A Self Start-up Circuit in Low Voltage Power Conversions for Electromagnetic Energy Harvesting with optimized Power Distributions

A start-up system for AC-DC converter in low voltage electromagnetic energy harvesting (EMEH) is presented in this paper. Power conversion circuit is required in EMEH to regulator the low voltage AC to a stable DC output. Switchable AC-DC converter is efficient and well controllable, making it an optimal choice. However, the gate driver and control circuits in AC-DC converter needs to start up prior to main power stage. The output amplitude of EMEH is usually quite low to power these circuits directly through passive rectifier. Hence, a self-start-up circuit will be an optimal choice. Furthermore, in such a low power system, the power consumptions of low power control and logic circuits are comparable to actual output power. To have better utilizations of the harvested power, the power distributions of the whole power conversion is worth investigating. In this paper, an output regulated voltage multiplier based start-up circuit (SUC) is employed with comprehensive design considerations from output gain, charging time and efficiency. The AC-DC converter is firstly started through SUC. Once stable output is established, the output of AC-DC converter is employed to provide power to control circuits and the start-up circuit is cut off to reduce unnecessary energy consumption.