| Presently, the storage battery chargers, used by UPS products, make use of phase control mode power supply all the same. The demerits of traditional phase control mode power supply are large bulk, heavy weight, slow response, high EMI etc. Although some battery chargers adopt hard-switching techniques, so much loss generates in switching course that large cooler and fan should be designed to fit for switching. It's impossible to satisfy the requirement of high efficiency (more than 90%) by using hard-switching technique.In this thesis, phase shifted full bridge ZVS topology is proposed to use in middle and high power chargers of storage battery to replace traditional charger. On the basis of this topology, a 5kW storage battery charger is made, which is controlled by UC3875 and working at 80 kHz. It realizes ZVS, diminishes switching loss and really improves the charging condition.The background and meaning of this task is demonstrated firstly, and then the evolution of switching power supply and soft switching techniques is analyzed in this paper. Based on this, the former 6 operating courses of this topology are detailed. In addition, the theories of controlling circuits, the protecting circuits and the auxiliary power supply circuits are analyzed. The design and calculation of main components'parameters are also offered.There is also an introduction of the simulation software——Saber, and a method of auxiliary design for switching power supply is proposed in this article. A phase shifted full bridge ZVS topology model is built simulation environment. The simulation plots which are got in loaded condition illustrate the feasibility and superiority about the use of this technique in high power field. Finally, the experimental results of the sample are given about the unloaded characteristic. |
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