The control performance of the APF is affected by neutral point potential drift of the DC bus when the APF runs in the fault-tolerant mode; thus, in this paper, a compensation method of neutral point voltage difference feed-forward control is proposed. After detecting fault in the APF via the current vector trajectory slope method and switching the APF to the fault-tolerant state, the method regards the difference between the two split capacitor voltages of the DC bus as the feed-forward value, then combines it with the feed-forward coefficient that originates from the mathematical modeling of the fault-tolerant APF, and the resulting value is added to the fundamental active component of the current reference value to suppress the potential drift. The feasibility of this method is verified via both simulation and experimentation. The results demonstrate that the fault-tolerant APF can effectively compensate the harmonics of the power grid; the THD was found to be reduced from 27.24% to less than 5%, which satisfies the national standard under fault-tolerant circumstances, and the results conform to the theoretical analysis. This illustrates that the proposed method can guarantee the stable operation of the APF during fault-tolerant operation, and that the APF can effectively compensate harmonics with high reliability.

APF在容错模式下运行时，其控制性能受直流母线中性点电位漂移的影响；因此，本文提出了一种中性点电压差前馈控制的补偿方法。该方法通过电流矢量轨迹斜率法检测出APF故障，将APF切换到容错状态后，将直流母线的两个分裂电容电压之差作为前馈值，然后将其与源自容错 APF 数学建模的前馈系数，并将所得值添加到当前参考值的基波有源分量以抑制潜在漂移。通过仿真和实验验证了该方法的可行性。结果表明，容错型APF能够有效补偿电网谐波；发现THD从27.24%降低到5%以下，在容错情况下满足国家标准，结果符合理论分析。这说明提出的方法能够保证APF在容错运行时的稳定运行，并且APF能够有效补偿谐波，可靠性高。