三电平PWM整流器定频直接功率控制的研究

摘要

Based on the mathematical model of the three-level voltage source PWM rectifier and the theory of instantaneous power, in this paper, a Direct Power Control (DPC) scheme for three-level PWM rectifier with constant switching frequency is proposed, which based on Space Vector Pulse Width Modulation (SVPWM). The new control structure is a double closed-loop system which uses closed-loop DC voltage control as outside control and closed-loop power control as internal control. On the one hand, The using of power feed forward decoupling realized the direct decoupling control between active power and reactive power during the dynamic course;On the other hand, the using of Space Vector Pulse Width Modulation made the switching frequency fixed, which simplifies the design of filter. Simulation results show that unity power factor is achieved, and the neutral-point potential is balanced, and harmonic distortion of current is low, and the performances that system obtains are excellent dynamic and steady.%　　以三电平电压型 PWM 整流器的数学模型为基础，结合瞬时功率理论，本文提出了一种基于空间电压矢量脉宽调制的三电平 PWM 整流器定频直接功率控制策略。其控制结构是由电压外环、功率内环组成的双闭环控制系统。该系统一方面采用功率前馈解耦控制，实现了动态过程中有功功率和无功功率的解耦直接控制；另一方面采用空间电压矢量调制，固定了开关频率，从而简化了滤波器的设计。仿真结果表明：该控制策略实现了单位功率因数运行、中点电位平衡、电流谐波小的良好动、静态性能。