Modified electromagnetic microgenerator design for improved performance of low-voltage energy-harvesting systems

The recent work in literature has shown the potential of energy harvesting as means to power wireless sensors. An energy harvester typically consists of a transducer and low-power management circuits. However, current systems suffer from crude design methodology with no synergy between these two stages. In this work, the authors present two design modules of a modified electromagnetic microgenerator system, which aid in the performance of the associated power converter. Startup is a critical issue for such systems, since the transducer voltage is quite low (a few hundred millivolts AC). For the first design module, a thin piezoelectric strip is added to the electromagnetic microgenerator to provide the start-up power for the converter system. The second module unifies the design of the input filter for the converter with the microgenerator. The microgenerator parasitics are utilised to satisfy the input filter requirements of the converter. Such an approach reduces the overall inductive losses in the system compared with other set-ups reported in the literature. Both the microgenerator and the input filter are fabricated along with a suitable AC-DC boost converter using discrete components. Both simulation and experimental results are shown to demonstrate the start-up capability of such a system and efficacy of the input filter design.