strategy and voltage loop control strategy based on sliding mode.The second, Shows hardware and software of the three-phase voltage source PWM rectifier control system, got the overall structure of the whole system design on the basis of theoretical analysis. Effects and selection principle of inductance L the ac and dc side capacitor C in the main circuit are introduced by hardware design in detail Drive circuit and detection circuit are introduced by it also. Modular design approach was used in software design, it can increase the readability and portability of the system, which greatly shortens the development cycle. Program flow chart are given, such as system of main program and interrupt service subroutine, etc. The overall structure of the software system and the relationship between the parts are introduced.Finally, give the result of resistance load and nonlinear load, and compared with expectations, draw the conclusion.