Multimodal piezoelectric device for energy harvesting from engine vibration

Abstract

In a conventional transport vehicle, only about 10% to 16% of the energy from the fuel is used to move it down the road. The rest of the energy is lost in the brakes, transmission, engine, accessories, rolling resistance, aerodynamic drag, and idle losses. Among all of these, the largest loss is the energy lost in the engine (approximately 63%), which is mostly wasted as vibration. Our work develops an energy harvesting device that is capable of collecting energy for different gear ratios in a car. For this reason, the structural design is oriented to create a harvesting structure with several resonant modes in a frequency bandwidth between 1600 rpm-4600 rpm, which was the range obtained through driving tests in a conventional diesel car. The harvesting device is based on a piezoelectric fiber composite beam with a high fatigue resistance placed in the middle of two mass-spring systems, which provide the multimodal character of the device. A one-dimensional analytical model based on a Lagrangian formulation is used to predict the dynamical behavior of the device. The equations provide a very good quantitative description of the system, which is also modeled with a three-dimensional finite element code (Abaqus) for numerical validation. Experimental tests are then carried out and compared with theoretical findings. The results show a very good agreement between both of them, revealing the multimodal nature of the device in the operating bandwidth, with a significant output power for different engine speeds, sufficient to feed low-power monitoring wireless systems.