An efficient piezoelectric energy-harvesting interface circuit using a bias-flip rectifier and shared inductor

Energy harvesting is an emerging technology with applications to handheld, portable and implantable electronics. Harvesting ambient vibration energy through piezoelectric (PE) means is a popular energy harvesting technique that can potentially supply 10 to 100´s of muW of available power. One of the limitations of existing PE harvesters is in their interface circuitry. Commonly used full-bridge rectifiers and voltage doublers severely limit the electrical power extractable from a PE harvesting element. Further, the power consumed in the control circuits of these harvesters reduces the amount of usable electrical power. In this paper, a bias-flip rectifier that can improve upon the power extraction capability of existing full-bridge rectifiers by up to 4.2times is presented. An efficient control circuit with embedded DC-DC converters that can share their filter inductor with the bias-flip rectifier thereby reducing the volume and component count of the overall solution is demonstrated. The circuit diagram and figures are also given.