A single-inductor triple-input-triple-output (SITITO) energy harvesting interface with cycle-by-cycle source tracking and adaptive peak-inductor-current control

In this paper, a single-inductor triple-input-triple-output (SITITO) buck-boost converter with cycle-by-cycle source tracking (CCST) is developed for multi-source energy harvesting. The proposed CCST is capable of harvesting power from the PV and TEG simultaneously, and automatically selects the appropriate source according to the maximum power point (MPP) of the transducers in each switching cycle. The converter provides two regulated outputs for the analog (Vout1 = 1.2 V) and the digital (Vout2 = 0.4-0.6 V) circuits, while storing the excess energy in a storage capacitor (Cout3). An adaptive on-time (AOT) circuit with an adaptive peak-inductor-current (APIC) control is developed for dynamically adjusting the on-time based on the input voltage (VIN) to obtain high conversion efficiency under different VIN. The proposed converter achieves a peak efficiency of 84.4% with an available input voltage of 0.05 V to 0.8 V. Compared to the conventional constant peak-inductor-current (CPIC) control, the proposed APIC improves 11 % efficiency at low Vin.