UPS逆变器谐波抑制环的分析与设计

在非线性负载电流峰值系数较大时,不间断电源UPS(uninterruptible power supply)逆变器的输出电压的总谐波失真度THD(total harmonic distortion)难以达到标准要求。基于dq0同步旋转坐标系的谐波抑制方法可消除指定次谐波,从而改善输出电压的THD。介绍了该谐波抑制方法应用于三相四线制UPS逆变器的控制环路结构,并推导了谐波抑制环在dq0同步旋转坐标系下的控制方程,从而得到了环路被控系统的动态模型。在此基础上,改进了谐波抑制环的环路结构以实现dq轴在低频段的解耦,并设计了环路控制参数。最后,在三相四线制T型三电平逆变器平台上通过实验验证了谐波抑制环设计的有效性。

Analysis and Design of Harmonic Suppression Loop in UPS Inverter

Under non-linear load with large crest factor current, the total harmonic distortion(THD) of uninterrupti-ble power supply(UPS) inverter output voltage is difficult to meet the regulation requirement. The harmonic suppression method based on dq0 synchronous rotating frame can eliminate the harmonics of specified order, thereby improving the THD of the UPS output voltage. In this paper, the structure of harmonic suppression loop was introduced, with which the harmonic suppression method was applied to a three-phase four-wire UPS inverter; the control equation for the harmonic suppression loop in dq0 synchronous rotating frame was deduced, thus the loop''s dynamic model was obtained. On this basis, the structure of the harmonic suppression loop was improved to realize dq axes decoupling at low frequency, and the loop control parameters were also designed. Finally, the validity of the design of harmonic suppression loop was experimentally verified on a three-phase four-wire T-type three-level inverter platform.