A high voltage triboelectric energy harvesting system utilizing parallel-SSHI rectifier and DC-DC converters for sub-5 Hz motions

In this thesis, the first integrated circuit (IC) implementation of parallel synchronized switching harvesting on inductor (parallel-SSHI) is presented for triboelectric energy harvester targeting 1 Hz to 5 Hz mechanical motions. It is accompanied by on-chip buck and switched-capacitor DC-DC converters, all capable of handling 70 V levels. Unlike piezoelectric harvesters, triboelectric nanogenerators (TENGs) can produce very high open-circuit voltages; thus, the proposed system utilizes this property within the technology limits to maximize the extracted power. An in-house manufactured TENG using steel and polytetrafluoroethylene (PTFE) is modeled for sub-5 Hz motions. The energy is extracted and stored in an external capacitance until its voltage reaches 70 V, which is achieved in three press-and-release mechanical cycles. 70-to-2 V down conversion is carried on by a 70-to-10 V buck converter followed by a 10-to-2 V switched-capacitor DC-DC converter. A chip is manufactured in TSMC 0.18 um HV BCD process with an active area of 6.25 mm2. End-to-end peak efficiency is measured as 32.71% for 1 Hz motion with a 722 uW total power delivery to the load for 4 ms.