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Bridgeless active rectifier for piezoelectric energy harvesting

The low power energy harvesters need efficient single-stage direct ac–dc conversion evading diode bridge rectifier. An active rectifier circuit is proposed for piezoelectric energy harvester working on the principle of the buck–boost converter. The active rectifier circuit provides dual output with a reduced number of components. The analysis of the active rectifier is carried out, and expression for the optimum duty cycle is derived for maximum power extraction. The active rectifier configuration is extended for connecting multiple piezoelectric energy harvesters, and maximum power extraction is achieved through time multiplexed switching of energy harvesters. Proposed active rectifier topology is validated through simulation and experimentation. The results demonstrate that the harvested power is improved by the factor of 1.4 and 3.2 for single input and multiple input configurations, respectively, as compared to the power harvested using dual output rectifier. The charging time of the supercapacitor is reduced by 17 min while charging through the single input configuration and 15 min while charging through the multiple input configuration of the proposed active rectifier circuit.