A piezoelectric impact-induced vibration cantilever energy harvester from speed bump with a low-power power management circuit

An energy harvesting system for road speed bumps was proposed, which consists of a piezoelectric impact-induced vibration cantilever energy harvester and a low-power power management circuit. The piezoelectric impact-induced vibration cantilever was used to harvest the energy from speed bump as it is suitable for converting the low-frequency mechanical impact to high-frequency vibrations. Furthermore, considering the characteristics of piezoelectric energy harvester for speed bumps, a high-efficiency and low-power power management circuit was designed to collect the electric energy from the harvester. A buck-boost DC-DC switching converter is used to match the impedance of PZT and so as to obtain the maximum energy from the harvester, and a wake-up circuit is designed to reduce the power dissipation of the power management circuit itself. A prototype of the piezoelectric impact-induced vibration cantilever energy harvesting system was constructed and the experiment results showed that, the controller in the power management circuit consumed only 3% of the ideal energy generated by one tire in the awake mode and less than 1% of it in the sleep mode. The efficiency of the circuit was around 74% at various vehicle speeds. In addition, the total ideal energy generated by one piezoelectric cantilever from one car passing the speed bump was 1.26 mJ. This energy was exhausted by the power management circuit without sleep mode within 25 s, whereas with sleep mode, the energy of 0.82 μJ was delivered to the battery. Therefore, the sleep mode function in the circuit is essential to reduce the energy loss and improve the efficiency of the speed bump energy harvester.