High-efficiency stepdown/step-up converter for series-connected energy storage system

This work introduces a novel stepdown/step-up converter designed to optimize the run time of series-connected Battery, whose voltage drops progressively with increased usage, eventually falling below the necessary operating levels. The proposed converter automatically transitions between stepdown, step-up, and stepdown/step-up modes based on a comparison of input and output voltages, with the stepdown/step-up mode restricted to the narrowest range to minimize its lower efficiency in power conversion. It supports an input voltage range from 2.5 to 8 V and incorporates a capacitive coupling level shift circuit to maintain the gate-source voltage of the power transistor under 5 V, protecting against gate oxide layer damage. Fabricated with 180 nm BCD technology, the converter's compact size is 1.44 mm by 0.73 mm. Testing reveals that this converter achieves up to 93% power conversion efficiency, an 11% improvement over conventional models, and supports an output current up to 500 mA, a 67% increase, enhancing the performance and longevity of Battery in compact electronic devices.