基于叠加法和正弦幅度调制的阻抗测量注入扰动电流信号形式

Injected Current Perturbation Signal Form for Impedance Measurement Based on Superposition Method and Sinusoidal Amplitude Modulation

电力电子系统的稳定性在很大程度上取决于系统的输入输出阻抗,因此,在系统的控制和设计中,阻抗测量就显得十分重要。文中提出了一种新的谐波电流注入形式,采用这种形式的电流信号进行阻抗测量,可以更加快速准确地获取阻抗特性。该方法采用正弦幅度调制,将方波信号频移到不同的频率区间,然后将这些调制后的信号叠加,即可得到一个包含频谱丰富且整个频段幅值衰减都很小的信号。采用这种形式的信号作为扰动电流注入待测系统,相对于注入传统脉冲电流形式的方法,可以更加准确地测量系统高频段阻抗特性;相对于正弦扰动注入方法,测量时间更短。MATLAB仿真结果表明该方法的有效性。

Impedance measurement is very important in power electronics systems because of the close relationship between impedance and stability. This paper presented a new current injection waveform for impedance measurement, in which sinusoidal amplitude modulation was used to shift square pulse to different frequency bands and superposition principle was applied to obtain a new signal with large frequency bandwidth and small amplitude attenuation. When the superposed signal was injected to the system as a current source, the measured impedance was more accurate in high frequency regions compared to the impulse signal injection method and the time cost was much fewer than that of sinusoidal perturbation injection method. The simulation results demonstrate the effectiveness of the proposed injection waveform.