Dual-Source Energy-Harvesting Interface With Cycle-by-Cycle Source Tracking and Adaptive Peak-Inductor-Current Control

In this paper, we present a single-inductor triple-input-triple-output (SITITO) buck-boost converter in a 0.18- \mu \text{m} CMOS process for dual-source energy harvesting. The converter operates in the single-source mode, dual-source mode (DSM), and backup mode automatically by detecting the input and output conditions. Converter operation in the proposed DSM enables extraction of power from both a photovoltaic cell and a thermoelectric generator in one switching cycle for efficient power extraction. The cycle-by-cycle source-tracking approach selects the appropriate input source according to the maximum power point of the energy transducers. The adaptive on-time circuit with the proposed adaptive peak-inductor-current (APIC) control adjusts the on-time of power transistors to obtain high conversion efficiency under different input voltages. The experimental results demonstrate that the proposed SITITO converter has a peak efficiency of 84.4%. When compared with the conventional constant peak-inductor-current control, an efficiency improvement of 11% is obtained via the proposed APIC control.