Research Of Recharger For HXD₂ Locomotive

Recharger is an important component unit in the auxiliary system of the locomotive HXD2. Besides the storage battery charging, it works as a stable 110V auxiliary power supply which provides electric energy to the control system and signal produced circuit. During the actual operation of HXD2 locomotive, many problems appeared on the recharger. This will be a great test for the maintenance beyond the warranty period. In order to solve the hidden trouble, it is the most effective method that realizes localization based on grasping the key technology of recharger. It will have important significance that developing a recharger with reasonable structure, stable working and good performance of output for good operation of HXD2 electric locomotive and improvement of Recharger technology in the future.This paper designs the main circuit of the recharger, control methods under different charging ways, and does experimental analysis for different control modes. In consideration of safety performance, power rating and applications of the recharger, the isolated half-bridge converter circuit is adopted in the main circuit topology. Meanwhile, the power transistor IGBT is carefully selected and isolated transformer is designed and studied. Moreover, the output filter inductor and capacitance are also designed.In this paper, the principles of the constant voltage charging, constant current-constant voltage charging,variable current intermittent charging, variable voltage intermittent charging, etc are analyzed. Considering the operation environment and stability problem of the recharger in the locomotive, too complex controlling methods for charging are not suitable. Therefore, this paper mainly aims at the controlling method design of usual constant voltage charging and constant current-constant voltage charging. Based on the fixed frequency PWM controller SG3525, the controlling circuit for constant voltage charging is designed. By adjusting under voltage regulation loop, it achieves the function of providing stable 110V DC output. As the battery is charging, the internal resistance is increasing. Before constant voltage charging, as the charging electric current is larger, the battery will have an overheating problem.Considering the charging quality, energy saving and battery longevity, the constant current-constant voltage control method is researched and the constant current-constant voltage automatic conversion circuit is designed in this paper. By adjusting under voltage and current regulation loop, the function of the auto switch from constant current mode to the constant voltage mode is realized.Further more, the heat loss of the power transistor in the recharger is also analyzed in this paper. With the heat sink modeling and its analysis in icepak, the structure of heat sink is optimized.Finally, a recharger machine is designed and built. By doing the experiments, the function of the recharger, including 110V stable DC output within the maximum fluctuate under the constant voltage control and the auto switch from constant current mode to constant voltage mode are achieved. The results of experiments demonstrate the validity of design including the main circuit and the control circuit.