Design Of High Gain DC/DC Converter With Low Voltage High Current Input For Energy Feedback Electronic Load

Traditionally, resistances are used as the load of power supplies in burn-in tests before being sold, however, resistances have many drawbacks such as huge volume, discontinuous value, waste energy. Energy feedback electronic load sends energy from the tested power supplies to grid, so it can realize energy recycle, and the losts of burn-in tests are reduced. Energy feedback electronic load is better than resistance in many ways, so it is applied widely in recent.This converter, used as the first stage of energy feedback electronic load system, must meets the requirements of input voltage1V, full-load input current200A, output voltage48V and input current ripple lower than3%of full-load input current. The requirements of low input voltage, high input current and high gain can not be met for common DC-DC converter, so an active clamping current-fed push-pull converter with input parallel and output series is applied in this paper, which satisfies the all requirements and keep high efficiency, maximum efficiency is up to86.74%, efficiency with full load reaches67.72%.The operating principle of the active clamping current-fed push-pull converter is studied in this paper when duty is bigger than0.5and less than0.5, then detailed design guidelines of all devices are presented. The influence of current sharing performance of the converter due to the differences on inductance, conduction resistance and duty is analyzed, then the conclusion that the converter has the ability of auto current sharing is obtained, and it is verified by simulation. The control strategy on input current sharing of the PISO active clamping current-fed push-pull converter is presented, input current loop control is adopted to fulfill the equal both input current and reference, the design of control parameters is presented on the base of the small signal model.According to the requirements of the converter’s operation, sampling circuit and protecting circuit are designed, which include input over-current protection, input low-voltage protection, input over-voltage protection and output over-voltage protection, these protection can ensure the converter operates normally and it is shut down immediately when an abnormal happens. What’s more, to obtain better performance, the loss of the converter is analyzed. Finally, a200W prototype is built, experiments are carried out on single stage and three stages cascaded. The experiments results show that the proposed converter is suitable for energy feedback electronic load system, at the same time, it can keep high efficiency and stable in cascaded system.