A High-Voltage Dual-Input Buck Converter Achieving 52.9% Maximum End-to-End Efficiency for Triboelectric Energy-Harvesting Applications

This article presents a high-voltage (HV) dual-input (DI) buck converter for triboelectric (TE) energy-harvesting applications with a maximum power point tracking (MPPT) for TE nanogenerators (TENGs). An important characteristic of TENGs is their ac output voltage with different positive and negative peak voltages; thus, the proposed system separately harvests each half-wave (HW) with a dual-output rectifier for better extraction efficiency. Furthermore, given the similarity between the electrical models of piezoelectric transducers and TENGs, a root-mean-square MPP analysis is proposed with a fractional open-circuit voltage (FOCV) method according to each HW from the TENGs. The HV DI buck converter regulates two HVs from the TENGs for MPPT with a single inductor. The proposed HV protector prevents the breakdown of the power transistor due to HV stress. To regulate the two input voltages of the buck converter at each MPP, a synchronous pulse-skipping modulation technique is implemented in the system. The entire system is fabricated in a 180-nm BCDMOS process with an active area of 2.482 mm². The maximum input voltage of the HV DI buck converter is 70 V, and the maximum end-to-end efficiency of 52.90% is achieved with human skin-based and polytetrafluoroethylene-based TENGs.