Dynamic current distribution controls of a parallel connected converter system

Based on the central-limit control algorithm for the parallel connected converter system, two improved dynamic current distribution control methods are introduced: the programmable current distribution control (PCDC) and the maximum current limit control (MCLC). In PCDC, the ratio of the output current of each converter to the total output current can be programmed according to the desired application objective while the output voltage remains regulated. In the MCLC, all converters in the system may not be turned on at the same time depending on the load conditions. The steady-state analyses and design consideration of the PCDC controlled converter system are presented. The steady-state current distribution error (CDE) between the output current of converters is used as a criterion to evaluate the system performance. The design consideration of choosing proper loop compensators, and scaling factors to reduce the CDE is also introduced. These two schemes can be combined to achieve better system performance, which increase the life-time, reliability, and efficiency of the overall converter system