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Description

Electromagnetic energy harvesting-powered wireless sensors must operate with ultra-low power, remain functional under low vibrations, and autonomously restart after long energy interruptions. However, most systems are inefficient, need dedicated start-up and complex gate drivers, often need up to 5 V supply, and rarely report restart time after unpowered phases. This thesis proposes two self-powered AC/DC boost converters that start from zero voltage under ultra-low excitation without dedicated start-up circuits. A passive multi-stage voltage multiplier (VM) is integrated in the rectification stage to fast reach the 1.6 V threshold, while the harvester inductance is used as the boost element. The converters operate in start-up and boost modes using two validated topologies: bidirectional and parallel. Both use a three-stage VM; the bidirectional blocks reverse conduction, while the parallel reduces conduction losses. Boost-mode experiments show efficiency and charging speed strongly depend on switching frequency and duty cycle, with optimal performance at 32 kHz. At 0.22g and 29Hz with a 47mF supercapacitor, the bidirectional converter performs best at 78% duty cycle and the parallel at 68.4%. Both start autonomously from 0.65V and reach 1.6V within 20s. In boost mode, the bidirectional topology delivers 4.16V, 1.2mW, 72% efficiency, while the parallel topology reaches 5V, 1.84mW, and 79.2% efficiency, enabling reliable restart and long-term autonomous wireless sensing.