Dae-Taek Chung’s research while affiliated with Dankook University and other places

This paper proposes a new secondary battery charger/discharger available for zero voltage discharge which is used for test equipments and formation process. The proposed system is a switching type converter, and thus the system is high efficiency and more compact as compared with linear type charger/discharger. Conventional switching type charger/discharger can not discharge secondary batteries to zero voltage because of voltage drops in the switching elements and long distributing line(typically 10m). However, the proposed system is able to discharge the battery to zero voltage in constant current mode regardless of the voltage drops. In this paper, we analyze the proposed charger/discharger and the validity of the system is verified by simulation and experiment.

This paper proposes a switching type secondary battery discharge system capable of zero-voltage discharge. The proposed system can discharge until the voltage of a battery reaches 0[V] even in the domain with low battery voltage, while maintaining the discharge current uniformly at a set point. In order to confirm usefulness of the proposed system, this paper performed its simulation and verified its results through an experiment.

Lithium battery is widely used as the power source of various electronic devices. The formation process which is the repeated charging and discharging process is essential in the production of lithium battery. In this paper, it is proposed and designed the DC-DC converter that can charge and also discharge the lithium battery in one converter. The proposed converter is designed by considering the charge/discharge characteristics of the lithium battery. The converter is operated as a forward converter in charging process and a electrically isolated boost converter in discharging process. Based on the analyses, the number of transformer turns, inductor, capacitor, and switching devices are designed. Finally, the validity of the design for the proposed converter is verified by both simulations and experiments.

Isolated boost converter is desirable in the dc/dc converter applications where isolation is required and extremely high step up is needed. Transformer used to step up low input voltage into high output voltage must satisfy the volt-sec balance condition. Conventional isolated boost converter is controlled with conducting intervals overlapping. In this case, there is a problem that control circuit is complicated. In this paper, it is proposed and analyzed the isolated boost converter which set up a reset winding for the volt-sec balance of transformer and can construct the control circuit simple by using a self-driven switch. Finally, the validity of the theoretical analyses for the proposed converter is verified by both simulations and experiments on the 10[W] class isolated boost converter.

The formation process is presently used in the manufacture of secondary batteries such as a lithium battery. Therefore, charging and discharging processes for lithium battery are essential for the formation process. In case that the nominal capacity is 2,600 mAh and lithium battery is charged/discharged at 0.5 C, the lithium battery charge/discharge system takes very long time over two hours for charging and discharging processes, respectively. Also, to simulate such a system in a conventional way takes very long time and huge files are produced. Eventually, the simulation would be unable with general PC class. In this paper, the lithium battery charge/discharge system is analyzed by using state space averaging method and its validity is verified by both simulations and experiments. As a result, the simulation time is dramatically reduced and the charge/discharge characteristics of the lithium battery can be observed.

This paper proposes a new sustaining driver for AC PDPs (plasma display panels) with reduced sustain voltage by half, which improves the performance of conventional circuits such as TERES(technology of reciprocal sustainer). In the TERES circuit, the sustain voltage is the half of general sustaining driver, however, there is no energy recovery circuit. In the proposed circuit, energy recovery circuit is added and zero voltage switching or zero current switching is performed in switching devices. Although the energy recovery circuit is added, the number of active switching elements is the same as that of the TERES circuit. The operations of the proposed circuit are analyzed for each mode and its validity is verified by the simulations and experimentation