Rotational Energy Harvesting Based on an Integrated Magnetic and Piezoelectric Pair

The population of the world increased significantly over the past few decades, and every person is looking for enough power to supply the needs. As a result, the demand for energy keeps growing. With the high consumptions of fossil fuel resources and the growing problems of climate change, alternative solutions to clean energy sources need to be found. Energy harvesting based on piezoelectric and other technologies has been studied widely for a variety of applications, ranging from harvesting energy from a sneaker of a runner to vibration of a large infrastructure, such as a bridge. This work presents a novel energy harvester designed based on a magnetic and piezoelectric material attached to noncontact rings to avoid frictional power loss. The harvester is developed for applications that have a rotational mechanism to enhance the recovery from ambient sources such as wind, ocean, and vibration energy and convert it to electrical energy. In terms of energy conversion, piezoelectric density is three times higher than the electromagnetic transducer. We hypothesize that the harvester tackles the current limitation of the low energy density of the electromagnetic and decreased energy efficiency. The energy conversion component consists of two concentric rings. A series of rectangular magnetic plates are uniformly distributed on the inner surface of the outer ring, which is the stator ring. The double layer of piezoelectric patches is attached between the outer ring and the magnetic plates. The outer surface of the rotator ring also has magnetic plates to cause a repelling force due to periodic magnetic forces that compress the piezoelectric material to generate an extractable charge. The experimental and mathematical models will be presented to describe the harvesting mechanism. The parameters that influence the energy output will be addressed, for instance, residual flux density and the spacing between the rings. The simulation studies conducted show that the power harvested is upwards of 5 kilowatts. Results are based on a representative design that has 0.5 m diameter ring harvester, 0.01 m thick of piezoelectric material, 0.2 m long and 0.02m wide magnetic plate, and 0.0001 m the spacing between the rings. Our results illustrate that doubling the number of piezoelectric plates radially results in extracting 16 times the power as compared to a design with a single plate.  Results from a scaled-down prototype will be presented that investigates the parameters that affect the power conversion under real environmental conditions. Neodymium Magnets N52 is used as a permanent magnetic material, while a rectangular PZT Piezoelectric ceramic material is used in the experimental design for energy harvesting. The piezoelectric harvester has flexibility with respect to its design, which can be scaled up to be used for ocean and wind energy or scaled down to be used on a car suspension system to convert the vibration energy to electrical energy.