一种实现电流型PWM整流器直流侧电压波动抑制的控制方法

Control method for suppressing DC side voltage fluctuation of current-source PWM rectifier

三相电流源型脉宽调制整流器发生负载突变时,将导致直流侧输出电压波动。针对该问题,提出一种自抗扰控制与无差拍预测控制级联的综合控制策略。首先,建立整流器在两相静止坐标系下离散化数学模型,电流内环引入无差拍控制策略实现对网侧电流的快速跟踪。为降低控制延时带来的影响,将控制算法预测至k+2时刻并利用算术迭代过程消掉k+1时刻电流,从而提高了网侧电流控制精度以及降低了电流谐波含量。此外,外环引入自抗扰控制直流侧输出电压,通过扩张状态观测器实时估计系统扰动量并加以补偿,克服了传统比例积分控制器参数控制裕度不足和抗干扰能力差等问题。最后,通过MATLAB/Simulink软件以及6 kW实验样机对所提控制策略进行验证。结果表明,系统负载在突增、突减变化时,其输出电压波动能有效抑制在22 V以内,同时保证满载运行时网侧电流总谐波畸变率低至1.98%。

When the load of three-phase current source pulse width modulation rectifier suddenly changes,it will cause the output voltage fluctuation on the DC side.To address this issue,an integrated control strategy of active disturbance rejection control and deadbeat predictive control cascade is proposed.Firstly,the discrete mathematical model of rectifier in the two-phase static coordinate system is formulated,and deadbeat control strategy is introduced into current inner loop to realize fast tracking of grid-side current.To reduce the influence of control delay,the control algorithm is predicted to time k+2 and the current at time k+1 is eliminated by arithmetic iteration process.Thus,the control accuracy of grid-side current and reducing the harmonic content of current is improved.In addition,the active disturbance rejection control is introduced into the outer loop to control the DC output voltage,and the disturbance of the system is estimated and compensated in real time by the extended state observer,which overcomes the problems of insufficient parameter control margin and poor anti-interference ability of the traditional proportional integral controller.Finally,the proposed control strategy is evaluated by MATLAB/Simulink software and 6 kW experimental prototype.The results show that the output voltage fluctuation can be effectively suppressed within 22 V when the system load suddenly increases or decreases,and the total harmonic distortion rate of the grid-side current is guaranteed to be as low as 1.98%under full load operation.