| Summary: | 碩士 === 崑山科技大學 === 電機工程研究所 === 96 === This thesis presents an efficient, small-sized, and cost-effective switched-mode converter for battery chargers. The lead-acid batteries are widely used in various applications such as automotive power system, uninterruptible power system (UPS), telecom power supply, and so on. However, poor battery energy density, charging characteristics, and lifetime encumber commercial applications. The main aim of this thesis is to improve the charge efficiency, provide well regulated output characteristics, and prolong the battery lifetime. Accordingly, a battery charger with half-bridge parallel-loaded resonant converter (HBPLRC) is proposed in this thesis.
In the proposed resonant converter, an L-C resonant tank is used that results in oscillating output voltage and charging current and thus provides zero-voltage and/or zero-current switching. Three possible operating modes of the HBPLRC charger circuit with the advantages of simple structure, light weight, low switching losses, low cost and high efficiency for lead-acid batteries. The control method of varying the switching frequency of the power switches is utilized for the three operating possible modes. With carefully designed circuit parameters, the power switches can exhibit low switching power losses. As a result, high charging efficiency can be achieved.
The operating principles and equivalent circuit are analyzed and discussed in detail. Simulation and experimental results are conducted for a 12V-48Ah lead-acid battery to verify the feasibility of the proposed scheme.
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