Control of Inverters Via a Virtual Capacitor to Achieve Capacitive Output Impedance
Control of Inverters Via a Virtual Capacitor to Achieve Capacitive Output Impedance
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DOI：
10.1109/tpel.2013.2294425
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发表时间：
2014-10
影响因子：
6.7
通讯作者：
Qing-Chang Zhong;Yu Zeng
中科院分区：
文献类型：
--
作者：
Qing-Chang Zhong;Yu Zeng
主流逆变器在低频下具有感应输出阻抗(这种逆变器被称为L逆变器)。本文提出了一种控制策略，使逆变器的输出阻抗在低频下容纳化(这类逆变器称为C逆变器)。所提出的控制策略包括通过积分器反馈电感电流，该电流实际上是虚拟电容器的阻抗。首先选择积分器的增益或虚拟电容来保证电流反馈环的稳定性，然后优化以最小化输出电压的总谐波失真(THD)。此外，还提出了一些指导原则，以便于选择C逆变器的滤波元件。仿真和实验结果证明了C逆变器的可行性和优良的性能，并根据制定的准则选择了试验台的滤波参数。结果表明，在硬件相同的情况下，当逆变器设计为C逆变器时，THD电压最低。这项研究的一个副产品是，只要电流纹波保持在所需的范围内，就应该选择尽可能小的滤波电感，以减少电压谐波。这有助于减小电感的尺寸、重量和体积，并提高逆变器的功率密度。
Mainstream inverters have inductive output impedance at low frequencies (such inverters are called L-inverters). In this paper, a control strategy is proposed to make the output impedance of an inverter capacitive at low frequencies (such inverters are called C-inverters). The proposed control strategy involves the feedback of the inductor current through an integrator, which is actually the impedance of a virtual capacitor. The gain of the integrator or the virtual capacitance is first selected to guarantee the stability of the current feedback loop and then optimized to minimize the total harmonic distortion (THD) of the output voltage. Moreover, some guidelines are developed to facilitate the selection of the filter components for C-inverters. Simulation and experimental results are provided to demonstrate the feasibility and excellent performance of C-inverters, with the filter parameters of the test rig selected according to the guidelines developed. It is shown that, with the same hardware, the lowest voltage THD is obtained when the inverter is designed to be a C-inverter. A by product of this study is that, as long as the current ripples are kept within the desired range, the filter inductor should be chosen as small as possible in order to reduce voltage harmonics. This helps reduce the size, weight, and volume of the inductor and improve the power density of the inverter.