As A Lithium Battery Charger, Switching Power Supply Design And Development,

Switching mode power supply(SMPS)is an important part of the power electronics. More and more countries attach importance to it because of its smaller volume, lighter weight and high efficiency. Recently, the increasing portable equipments bring advantage to the people's life with the developmet trend to miniaturization and integration of the electro-equipments. These equipments require the powerful batteries. And the chargers of these batteris are also important. The SMPS become the appropriate structure of the chargers of the Li-ion battery beacause of its characteristics.A charger of the Li-ion battery using SMPS was designed and manufactured in this dissertation. Two Li-ion batteries can be charged up at the same time. The charger also can be switched to DC mode as a DC power supply. Its efficiency was 20% higher than the similar product on the market. And its cost was much reduced.The following contents were discussed in this dissertation.1,The theory of the power factor correcter(PFC)was studied, and the working theory of a kind of PFC was discussed. Then a method of designing PFC was introduced, and a PFC was designed with this method.2,The theory of the LLC half-brige resonance converter was investigated, and consequently a design method was introduced. A proto type was manufactured with this method finally.3,The theory of fly-back converter was discussed. Afterwards, a kind method of design fly-back converter was introduced. With this method, several fly-back converters were designed and manufactured. At last, a charger of the Li-ion battery was designed and manufactured using fly-back converter as the basic circuit.4,A feedback circuit which had the function of constant-current and limit-voltage, as a Li-ion battery can be charged up, was designed and manufactured. Its output voltage is 10~16.8Vdc, output current 0~1.8A at the charging mode; and output is 15.5Vdc and 5A at the DC mode. Two Li-ion batteries can be charged up at the same time, and the ripple factor was less than 0.5%. Finally, an examination that a Li-ion battery could be charged up with the proposal charger was done.