逆变器数字控制频率混叠现象分析与抗混叠策略研究

Analysis of Freguency Alias of Digital Controlled Inverters and Its Suppression Method

数字控制逆变器系统中不可避免的存在频率混叠问题,频率混叠会恶化系统的输出电能质量。本文重点分析了采样信号中混叠成分(混叠信号)与原始信号频率、幅值和相角的关系,以单极性倍频调制的单相逆变器为例分析了频率混叠在逆变器数字控制中造成低频谐波的机理,并揭示了采样滤波、A-D转换时间以及控制算法时间对混叠现象的影响。在上述定量分析的基础上,本文提出了选择性延时采样和互补采样方案抑制系统中产生的混叠信号,实验表明了这两种方案的有效性。

The digital controlled inverter system inevitably has the problem of frequency aliasing which brings deterioration of system power quality. This paper focuses on the relationship between the frequency, amplitude and phase angle of aliasing signals and the original signal. Then the frequency aliasing phenomenon of single phase inverter under SPWM is analyzed, and the influence of sampling filter, the time of the A-D conversion and the time of control algorithms on the aliasing signal are revealed On the basis of the above quantitative analysis, this paper presents a selective delay sampling and complementary sampling scheme to suppress aliasing signal generated by the system. Experiments verify the effectiveness of these two programs.