内环采用改进无差拍的PWM整流器优化控制

A PWM Optimal Control Method Based on Improved Deadbeat Current Control

无差拍电流控制易受到采样误差和控制延时的影响,而导致电流畸变、电流谐波含量增大甚至系统不稳定。针对该问题,首先提出了三相脉宽调制(PWM)整流器在三相静止a,b,c坐标系下的数学模型。通过坐标变换和离散化获得了一种在两相静止α,β坐标系下基于无差拍控制(DBC)的离散化数学模型。在对给定电流进行"两步预测"的基础上提出一种电流校正算法,该算法可解决延时补偿问题,并降低由于采样引起的误差。最后,在实验室搭建了PWM整流器实验平台,验证了所提控制方法的可行性。

The sampling error and control delay will degrade the accuracy of the deadbeat current control method which can result in current distortion, increasing current harmonics and even making the system unstable.To solve the above problems,the mathematical model of three-phase voltage pulse width modulation （PWM） rectifier in the threephase a,b ,c stationary frame is introduced firstly.On this basis,by coordinate transformation and discretization,the discretization mathematical model based on deadbeat control（DBC） in the two-phase stationary α,β frame is obtained. Based on ＂two-step prediction＂ of the reference current, a new current correction algorithm is proposed.This method can deal with the problem of control delay,and reduce the error caused by sampling.Finally,the experimental plat- form of PWM rectifier is built up in the laboratory, and the practicability of the proposed control method is verified.