Research On Controller Of Three-Level PWM Rectifier

The generation and development of Multi-level PWM rectifier technology is based on the development needs of power system, high power AC moter frequency control, energy, the twice seriously global energy crisis since the 1970s, and the background of widespread concern of global energy-saving technologies and environmental technology caused by the environmental pollution. The Multi-level PWM rectifier technology has the advantages of flexible control options, easy to adjust and control of phase and amplitude of the output voltage, low output voltage harmonic content, high efficiency rectifier and suitable for high power output. Therefore, it's has great significance to solve energy, environmental and economic problems by study of Multi-level PWM rectifier technology.This paper studies the three-level PWM rectifier system, mainly for theoretical analysis of three-level PWM rectifier, MATLAB simulation of double-loop controller and the system implementation of hardware and software. The platform of this system is Protel DXP and TMS320F2812 and the software of this system is MATLAB and CCStduio 3.3.First, analysis the circuit topology and mathematical models of three-level PWM rectifier system and focus on the main circuit of diode-clamped topology, then analysis the principle of work and build the models of the circuit by coordinate transformation of equiamplitude and d, q.Second, research space voltage phase control method of three-level PWM rectifier and build, analysis the effect to the midpoint voltage by the basic phasor and research the algorithm of 60°coordinate system, the choice of the basic phasor, the calculation of action time and the determination of output switch state. Then, bulid SVPWM pluse simulation system by MATLAB and get the experimental results.Third, design the controller of three-level PWM rectifier and make the simulation study. Analysis control theory of the current loop and voltage loop. Get mathematical model of current loop by stationary and rotating coordinate transformation and design PI and PR parameter of current loop controller. From the experimental results, the current and voltage achieve the same phase, the DC bus voltage follows the expectation voltage and the total harmonic distortion of network side current is 1.32%.Finally, design the experimental platform of three-level PWM rectifier system, including the hardware design of main circuit, sampling circuit, drive circuit, protection circuit, control circuit and the software of control system. The run results are consistent with the desired effect.