中文摘要：

为有效减小逆变器并联系统中直流环流的危害，通过对直流环流进行分析，提出了一干呻噬十改进重复控制的直流环流瞬时抑制策略。该策略将重复控制的补偿周期设为载波周期，以解决传统重复控制动态响应特性差的问题。逆变器输出电压直流分量具有波动性，因此以载波周期为单位对其进行计算，并将计算结果作为反馈与比例积分（PI）控制一起调整正弦脉冲宽度调制（SPWM）占空比，以实现对逆变器并联系统直流环流的瞬时抑制。模拟并联系统半波负载突变实验表明，在加载半波负载前后，逆变器输出电压直流分量可以分别被抑制到0．02％～0．03％和0．04％-0．05％，补偿延时可控制在40ms以内。实验结果表明，提出的策略能够有效提高逆变器输出电压直流分量的补偿精度和并联系统直流环流抑制的动态响应特性。

英文摘要：

In order to decrease the impair brought by DC circulating current in parallel inverter systems, we analyzed the DC circulating current and proposed an instantaneous restraining strategy based on improved repetitive control. The strategy sets compensation cycle as the carrier cycle to improve system＇s dynamic response, which is poor in conventional repetitive controls. The DC component is calculated by every carrier cycle since it is featured with volatility, and the cal- culated results are used as a feedback to adjust the duty cycle of SPWM （sinusoidal pulse width modulation） together with PI （proportional integral） control. This eventually helps to achieve the instantaneous restraint of DC circulating current in parallel inverter systems. The experiments of simulating half-wave sudden load-change in a parallel system indicate that, before and after applying the half-wave load, the DC components are restrained within 0.02%-0.03% and 0.04%-0.05%, respectively, while compensation delay is within 40 ms. The experiments prove that using the proposed strategy can greatly increase the accuracy of compensating DC component and improve the dynamic response of restraining DC cir- culating currents.