Analysis And Design Of Cascaded DC Distributed Power Systems

The interaction between subsystems of DC distributed power systems, might cause both dynamic and static behaviors of a single converter, or even the whole system degradated or even instable. And the interaction is a key technology of power elctronics system integration. This paper studies two-stage Cascaded DC Distributed Power Systems.Based on a two-stage Cascaded DC converter, this paper analyzes and compares the Middlebrook's criterion and the improved impedance specification for the source converter, and the factor that affects the input impedance and the out impedance of converter is also studied. When the improved impedance specification is satisfied, the source converter has the same stability and dynamic performance. Theoretical analysis is verified by the simulational and experimental results.Based on a two-stage single phase aeronautical static inverter, the operating principle of push-pull forward DC-DC converter with a novel lossless snubber circuit is analyzed. Three DC-DC prototype converters of 27V input, 360V/500W, 360V/1000W, 360V/1500W output are built, and the efficiency of DC-DC prototype converters is high. Based on the two-stage inverter system, interaction between DC-DC converter and inverter are explored. DC-DC converter output voltage contains plentiful low-frequency ripple caused by the nonlinear inverter load. In reverse, the ripple causes bad step load response: inverter output voltage is distorted and dynamic performance is degraded. Two kinds of inductor current operate mode of DC-DC converter with the inverter load are proposed. The quick trace mode and the slow trace mode is compared and verfied by the experimental results.