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Input-series-output-parallel (ISOP) inverter system is very suitable for high input voltage and large output current power conversion applications. One of many merits of this assembly system lies in that its characteristic of multimodule series–parallel combination can significantly improve the reliability of the operation. To address this point, redundancy should be realized for the whole system. However, the existing methods for the ISOP inverter system all belong to centralized control, which restricts the modularity of the system. From the above perspective, this paper proposes a new scheme to achieve both power balance and distributed configuration according to the conception of compound control. Also, the relationship of control loops is analyzed and the design procedure of them is given. Based on the fully modular system actualized by the distributed control, the hot-swap technique is then raised to get a redundant system with superior reliability. Here, the way of bypassing other than cutting off is adopted to fulfill withdrawal of the faulty module from the system due to series connection at the input terminal. In addition, the detailed timing sequence of system operation is provided to ensure the smooth transition during the hot-plugging transient. Finally, a three-module prototype is built and the experimental results validate the effectiveness of the presented strategy. [ABSTRACT FROM AUTHOR]

In order to realize high reliability, parallel operation should be employed to realize the redundancy of the static inverter, uninterruptible power supply (UPS), and so on. There are several control strategies suitable for the parallel operation of inverters, such as frequency and voltage droop technique and master-slave method. The disadvantage of the former one is that it often results in poor output characteristic. The latter one can not virtually realize the redundancy because the slave module is dependant on the master module. A distributed control strategy suitable for the hot swap of inverters is employed with the load current feed-forward control to improve the output characteristic. The output characteristic and circulating current with and without the load current feed-forward control are compared and the implementation procedure of the hot swap is studied. Furthermore, the prototype of three-phase inverter is built to verify the analysis above. The hot swap experiment is carried out to realize the redundancy. [ABSTRACT FROM AUTHOR]