基于级联结构Thiran滤波器的分数阶双模重复控制

FRACTIONAL-ORDER DUAL-MODE REPETITIVE CONTROL BASED ON CASCADED STRUCTURE THIRAN FILTER

针对双模重复控制器在电网频率波动时稳态误差大的问题,提出一种基于级联结构Thiran算法的无限脉冲响应滤波器(infinite impulse response filter,IIR)来逼近分数延迟环节,提高系统的稳态跟踪精度。该文采用一种由连分式推导得来的级联结构替代以往实现Thiran算法的直接结构,所设计的级联结构Thiran算法用于IIR滤波器中能在线调整滤波器参数,且相较于以往的直接结构,级联结构每个“积木块”的功能仅用两个乘法器就可实现,简化了参数设计,便于应用推广。基于分数阶双模重复控制器,并采用比例-双模重复控制复合的电流控制策略,控制逆变器输出高质量的并网电流。最后,通过仿真与实验结果验证所提策略的准确性及有效性。

Aiming at the problem of large steady-state error of dual-mode repetitive control in grid frequency fluctuations,an improved infinite impulse response(IIR)filter based on Thiran algorithm of cascaded structure is proposed.This improved IIR filter can effectively approximate the fractional delay link and improve the steady-state tracking accuracy of the system.In this paper,a cascade structure derived from the continued fraction is used to replace the direct structure of the previous implementation of the Thiran algorithm.Moreover,the designed cascade structure Thiran algorithm can be used in the IIR filter to adjust the filter parameters online,and compared with the previous direct structure,each block of the cascade structure can be implemented with two multipliers,which simplifies the parameter design and facilitates the application and promotion.Based on the fractional-order dual-mode repetitive controller(FO-DMRC),and using the current control strategy of proportional and FO-DMRC combination,the inverter is controlled to output high-quality grid-connected current.Finally,simulation and experimental results verify the accuracy and effectiveness of the proposed strategy.