Adaptive Self-Configurable Rectifier for Extended Operating Range of Piezoelectric Energy Harvesting

This paper presents an adaptive self-configurable rectifier to increase the range of vibration excitation that a piezoelectric energy harvesting power management circuit (PMC) can operate with. The proposed circuit configures itself as a voltage doubler (VD) to increase the low voltage of piezoelectric energy harvesters to meet the minimum operating voltage of the PMC. This allows energy harvesting from low voltage range that is not viable using a full-wave bridge (FB) rectifier. When the piezoelectric voltage increases and causes the voltage amplified by the VD to approach the maximum operating voltage of the PMC, the proposed circuit reconfigures itself to an FB rectifier that does not amplify the voltage. This allows operation at a higher voltage range that is restricted by the VD topology. Two different reference voltages each for the VD topology and the FB rectifier topology with low-pass filtering are used to ensure correct switching of the rectifier topology. The proposed control circuit can cold start from a piezoelectric voltage of 1.2 V in the VD topology to amplify the voltage to allow an existing PMC that needs a minimum input voltage higher than 1.2 V to operate while consuming 240–410 nW of power. With the two-reference-voltages control method, 20% more energy can be transferred through the PMC than the one without it.