A multilevel converter charger utilizing superimposed pulse frequency method for prolonging lead-acid battery lifetime

A multilevel converter charger using superimposed pulse frequency technique for prolonging lead-acid battery lifetime is developed in this paper. The proposed state of charge is divided to three states: superimposed pulse frequency charge (SPF), Constant current charge (CC) and Constant voltage charge (CV). SPF is charging state for rejuvenating a deteriorated battery due to sulfation at the plates. In this state, the pulse frequency of voltage output will vary from 10 kHz to 20 kHz to scan for mechanical resonance. A dc to dc multilevel converter is applied to generate the superimposed pulse frequency. The mechanical resonance at the plates and the sulfation reasons are also studied. The simulation and experiment are also validated the proposed charging technique. The simulation and experimental results suggest that the proposed multilevel converter charger can rejuvenate the voltage terminal of the battery even though the voltage terminal falling under 10% of SOC which is normally considering as a worn-out battery. Also, the charging efficiency would improve by using proposed charging technique with a combination of three states of charge.