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This paper presents a battery float charge technique based on a parallel-loaded resonant converter. The main purpose of the float charge is to ensure that the battery remains fully charged indefinitely. With a simple circuit configuration and few components, low switching loss and high efficiency are achieved. The proposed parallel-loaded resonant converter is operated in discontinuous current mode to achieve high efficiency at a fixed switching frequency. With carefully designed circuit parameters, the power switches can support zero voltage switching and zero current switching. The operating principles and equivalent circuit are analyzed in detail. Experimental results are obtained using a 12-V 150-Ah rechargeable battery to confirm the feasibility of the proposed scheme. The maximum charging efficiency of the proposed topology during the overall float charge period is 97.6%. The measurements yield satisfactory performance. [ABSTRACT FROM PUBLISHER]

This paper presents a novel application of half-bridge series–parallel resonant converter (HBSPRC) for dc source and secondary battery interface. The converter practically eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger circuit. Moreover, operation above resonance is preferred, because the power switches turn on at zero current and zero voltage; thus, the freewheeling diodes do not need to have very fast reverse-recovery characteristics. The proposed battery charger circuit has few components and low-energy conversion loss, which enhance the system's overall efficiency. Circuit operation modes are determined from the conduction profiles. Operating equations and an operating theory are also developed. Experimental results based on a 12-V 48-Ah battery charger are proposed to validate the analysis and to demonstrate the performance of the proposed approach. The maximum charging efficiency of the proposed topology during the overall charging period is 93.98%. Satisfactory performance is obtained from the measured results. [ABSTRACT FROM AUTHOR]