高功率密度单相变换器的直流有源滤波器研究

Researches on DC Active Power Filters for High Power Density Single Phase Converters

单相变换器系统会产生二次脉动功率,使直流母线电压出现二次脉动,危害整个系统。一般采用在直流侧并联大电容或LC谐振电路的方法来抑制直流母线电压的二次脉动,但增加了系统的体积和重量,功率密度较低。为提高系统的功率密度,采用了一种能量双向流动的Buck有源滤波器来抑制直流母线电压的二次脉动。推导滤波器完全补偿脉动功率时电容电压和电流方程,并在此基础上针对高压大功率场合提出双闭环无差拍加重复的控制策略。无差拍控制可提高系统阻尼,重复控制可增加稳态精度。从脉动能量存储、控制带宽两方面讨论APF的参数设计。仿真和实验证明了所提方案能显著减小直流侧滤波电容,提高系统功率密度。

Single-phase converters will produce correlative power and voltage pulsation on the DC bus, which is harmful to the whole system. The pulsating power is usually absorbed by a bulky capacitor bank and/or a dedicative LC resonant link, which results in large volume, low power density and high cost. To improve the power density, an active power filter （APF） topology based on a bidirectional buck circuit was used to reduce the ripple voltage of the DC bus. The equations of the APF capacitor＇s voltage and current when the ripple power is compensated completely was rigorously derived. An effective control strategy based on the dual-loop deadbeat plus repetitive control for high voltage and power converter application with low switching frequency was proposed. The deadbeat loop increases the system damp and the repetitive control improves the stable accuracy. This topology with the proposed control strategy can dramatically reduce the voltage pulsation on the DC bus and improve the power density of the system.