Abstract The multiple parallel-connected inverter technique can improve the power capacity of the motor-drive system effectively. However, the above technology causes some problems, such as the circulating current, the unbalanced current, and so on. To solve these problems, the mathematic model of multiple parallel-connected inverters is constructed, the concept of the unbalanced current degree is presented, and the expression of the circulating current and the unbalanced current degree are also given. Moreover, the reason for the circulating current and the unbalanced current is analyzed. It can be seen that the circulating current is caused by the different output voltages of the parallel inverters. Based on the above analysis, the master-slave controller hardware circuit block is proposed to suppress the circulating current and the unbalanced current. The question is solved by the pulse delay compensation method. The experimental results verify the correction of the proposed method.
Zhang Jianwen,Wang Peng,Wang Han等. Average-Current Control Strategy of Multiple Parallel Inverters[J]. Transactions of China Electrotechnical Society, 2015, 30(18): 61-68.
[1] Boldea M I, Tutelea L, Serban I. Variable speed electric generators and their control: an emerging technology[J]. Journal of Electrical Engineering, 2002, l(3): 20-28. [2] 余蜜, 康勇, 张宇, 等. 基于环流阻抗的逆变器并联控制策略[J]. 中国电机工程学报, 2008, 28(18): 42-46. Yu Mi, Kang Yong, Zhang Yu, et al. Research on a novel current-sharing scheme based on circulating impedance of multi-inverter parallel system[J]. Proceedings of the CSEE, 2008, 28(18): 42-46. [3] 于玮, 徐德鸿. 基于虚拟阻抗的不间断电源并联系统均流控制[J]. 中国电机工程学报, 2009, 29(24): 32-39. Yu Wei, Xu Dehong. Control scheme of parallel UPS system based on output virtual resistance[J]. Proceedings of the CSEE, 2009, 29(24): 32-39. [4] Ye Zhihong, Boroyevich D, Choi Jae-Young, et al. ntrol of circulating current in two parallel three-phase boost rectifiers[J]. IEEE Transactions on Power Electronics, 2002, 17(5): 609-615. [5] 张宇, 段善旭, 康勇, 等. 三相逆变器并联系统中零序环流的研究[J]. 中国电机工程学报, 2006, 26(13): 62-67. Zhang Yu, Duan Shanxu, Kang Yong, et al. The research of zero-sequence circulating currents between parallel three-phase inverters[J]. Proceedings of the CSEE, 2006, 26(13): 62-67. [6] 于玮, 徐德鸿, 周朝阳. 并联UPS 系统均流控制[J]. 中国电机工程学报, 2008, 28(21): 63-67. Yu Wei, Xu Dehong, Zhou Chaoyang. Control strategy of paralleled UPS system[J]. Proceedings of the CSEE, 2008, 28(21): 63-67. [7] Kun Xing, Lee F C. Interleaved PWM with discontinuous space-vector modulation[J]. IEEE Transactions on Energy Conversion, 1999, 14(5): 906-917. [8] 李建林, 高志刚, 胡书举, 等. 并联背靠背PWM 变流器在直驱型风力发电系统的应用[J]. 电力系统自动化, 2008, 32(5): 59-62. Li Jianlin, Gao Zhigang, Hu Shuju, et al. Application of parallel back-to-back PWM converter on the direct-drive wind power system[J]. Automation of Electric Power Systems, 2008, 32(5): 59-62. [9] Yoshihiro K. Cross current control for parallel operating three phase inverter[C]. IEEE Power Elec- tronics Specialists Conference, Taipei, China, 1994: 943-950.
2015, Vol. 30 
