三相电压源整流器有限控制集扩充方法研究

Research on Finite Control Set Expansion Method of Three-phase Voltage Source Rectifier

有限集模型预测控制(finite control set model predictive control,FCS-MPC)处理优化问题有较大优势,但其控制精度在低采样频率下会急剧下降。以三相电压源整流器为例,现有解决方法多采用扩充矢量或改用调制型预测控制(modulated model predictive control,M-MPC),其本质在于通过增加开关频率提升控制精度,并未起到优化效果。为解决FCS-MPC在低采样频率下控制效果差的问题,同时为了能以较低的开关频率最大限度地提升控制精度,在分析FCS-MPC开关频率与控制误差间非线性关系的基础上,提出一种新的控制集扩充方法。通过构建12个新的电压矢量来扩充控制集,显著提升了FCS-MPC在低采样频率下的控制精度,且带来的开关频率增加较小。同时,在相同开关频率下,所提方法能够取得更优于M-MPC的控制效果。此外,通过调节目标矢量的权重还可改变其扩充模式,保留了FCS-MPC简单、直接的特点。最后,通过对比仿真及实验验证所提方法的有效性。

Finite control set model predictive control(FCS-MPC)has great advantages in dealing with optimization problems,but its control accuracy declines sharply at low sampling frequency.Taking three-phase voltage source rectifier(VSR)as an example,the essence of traditional solutions for this problem,mostly the extended vector or modulated MPC(M-MPC),is to improve the control accuracy by increasing the switching frequency,which can not achieve an optimization effect.To solve the problem of poor performance of FCS-MPC under low sampling frequency and improve the control accuracy with the minimum increase of switching frequency,a new control set expansion method for three-phase VSR is proposed based on the analysis of the nonlinear relationship between switching frequency and control error of FCS-MPC.The control set is expanded in the proposed method by constructing 12 new voltage vectors and by using these new added voltage vectors.The control accuracy of FCS-MPC at low sampling frequency is significantly improved and the increase of switching frequency is minimized.The proposed method could also achieve better performance than M-MPC under the same switching frequency.In addition,the expansion mode could be changed easily by adjusting the weighting factor of the added vectors,which retained the characteristics of simple and direct of FCS-MPC.The effectiveness of the proposed method is verified by simulation and experiment.