A design of a digital frequency-locked battery charger for Li-ion batteries

In this paper, a digital frequency-locked battery charger (DFLBC) for Li-ion battery is proposed. The circuit topology of the proposed DFLBC is same as that of the phase/frequency-locked loop, which means that the proposed DFLBC has lots of inherently abilities as those of phase/frequency-locked loops, such as auto-tracking, auto-locking, and high accuracy. Using the above-mentioned abilities, a complete charging process, consisting of three sub-processes: bulk current charge process, variable current charge process and float charge process can be inherently implemented. In the proposed DFLBC, the charge trajectory can be digitally programmed according to the behaviors of the Li-ion battery to achieve a better charge performance. Experimental results show that the charge speed of the proposed DFLBC compared with that of a typical frequency-locked battery charger (FLBC) is improved about 16%.